Publications by year
2023
Cornwall CE, Comeau S, Donner SD, Perry C, Dunne J, van Hooidonk R, Ryan JS, Logan CA (2023). Coral adaptive capacity insufficient to halt global transition of coral reefs into net erosion under climate change.
Global Change Biology,
29(11), 3010-3018.
Abstract:
Coral adaptive capacity insufficient to halt global transition of coral reefs into net erosion under climate change
Projecting the effects of climate change on net reef calcium carbonate production is critical to understanding the future impacts on ecosystem function, but prior estimates have not included corals' natural adaptive capacity to such change. Here we estimate how the ability of symbionts to evolve tolerance to heat stress, or for coral hosts to shuffle to favourable symbionts, and their combination, may influence responses to the combined impacts of ocean warming and acidification under three representative concentration pathway (RCP) emissions scenarios (RCP2.6, RCP4.5 and RCP8.5). We show that symbiont evolution and shuffling, both individually and when combined, favours persistent positive net reef calcium carbonate production. However, our projections of future net calcium carbonate production (NCCP) under climate change vary both spatially and by RCP. For example, 19%–35% of modelled coral reefs are still projected to have net positive NCCP by 2050 if symbionts can evolve increased thermal tolerance, depending on the RCP. Without symbiont adaptive capacity, the number of coral reefs with positive NCCP drops to 9%–13% by 2050. Accounting for both symbiont evolution and shuffling, we project median positive NCPP of coral reefs will still occur under low greenhouse emissions (RCP2.6) in the Indian Ocean, and even under moderate emissions (RCP4.5) in the Pacific Ocean. However, adaptive capacity will be insufficient to halt the transition of coral reefs globally into erosion by 2050 under severe emissions scenarios (RCP8.5).
Abstract.
Cornwall CE, Carlot J, Branson O, Courtney TA, Harvey BP, Perry CT, Andersson AJ, Diaz-Pulido G, Johnson MD, Kennedy E, et al (2023). Crustose coralline algae can contribute more than corals to coral reef carbonate production. Communications Earth & Environment, 4(1).
Lloyd Newman JE, Perry CT, Lange ID (2023). Quantifying endolithic bioerosion rates on remote coral reefs in the Central Indian Ocean.
Coral Reefs,
42(5), 1163-1173.
Abstract:
Quantifying endolithic bioerosion rates on remote coral reefs in the Central Indian Ocean
Bioerosion of calcium carbonate is a fundamental process that impacts net coral reef accretion. Besides large grazers, endolithic organisms play a major role in carbonate removal. Here we provide the first rate data for both macro- and microendolithic bioerosion in the remote Chagos Archipelago, Indian Ocean. Based on analysis of experimental blocks using computer tomography, we show similar macrobioerosion rates at 5 m (0.086 ± 0.026 kg m−2 yr−1) compared to at 10 m depth (0.066 ± 0.016 kg m−2 yr−1) after three years of exposure, with a succession from worm to sponge bioeroders over time. Microbioerosion rates analysed with scanning electron microscopy were 2–5 × higher than macrobioerosion rates at 5 m (0.187 ± 0.028 kg m−2 yr−1) and 10 m depth (0.313 ± 0.049 kg m−2 yr−1), but the microborer community was dominated by cyanobacteria in all samples. Total endolithic erosion was small compared to external erosion by parrotfishes, which increased over time, but did not show significant differences between 5 m (0.74 ± 0.11) and 10 m depth (1.12 ± 0.16 kg m−2 yr−1) after three years of exposure. These erosion rates are indicative of the oligotrophic and remote reef setting in the Chagos Archipelago (clear water, low nutrients, high fish biomass). The data will help to improve local carbonate budget estimates and provide a context for wider regional and environmental comparisons.
Abstract.
Perry CT, Lange ID, Stuhr M (2023). Quantifying reef-derived sediment generation: Introducing the SedBudget methodology to support tropical coastline and island vulnerability studies. Cambridge Prisms Coastal Futures, 1
Lange ID, Perry CT, Stuhr M (2023). Recovery trends of reef carbonate budgets at remote coral atolls 6 years post-bleaching.
Limnology and Oceanography,
68(S1), S8-S22.
Abstract:
Recovery trends of reef carbonate budgets at remote coral atolls 6 years post-bleaching
Coral bleaching events and resultant changes in benthic community composition and population size structure can diminish the important geo-ecological functions reefs provide, including habitat provision and carbonate production to support reef accretion. Net reef carbonate budgets, the balance between carbonate production and erosion processes, are thus important functional indicators of reef health. This study quantifies changes in coral community composition and colony size structures, and the resultant reef carbonate budget trajectories after the 2015/2016 bleaching event in the remote Chagos Archipelago, Indian Ocean. ReefBudget surveys were conducted at 12 sites across three atolls in 2015, 2018, and 2021, with calculations of biological carbonate production and erosion supported by locally obtained calcification and bioerosion rates. Carbonate budgets (in G = kg CaCO3 m−2 yr−1) shifted from net positive states in 2015 (mean ± SD: 3.8 ± 2.6 G) to net negative states in 2018 (−2.4 ± 1.4 G) in response to bleaching-driven mass coral mortality. By 2021, all sites were on a trajectory of recovery, but net budgets differed significantly between atolls (−2.0 ± 1.7 to 2.2 ± 1.4 G). At Salomon atoll, the threefold faster recovery of carbonate production and return to positive reef budget states only 6 yr post-bleaching was associated with the persistence of high structural complexity and the rapid recovery of fast growing tabular Acropora spp. Inter-atoll differences in colony size distributions furthermore illustrate that coral identity and size class are more important predictors of reef functions and post-disturbance recovery speed than coral cover alone.
Abstract.
Holmes S (2023). Sclerochronology and modelling: combining annually resolved bivalve records and biogeochemical models to understand the shelf seas.
Abstract:
Sclerochronology and modelling: combining annually resolved bivalve records and biogeochemical models to understand the shelf seas
The shelf seas are extremely vulnerable to the effects of climate change. Projected to warm at substantially greater rates than the open ocean, understanding how shelf sea systems operate and how they will respond to future change is of vital importance. Policy decision-makers rely on high quality information to ensure the protection of marine habitats and ecosystem services. While model studies can provide such data, they require spatially and temporally-extensive datasets for verification. Currently, this type of data is highly limited for the shelf seas, particularly at depth.
Sclerochronology of bivalve molluscs has shown great potential to extend instrumental data for the shelf seas, providing absolutely-dated, multi-centennial, annually-resolved archives of past ocean environment, analogous to dendrochronology in terrestrial environments. Bivalve molluscs have a wide distribution, and can be found on the shelf environments living at depth on the sea floor. Yet sclerochronology is a developing field with a number of fundamental research gaps limiting the use of sclerochronology as a valuable marine proxy. This thesis addresses three of those gaps:
Chapter 2 (Methods Development: Imaging shells for sclerochronology) presents a novel and non-destructive method for imaging the internal growth bands of bivalves used in sclerochronology – micro computed tomography (micro-CT). Micro-CT uses x-rays to create 3D high resolution images of the internal structure of specimens. Experiments evaluated whether density or resolution could limit bivalves from being imaged and showed that subtle microstructural features can be seen in the micro-CT images of even the most dense bivalve species. The research suggested that with future development in micro-CT technology including increased resolution and power, analysis of bivalve growth bands via micro-CT may be possible, significantly reducing the time required to produce highly valuable sclerochronology records and allowing more records to be constructed.
Chapter 3 (Sclerochronology and 1D modelling: a novel study using a 1D ecosystem model to better interpret sclerochronology records) focuses on a fundamental problem in sclerochronology - the lack of understanding regarding the mechanistic drivers of shell growth. Here, a 1D ecosystem model GOTM-ERSEM- BFM was used explore these mechanisms. The model was able to simulate the shell growth of a central North Sea composite chronology which allowed exploration of ecosystem processes to understand the mechanisms that lead to growth. Experiments manipulating the meteorological inputs to the model mechanistically attributed variability in surface heating and wind temperature as key controls on shell growth in the central North Sea.
Chapter 4 (Southern North Sea sclerochronologies: using shell records to test hypotheses across hydrological and biological gradients) addresses the scarcity of long-term productivity information in the North Sea which currently limits an understanding of historical variability. In particular, accurate measurements of North Sea productivity are limited by the poor quantification of sub-surface chlorophyll which cannot be measured by remote sensing or surface phytoplankton surveying. 12 new sclerochronology records of the bivalve mollusc Arctica islandica were produced from 4 locations in the southern North Sea to test if bivalve growth differs across productivity and hydrography gradients, and investigate whether shell records capture sub-surface chlorophyll variability. Differences in the rate of raw growth of Arctica islandica was demonstrated between regions of high and low productivity, supported by variations in synchronicity (estimated population signals) of multiple composite chronologies constructed using the shells records. These results suggest that sub surface chlorophyll may play a role in Arctica islandica shell growth but how this interacts with stratification regimes in the North Sea is difficult to quantify due to complex interactions of biology and other hydrographical features in the region. Further research is required in other locations to better understand impact of stratification and sub-surface productivity on shell growth and subsequently North Sea ecosystems.
The novel research presented in this thesis has advanced the fields of sclerochronology and ecosystem modelling and has laid the foundation for transformative approaches to sclerochronology. By developing the methods needed to understand long-term variability of shelf sea environments, particularly at depth, this work has contributed to improving the understanding of past and future climate change in the shelf seas.
Abstract.
East HK, Johnson JA, Perry CT, Finlay G, Musthag A, Zahir H, Floyd M (2023). Seagrass meadows are important sources of reef island-building sediment.
Communications Earth & Environment,
4(1).
Abstract:
Seagrass meadows are important sources of reef island-building sediment
AbstractThe future vulnerability of low-lying atoll nations is inextricably linked to the production of carbonate sediments by organisms living in their adjacent marine environments. Seagrass meadows are commonly found adjacent to reef islands, but their role as sources of reef island-building sediments has been overlooked. Here, we combine field, satellite and sedimentological data to quantify rates of sediment production by seagrass epibionts in a reef island sediment supply context. Total seagrass epibiont sediment production at our study site (Huvadhoo Atoll, Maldives) was 853,000 ± 90,000 kg CaCO3 yr−1 over an area of 1.1 km2. of this total sediment production, 541,000 ± 23,000 kg CaCO3 yr−1 was estimated to be suitable to contribute to reef island building (sand-sized, post-agitation). Our findings highlight a valuable ecosystem service provided by tropical seagrass meadows as important potential sources of reef island-building sediment. This study, therefore, presents a compelling geomorphic argument for seagrass conservation.
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Ghilardi M, Salter MA, Parravicini V, Ferse SCA, Rixen T, Wild C, Birkicht M, Perry CT, Berry A, Wilson RW, et al (2023). Temperature, species identity and morphological traits predict carbonate excretion and mineralogy in tropical reef fishes.
Nature Communications,
14(1).
Abstract:
Temperature, species identity and morphological traits predict carbonate excretion and mineralogy in tropical reef fishes
Anthropogenic pressures are restructuring coral reefs globally. Sound predictions of the expected changes in key reef functions require adequate knowledge of their drivers. Here we investigate the determinants of a poorly-studied yet relevant biogeochemical function sustained by marine bony fishes: the excretion of intestinal carbonates. Compiling carbonate excretion rates and mineralogical composition from 382 individual coral reef fishes (85 species and 35 families), we identify the environmental factors and fish traits that predict them. We find that body mass and relative intestinal length (RIL) are the strongest predictors of carbonate excretion. Larger fishes and those with longer intestines excrete disproportionately less carbonate per unit mass than smaller fishes and those with shorter intestines. The mineralogical composition of excreted carbonates is highly conserved within families, but also controlled by RIL and temperature. These results fundamentally advance our understanding of the role of fishes in inorganic carbon cycling and how this contribution will change as community composition shifts under increasing anthropogenic pressures.
Abstract.
Saintilan N, Horton B, Törnqvist TE, Ashe EL, Khan NS, Schuerch M, Perry C, Kopp RE, Garner GG, Murray N, et al (2023). Widespread retreat of coastal habitat is likely at warming levels above 1.5 °C.
Nature,
621(7977), 112-119.
Abstract:
Widespread retreat of coastal habitat is likely at warming levels above 1.5 °C.
Several coastal ecosystems-most notably mangroves and tidal marshes-exhibit biogenic feedbacks that are facilitating adjustment to relative sea-level rise (RSLR), including the sequestration of carbon and the trapping of mineral sediment1. The stability of reef-top habitats under RSLR is similarly linked to reef-derived sediment accumulation and the vertical accretion of protective coral reefs2. The persistence of these ecosystems under high rates of RSLR is contested3. Here we show that the probability of vertical adjustment to RSLR inferred from palaeo-stratigraphic observations aligns with contemporary in situ survey measurements. A deficit between tidal marsh and mangrove adjustment and RSLR is likely at 4 mm yr-1 and highly likely at 7 mm yr-1 of RSLR. As rates of RSLR exceed 7 mm yr-1, the probability that reef islands destabilize through increased shoreline erosion and wave over-topping increases. Increased global warming from 1.5 °C to 2.0 °C would double the area of mapped tidal marsh exposed to 4 mm yr-1 of RSLR by between 2080 and 2100. With 3 °C of warming, nearly all the world's mangrove forests and coral reef islands and almost 40% of mapped tidal marshes are estimated to be exposed to RSLR of at least 7 mm yr-1. Meeting the Paris agreement targets would minimize disruption to coastal ecosystems.
Abstract.
Author URL.
2022
McWhorter J (2022). A Multidimensional Analysis of Climate Projections on the Great Barrier Reef.
Abstract:
A Multidimensional Analysis of Climate Projections on the Great Barrier Reef
Tropical coral reefs are increasingly threatened due to global warming. Corals live within a narrow thermal threshold making them one of the most sensitive species to changes in temperature. Recent warming events on the Great Barrier Reef (GBR) (2016, 2017, 2020) have caused mass coral mortality on approximately 30% of the reef (Bozec et al. 2020; Hughes, Kerry et al. 2018). This research focuses on the development and implementation of a 1-D semi-dynamic downscaling method to improve climate projections on the GBR. Coral stress metrics are used to provide detailed projections on the magnitude and frequency of warming for four socio-economic pathways (SSP) under the 6th phase of the Climate Model Intercomparison Project. Following a chapter on methods and model validation, the results in chapter 3 reveal the importance of adhering to the lowest possible emissions trajectory which limits warming to 1.5°C by the end of the century. This scenario keeps projected warming to slightly above current conditions. Under the higher emissions trajectories (~4°C and ~5°C of global average warming) coral stress metrics quadruple present-day warming conditions which would result in annual mass coral mortality events by 2080. In chapter 4, climate refugia have been identified from present-day conditions based on downscaled surface temperature outputs in agreement with observations. The lower emissions trajectories maintain these locations as refugia while the higher emissions trajectories reveal the loss of these increasingly valuable locations. Areas of climate refugia can be attributed to tidal and wind energy fluctuations providing relief from warming. However, this advantage does not persist after global warming exceeds ~3°C. Refugia are more likely to persist in the northern GBR under increased warming even though recent evidence suggests there are fewer refugia in this region. Atmospheric spatial patterns on the GBR under warming above ~3° C reveal a change in wind and shortwave radiation patterns driving a loss in the identified climate refugia locations. Lastly, stratification was tested in chapter 5 to determine if increases in stratification could provide thermal relief to bottom temperature waters from 0-50 m under increased warming into the future using downscaled bottom temperature projections. Chapter 5 results demonstrate that warming influences bottom temperatures of stratified locations, showing little support for deeper reefs to act as a climate refuge. The temporal, spatial, and bottom temperature analysis of downscaled climate projections provides insight into the consequences of a warming planet for the GBR and can be used to inform management and policy decisions to protect coral reefs.
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Berry A (2022). Calcium carbonate production by teleost fish: an investigation into the effects of temperature and dietary calcium intake.
Abstract:
Calcium carbonate production by teleost fish: an investigation into the effects of temperature and dietary calcium intake
The marine environment is hyperosmotic to the tissues of marine teleost fish, which results in passive water loss and ion gain throughout their lifetime. In order to avoid dehydration, marine teleosts drink seawater. Ingested seawater travels through the digestive tract, where it is manipulated in order to absorb water and selected ions. Calcium carbonate (CaCO3) is precipitated as part of this process, and aids water absorption by removing Ca2+ (calcium) and HCO3- (bicarbonate) ions from solution. This precipitate (hereby referred to as carbonate), which also contains some MgCO¬3, is then excreted to the environment as a waste product, where it can dissolve or become part of the sediment. The precipitation and dissolution of carbonate forms the marine inorganic carbon cycle, which we have only recently understood that fish form a significant part. In chapter one of this thesis, I have reviewed the literature to explore the many factors that affect the production of gut carbonates by fish, including absolute quantity, composition and how they affect the fate of carbonate after excretion. In chapter two I have experimentally investigated the effect of low temperature, from 3 to 14 °C, on the quantity and composition of carbonate excreted by lumpfish, Cyclopterus lumpus. Between 3 and 7 °C, carbonate excretion increased with a Q10 of 3.50, which is comparable to other species, and had no effect on the incorporation of MgCO3. This confirms that carbonate excretion rate responds to temperatures
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Molina-Hernández A, Medellín-Maldonado F, Lange ID, Perry CT, Álvarez-Filip L (2022). Coral reef erosion: in situ measurement on different dead coral substrates on a Caribbean reef.
Limnology and Oceanography,
67(12), 2734-2749.
Abstract:
Coral reef erosion: in situ measurement on different dead coral substrates on a Caribbean reef
Widespread mortality of reef-building coral substantially reduces the capacity for reef growth and makes available extensive bare substrate areas that in the absence of coral recovery will be eroded by a variety of external and internal bioeroders. Here, we analyze rates of external erosion on six different types of carbonate substrates under in situ conditions over a 2-yr period. We measure vertical changes in the surface elevation of four species of recently dead corals afflicted by the stony coral tissue loss disease outbreak, and other two common types of calcareous substrates, long-dead Acropora palmata fronds and bare calcareous hardground, as a reference for “bare” carbonate substrates that occur widely in Caribbean reefs. The surface of the recently dead colonies experienced significant erosion after 2 yr of exposure, but at different rates depending on the species. Dead skeletons of Orbicella faveolata experienced the greatest rates of erosion after 2 yr at −9.9 mm (±3.2 mm); Dendrogyra cylindrus eroded −3.6 mm (±2.8 mm), Pseudodiploria strigosa −3.3 mm (±3.7 mm), and Siderastrea siderea −1.2 mm (±0.9 mm), while long-dead substrates remained unchanged. There was significant erosion in the presence of parrotfish grazing scars and of short algal turf mats, while crustose coralline algae cover and sand-and-high turf mats were not associated with significant changes in elevation, arguably indicating a protective effect. This study provides new insights into how and at what rates external carbonate erosion is shaping contemporary reefs at fine spatial and temporal scales.
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Husband E, Perry CT, Lange ID (2022). Estimating rates of coral carbonate production from aerial and archive imagery by applying colony scale conversion metrics.
Coral Reefs,
41(4), 1199-1209.
Abstract:
Estimating rates of coral carbonate production from aerial and archive imagery by applying colony scale conversion metrics
Recent interest in assessing coral reef functions has raised questions about how carbonate production rates have altered over the past few decades of ecological change. At the same time, there is growing interest in quantifying carbonate production on larger reef-scales. Resolving these issues is challenging because carbonate production estimates require three-dimensional survey data, which are typically collected in-situ over small spatial scales. In contrast, data that can be extracted from archive photograph or video imagery and high-resolution aerial imagery are generally planar. To address this disconnect, we collected data on the relationship between linear planar and 3D contour lengths of 62 common Indo-Pacific hard coral genera-morphotypes to establish appropriate conversion metrics (i.e. coral class rugosity values, hereafter termed Rcoral). These conversion values allow planar colony dimensions to be converted to estimates of 3D colony contour length, which can be employed within existing census budget methodologies like ReefBudget to estimate coral carbonate production (G, in kg CaCO3 m−2 yr−1). We tested this approach by comparing in-situ carbonate production data collected using the ReefBudget methodology against estimates derived from converted colony length data from video imagery. The data show a high level of consistency with an error of ~ 10%. We then demonstrate potential applications of the conversion metrics in two examples, the first using time-series (2006 to 2018) photo-quadrat imagery from Moorea, and the second using high-resolution drone imagery across different reef flat habitats from the Maldives. Whilst some degree of error must necessarily be accepted with such conversion techniques, the approach presented here offers exciting potential to calculate coral carbonate production: (1) from historical imagery to constrain past coral carbonate production rates; (2) from high quality aerial imagery for spatial up-scaling exercises; and (3) for use in rapid photograph or video-based assessments along reef systems where detailed surveys are not possible.
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Perry CT, Salter MA, Lange ID, Kochan DP, Harborne AR, Graham NAJ (2022). Geo-ecological functions provided by coral reef fishes vary among regions and impact reef carbonate cycling regimes.
Ecosphere,
13(12).
Abstract:
Geo-ecological functions provided by coral reef fishes vary among regions and impact reef carbonate cycling regimes
Coral reef fishes perform essential and well-documented ecological functions on reefs, but also contribute important geo-ecological functions, which influence reef carbonate cycling regimes. These functions include reef framework modification (through bioerosion and breakage), and the production, reworking, and transport of reefal sediments. To explore how these functions vary across reefs and regions, we compiled a dataset of available taxa-specific function rates and applied these to fish census data from sites in the Pacific Ocean (PO), Indian Ocean (IO), and Greater Caribbean (GC), each region displaying a gradient in fish biomass. The highest overall function rates occur at the highest fish biomass sites in the PO (Kingman Reef) and IO (Chagos Archipelago), where bioerosion dominates framework modification and sediment generation (up to 7 kg m−2 year−1). At the lowest biomass PO and IO sites, framework modification and sediment generation are driven mainly by breakage and occur at lower rates (~2 kg m−2 year−1). Sediment reworking rates are high across all PO and IO sites (~1–5 kg m−2 year−1) and higher than other function rates at low biomass sites. Geo-ecological function rates are generally low across the GC sites, despite total fish biomass being comparable to, or even exceeding, some PO and IO sites, with sediment reworking (up to ~1 kg m−2 year−1) being the dominant function. These site-level differences partly reflect total fish biomass, but fish assemblage size structure and species identity are critical, with a few fish families (and species) underpinning the highest function rates and regulating the “health” of the fish-driven carbonate cycling regime. Reefs with high fish-driven framework modification, sediment production and reworking rates define one end of this spectrum, while at lower biomass sites little new sediment is produced and sediment reworking dominates. While additional species-level rate data are urgently needed to better constrain function rates, these transitions align with ideas about the progressive shutdown of carbonate production regimes on ecologically perturbed reefs, with important implications for reef-building, shoreline sediment supply, and sediment carbon and nutrient cycling.
Abstract.
Perry C, Salter M, Lange I, Kochan D, Harborne A, Graham N (2022). Geo-ecological functions provided by coral reef fishes vary among regions and impact reef carbonate cycling regimes (dataset).
Abstract:
Geo-ecological functions provided by coral reef fishes vary among regions and impact reef carbonate cycling regimes (dataset)
This is the dataset used for the Perry et al. (2022) article "Geo-ecological functions provided by coral reef fishes vary among regions and impact reef carbonate cycling regimes" published in Ecosphere.
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Lange I, Perry C, Stuhr M (2022). Recovery trends of reef carbonate budgets at remote coral atolls six years post-bleaching (dataset).
Abstract:
Recovery trends of reef carbonate budgets at remote coral atolls six years post-bleaching (dataset)
Coral bleaching events and resultant changes in benthic community composition and population size structure can diminish the important geo-ecological functions reefs provide, including habitat provision and carbonate production to support reef accretion. Net reef carbonate budgets, the balance between carbonate production and erosion processes, are thus important functional indicators of reef health. This study quantifies changes in coral community composition and colony size structures, and the resultant reef carbonate budget trajectories after the 2015/2016 bleaching event in the remote Chagos Archipelago, Indian Ocean. ReefBudget surveys were conducted at 12 sites across three atolls in 2015, 2018 and 2021, with calculations of biological carbonate production and erosion supported by locally obtained calcification and bioerosion rates. Carbonate budgets (in G = kg CaCO3 m-2 yr-1) shifted from net positive states in 2015 (mean±SD: 3.8±2.6 G) to net negative states in 2018 (-2.4±1.4 G) in response to bleaching-driven mass coral mortality. By 2021, all sites were on a trajectory of recovery, but net budgets differed significantly between atolls (-2.0±1.7 to 2.2±1.4 G). At Salomon atoll, the 3-fold faster recovery of carbonate production and return to positive reef budget states only six years post-bleaching was associated with the persistence of high structural complexity and the rapid recovery of fast growing tabular Acropora spp. Inter-atoll differences in colony size distributions furthermore illustrate that coral identity and size class are more important predictors of reef functions and post-disturbance recovery speed than coral cover alone.
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Lange ID, Molina-Hernández A, Medellín-Maldonado F, Perry CT, Álvarez-Filip L (2022). Structure-from-motion photogrammetry demonstrates variability in coral growth within colonies and across habitats.
PLoS ONE,
17(11 November).
Abstract:
Structure-from-motion photogrammetry demonstrates variability in coral growth within colonies and across habitats
Coral growth is an important metric of coral health and underpins reef-scale functional attributes such as structural complexity and calcium carbonate production. There persists, however, a paucity of growth data for most reef-building regions, especially for coral species whose skeletal architecture prevents the use of traditional methods such as coring and Alizarin staining. We used structure-from-motion photogrammetry to quantify a range of colony-scale growth metrics for six coral species in the Mexican Caribbean and present a newly developed workflow to measure colony volume change over time. Our results provide the first growth metrics for two species that are now major space occupiers on Caribbean reefs, Agaricia agaricites and Agaricia tenuifolia. We also document higher linear extension, volume increase and calcification rates within back reef compared to fore reef environments for four other common species: Orbicella faveolata, Porites astreoides, Siderastrea siderea and Pseudodiploria strigosa. Linear extension rates in our study were lower than those obtained via computed tomography (CT) scans of coral cores from the same sites, as the photogrammetry method averages growth in all dimensions, while the CT method depicts growth only along the main growth axis (upwards). The comparison of direct volume change versus potential volume increase calculated from linear extension emphasizes the importance of assessing whole colony growth to improve calcification estimates. The method presented here provides an approach that can generate accurate calcification estimates alongside a range of other whole-colony growth metrics in a non-invasive way.
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McWhorter JK, Halloran PR, Roff G, Skirving WJ, Perry CT, Mumby PJ (2022). The importance of 1.5°C warming for the Great Barrier Reef.
Global Change Biology,
28(4), 1332-1341.
Abstract:
The importance of 1.5°C warming for the Great Barrier Reef
Tropical coral reefs are among the most sensitive ecosystems to climate change and will benefit from the more ambitious aims of the United Nations Framework Convention on Climate Change's Paris Agreement, which proposed to limit global warming to 1.5° rather than 2°C above pre-industrial levels. Only in the latest Intergovernmental Panel on Climate Change focussed assessment, the Coupled Model Intercomparison Project phase 6 (CMIP6), have climate models been used to investigate the 1.5° warming scenario directly. Here, we combine the most recent model updates from CMIP6 with a semi-dynamic downscaling to evaluate the difference between the 1.5 and 2°C global warming targets on coral thermal stress metrics for the Great Barrier Reef (GBR). By ~2080, severe bleaching events are expected to occur annually under intensifying emissions (shared socioeconomic pathway SSP5-8.5). Adherence to 2° warming (SSP1-2.6) halves this frequency but the main benefit of confining warming to 1.5° (SSP1-1.9) is that bleaching events are reduced further to 3 events per decade. Attaining low emissions of 1.5° is also paramount to prevent the mean magnitude of thermal stress from stabilizing close to a critical thermal threshold (8 Degree Heating Weeks). Thermal stress under the more pessimistic pathways SSP3-7.0 and SSP5-8.5 is three to fourfold higher than the present day, with grave implications for future reef ecosystem health. As global warming continues, our projections also indicate more regional warming in the central and southern GBR than the far north and northern GBR.
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2021
Cornwall CE, Comeau S, Kornder NA, Perry CT, van Hooidonk R, DeCarlo TM, Pratchett MS, Anderson KD, Browne N, Carpenter R, et al (2021). Global declines in coral reef calcium carbonate production under ocean acidification and warming.
Proceedings of the National Academy of Sciences of the United States of America,
118(21).
Abstract:
Global declines in coral reef calcium carbonate production under ocean acidification and warming
Ocean warming and acidification threaten the future growth of coral reefs. This is because the calcifying coral reef taxa that construct the calcium carbonate frameworks and cement the reef together are highly sensitive to ocean warming and acidification. However, the global-scale effects of ocean warming and acidification on rates of coral reef net carbonate production remain poorly constrained despite a wealth of studies assessing their effects on the calcification of individual organisms. Here, we present global estimates of projected future changes in coral reef net carbonate production under ocean warming and acidification. We apply a meta-analysis of responses of coral reef taxa calcification and bioerosion rates to predicted changes in coral cover driven by climate change to estimate the net carbonate production rates of 183 reefs worldwide by 2050 and 2100. We forecast mean global reef net carbonate production under representative concentration pathways (RCP) 2.6, 4.5, and 8.5 will decline by 76, 149, and 156%, respectively, by 2100. While 63% of reefs are projected to continue to accrete by 2100 under RCP2.6, 94% will be eroding by 2050 under RCP8.5, and no reefs will continue to accrete at rates matching projected sea level rise under RCP4.5 or 8.5 by 2100. Projected reduced coral cover due to bleaching events predominately drives these declines rather than the direct physiological impacts of ocean warming and acidification on calcification or bioerosion. Presently degraded reefs were also more sensitive in our analysis. These findings highlight the low likelihood that the world’s coral reefs will maintain their functional roles without near-term stabilization of atmospheric CO2 emissions.
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Pereira-Filho GH, Mendes VR, Perry CT, Shintate GI, Niz WC, Sawakuchi AO, Bastos AC, Giannini PCF, Motta FS, Millo C, et al (2021). Growing at the limit: Reef growth sensitivity to climate and oceanographic changes in the South Western Atlantic. Global and Planetary Change, 201, 103479-103479.
Yarlett RT, Perry CT, Wilson RW (2021). Quantifying production rates and size fractions of parrotfish-derived sediment: a key functional role on Maldivian coral reefs.
Ecology and Evolution,
11(22), 16250-16265.
Abstract:
Quantifying production rates and size fractions of parrotfish-derived sediment: a key functional role on Maldivian coral reefs
Coral reef fish perform numerous important functional roles on coral reefs. of these, carbonate sediment production, as a by-product of parrotfish feeding, is especially important for contributing to reef framework construction and reef-associated landform development. However, only limited data exist on: (i) how production rates vary among reef habitats as a function of parrotfish assemblages, (ii) the relative importance of sediment produced from eroded, reworked, and endogenous sources, or (iii) the size fractions of sediment generated by different parrotfish species and size classes. These parameters influence not only overall reef-derived sediment supply, but also influence the transport potential and depositional fate of this sedimentary material. Here, we show that parrotfish sediment production varies significantly between reef-platform habitats on an atoll-margin Maldivian reef. Highest rates of production (over 0.8 kg m−2 year−1) were calculated in three of the eight platform habitats; a rubble-dominated zone, an Acropora spp. dominated zone, and a patch reef zone. Habitat spatial extent and differences in associated parrotfish assemblages strongly influenced the total quantities of sediment generated within each habitat. Nearly half of total parrotfish sediment production occurred in the rubble habitat, which comprised only 8% of the total platform area. Over 90% of this sedimentary material originated from eroded reef framework as opposed to being reworked existing or endogenously produced sediment, and comprised predominantly coral sands (predominantly 125–1000 µm in diameter). This is comparable to the dominant sand types and size fractions found on Maldivian reef islands. By contrast, nearly half of the sediment egested by parrotfish in the Acropora spp. dominated and patch reef habitats resulted from reworked existing sediments. These differences between habitats are a result of the different parrotfish assemblages supported. Endogenous carbonate production was found to be insignificant compared to the quantity of eroded and reworked material. Our findings have important implications for identifying key habitats and species which act as major sources of sediment for reef-island systems.
Abstract.
Yarlett R, Perry C, Wilson RW (2021). Quantifying production rates and size fractions of parrotfish-derived sediment: a key functional role on Maldivian coral reefs (dataset).
Abstract:
Quantifying production rates and size fractions of parrotfish-derived sediment: a key functional role on Maldivian coral reefs (dataset)
This is the dataset used for the Yarlett et al. (2021) article "Quantifying production rates and size fractions of parrotfish-derived sediment: a key functional role on Maldivian coral reefs" published in Ecology and Evolution.
Abstract.
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Duvat VKE, Magnan AK, Perry CT, Spencer T, Bell JD, Wabnitz CCC, Webb AP, White I, McInnes KL, Gattuso JP, et al (2021). Risks to future atoll habitability from climate-driven environmental changes.
Wiley Interdisciplinary Reviews: Climate Change,
12(3).
Abstract:
Risks to future atoll habitability from climate-driven environmental changes
Recent assessments of future risk to atoll habitability have focused on island erosion and submergence, and have overlooked the effects of other climate-related drivers, as well as differences between ocean basins and island types. Here we investigate the cumulative risk arising from multiple drivers (sea-level rise; changes in rainfall, ocean–atmosphere oscillations and tropical cyclone intensity; ocean warming and acidification) to five Habitability Pillars: Land, Freshwater supply, Food supply, Settlements and infrastructure, and Economic activities. Risk is assessed for urban and rural islands of the Pacific and Indian Oceans, under RCP2.6 and RCP8.5, in 2050 and 2090, and considering a moderate adaptation scenario. Risks will be highest in the Western Pacific which will experience increased island destabilization together with a high threat to freshwater, and decreased land-based and marine food supply from reef-dependent fish and tuna and tuna-like resources. Risk accumulation will occur at a lower rate in the Central Pacific (lower pressure on land, with more limited cascading effects on other Habitability Pillars; increase in pelagic fish stocks) and the Central Indian Ocean (mostly experiencing increased land destabilization and reef degradation). Risk levels will vary significantly between urban islands, depending on geomorphology and local shoreline disturbances. Rural islands will experience less contrasting risk levels, but higher risks than urban islands in the second half of the century. This article is categorized under: Trans-Disciplinary Perspectives > Regional Reviews.
Abstract.
Lange ID, Benkwitt CE, McDevitt-Irwin JM, Tietjen KL, Taylor B, Chinkin M, Gunn RL, Palmisciano M, Steyaert M, Wilson B, et al (2021). Wave exposure shapes reef community composition and recovery trajectories at a remote coral atoll.
Coral Reefs,
40(6), 1819-1829.
Abstract:
Wave exposure shapes reef community composition and recovery trajectories at a remote coral atoll
In a time of unprecedented ecological change, understanding natural biophysical relationships between reef resilience and physical drivers is of increasing importance. This study evaluates how wave forcing structures coral reef benthic community composition and recovery trajectories after the major 2015/2016 bleaching event in the remote Chagos Archipelago, Indian Ocean. Benthic cover and substrate rugosity were quantified from digital imagery at 23 fore reef sites around a small coral atoll (Salomon) in 2020 and compared to data from a similar survey in 2006 and opportunistic surveys in intermediate years. Cluster analysis and principal component analysis show strong separation of community composition between exposed (modelled wave exposure > 1000 J m−3) and sheltered sites (< 1000 J m−3) in 2020. This difference is driven by relatively high cover of Porites sp. other massive corals, encrusting corals, soft corals, rubble and dead table corals at sheltered sites versus high cover of pavement and sponges at exposed sites. Total coral cover and rugosity were also higher at sheltered sites. Adding data from previous years shows benthic community shifts from distinct exposure-driven assemblages and high live coral cover in 2006 towards bare pavement, dead Acropora tables and rubble after the 2015/2016 bleaching event. The subsequent recovery trajectories at sheltered and exposed sites are surprisingly parallel and lead communities towards their respective pre-bleaching communities. These results demonstrate that in the absence of human stressors, community patterns on fore reefs are strongly controlled by wave exposure, even during and after widespread coral loss from bleaching events.
Abstract.
Lange I, Benkwitt CE, McDevitt-Irwin JM, Tietjen KL, Taylor B, Chinkin M, Gunn RL, Palmisciano M, Steyaert M, Wilson B, et al (2021). Wave exposure shapes reef community composition and recovery trajectories at a remote coral atoll (dataset).
Abstract:
Wave exposure shapes reef community composition and recovery trajectories at a remote coral atoll (dataset)
In a time of unprecedented ecological change, understanding natural biophysical relationships between reef resilience and physical drivers is of increasing importance. This study evaluates how wave forcing structures coral reef benthic community composition and recovery trajectories after the major 2015/2016 bleaching event in the remote Chagos Archipelago, Indian Ocean. Benthic cover and substrate rugosity were quantified from digital imagery at 23 fore reef sites around a small coral atoll (Salomon) in 2020 and compared to data from a similar survey in 2006 and opportunistic surveys in intermediate years. Cluster analysis and principal component analysis show strong separation of community composition between exposed (modelled wave exposure >1000 J m-3) and sheltered sites (
Abstract.
Full text.
2020
Lange ID, Perry CT (2020). A quick, easy and non-invasive method to quantify coral growth rates using photogrammetry and 3D model comparisons.
Methods in Ecology and Evolution,
11(6), 714-726.
Abstract:
A quick, easy and non-invasive method to quantify coral growth rates using photogrammetry and 3D model comparisons
Coral growth rates vary significantly with environmental conditions and are thus important indicators of coral health and reef carbonate production. Despite the importance of this metric, data are sparse for most coral genera and species globally, including for many key reef-building species. Traditional methods to obtain growth rates, such as coral coring or staining with Alizarin are destructive and only work for a limited number of species and morphological growth forms. Emerging approaches, using underwater photogrammetry to create digital models of coral colonies, are providing novel and non-invasive ways to explore colony-scale growth patterns and to address existing knowledge gaps. We developed an easy-to-follow workflow to construct three-dimensional (3D) models from overlapping photographs and to measure linear, radial and vertical extension rates of branching, massive and encrusting corals after aligning colony models from subsequent years. The method presented here was applied to measure extension rates for 46 colonies of nine coral species in the remote Chagos Archipelago, Indian Ocean. Proposed image acquisition and software settings produced 3D models of consistently high resolution and detail (precision ≤ 0.2 mm) and variability in growth measurements was small despite manual alignment, clipping and ruler placement (SD ≤ 0.9 mm). Measured extension rates for the Chagos Archipelago are similar to published rates in the Indo-Pacific where comparable data are available, and provide the first published rates for several species. For encrusting corals, the results emphasize the importance of differentiating between radial and vertical growth. Photogrammetry and 3D model comparisons provide a fast, easy, inexpensive and non-invasive method to quantify coral growth rates for a range of species and morphological growth forms. The simplicity of the presented workflow encourages its repeatability and permits non-specialists to learn photogrammetry with the goal of obtaining linear coral growth rates. Coral growth rates are essential metrics to quantify functional consequences of ongoing community changes on coral reefs and expanded datasets for key coral taxa will aid predictions of geographic variations in coral reef response to increasing global stressors.
Abstract.
Lange I, Perry C (2020). A quick, easy and non-invasive method to quantify coral growth rates using photogrammetry and 3D model comparisons (dataset).
Abstract:
A quick, easy and non-invasive method to quantify coral growth rates using photogrammetry and 3D model comparisons (dataset)
This is the dataset used for the Lange et al. (2020) article "A quick, easy and non-invasive method to quantify coral growth rates using photogrammetry and 3D model comparisons" published in Methods in Ecology & Evolution.
Abstract.
Full text.
Hays GC, Koldewey HJ, Andrzejaczek S, Attrill MJ, Barley S, Bayley DTI, Benkwitt CE, Block B, Schallert RJ, Carlisle AB, et al (2020). A review of a decade of lessons from one of the world’s largest MPAs: conservation gains and key challenges.
Marine Biology,
167(11).
Abstract:
A review of a decade of lessons from one of the world’s largest MPAs: conservation gains and key challenges
Given the recent trend towards establishing very large marine protected areas (MPAs) and the high potential of these to contribute to global conservation targets, we review outcomes of the last decade of marine conservation research in the British Indian Ocean Territory (BIOT), one of the largest MPAs in the world. The BIOT MPA consists of the atolls of the Chagos Archipelago, interspersed with and surrounded by deep oceanic waters. Islands around the atoll rims serve as nesting grounds for sea birds. Extensive and diverse shallow and mesophotic reef habitats provide essential habitat and feeding grounds for all marine life, and the absence of local human impacts may improve recovery after coral bleaching events. Census data have shown recent increases in the abundance of sea turtles, high numbers of nesting seabirds and high fish abundance, at least some of which is linked to the lack of recent harvesting. For example, across the archipelago the annual number of green turtle clutches (Chelonia mydas) is ~ 20,500 and increasing and the number of seabirds is ~ 1 million. Animal tracking studies have shown that some taxa breed and/or forage consistently within the MPA (e.g. some reef fishes, elasmobranchs and seabirds), suggesting the MPA has the potential to provide long-term protection. In contrast, post-nesting green turtles travel up to 4000 km to distant foraging sites, so the protected beaches in the Chagos Archipelago provide a nesting sanctuary for individuals that forage across an ocean basin and several geopolitical borders. Surveys using divers and underwater video systems show high habitat diversity and abundant marine life on all trophic levels. For example, coral cover can be as high as 40–50%. Ecological studies are shedding light on how remote ecosystems function, connect to each other and respond to climate-driven stressors compared to other locations that are more locally impacted. However, important threats to this MPA have been identified, particularly global heating events, and Illegal, Unreported and Unregulated (IUU) fishing activity, which considerably impact both reef and pelagic fishes.
Abstract.
Perry CT, Morgan KM, Lange ID, Yarlett RT (2020). Bleaching-driven reef community shifts drive pulses of increased reef sediment generation.
Royal Society Open Science,
7(4).
Abstract:
Bleaching-driven reef community shifts drive pulses of increased reef sediment generation
The ecological impacts of coral bleaching on reef communities are well documented, but resultant impacts upon reef-derived sediment supply are poorly quantified. This is an important knowledge gap because these biogenic sediments underpin shoreline and reef island maintenance. Here, we explore the impacts of the 2016 bleaching event on sediment generation by two dominant sediment producers (parrotfish and Halimeda spp.) on southern Maldivian reefs. Our data identifies two pulses of increased sediment generation in the 3 years since bleaching. The first occurred within approximately six months after bleaching as parrotfish biomass and resultant erosion rates increased, probably in response to enhanced food availability. The second pulse occurred 1 to 3 years post-bleaching, after further increases in parrotfish biomass and a major (approx. fourfold) increase in Halimeda spp. abundance. Total estimated sediment generation from these two producers increased from approximately 0.5 kg CaCO3 m-2 yr-1 (pre-bleaching; 2016) to approximately 3.7 kg CaCO3 m-2 yr-1 (post-bleaching; 2019), highlighting the strong links between reef ecology and sediment generation. However, the relevance of this sediment for shoreline maintenance probably diverges with each producer group, with parrotfish-derived sediment a more appropriate size fraction to potentially contribute to local island shorelines.
Abstract.
Hattam C, Evans L, Morrissey K, Hooper T, Young K, Khalid F, Bryant M, Thani A, Slade L, Perry C, et al (2020). Building resilience in practice to support coral communities in the Western Indian Ocean.
Environmental Science and Policy,
106, 182-190.
Abstract:
Building resilience in practice to support coral communities in the Western Indian Ocean
Global environmental change and other site specific pressures (e.g. over fishing and pollution) are threating coral reefs and the livelihoods of dependent coastal communities. Multiple strategies are used to build the resilience of both coral reefs and reef dependent communities but the effectiveness of these strategies is largely unknown. Using the Western Indian Ocean (WIO) as a case study, this paper combines published literature and expert opinion elicited through a multi-stakeholder workshop to assess the intended and realised social and ecological implications of strategies commonly applied in the region. Findings suggest that all strategies can contribute to building social and ecological resilience, but this varies with context and the overall strategy objectives. The ability of strategies to be successful in the future is questioned. To support effective resilience policy development more nuanced lesson learning requires effective monitoring and evaluation as well as a disaggregated understanding of resilience in terms of gender, agency and the interaction between ecological and social resilience. Opportunities for further lesson sharing between experts in the region are needed.
Abstract.
Lange ID, Perry CT, Alvarez-Filip L (2020). Carbonate budgets as indicators of functional reef “health”: a critical review of data underpinning census-based methods and current knowledge gaps.
Ecological Indicators,
110Abstract:
Carbonate budgets as indicators of functional reef “health”: a critical review of data underpinning census-based methods and current knowledge gaps
The carbonate budget of a reef describes the net rate of carbonate production resulting from various biologically-, physically- and chemically-driven production and erosion processes. Thus, budget state metrics can provide important information on a reef's growth potential and on the capacity of reefs to sustain key geo-ecological services such as habitat provision and coastal protection. Whilst various approaches for estimating carbonate budgets exist, census-based methods have gained recent interest because they quantify the contribution of different functional groups and taxa, and allow assessments of the links between changing reef ecology and budget states. However, the present paucity of supporting data on growth and erosion rates for the majority of coral species and reef-associated taxa represents a constraint on these budget estimates and limits meaningful between-site comparisons. In light of the growing interest in using carbonate budgets as a functional reef “health” assessment tool, this review thus considers our current state of knowledge regarding the geographic coverage of existing reef budget states and the availability of relevant supporting data. We use this to highlight current knowledge gaps, future challenges, and opportunities that emerging techniques may offer. The primary aim of this review is to encourage increased research efforts on budget states and underlying metrics in order to better constrain reef carbonate budget estimates from across a broad range of sites and environments.
Abstract.
Yarlett RT, Perry CT, Wilson RW, Harborne AR (2020). Inter-habitat variability in parrotfish bioerosion rates and grazing pressure on an indian ocean reef platform.
Diversity,
12(10), 1-17.
Abstract:
Inter-habitat variability in parrotfish bioerosion rates and grazing pressure on an indian ocean reef platform
Parrotfish perform a variety of vital ecological functions on coral reefs, but we have little understanding of how these vary spatially as a result of inter-habitat variability in species assemblages. Here, we examine how two key ecological functions that result from parrotfish feeding, bioerosion and substrate grazing, vary between habitats over a reef scale in the central Maldives. Eight distinct habitats were delineated in early 2015, prior to the 2016 bleaching event, each supporting a unique parrotfish assemblage. Bioerosion rates varied from 0 to 0.84 ± 0.12 kg m−2 yr−1 but were highest in the coral rubble-and Pocillopora spp.-dominated habitat. Grazing pressure also varied markedly between habitats but followed a different inter-habitat pattern from that of bioerosion, with different contributing species. Total parrotfish grazing pressure ranged from 0 to ~264 ± 16% available substrate grazed yr-1 in the branching Acropora spp.-dominated habitat. Despite the importance of these functions in influencing reef-scale physical structure and ecological health, the highest rates occurred over less than 30% of the platform area. The results presented here provide new insights into within-reef variability in parrotfish ecological functions and demonstrate the importance of considering how these interact to influence reef geo-ecology.
Abstract.
Yarlett R, Perry C, Wilson RW, Harborne A (2020). Interhabitat Variability in Parrotfish Bioerosion Rates and Grazing Pressure on an Indian Ocean Reef Platform (dataset).
Abstract:
Interhabitat Variability in Parrotfish Bioerosion Rates and Grazing Pressure on an Indian Ocean Reef Platform (dataset)
This is the dataset used for the Yarlett et al. (2020) article "Inter-Habitat Variability in Parrotfish Bioerosion Rates and Grazing Pressure on an Indian Ocean Reef Platform" published in Diversity."
Abstract.
Full text.
East HK, Perry CT, Beetham EP, Kench PS, Liang Y (2020). Modelling reef hydrodynamics and sediment mobility under sea level rise in atoll reef island systems. Global and Planetary Change, 192, 103196-103196.
Salter MA, Rodríguez-Martínez RE, Álvarez-Filip L, Jordán-Dahlgren E, Perry CT (2020). Pelagic Sargassum as an emerging vector of high rate carbonate sediment import to tropical Atlantic coastlines.
Global and Planetary Change,
195Abstract:
Pelagic Sargassum as an emerging vector of high rate carbonate sediment import to tropical Atlantic coastlines
Since 2011, pelagic Sargassum has inundated Caribbean, West African, and northern Brazilian shorelines in increasing volumes. These events are linked to the emergence of a major new Sargassum bloom region in the Atlantic Ocean, and annual high-volume Sargassum beachings are seemingly becoming an established norm. Resultant socio-economic and ecological implications are widespread and potentially serious, but an important question that has so far received no attention is whether these Sargassum inundations might represent a new source of carbonate sediment in affected coastal areas. This sediment derives from calcareous epiphyte communities that colonise Sargassum (e.g. bryozoans, serpulid worms, and red algae), and if volumetrically significant, may help to counteract aspects of Sargassum beachings thought to reduce sediment supply and decrease coastal stability. Here we determine the carbonate contents of Sargassum from coastal waters of the Mexican Caribbean. Integrating these with volumetric data on beached Sargassum, we then estimate total epiphytic carbonate import during 2018 at 11 sites along a 60 km section of the Quintana Roo coast, Mexico. Based on measured mean carbonate content of Sargassum (2.09% wet weight; 95% confidence interval [CI]: 1.83–2.32), and estimates of annual beached Sargassum (7.0 × 103 kg drained weight·m−1 of shoreline; 95% CI: 6.9–7.2), our findings indicate that Sargassum beachings in the Mexican Caribbean contributed an average of 179 kg CaCO3·m−1 of shoreline (95% CI: 173–185) in 2018: close to our upper estimate of seagrass epiphyte contributions (210 kg·m−1). Although quantitative data on Sargassum beachings from other locations are sparse, numerous media reports suggest the scale of these events is comparable for many exposed tropical Caribbean and Atlantic shorelines. This represents the first documentation of pelagic Sargassum as a major vector of coastal sediment import, the significance of which has likely only arisen since the onset of large-scale inundations in 2011.
Abstract.
Morgan KM, Perry CT, Arthur R, Williams HTP, Smithers SG (2020). Projections of coral cover and habitat change on turbid reefs under future sea-level rise.
Proceedings of the Royal Society B: Biological Sciences,
287(1929).
Abstract:
Projections of coral cover and habitat change on turbid reefs under future sea-level rise
Global sea-level rise (SLR) is projected to increase water depths above coral reefs. Although the impacts of climate disturbance events on coral cover and three-dimensional complexity are well documented, knowledge of how higher sea levels will influence future reef habitat extent and bioconstruction is limited. Here, we use 31 reef cores, coupled with detailed benthic ecological data, from turbid reefs on the central Great Barrier Reef, Australia, to model broad-scale changes in reef habitat following adjustments to reef geomorphology under different SLR scenarios. Model outputs show that modest increases in relative water depth above reefs (Representative Concentration Pathway (RCP) 4.5) over the next 100 years will increase the spatial extent of habitats with low coral cover and generic diversity. More severe SLR (RCP8.5) will completely submerge reef flats and move reef slope coral communities below the euphotic depth, despite the high vertical accretion rates that characterize these reefs. Our findings suggest adverse future trajectories associated with high emission climate scenarios which could threaten turbid reefs globally and their capacity to act as coral refugia from climate change.
Abstract.
Lange ID, Perry CT, Morgan KM, Roche R, Benkwitt CE, Graham NAJ (2020). Site-level variation in parrotfish grazing and bioerosion as a function of species-specific feeding metrics.
Diversity,
12(10), 1-16.
Abstract:
Site-level variation in parrotfish grazing and bioerosion as a function of species-specific feeding metrics
Parrotfish provide important ecological functions on coral reefs, including the provision of new settlement space through grazing and the generation of sediment through bioerosion of reef substrate. Estimating these functions at an ecosystem level depends on accurately quantifying the functional impact of individuals, yet parrotfish feeding metrics are only available for a limited range of sites, species and size classes. We quantified bite rates, proportion of bites leaving scars and scar sizes in situ for the dominant excavator (Cetoscarus ocellatus, Chlorurus strongylocephalus, Ch. sordidus) and scraper species (Scarus rubroviolaceus, S. frenatus, S. niger, S. tricolor, S. scaber, S. psittacus) in the central Indian Ocean. This includes the first record of scar frequencies and sizes for the latter three species. Bite rates varied with species and life phase and decreased with body size. The proportion of bites leaving scars and scar sizes differed among species and increased with body size. Species-level allometric relationships between body size and each of these feeding metrics were used to parameterize annual individual grazing and bioerosion rates which increase non-linearly with body size. Large individuals of C. ocellatus, Ch. strongylocephalus and S. rubroviolaceus can graze 200–400 m2 and erode >500 kg of reef substrate annually. Smaller species graze 1–100 m2 yr−1 and erode 0.2–30 kg yr−1. We used these individual functional rates to quantify community grazing and bioerosion levels at 15 sites across the Maldives and the Chagos Archipelago. Although parrotfish density was 2.6 times higher on Maldivian reefs, average grazing (3.9 ± 1.4 m2 m−2 reef yr−1) and bioerosion levels (3.1 ± 1.2 kg m−2 reef yr−1) were about 15% lower than in the Chagos Archipelago (4.5 ± 2.3 and 3.7 ± 3.0, respectively), due to the dominance of small species and individuals in the Maldives (90%
Abstract.
Lange ID, Perry CT, Morgan KM, Roche R, Benkwitt CE, Graham NAJ (2020). Site-level variation in parrotfish grazing and bioerosion as a function of species-specific feeding metrics (dataset).
Abstract:
Site-level variation in parrotfish grazing and bioerosion as a function of species-specific feeding metrics (dataset)
This is the dataset used for the Lange et al (2020) article "Site-level variation in parrotfish grazing and bioerosion as a function of species-specific feeding metrics" published in Diversity.
Abstract.
Full text.
Winter G, Storlazzi C, Vitousek S, van Dongeren A, McCall R, Hoeke R, Skirving W, Marra J, Reyns J, Aucan J, et al (2020). Steps to Develop Early Warning Systems and Future Scenarios of Storm Wave-Driven Flooding Along Coral Reef-Lined Coasts. Frontiers in Marine Science, 7
Molina-Hernández A, González-Barrios FJ, Perry CT, Álvarez-Filip L (2020). Two decades of carbonate budget change on shifted coral reef assemblages: Are these reefs being locked into low net budget states?: Caribbean reefs carbonate budget trends.
Proceedings of the Royal Society B: Biological Sciences,
287(1940).
Abstract:
Two decades of carbonate budget change on shifted coral reef assemblages: Are these reefs being locked into low net budget states?: Caribbean reefs carbonate budget trends
The ecology of coral reefs is rapidly shifting from historical baselines. One key-question is whether under these new, less favourable ecological conditions, coral reefs will be able to sustain key geo-ecological processes such as the capacity to accumulate carbonate structure. Here, we use data from 34 Caribbean reef sites to examine how the carbonate production, net erosion and net carbonate budgets, as well as the organisms underlying these processes, have changed over the past 15 years in the absence of further severe acute disturbances. We find that despite fundamental benthic ecological changes, these ecologically shifted coral assemblages have exhibited a modest but significant increase in their net carbonate budgets over the past 15 years. However, contrary to expectations this trend was driven by a decrease in erosion pressure, largely resulting from changes in the abundance and size-frequency distribution of parrotfishes, and not by an increase in rates of coral carbonate production. Although in the short term, the carbonate budgets seem to have benefitted marginally from reduced parrotfish erosion, the absence of these key substrate grazers, particularly of larger individuals, is unlikely to be conducive to reef recovery and will thus probably lock these reefs into low budget states.
Abstract.
2019
Lange ID, Perry CT (2019). Bleaching impacts on carbonate production in the Chagos Archipelago: influence of functional coral groups on carbonate budget trajectories.
Coral Reefs,
38(4), 619-624.
Abstract:
Bleaching impacts on carbonate production in the Chagos Archipelago: influence of functional coral groups on carbonate budget trajectories
Reefs in the remote Chagos Archipelago (central Indian Ocean) were severely affected by sea surface temperature warming and coral bleaching in 2015–2016. Here we assess the impacts of this event on community composition and reef carbonate production at twelve fore reefs sites across three atolls. Bleaching caused a 69% decline in coral cover, mostly driven by mortality of tabular Acropora spp. and a 77% decline in mean coral carbonate production (2015: 13.1 ± 4.8; 2018: 3.0 ± 1.2 kg CaCO3 m2 yr−1). Changes were accompanied by a major shift from competitive to stress-tolerant coral taxa, with magnitudes of decline comparable to those reported elsewhere in the Indian Ocean, despite inter-site differences in dominant coral species. These trends differ from those on reefs already dominated by stress-tolerant taxa, which experienced minor declines in production post-warming. The study highlights the potential for different suites of functional coral groups to drive divergent post-bleaching budget responses.
Abstract.
Salter MA, Perry CT, Smith AM (2019). Calcium carbonate production by fish in temperate marine environments.
Limnology and Oceanography,
64(6), 2755-2770.
Abstract:
Calcium carbonate production by fish in temperate marine environments
Marine bony fishes are an important source of calcium carbonate with relevance to sediment production and inorganic carbon cycling. However, knowledge of the production and fate of these carbonates is based primarily on data from warm-water reef fishes, with efforts to assess global-scale implications constrained by assumptions that this small cross section of the global fish community is widely representative. Here we test the extent to which temperature influences fish carbonate mineralogy and morphology by comparing products from temperate settings (20 species at temperatures spanning 10–18°C) against existing data (23–27°C). Overall, carbonate products were mineralogically, compositionally, and morphologically similar throughout the thermal range, and in most cases, we observed no differences within species (18 vs. 24°C) or families (10 vs. 25°C). Confirmation of within-family consistency over large thermal gradients is significant because: (1) it facilitates a substantial range expansion over which fish carbonate production models can be constructed, even where family-level product data are geographically limited; and (2) it implies that the solubility of products from any given fish family varies only due to local carbonate saturation states at excretion (and not crystallographic differences). The only exception was in two members of the Labridae (wrasses), which produced low-Mg calcite (LMC) and minor amorphous calcium–magnesium carbonate (ACMC) at 10°C; the inverse of products from confamilials at 25°C. This finding could have significant implications for understanding the role of fish carbonates globally because ACMC is a highly unstable carbonate polymorph, whereas LMC is very stable.
Abstract.
Perry CT, Salter MA, Morgan KM, Harborne AR (2019). Census estimates of algal and epiphytic carbonate production highlight tropical seagrass meadows as sediment production hotspots.
Frontiers in Marine Science,
6(APR).
Abstract:
Census estimates of algal and epiphytic carbonate production highlight tropical seagrass meadows as sediment production hotspots
Tropical shelf, platform and reef-lagoon systems are dominated by calcium carbonate (CaCO 3 ) sediments. However, data on habitat-specific CaCO 3 sediment production rates by different sediment producing taxa are sparse, limiting understanding of where and in what form CaCO 3 sediment is produced, and how overall sediment budgets are influenced by habitat type and scale. Using novel census methodologies, based primarily on measures of plant biovolumes and carbonate content, we assessed habitat-scale production by two ubiquitous biogenic CaCO 3 sediment producers, calcareous green algae and seagrass epiphytes, across southern Eleuthera Bank, Bahamas (area -140 km 2 ). Data from species-specific plant disaggregation experiments and from X-ray diffraction (XRD) analysis of calcified plants also allowed us to resolve questions about the size fractions and mineralogies of the carbonates produced. Production rates varied significantly among habitats (range: 1.8-237.3 g CaCO 3 m -2 yr -1 ), collectively totaling -0.98 M kg annually across the study area. Outputs comprise similar amounts of aragonite and high Mg-calcite, with -54% of the CaCO 3 produced being contributed as mud-grade (
Abstract.
Perry CT, Alvarez-Filip L (2019). Changing geo-ecological functions of coral reefs in the Anthropocene.
Functional Ecology,
33(6), 976-988.
Abstract:
Changing geo-ecological functions of coral reefs in the Anthropocene
The ecology of many coral reefs has changed markedly over recent decades in response to various combinations of local and global stressors. These ecological changes have important implications for the abundance of taxa that regulate the production and erosion of skeletal carbonates, and thus for many of the geo-ecological functions that coral reefs provide, including reef framework production and sediment generation, the maintenance of reef habitat complexity and reef growth potential. These functional attributes underpin many of the ecosystem goods and services that reefs provide to society. Rapidly changing conditions of reefs in the Anthropocene are likely to significantly impact the capacity of reefs to sustain these geo-ecological functions. Although the Anthropocene footprint of disturbance will be expressed differently across ecoregions and habitats, the end point for many reefs may be broadly similar: (a) progressively shifting towards net neutral or negative carbonate budget states; (b) becoming structurally flatter; and (c) having lower vertical growth rates. It is also likely that a progressive depth-homogenisation will occur in terms of these processes. The Anthropocene is likely to be defined by an increasing disconnect between the ecological processes that drive carbonate production on the reef surface, and the net geological outcome of that production, that is, the accumulation of the underlying reef structure. Reef structures are thus likely to become increasingly relict or senescent features, which will reduce reef habitat complexity and sediment generation rates, and limit reef potential to accrete vertically at rates that can track rising sea levels. In the absence of pervasive stressors, recovery of degraded coral communities has been observed, resulting in high net-positive budgets being regained. However, the frequency and intensity of climate-driven bleaching events are predicted to increase over the next decades. This would increase the spatial footprint of disturbances and exacerbate the magnitude of the changes described here, limiting the capacity of many reefs to maintain their geo-ecological functions. The enforcement of effective marine protection or the benefits of geographic isolation or of favourable environmental conditions (“refugia” sites) may offer the hope of more optimistic futures in some locations. A >plain language summary is available for this article.
Abstract.
Husband E (2019). Coral Colony-Scale Rugosity Metrics and Applications for Assessing Temporal Trends in the Structural Complexity of Coral Reefs.
Abstract:
Coral Colony-Scale Rugosity Metrics and Applications for Assessing Temporal Trends in the Structural Complexity of Coral Reefs.
Globally, coral reefs are experiencing reductions in structural complexity, primarily due to a loss of key reef building taxa. Monitoring these changes is difficult due to the time-consuming nature of in-situ measurements and lack of data concerning coral genus-specific contributions to reef structure. This research aimed to develop a new technique that uses coral colony level data to quantify reef rugosity (a 3-dimensional measure of reef structure) from three sources of coral survey data: 2D video imagery, line intercept data and UAV imagery. A database of coral colony rugosity data, comparing coral colony planar and contour length for 40 coral genera, 14 morphotypes and 9 abiotic reef substrates, was created using measurements from the Great Barrier Reef and Natural History Museum. Mean genus rugosity was identified as a key trait related to coral life history strategy. Linear regression analyses (y = mx) revealed statistically significant (p < 0.05) relationships between coral colony size and rugosity for every coral genus, morphotype and substrate. The gradient governing these relationships was unique for each coral taxa, ranging from mean = 1.23, for (encrusting) Acanthastrea, to m = 3.84, for (vase-shape) Merulina. These gradients were used as conversion factors to calculate reef rugosity from linear distances measured in video transects of both artificial reefs, used as a control test, and in-situ natural coral reefs, using Kinovea software. This calculated, ‘virtual’ rugosity had a strong, positive relationship with in-situ microscale rugosity (r2 = 0.96) measured from the control transects, but not with that measured at the meso-scale in natural, highly heterogeneous reef environments (r2 < 0.2). This showed that the technique can provide accurate rugosity information when considered at the coral colony level. The conversion factors were also applied to historic line intercept data from the Seychelles, where temporal changes in calculated rugosity were consistent with changes in coral cover between 2008 and 2017. Finally, on application to 2,283 corals digitised from UAV imagery of the Maldives, the conversion factors enabled calculation of rugosity for three 100 m2 reef areas and prediction of how this rugosity will decrease during two future scenarios of coral reef degradation and community change. The study highlights that the application of genera-specific coral rugosity data to both new and existing coral reef survey datasets could be a valuable tool for monitoring reef structural complexity over large spatial scales.
Abstract.
Full text.
de Bakker DM, van Duyl FC, Perry CT, Meesters EH (2019). Extreme spatial heterogeneity in carbonate accretion potential on a Caribbean fringing reef linked to local human disturbance gradients.
Global Change Biology,
25(12), 4092-4104.
Abstract:
Extreme spatial heterogeneity in carbonate accretion potential on a Caribbean fringing reef linked to local human disturbance gradients
The capacity of coral reefs to maintain their structurally complex frameworks and to retain the potential for vertical accretion is vitally important to the persistence of their ecological functioning and the ecosystem services they sustain. However, datasets to support detailed along-coast assessments of framework production rates and accretion potential do not presently exist. Here, we estimate, based on gross bioaccretion and bioerosion measures, the carbonate budgets and resultant estimated accretion rates (EAR) of the shallow reef zone of leeward Bonaire – between 5 and 12 m depth – at unique fine spatial resolution along this coast (115 sites). Whilst the fringing reef of Bonaire is often reported to be in a better ecological condition than most sites throughout the wider Caribbean region, our data show that the carbonate budgets of the reefs and derived EAR varied considerably across this ~58 km long fringing reef complex. Some areas, in particular the marine reserves, were indeed still dominated by structurally complex coral communities with high net carbonate production (>10 kg CaCO3 m−2 year−1), high live coral cover and complex structural topography. The majority of the studied sites, however, were defined by relatively low budget states (
Abstract.
Estrada-Saldívar N, Jordán-Dalhgren E, Rodríguez-Martínez RE, Perry C, Alvarez-Filip L (2019). Functional consequences of the long-term decline of reef-building corals in the Caribbean: evidence of across-reef functional convergence.
Royal Society Open Science,
6(10), 190298-190298.
Abstract:
Functional consequences of the long-term decline of reef-building corals in the Caribbean: evidence of across-reef functional convergence
Functional integrity on coral reefs is strongly dependent upon coral cover and coral carbonate production rate being sufficient to maintain three-dimensional reef structures. Increasing environmental and anthropogenic pressures in recent decades have reduced the cover of key reef-building species, producing a shift towards the relative dominance of more stress-tolerant taxa and leading to a reduction in the physical functional integrity. Understanding how changes in coral community composition influence the potential of reefs to maintain their physical reef functioning is a priority for their conservation and management. Here, we evaluate how coral communities have changed in the northern sector of the Mexican Caribbean between 1985 and 2016, and the implications for the maintenance of physical reef functions in the back- and fore-reef zones. We used the cover of coral species to explore changes in four morpho-functional groups, coral community composition, coral community calcification, the reef functional index and the reef carbonate budget. Over a period of 31 years, ecological homogenization occurred between the two reef zones mostly due to a reduction in the cover of framework-building branching (Acroporaspp.) and foliose-digitiform (Porites poritesandAgaricia tenuifolia) coral species in the back-reef, and a relative increase in non-framework species in the fore-reef (Agaricia agaricitesandPorites astreoides). This resulted in a significant decrease in the physical functionality of the back-reef zone. At present, both reef zones have negative carbonate budgets, and thus limited capacity to sustain reef accretion, compromising the existing reef structure and its future capacity to provide habitat and environmental services.
Abstract.
Johnson JA, Perry CT, Smithers SG, Morgan KM, Woodroffe SA (2019). Reef shallowing is a critical control on benthic foraminiferal assemblage composition on nearshore turbid coral reefs. Palaeogeography, Palaeoclimatology, Palaeoecology, 533, 109240-109240.
2018
Yarlett RT, Perry CT, Wilson RW, Philpot KE (2018). Constraining species-size class variability in rates of parrotfish bioerosion on Maldivian coral reefs: Implications for regional-scale bioerosion estimates.
Marine Ecology Progress Series,
590, 155-169.
Abstract:
Constraining species-size class variability in rates of parrotfish bioerosion on Maldivian coral reefs: Implications for regional-scale bioerosion estimates
Parrotfish are important bioeroders on coral reefs, and thus influence reef carbonate budgets and generate large volumes of carbonate sand that contribute to local beach and reef island maintenance. However, despite the importance of this process, there is a paucity of data with which variations in bioerosion rates as a function of species, feeding modes, and body size of parrotfish can be constrained. There is, in addition, limited knowledge regarding how resultant rates may vary within and between reef-building regions. Here, direct estimates of parrotfish bioerosion rates were quantified across different size classes of 6 common species of Maldivian parrotfish. These species comprise both 'scraper' and 'excavator' taxa, and our data indicate marked variations in mean bioerosion rates among these species. We also note that all species exhibited an apparent bimodal feeding cycle, with peaks in the late morning and early afternoon. Highest bioerosion rates were found in the 'excavator' Chlorurus strongylocephalus (∼460 kg ind.-1 yr-1), nearly 130 times greater than rates calculated for comparably sized (>45 cm) 'scraper' species. Our data provide metrics that can be used in conjunction with parrotfish biomass or density data to improve estimates of parrotfish bioerosion on central Indian Ocean reefs, a region of high parrotfish density, but from which only limited metrics exist. We emphasise the importance of obtaining sub-regional scale process data to better inform estimates of reef bioerosion, especially to support attempts to model the impacts of fishing pressure, which commonly results in removal of high-rate bioeroding taxa.
Abstract.
Yarlett RT, Perry CT, Wilson RW, Philpot KE (2018). Constraining species-size class variability in rates of parrotfish bioerosion on Maldivian coral reefs: implications for regional-scale bioerosion estimates (article).
Marine Ecology Progress Series,
590, 155-169.
Abstract:
Constraining species-size class variability in rates of parrotfish bioerosion on Maldivian coral reefs: implications for regional-scale bioerosion estimates (article)
Parrotfish are important bioeroders on coral reefs, and thus influence reef carbonate budgets and generate large volumes of carbonate sand that contribute to local beach and reef island maintenance. However, despite the importance of this process, there is a paucity of data with which variations in bioerosion rates as a function of species, feeding modes, and body size of parrotfish can be constrained. There is, in addition, limited knowledge regarding how resultant rates may vary within and between reef-building regions. Here, direct estimates of parrotfish bioerosion rates were quantified across different size classes of 6 common species of Maldivian parrotfish. These species comprise both ‘scraper’ and ‘excavator’ taxa, and our data indicate marked variations in mean bioerosion rates among these species. We also note that all species exhibited an apparent bimodal feeding cycle, with peaks in the late morning and early afternoon. Highest bioerosion rates were found in the ‘excavator’ Chlorurus strongylocephalus (~460 kg ind.-1 yr-1), nearly 130 times greater than rates calculated for comparably sized (>45 cm) ‘scraper’ species. Our data provide metrics that can be used in conjunction with parrotfish biomass or density data to improve estimates of parrotfish bioerosion on central Indian Ocean reefs, a region of high parrotfish density, but from which only limited metrics exist. We emphasise the importance of obtaining sub-regional scale process data to better inform estimates of reef bioerosion, especially to support attempts to model the impacts of fishing pressure, which commonly results in removal of high-rate bioeroding taxa.
Abstract.
Full text.
East HK, Perry CT, Kench PS, Liang Y, Gulliver P (2018). Coral Reef Island Initiation and Development Under Higher Than Present Sea Levels.
Geophysical Research Letters,
45(20), 11-274.
Abstract:
Coral Reef Island Initiation and Development Under Higher Than Present Sea Levels
Coral reef islands are considered to be among the most vulnerable environments to future sea level rise. However, emerging data suggest that different island types, in contrasting locations, have formed under different conditions in relation to past sea level. Uniform assumptions about reef island futures under sea level rise may thus be inappropriate. Using chronostratigraphic analysis from atoll rim islands (sand- and gravel-based) in the southern Maldives, we show that while island building initiated at different times around the atoll (~2,800 and ~4,200 calibrated years before present at windward and leeward rim sites, respectively), higher than present sea levels and associated high-energy wave events were actually critical to island initiation. Findings thus suggest that projected sea level rise and increases in the magnitude of distal high-energy wave events could reactivate this process regime, which, if there is an appropriate sediment supply, may facilitate further vertical reef island building.
Abstract.
Perry CT, Alvarez-Filip L, Graham NAJ, Mumby PJ, Wilson SK, Kench PS, Manzello DP, Morgan KM, Slangen ABA, Thomson DP, et al (2018). Loss of coral reef growth capacity to track future increases in sea level.
Nature,
558(7710), 396-400.
Abstract:
Loss of coral reef growth capacity to track future increases in sea level
Sea-level rise (SLR) is predicted to elevate water depths above coral reefs and to increase coastal wave exposure as ecological degradation limits vertical reef growth, but projections lack data on interactions between local rates of reef growth and sea level rise. Here we calculate the vertical growth potential of more than 200 tropical western Atlantic and Indian Ocean reefs, and compare these against recent and projected rates of SLR under different Representative Concentration Pathway (RCP) scenarios. Although many reefs retain accretion rates close to recent SLR trends, few will have the capacity to track SLR projections under RCP4.5 scenarios without sustained ecological recovery, and under RCP8.5 scenarios most reefs are predicted to experience mean water depth increases of more than 0.5 m by 2100. Coral cover strongly predicts reef capacity to track SLR, but threshold cover levels that will be necessary to prevent submergence are well above those observed on most reefs. Urgent action is thus needed to mitigate climate, sea-level and future ecological changes in order to limit the magnitude of future reef submergence.
Abstract.
Yarlett R, Perry C (2018). Parrotfish bite rates.
Abstract:
Parrotfish bite rates
Raw field data
Abstract.
Salter MA, Perry CT, Stuart-Smith RD, Edgar GJ, Wilson RW, Harborne AR (2018). Reef fish carbonate production assessments highlight regional variation in sedimentary significance.
Geology,
46(8), 699-702.
Abstract:
Reef fish carbonate production assessments highlight regional variation in sedimentary significance
Recent studies show that all marine bony fish produce mud-sized (< 63 μm) carbonate at rates relevant to carbonate sediment budgets, thus adding to the debate about the often enigmatic origins of finegrained marine carbonates. However, existing production data are geographically and taxonomically limited, and because different fish families are now known to produce different carbonate polymorphs- an issue relevant to predicting their preservation potential-these limitations represent an important knowledge gap. Here we present new data from sites in the Western Pacific Ocean, based on an analysis of 45 fish species. Our data show that previously reported production outputs (in terms of rates and family-specific mineralogies) are applicable across different biogeographic regions. On this basis, we model carbonate production for nine coral reef systems around Australia, with production rates averaging 2.1-9.6 g m-2 yr-1, and up to 105 g m-2 yr-1 at discrete sites with high fish biomass. With projected production rates on lower-latitude reefs up to two-fold higher, these outputs indicate that carbonate production rates by fish can be comparable with other fine-grained carbonate-producing taxa such as codiacean algae. However, carbonates produced by Australian reef fish assemblages are dominated by a highly unstable amorphous polymorph; a marked contrast to Caribbean assemblages in which Mg calcite dominates. These findings highlight important regional differences in the sedimentary relevance and preservation potential of fish carbonates as a function of historical biogeographic processes that have shaped the world's marine fish faunas.
Abstract.
Salter MA, Perry C, Stuart-Smith RD, Edgar GJ, Wilson R, Harborne AR (2018). Reef fish carbonate production assessments highlight regional variation in sedimentary significance (dataset).
Abstract:
Reef fish carbonate production assessments highlight regional variation in sedimentary significance (dataset)
This is the dataset used for the Salter et al. (2018) article "Reef fish carbonate production assessments highlight regional variation in sedimentary significance" published in the Geology journal.
Abstract.
Full text.
2017
Perry CT, Morgan KM (2017). Bleaching drives collapse in reef carbonate budgets and reef growth potential on southern Maldives reefs.
Scientific Reports,
7Abstract:
Bleaching drives collapse in reef carbonate budgets and reef growth potential on southern Maldives reefs
Sea-surface temperature (SST) warming events, which are projected to increase in frequency and intensity with climate change, represent major threats to coral reefs. How these events impact reef carbonate budgets, and thus the capacity of reefs to sustain vertical growth under rising sea levels, remains poorly quantified. Here we quantify the magnitude of changes that followed the ENSO-induced SST warming that affected the Indian Ocean region in mid-2016. Resultant coral bleaching caused an average 75% reduction in coral cover (present mean 6.2%). Most critically we report major declines in shallow fore-reef carbonate budgets, these shifting from strongly net positive (mean 5.92 G, where G = kg CaCO 3 m â '2 yr â '1) to strongly net negative (mean â '2.96 G). These changes have driven major reductions in reef growth potential, which have declined from an average 4.2 to â '0.4 mm yr â '1. Thus these shallow fore-reef habitats are now in a phase of net erosion. Based on past bleaching recovery trajectories, and predicted increases in bleaching frequency, we predict a prolonged period of suppressed budget and reef growth states. This will limit reef capacity to track IPCC projections of sea-level rise, thus limiting the natural breakwater capacity of these reefs and threatening reef island stability.
Abstract.
Januchowski-Hartley FA, Graham NAJ, Wilson SK, Jennings S, Perry CT (2017). Drivers and predictions of coral reef carbonate budget trajectories.
Proceedings of the Royal Society B: Biological Sciences,
284(1847), 20162533-20162533.
Abstract:
Drivers and predictions of coral reef carbonate budget trajectories
Climate change is one of the greatest threats to the long-term maintenance of coral-dominated tropical ecosystems, and has received considerable attention over the past two decades. Coral bleaching and associated mortality events, which are predicted to become more frequent and intense, can alter the balance of different elements that are responsible for coral reef growth and maintenance. The geomorphic impacts of coral mass mortality have received relatively little attention, particularly questions concerning temporal recovery of reef carbonate production and the factors that promote resilience of reef growth potential. Here, we track the biological carbonate budgets of inner Seychelles reefs from 1994 to 2014, spanning the 1998 global bleaching event when these reefs lost more than 90% of coral cover. All 21 reefs had positive budgets in 1994, but in 2005 budgets were predominantly negative. By 2014, carbonate budgets on seven reefs were comparable with 1994, but on all reefs where an ecological regime shift to macroalgal dominance occurred, budgets remained negative through 2014. Reefs with higher massive coral cover, lower macroalgae cover and lower excavating parrotfish biomass in 1994 were more likely to have positive budgets post-bleaching. If mortality of corals from the 2016 bleaching event is as severe as that of 1998, our predictions based on past trends would suggest that six of eight reefs with positive budgets in 2014 would still have positive budgets by 2030. Our results highlight that reef accretion and framework maintenance cannot be assumed from the ecological state alone, and that managers should focus on conserving aspects of coral reefs that support resilient carbonate budgets.
Abstract.
Morgan KM, Perry CT, Johnson JA, Smithers SG (2017). Nearshore turbid-zone corals exhibit high bleaching tolerance on the Great Barrier Reef following the 2016 ocean warming event.
Frontiers in Marine Science,
4(JUL).
Abstract:
Nearshore turbid-zone corals exhibit high bleaching tolerance on the Great Barrier Reef following the 2016 ocean warming event
High sea surface temperatures (SSTs) on the Great Barrier Reef (GBR) during summer 2015/2016 caused extensive coral bleaching, with aerial and in-water surveys confirming high (but variable) bleaching-related coral mortality. In contrast, bleaching impacts on nearshore turbid-zone reefs, traditionally considered more "marginal" coral habitats, remain poorly documented. This is because rapid ecological surveys are difficult in these turbid water settings, and baseline coral community data from which to quantify disturbance are rare. However, models suggest that the extreme environmental conditions characteristic of nearshore settings (e.g. fluctuating turbidity, light, and temperature) may acclimate corals to the thermal anomalies associated with bleaching on offshore reefs, although validation by field evidence has to-date been sparse. Here we present a novel pre- (June 2013/2014) and post-warming (August 2016) assessment of turbid-zone coral communities and examine the response of corals to prolonged and acute heat stress within the Paluma Shoals reef complex, located on the central GBR. Our analysis of 2,288 still video frames (~1,200 m2) which include 11,374 coral colonies (24 coral genera) suggest a high tolerance of turbid-zone corals to bleaching, with no significant changes in coral cover (pre: 48 ± 20%; post: 55 ± 26%) or coral community structure (e.g.Acropora, Montipora, Turbinaria, Porites) following the warming event. Indeed, only one coral colony (Lobophyllia sp.) exhibited full colony bleaching, and just 1.5% of colonies displayed partial pigmentation loss (
Abstract.
Johnson JA, Perry CT, Smithers SG, Morgan KM, Santodomingo N, Johnson KG (2017). Palaeoecological records of coral community development on a turbid, nearshore reef complex: baselines for assessing ecological change.
Coral Reefs,
36(3), 685-700.
Abstract:
Palaeoecological records of coral community development on a turbid, nearshore reef complex: baselines for assessing ecological change
Understanding past coral community development and reef growth is crucial for placing contemporary ecological and environmental change within appropriate reef-building timescales. On Australia’s Great Barrier Reef (GBR), coral reefs situated within coastal inner-shelf zones are a particular priority. This is due to their close proximity to river point sources, and therefore susceptibility to reduced water quality discharged from coastal catchments, many of which have been modified following European settlement (ca. 1850 AD). However, the extent of water-quality decline and its impacts on the GBR’s inner-shelf reefs remain contentious. In this study, palaeoecological coral assemblage records were developed for five proximal coral reefs situated within a nearshore turbid-zone reef complex on the central GBR. A total of 29 genera of Scleractinia were identified from the palaeoecological inventory of the reef complex, with key contributions to reef-building made by Acropora, Montipora, and Turbinaria. Discrete intervals pre- and post-dating European settlement, but associated with equivalent water depths, were identified using Bayesian age–depth modelling, enabling investigation of competing ideas of the main drivers of nearshore coral assemblage change. Specifically, we tested the hypotheses that changes in the composition of nearshore coral assemblages are: (1) intrinsically driven and linked to vertical reef development towards sea level, and (2) the result of changes in water quality associated with coastal river catchment modification. Our records found no discernible evidence of change in the generic composition of coral assemblages relative to European settlement. Instead, two distinctive depth-stratified assemblages were identified. This study demonstrates the robust nature of nearshore coral communities under reported water-quality decline and provides a useful context for the monitoring and assessment of ecological change on reefs located within the most nearshore turbid-zone environments of the central GBR.
Abstract.
Salter MA, Harborne AR, Perry CT, Wilson RW (2017). Phase heterogeneity in carbonate production by marine fish influences their roles in sediment generation and the inorganic carbon cycle.
Scientific Reports,
7(1).
Abstract:
Phase heterogeneity in carbonate production by marine fish influences their roles in sediment generation and the inorganic carbon cycle
Marine teleost fish are important carbonate producers in neritic and oceanic settings. However, the fates of the diverse carbonate phases (i.e. mineral and amorphous forms of CaCO3) they produce, and their roles in sediment production and marine inorganic carbon cycling, remain poorly understood. Here we quantify the carbonate phases produced by 22 Bahamian fish species and integrate these data with regional fish biomass data from the Bahamas to generate a novel platform-scale production model that resolves these phases. Overall carbonate phase proportions, ordered by decreasing phase stability, are: ∼20% calcite, ∼6% aragonite, ∼60% high-Mg calcite, and ∼14% amorphous carbonate. We predict that these phases undergo differing fates, with at least ∼14% (amorphous carbonate) likely dissolving rapidly. Results further indicate that fisheries exploitation in the Bahamas has potentially reduced fish carbonate production by up to 58% in certain habitats, whilst also driving a deviation from natural phase proportions. These findings have evident implications for understanding sedimentary processes in shallow warm-water carbonate provinces. We further speculate that marked phase heterogeneity may be a hitherto unrecognised feature of fish carbonates across a wide range of neritic and oceanic settings, with potentially major implications for understanding their role in global marine inorganic carbon cycling.
Abstract.
Perry CT, Morgan KM (2017). Post-bleaching coral community change on southern Maldivian reefs: is there potential for rapid recovery?.
Coral Reefs,
36(4), 1189-1194.
Abstract:
Post-bleaching coral community change on southern Maldivian reefs: is there potential for rapid recovery?
Given the severity of the 2016 global bleaching event, there are major questions about how quickly reef communities will recover. Here, we explore the ecological and physical structural changes that occurred across five atoll interior reefs in the southern Maldives using data collected at 6 and 12 months post-bleaching. Following initial severe coral mortality, further minor coral mortality had occurred by 12 months post-bleaching, and coral cover is now low (
Abstract.
Perry CT, Morgan KM, Yarlett RT (2017). Reef habitat type and spatial extent as interacting controls on platform-scale carbonate budgets.
Frontiers in Marine Science,
4(JUN).
Abstract:
Reef habitat type and spatial extent as interacting controls on platform-scale carbonate budgets
A coral reefs carbonate budget strongly influences reef structural complexity and net reef growth potential, and thus is increasingly recognized as a key "health" metric. Despite this, understanding of habitat specific budget states, how these scale across reef platforms, and our ability to quantify both framework and sediment production values remains limited. Here, we use in-situ census data from an atoll rim reef platform in the central Maldives to quantify rates of both reef framework and sediment production and loss within different platform habitats, and then combine these data with high-resolution habitat maps to quantify contributions to platform wide carbonate budgets. The net reef framework budget for the entire platform is extremely low (0.12 G, where G = Kg CaCO3 m-2 year-1), with a very high proportion (143,745 kg or 65.1%) of total framework production generated within the platform margin reef zones, despite these comprising only ~8% of platform area. Net platform-scale sediment budgets are higher (1.04 G), but most is produced in the reef and platform margin hardground habitats, of which ~80% derives from parrotfish bioerosion. Significant quantities of new sediment (up to ~1 G derived from the calcareous green algae Halimeda) are produced only in one habitat. All lagoonal habitats have negative or neutral net carbonate budgets. These data demonstrate the marked inter-habitat differences in reef carbonate budgets that occur across reef platforms, and the major dampening effect on overall platform scale budgets when rates are factored for habitat type and size. Furthermore, the data highlights the disproportionately important role that relatively small areas of reef habitat can have on the maintenance of net positive platform scale budgets. Because of the intrinsic link between carbonate production rates and reef-associated landform development and maintenance, these findings also have implications for understanding reef-associated landform stability. In this context the reef island at this site has been highly mobile over the last ~40 years, and we hypothesize that such instability may be being exacerbated by the measured low overall rates of framework and sediment generation.
Abstract.
Perry C, Kench P, Smithers S, Riegl B, Gulliver P, Daniells J (2017). Terrigenous sediment-dominated reef platform infilling: an unexpected precursor to reef island formation and a test of the reef platform size–island age model in the Pacific.
Coral Reefs,
36(3), 1013-1021.
Abstract:
Terrigenous sediment-dominated reef platform infilling: an unexpected precursor to reef island formation and a test of the reef platform size–island age model in the Pacific
Low-lying coral reef islands are considered highly vulnerable to climate change, necessitating an improved understanding of when and why they form, and how the timing of formation varies within and among regions. Several testable models have been proposed that explain inter-regional variability as a function of sea-level history and, more recently, a reef platform size model has been proposed from the Maldives (central Indian Ocean) to explain intra-regional (intra-atoll) variability. Here we present chronostratigraphic data from Pipon Island, northern Great Barrier Reef (GBR), enabling us to test the applicability of existing regional island evolution models, and the platform size control hypothesis in a Pacific context. We show that reef platform infilling occurred rapidly (~4–5 mm yr−1) under a “bucket-fill” type scenario. Unusually, this infilling was dominated by terrigenous sedimentation, with platform filling and subsequent reef flat formation complete by ~5000 calibrated years BP (cal BP). Reef flat exposure as sea levels slowly fell post highstand facilitated a shift towards intertidal and subaerial-dominated sedimentation. Our data suggest, however, a lag of ~1500 yr before island initiation (at ~3200 cal BP), i.e. later than that reported from smaller and more evolutionarily mature reef platforms in the region. Our data thus support: (1) the hypothesis that platform size acts to influence the timing of platform filling and subsequent island development at intra-regional scales; and (2) the hypothesis that the low wooded islands of the northern GBR conform to a model of island formation above an elevated reef flat under falling sea levels.
Abstract.
2016
East HK, Perry CT, Kench PS, Liang Y (2016). Atoll-scale comparisons of the sedimentary structure of coral reef rim islands, Huvadhu Atoll, Maldives.
Journal of Coastal Research,
1(75), 577-581.
Abstract:
Atoll-scale comparisons of the sedimentary structure of coral reef rim islands, Huvadhu Atoll, Maldives
Maldivian coral reef rim islands host the majority of the nation's population, land area and infrastructure. However, understanding of the controls on rim island development and their accretionary histories is poor. Here, we present the first detailed sedimentary study of Maldivian rim islands through analyses of core logs from windward and leeward sites around Huvadhu Atoll. Island composition was dominated by a very restricted range of grain producers, with sediment dominated by coral (76.6 ± 0.6%). Material was predominantly rubble and sand-sized, the former likely generated by low-frequency high-magnitude events and the latter as a by-product of parrotfish grazing. While consistencies were found between windward and leeward sites, we highlight intra-regional diversity in reef island development at the scale of an individual atoll.
Abstract.
Perry CT, Harborne AR (2016). Bioerosion on Modern Reefs: Impacts and Responses Under Changing Ecological and Environmental Conditions. In (Ed) Coral Reefs of the World, Springer Netherlands, 69-101.
Daw TM, Hicks CC, Brown K, Chaigneau T, Januchowski-Hartley FA, Cheung WWL, Rosendo S, Crona B, Coulthard S, Sandbrook C, et al (2016). Elasticity in ecosystem services: Exploring the variable relationship between ecosystems and human well-being.
Ecology and Society,
21(2).
Abstract:
Elasticity in ecosystem services: Exploring the variable relationship between ecosystems and human well-being
Although ecosystem services are increasingly recognized as benefits people obtain from nature, we still have a poor understanding of how they actually enhance multidimensional human well-being, and how well-being is affected by ecosystem change. We develop a concept of “ecosystem service elasticity” (ES elasticity) that describes the sensitivity of human well-being to changes in ecosystems. ES Elasticity is a result of complex social and ecological dynamics and is context dependent, individually variable, and likely to demonstrate nonlinear dynamics such as thresholds and hysteresis. We present a conceptual framework that unpacks the chain of causality from ecosystem stocks through flows, goods, value, and shares to contribute to the well-being of different people. This framework builds on previous conceptualizations, but places multidimensional well-being of different people as the final element. This ultimately disaggregated approach emphasizes how different people access benefits and how benefits match their needs or aspirations. Applying this framework to case studies of individual coastal ecosystem services in East Africa illustrates a wide range of social and ecological factors that can affect ES elasticity. For example, food web and habitat dynamics affect the sensitivity of different fisheries ecosystem services to ecological change. Meanwhile high cultural significance, or lack of alternatives enhance ES elasticity, while social mechanisms that prevent access can reduce elasticity. Mapping out how chains are interlinked illustrates how different types of value and the well-being of different people are linked to each other and to common ecological stocks. We suggest that examining chains for individual ecosystem services can suggest potential interventions aimed at poverty alleviation and sustainable ecosystems while mapping out of interlinkages between chains can help to identify possible ecosystem service trade-offs and winners and losers. We discuss conceptual and practical challenges of applying such a framework and conclude on its utility as a heuristic for structuring interdisciplinary analysis of ecosystem services and human wellbeing.
Abstract.
Morgan KM, Perry CT, Smithers SG, Johnson JA, Daniell JJ (2016). Evidence of extensive reef development and high coral cover in nearshore environments: Implications for understanding coral adaptation in turbid settings.
Scientific Reports,
6Abstract:
Evidence of extensive reef development and high coral cover in nearshore environments: Implications for understanding coral adaptation in turbid settings
Mean coral cover has reportedly declined by over 15% during the last 30 years across the central Great Barrier Reef (GBR). Here, we present new data that documents widespread reef development within the more poorly studied turbid nearshore areas (30 m) mesophotic equivalents and may have similar potential as refugia from large-scale disturbances.
Abstract.
Murphy GN, Perry CT, Chin P, McCoy C (2016). New approaches to quantifying bioerosion by endolithic sponge populations: applications to the coral reefs of Grand Cayman. Coral Reefs, 35(3), 1109-1121.
Perry CT, Morgan KM, Salter MA (2016). Sediment generation by Halimeda on atoll interior coral reefs of the southern Maldives: a census-based approach for estimating carbonate production by calcareous green algae.
Sedimentary Geology,
346, 17-24.
Abstract:
Sediment generation by Halimeda on atoll interior coral reefs of the southern Maldives: a census-based approach for estimating carbonate production by calcareous green algae
Methods for quantifying rates and size fractions of carbonate sand production on reefs remain limited, despite the urgent need for such data to support assessments of reef island and tropical beach-dominated shoreline resilience. Here we present a census-based approach that supports estimates of sediment generation by the calcareous green alga Halimeda spp. which is an often conspicuous reef and lagoon substrate coloniser. Based on data from Kandahalagala (South Huvadhoo atoll, southern Maldives), we present carbonate sediment production data for the two dominant Halimeda spp. (Halimeda macrophysa and Halimeda micronesica) that occur on the reef flat and reef slope habitats. Whilst total mean production rates by Halimeda spp. are similar in both habitats (reef flat average, 67.49 g CaCO3 m− 2 yr− 1; reef slope, 70.89 g), individual species contributions differ markedly. H. micronesica dominates on the reef flat (annual mean 41.91 g CaCO3 m− 2 yr− 1, compared to 25.08 g by H. macrophysa), whilst production is dominated by H. macrophysa on the reef slope (H. macrophysa 40.49 g, H. micronesica 29.01 g CaCO3 m− 2 yr− 1,). In terms of sediment generation we show that these species also contribute very differently to the sediment reservoir. Whilst the sedimentary breakdown products from H. micronesica are somewhat bimodal (~ 17% is in the medium to very coarse sand fraction, and ~ 76% in the silt and clay fraction), almost all (> 90%) of the segments produced by H. macrophysa rapidly degrade to silt and clay sized sediment. Based on our census data this suggests that Halimeda spp. will contribute only between 7 and 9 g m− 2 yr− 1 of sand grade sediment on the reef flat and shallow slope habitats, but ~ 55–60 g m− 2 yr− 1 of mud grade sediment. Scaled to the total area of combined reef habitat around Kandahalagala (~ 130,583 m2) this equates to Halimeda spp. producing ~ 2192 kg of sand-grade sediment, but ~ 15,181 kg of mud-grade sediment per year. However, sediment compositional data suggests that Halimeda sp. are actually a very minor constituent of reef and islands sediments, especially in the fine sediment fractions. This 1) suggests that much of the predominantly finer-grained sediment generated by Halimeda has little actual relevance to the later stages of reef island development, and 2) highlights the potential for marked discrepancies in terms of sediment generating reef species abundance and resultant sediment generation rates, especially in terms of the types and sizes of sediment that are appropriate to supply adjacent beaches and islands.
Abstract.
Morgan KM, Perry CT, Smithers SG, Johnson JA, Gulliver P (2016). Transitions in coral reef accretion rates linked to intrinsic ecological shifts on turbid-zone nearshore reefs.
Geology,
44(12), 995-998.
Abstract:
Transitions in coral reef accretion rates linked to intrinsic ecological shifts on turbid-zone nearshore reefs
Nearshore coral communities within turbid settings are typically perceived to have limited reef-building capacity. However, several recent studies have reported reef growth over millennial time scales within such environments and have hypothesized that depth-variable community assemblages may act as equally important controls on reef growth as they do in clear-water settings. Here, we explicitly test this idea using a newly compiled chronostratigraphic record (31 cores, 142 radiometric dates) from seven proximal (but discrete) nearshore coral reefs located along the central Great Barrier Reef (Australia). Uniquely, these reefs span distinct stages of geomorphological maturity, as reflected in their elevations below sea level. Integrated age-depth and ecological data sets indicate that contemporary coral assemblage shifts, associated with changing light availability and wave exposure as reefs shallowed, coincided with transitions in accretion rates at equivalent core depths. Reef initiation followed a regional ~1 m drop in sea level (1200-800 calibrated yr B.P.) which would have lowered the photic floor and exposed new substrate for coral recruitment by winnowing away fine seafloor sediments. We propose that a two-way feedback mechanism exists where past growth history influences current reef morphology and ecology, ultimately driving future reef accumulation and morphological change. These findings provide the first empirical evidence that nearshore reef growth trajectories are intrinsically driven by changes in coral community structure as reefs move toward sea level, a finding of direct significance for predicting the impacts of extrinsically driven ecological change (e.g. coral-algal phase shifts) on reef growth potential within the wider coastal zone on the Great Barrier Reef.
Abstract.
2015
Perry CT, Kench PS, O'Leary MJ, Morgan KM, Januchowski-Hartley F (2015). Linking reef ecology to island building: Parrotfish identified as major producers of island-building sediment in the Maldives.
Geology,
43(6), 503-506.
Abstract:
Linking reef ecology to island building: Parrotfish identified as major producers of island-building sediment in the Maldives
Reef islands are unique landforms composed entirely of sediment produced on the surrounding coral reefs. Despite the fundamental importance of these ecological-sedimentary links for island development and future maintenance, reef island sediment production regimes remain poorly quantified. Using census and sedimentary data from Vakkaru island (Maldives), a sand-dominated atoll interior island, we quantify the major sediment-generating habitats, the abundance of sediment producers in these habitats, and the rates and size fractions of sediment generated by different taxa. The estimated annual sediment production is 685,000 kg (or 370 m3), ~75% of which is produced on the narrow outer reef flat, despite composing only 21% of the total platform area. Approximately 65% of the platform acts solely as a sediment sink. Census data identify parrotfish as the major sediment producers, generating >85% of the 5.7 kg m-2 of new sand-grade sediment produced on the outer reef flat each year. Halimeda (macroalgae) produce a further 10%, most as gravelgrade material. Comparisons between production estimates and sedimentary data indicate that reef ecology and island sedimentology are tightly linked; reef flat and lagoon sediments are dominated by coral and Halimeda, although fine-to medium-grained coral sand is the dominant (~59%) island constituent. The generation of sediment suitable for maintaining this reef island is thus critically dependent on a narrow zone of high-productivity reef, but most especially on the maintenance of healthy parrotfish populations that can convert reef framework to sand-grade sediment.
Abstract.
Perry CT, Steneck RS, Murphy GN, Kench PS, Edinger EN, Smithers SG, Mumby PJ (2015). Regional-scale dominance of non-framework building corals on Caribbean reefs affects carbonate production and future reef growth. Global Change Biology
Perry CT, Murphy GN, Graham NAJ, Wilson SK, Januchowski-Hartley FA, East HK (2015). Remote coral reefs can sustain high growth potential and may match future sea-level trends.
Scientific Reports,
5Abstract:
Remote coral reefs can sustain high growth potential and may match future sea-level trends
Climate-induced disturbances are contributing to rapid, global-scale changes in coral reef ecology. As a consequence, reef carbonate budgets are declining, threatening reef growth potential and thus capacity to track rising sea-levels. Whether disturbed reefs can recover their growth potential and how rapidly, are thus critical research questions. Here we address these questions by measuring the carbonate budgets of 28 reefs across the Chagos Archipelago (Indian Ocean) which, while geographically remote and largely isolated from compounding human impacts, experienced severe (>90%) coral mortality during the 1998 warming event. Coral communities on most reefs recovered rapidly and we show that carbonate budgets in 2015 average +3.7 G (G = kg CaCO 3 m â '2 yr â '1). Most significantly the production rates on Acropora-dominated reefs, the corals most severely impacted in 1998, averaged +8.4 G by 2015, comparable with estimates under pre-human (Holocene) disturbance conditions. These positive budgets are reflected in high reef growth rates (4.2 mm yr â '1) on Acropora-dominated reefs, demonstrating that carbonate budgets on these remote reefs have recovered rapidly from major climate-driven disturbances. Critically, these reefs retain the capacity to grow at rates exceeding measured regional mid-late Holocene and 20th century sea-level rise, and close to IPCC sea-level rise projections through to 2100.
Abstract.
2014
Perry CT, Murphy GN, Kench PS, Edinger EN, Smithers SG, Steneck RS, Mumby PJ (2014). Changing dynamics of Caribbean reef carbonate budgets: Emergence of reef bioeroders as critical controls on present and future reef growth potential.
Proceedings of the Royal Society B: Biological Sciences,
281(1796).
Abstract:
Changing dynamics of Caribbean reef carbonate budgets: Emergence of reef bioeroders as critical controls on present and future reef growth potential
Coral cover has declined rapidly on Caribbean reefs since the early 1980s, reducing carbonate production and reef growth. Using a cross-regional dataset, we show that widespread reductions in bioerosion rates—a key carbonate cycling process—have accompanied carbonate production declines. Bioerosion by parrotfish, urchins, endolithic sponges and microendoliths collectively averages 2 G (where G = kg CaCO3 m−2 yr−1) (range 0.96–3.67 G). This rate is at least 75% lower than that reported from Caribbean reefs prior to their shift towards their present degraded state. Despite chronic overfishing, parrotfish are the dominant bioeroders, but erosion rates are reduced from averages of approximately 4 to 1.6 G. Urchin erosion rates have declined further and are functionally irrelevant to bioerosion on most reefs. These changes demonstrate a fundamental shift in Caribbean reef carbonate budget dynamics. To-date, reduced bioerosion rates have partially offset carbonate production declines, limiting the extent to which more widespread transitions to negative budget states have occurred. However, given the poor prognosis for coral recovery in the Caribbean and reported shifts to coral community states dominated by slower calcifying taxa, a continued transition from production to bioerosion-controlled budget states, which will increasingly threaten reef growth, is predicted.
Abstract.
Hepburn LJ, Blanchon P, Murphy G, Cousins L, Perry CT (2014). Community structure and palaeoecological implications of calcareous encrusters on artificial substrates across a Mexican Caribbean reef. Coral Reefs, 34(1), 189-200.
Perry CT, Smithers SG, Kench PS, Pears B (2014). Impacts of Cyclone Yasi on nearshore, terrigenous sediment-dominated reefs of the central Great Barrier Reef, Australia. Geomorphology, 222, 92-105.
Roche RC, Perry CT, Smithers SG, Leng MJ, Grove CA, Sloane HJ, Unsworth CE (2014). Mid-Holocene sea surface conditions and riverine influence on the inshore Great Barrier Reef.
Holocene,
24(8), 885-897.
Abstract:
Mid-Holocene sea surface conditions and riverine influence on the inshore Great Barrier Reef
We present measurements of Sr/Ca, δ18O, and spectral luminescence ratios (G/B) from a mid-Holocene Porites sp. microatoll recovered from the nearshore Great Barrier Reef (GBR). These records were used as proxies to reconstruct sea surface temperature (SST), the δ18O of surrounding seawater (δ18Osw), and riverine influence, respectively, and compared with records from a modern Porites sp. microatoll growing in the same environment. Strong riverine influence in the mid-Holocene record is indicated by (1) an increased annual δ18Osw range in the mid-Holocene record, (2) negative peaks in δ18O characteristic of flood events, and (3) a higher G/B luminescence ratio. Seasonal cycles in G/B suggest that humic acid inputs were elevated for a longer portion of the year during the mid-Holocene. The seasonal cycle of δ18Osw peaked earlier in the year in the mid-Holocene record relative to the modern, while mean δ18Osw values from the mid-Holocene record were similar to modern values. These records provide an insight into the oceanographic conditions the nearshore GBR experienced during mid-Holocene climatic shifts and are consistent with a strong Australian-Indonesian Summer Monsoon (AISM) system at ~ 4700 cal. yr BP. © the Author(s) 2014.
Abstract.
Salter MA, Perry CT, Wilson RW (2014). Size fraction analysis of fish-derived carbonates in shallow sub-tropical marine environments and a potentially unrecognised origin for peloidal carbonates.
Sedimentary Geology,
314, 17-30.
Abstract:
Size fraction analysis of fish-derived carbonates in shallow sub-tropical marine environments and a potentially unrecognised origin for peloidal carbonates
Marine bony fish are now known as primary producers of calcium carbonate. Furthermore, within the shallow sub-tropical platform settings of the Bahamas, this production process has been shown to occur at rates relevant to carbonate sediment production budgets. Fish excrete these carbonates as loosely aggregated pellets which, post-excretion, exhibit a range of distinctive crystal morphologies and have mineralogies ranging from low (0-4mol% MgCO3) to high (4-40mol% MgCO3) Mg-calcites, aragonite and amorphous carbonate phases. Here we provide the first quantitative assessment of the size fractions of the carbonates produced by a range of tropical fish species, and document the extent of post-excretion carbonate pellet break down under a range of physical agitation conditions. Specifically, we document the morphologies and size fractions of: i) intact pellets at the point of excretion; ii) intact pellets after agitation in seawater; and iii) the particles released from pellets post-disaggregation. Results indicate that fish-derived pellets initially fall within the very fine to very coarse sand fractions. Exposure to conditions of moderate seawater agitation for 30days results in significant pellet diminution; 66% of initial pellet mass being released as individual particles, whilst 34% is retained as partially intact pellets that are smaller (fine sand-grade) and more rounded than initial pellets. In contrast, pellets exposed to very gently agitated conditions for up to 200days show little change. Where pellet disaggregation does occur, particles are commonly released as individual clay- and silt-grade crystals. However, some morphotypes (e.g. polycrystalline spheres) can be intergrown and are released as strongly cohesive particle clusters falling within the coarse silt to fine sand fractions. Only very vigorous agitation may disaggregate such particles, resulting in the release of their component clay-grade crystals. We conclude that fish-derived carbonates may thus contribute not only to the mud-fraction of marine carbonates, but also to the fine sand fraction as intergrown particles, and to the fine to coarse sand fractions as intact and partially intact pellets. These experimental data indicate that hydrodynamic regimes local to sites of excretion will influence the generation of carbonates with different size fraction ranges. Rapid pellet disaggregation is more likely in high energy settings, hypothesised to result in redistribution of liberated mud-grade particles to lower energy platform-top settings and/or off-platform. In contrast, pellets excreted in lower energy settings are more likely to be preserved intact, and are thus proposed as a previously unrecognised source of pelletal and peloidal carbonate sediments. •Break-up of carbonate pellets produced by marine bony fish is investigated. •Pellets can remain intact and may contribute to sedimentary pellets and peloids. •Rapid pellet break-up releases component particles in agitated settings. •Particle size ranges from clay to fine sand grade: different depositional fates. •Relevant to surface sediments in shallow sub-tropical marine provinces.
Abstract.
Berkeley A, Perry CT, Smithers SG, Hoon S (2014). Towards a formal description of foraminiferal assemblage formation in shallow-water environments: Qualitative and quantitative concepts. Marine Micropaleontology, 112, 27-38.
2013
Gulliver P, Palmer S, Perry C, Smithers S (2013). Are coral clasts from a turbid near-shore reef environment a suitable material for radiocarbon analysis?.
Radiocarbon,
55(2-3), 624-630.
Abstract:
Are coral clasts from a turbid near-shore reef environment a suitable material for radiocarbon analysis?
Use of coral skeletons to determine growth histories of reefs situated in warm, clear tropical waters is well established. Recently, however, there has been increasing awareness of the significance of reefs occurring in environments that are considered as marginal for coral growth, such as turbid inshore settings characterized by episodes of elevated turbidity, low light penetration, and periodic sediment burial. While these conditions are generally considered as limiting for coral growth, coral reefs in these settings can exhibit high live coral cover and species diversity, and thus can be both ecologically and geologically significant. Turbid-zone reefs are also commonly concentrated along eroding shorelines with many analogues to erosional shorelines developed during the Holocene transgression. A growing number of studies of these previously undocumented reefs reveal that the reef deposits are detrital in nature, comprising a framework dominated by reef rubble and coral clasts and set within a fine-grained terrigenous sediment matrix. In addition to the recognized effects of diagenesis or algal encrustations on the radiocarbon signature of coral samples, episodic high-energy events may rework sediments and can result in age reversals in the same stratigraphic unit. As in other reef settings, the possibility of such reworking can complicate the reconstruction of turbid-zone reef growth chronologies. In order to test the accuracy of dating coral clasts for developing growth histories of these reef deposits, 5 replicate samples from 5 separate coral clasts were taken from 2 sedimentary units in a core collected from Paluma Shoals, an inshore turbid-zone reef located in Halifax Bay, central Great Barrier Reef, Australia. Results show that where care is taken to screen the clasts for skeletal preservation, primary mineralogical structures, and δ13C values indicative of marine carbonate, then reliable 14C dates can be recovered from individual turbid reef coral samples. In addition, the results show that these individual clasts were deposited coevally. © 2013 by the Arizona Board of Regents on behalf of the University of Arizona.
Abstract.
Kennedy EV, Perry CT, Halloran PR, Iglesias-Prieto R, Schönberg CHL, Wisshak M, Form AU, Carricart-Ganivet JP, Fine M, Eakin CM, et al (2013). Avoiding coral reef functional collapse requires local and global action.
Current Biology,
23(10), 912-918.
Abstract:
Avoiding coral reef functional collapse requires local and global action
Coral reefs face multiple anthropogenic threats, from pollution and overfishing to the dual effects of greenhouse gas emissions: rising sea temperature and ocean acidification [1]. While the abundance of coral has declined in recent decades [2, 3], the implications for humanity are difficult to quantify because they depend on ecosystem function rather than the corals themselves. Most reef functions and ecosystem services are founded on the ability of reefs to maintain their three-dimensional structure through net carbonate accumulation [4]. Coral growth only constitutes part of a reef's carbonate budget; bioerosion processes are influential in determining the balance between net structural growth and disintegration [5, 6]. Here, we combine ecological models with carbonate budgets and drive the dynamics of Caribbean reefs with the latest generation of climate models. Budget reconstructions using documented ecological perturbations drive shallow (6-10 m) Caribbean forereefs toward an increasingly fragile carbonate balance. We then projected carbonate budgets toward 2080 and contrasted the benefits of local conservation and global action on climate change. Local management of fisheries (specifically, no-take marine reserves) and the watershed can delay reef loss by at least a decade under "business-as-usual" rises in greenhouse gas emissions. However, local action must be combined with a low-carbon economy to prevent degradation of reef structures and associated ecosystem services. © 2013 Elsevier Ltd.
Abstract.
Browne NK, Smithers SG, Perry CT (2013). Carbonate and terrigenous sediment budgets for two inshore turbid reefs on the central Great Barrier Reef. Marine Geology, 346, 101-123.
Perry CT, Murphy GN, Kench PS, Smithers SG, Edinger EN, Steneck RS, Mumby PJ (2013). Caribbean-wide decline in carbonate production threatens coral reef growth.
Nature Communications,
4Abstract:
Caribbean-wide decline in carbonate production threatens coral reef growth
Global-scale deteriorations in coral reef health have caused major shifts in species composition. One projected consequence is a lowering of reef carbonate production rates, potentially impairing reef growth, compromising ecosystem functionality and ultimately leading to net reef erosion. Here, using measures of gross and net carbonate production and erosion from 19 Caribbean reefs, we show that contemporary carbonate production rates are now substantially below historical (mid-to late-Holocene) values. On average, current production rates are reduced by at least 50%, and 37% of surveyed sites were net erosional. Calculated accretion rates (mm year-1) for shallow fore-reef habitats are also close to an order of magnitude lower than Holocene averages. A live coral cover threshold of ∼10% appears critical to maintaining positive production states. Below this ecological threshold carbonate budgets typically become net negative and threaten reef accretion. Collectively, these data suggest that recent ecological declines are now suppressing Caribbean reef growth potential. © 2013 Macmillan Publishers Limited. All rights reserved.
Abstract.
Perry CT, Smithers SG, Gulliver P (2013). Rapid vertical accretion on a ‘young’ shore-detached turbid zone reef: Offshore Paluma Shoals, central Great Barrier Reef, Australia. Coral Reefs, 32(4), 1143-1148.
Perry CT, Kench PS, Smithers SG, Yamano H, O'Leary M, Gulliver P (2013). Time scales and modes of reef lagoon infilling in the maldives and controls on the onset of reef island formation.
Geology,
41(10), 1111-1114.
Abstract:
Time scales and modes of reef lagoon infilling in the maldives and controls on the onset of reef island formation
Faro are annular reefs, with reef fl ats near sea level and lagoons of variable depth, characteristic of both the perimeter and lagoons of Maldivian (Indian Ocean) atolls. Their geomorphic development remains largely unknown, but where faro lagoons (termed velu in Maldivian) have infilled and support reef islands, these provide precious habitable land. Understanding the timing and modes of velu infilling is thus directly relevant to questions about reef island development and vulnerability. Here we use a chronostratigraphic data set obtained from a range of atoll-interior faro with partially to fully filled velu (including those with reef islands) from Baa (South Maalhosmadulu) Atoll, Maldives, to determine time scales and modes of velu infilling, and to identify the temporal and spatial thresholds that control reef island formation. Our data suggest a systematic relationship between faro size, velu infilling, and island development. These relationships likely vary between atolls as a function of atoll lagoon depth, but in Baa Atoll, our data set indicates the following faro-size relationships exist: (1) faros 0.5 km2 but ~1.25 km2 have unfilled (deeper) velu which might only infill over long time scales and which are thus unlikely to support new island initiation. These new observations, when combined with previously published data on Maldivian reef island development, suggest that while the velu of the largest faro are unlikely to fill over the next few centuries (at least), other faro with near-infilled velu may provide important foci for future reef-island building, even under present highstand (and slightly rising) sea levels. © 2013 Geological Society of America.
Abstract.
2012
(2012). A Field-Based Technique for Measuring Sediment Flux on Coral Reefs: Application to Turbid Reefs on the Great Barrier Reef. Journal of Coastal Research, 28(5), 1247-1247.
Browne N, Smithers SG, Perry C (2012). Coral reefs of the turbid inner Great Barrier Reef: a geological perspective on occurrence, composition and growth. Earth-Science Reviews, in press
Perry CT, Edinger EN, Kench PS, Murphy GN, Smithers SG, Steneck RS, Mumby PJ (2012). Estimating rates of biologically driven coral reef framework production and erosion: a new census-based carbonate budget methodology and applications to the reefs of Bonaire.
Coral Reefs,
31(3), 853-868.
Abstract:
Estimating rates of biologically driven coral reef framework production and erosion: a new census-based carbonate budget methodology and applications to the reefs of Bonaire
Census-based approaches can provide important measures of the ecological processes controlling reef carbonate production states. Here, we describe a rapid, non-destructive approach to carbonate budget assessments, termed ReefBudget that is census-based and which focuses on quantifying the relative contributions made by different biological carbonate producer/eroder groups to net reef framework carbonate production. The methodology is presently designed only for Caribbean sites, but has potential to be adapted for use in other regions. Rates are calculated using data on organism cover and abundance, combined with annual extension or production rate measures. Set against this are estimates of the rates at which bioeroding species of fish, urchins and internal substrate borers erode reef framework. Resultant data provide a measure of net rates of biologically driven carbonate production (kg CaCO 3 m -2 year -1). These data have potential to be integrated into ecological assessments of reef state, to aid monitoring of temporal (same-site) changes in rates of biological carbonate production and to provide insights into the key ecological drivers of reef growth or erosion as a function of environmental change. Individual aspects of the budget methodology can also be used alongside other census approaches if deemed appropriate for specific study aims. Furthermore, the methodology spreadsheets are user-changeable, allowing local or new process/rate data to be integrated into calculations. Application of the methodology is considered at sites around Bonaire. Highest net rates of carbonate production, +9. 52 to +2. 30 kg CaCO 3 m -2 year -1, were calculated at leeward sites, whilst lower rates, +0. 98 to -0. 98 kg CaCO 3 m -2 year -1, were calculated at windward sites. Data are within the ranges calculated in previous budget studies and provide confidence in the production estimates the methodology generates. © 2012 Springer-Verlag.
Abstract.
Perry CT, Smithers SG, Gulliver P, Browne NK (2012). Evidence of very rapid reef accretion and reef growth under high turbidity and terrigenous sedimentation. Geology, 40(8), 719-722.
Salter MA, Perry CT, Wilson RW (2012). Production of mud-grade carbonates by marine fish: Crystalline products and their sedimentary significance. Sedimentology
Browne NK, Smithers SG, Perry CT (2012). Spatial and temporal variations in turbidity on two inshore turbid reefs on the Great Barrier Reef, Australia. Coral Reefs, 32(1), 195-210.
2011
Wilson RW, Reardon EE, Perry CT (2011). A fishy tale - a missing part of the inorganic ocean carbon cycle.
Biochemist,
33(3), 30-34.
Abstract:
A fishy tale - a missing part of the inorganic ocean carbon cycle
Human activities, such as burning fossil fuels, are playing an important role in the rising levels of carbon dioxide (CO2) in the Earth's atmosphere1. The oceans may store a large portion of CO2 that we are releasing into the atmosphere, with up to 40% already taken up by the oceans. Although this absorption helps to offset some of the greenhouse effect of atmospheric CO2, it also contributes to ocean acidification, or a fall in the pH of sea water. The historical global mean pH of oceanic sea water is about 8.2, and this has already declined by 0.1 pH units (a 30% increase in H+ concentration) and is predicted to reach pH ~7.7 by the end of the century if current rates of fossil fuel use continue, leading to an atmospheric CO2 level of 800 p.p.m.1,2. Even this extreme potential fall in pH would still leave seawater above the neutral point (pH 7.0), so technically it is more accurate to say that the ocean is becoming less alkaline, rather than truly acidic (i.e. below pH 7.0). However, the magnitude is perhaps less important than the speed of pH change which is occurring faster than at any time during the previous 20 million years. Over this time, the average ocean pH has probably never fallen below pH 8.0 2,3. It is only during the last decade that the importance of ocean acidification has come to the forefront of concerns for scientists1, 2. Consequences of these changes in global CO2 production are predicted to include elevated global temperatures, rising sea levels, more unpredictable and extreme weather patterns, and shifts in ecosystems1. In order to more fully understand the implications of ocean acidification, teams of researchers, including fisheries scientists, physiologists, geologists, oceanographers, chemists and climate modellers, are working to refine current understanding of the ocean carbon cycle. © 2011 the Biochemical Society.
Abstract.
Perry CT, Salter MA, Harborne AR, Crowley SF, Jelks HL, Wilson RW (2011). Fish as major carbonate mud producers and missing components of the tropical carbonate factory.
Proceedings of the National Academy of Sciences of the United States of America,
108(10), 3865-3869.
Abstract:
Fish as major carbonate mud producers and missing components of the tropical carbonate factory
Carbonate mud is a major constituent of recent marine carbonate sediments and of ancient limestones, which contain unique records of changes in ocean chemistry and climate shifts in the geological past. However, the origin of carbonate mud is controversial and often problematic to resolve. Here we show that tropical marine fish produce and excrete various forms of precipitated (nonskeletal) calcium carbonate from their guts ("low" and "high" Mg-calcite and aragonite), but that very fine-grained (mostly 4 mole % MgCO3) are their dominant excretory product. Crystallites from fish are morphologically diverse and species-specific, but all are unique relative to previously known biogenic and abiotic sources of carbonate within open marine systems. Using site specific fish biomass and carbonate excretion rate data we estimate that fish produce ∼6.1 × 106 kg CaCO3/year across the Bahamian archipelago, all as mud-grade (the
Abstract.
Perry CT, Kench PS, Smithers SG, Riegl B, Yamano H, O'Leary MJ (2011). Implications of reef ecosystem change for the stability and maintenance of coral reef islands.
Global Change Biology,
17(12), 3679-3696.
Abstract:
Implications of reef ecosystem change for the stability and maintenance of coral reef islands
Coral reef islands are among the most vulnerable environments on Earth to climate change because they are low lying and largely constructed from unconsolidated sediments that can be readily reworked by waves and currents. These sediments derive entirely from surrounding coral reef and reef flat environments and are thus highly sensitive to ecological transitions that may modify reef community composition and productivity. How such modifications - driven by anthropogenic disturbances and on-going and projected climatic and environmental change - will impact reef island sediment supply and geomorphic stability remains a critical but poorly resolved question. Here, we review the unique ecological-geomorphological linkages that underpin this question and, using different scenarios of environmental change for which reef sediment production responses can be projected, explore the likely resilience of different island types. In general, sand-dominated islands are likely to be less resilient than those dominated by rubble grade material. However, because different islands typically have different dominant sediment constituents (usually either coral, benthic foraminifera or Halimeda) and because these respond differently to individual ecological disturbances, island resilience is likely to be highly variable. Islands composed of coral sands are likely to undergo major morphological change under most near-future ecological change scenarios, while those dominated by Halimeda may be more resilient. Islands composed predominantly of benthic foraminifera (a common state through the Pacific region) are likely to exhibit varying degrees of resilience depending upon the precise combination of ecological disturbances faced. The study demonstrates the critical need for further research bridging the ecological-geomorphological divide to understand: (1) sediment production responses to different ecological and environmental change scenarios; and (2) dependant landform vulnerability. © 2011 Blackwell Publishing Ltd.
Abstract.
Roche RC, Perry CT, Johnson KG, Sultana K, Smithers SG, Thompson AA (2011). Mid-Holocene coral community data as baselines for understanding contemporary reef ecological states. Palaeogeography, Palaeoclimatology, Palaeoecology, 299(1-2), 159-167.
Perry CT, Smithers SG, Roche RC, Wassenburg J (2011). Recurrent patterns of coral community and sediment facies development through successive phases of Holocene inner-shelf reef growth and decline. Marine Geology, 289(1-4), 60-71.
2010
Perry CT (2010). Carbonate budgets and reef framework accumulation. In (Ed) Encyclopaedia of Modern Coral Reefs, Springer-Verlag, 185-190.
Kench PS, Perry CT, Spencer T (2010). Coral Reefs. In (Ed) Geomorphology and Global Environmental Change: Landscape Scale Implications, Cambridge: Cambridge University Press, 180-213.
PERRY CT, SMITHERS SG (2010). Cycles of coral reef ‘turn-on’, rapid growth and ‘turn-off’ over the past 8500 years: a context for understanding modern ecological states and trajectories. Global Change Biology, 17(1), 76-86.
Perry CT, Smithers SG (2010). Evidence for the episodic “turn on” and “turn off” of turbid-zone coral reefs during the late Holocene sea-level highstand. Geology, 38(2), 119-122.
Browne N, Smithers SG, Perry CT (2010). Geomorphology and community structure of Middle Reef, central Great Barrier Reef, Australia: an inner-shelf turbid zone reef subjected to episodic mortality events. Coral Reefs, 26, 683-689.
Perry CT (2010). Holocene high energy window. In Hopley D (Ed) Encyclopaedia of Modern Coral Reefs, Springer-Verlag, 558-561.
O'Leary MJ, Perry CT (2010). Holocene reef accretion on the Rodrigues carbonate platform: an alternative to the classic “bucket-fill” model. Geology, 38(9), 855-858.
Palmer SE, Perry CT, Smithers SG, Gulliver P (2010). Internal structure and accretionary history of a nearshore, turbid-zone coral reef: Paluma Shoals, central Great Barrier Reef, Australia. Marine Geology, 276(1-4), 14-29.
Roche RC, Abel RA, Johnson KG, Perry CT (2010). Quantification of porosity in Acropora pulchra (Brook 1891) using X-ray micro-computed tomography techniques. Journal of Experimental Marine Biology and Ecology, 396(1), 1-9.
Roche RC, Abel RL, Johnson KG, Perry CT (2010). Spatial variation in porosity and skeletal element characteristics in apical tips of the branching coral Acropora pulchra (Brook 1891). Coral Reefs, 30(1), 195-201.
Perry CT (2010). Turbid-zone and terrigenous sediment-influenced reefs. In (Ed) Encyclopaedia of Modern Coral Reefs, Springer-Verlag, 1110-1120.
2009
Berkeley A, Perry CT, Smithers SG, Horton BP, Cundy AB (2009). Foraminiferal biofacies across mangrove-mudflat environments at Cocoa Creek, north Queensland, Australia. Marine Geology, 263(1-4), 64-86.
Perry CT, Berkeley A (2009). Intertidal substrate modification as a result of mangrove planting: Impacts of introduced mangrove species on sediment microfacies characteristics. Estuarine, Coastal and Shelf Science, 81(2), 225-237.
Perry CT, Smithers SG, Johnson KG (2009). Long-term coral community records from Lugger Shoal on the terrigenous inner-shelf of the central Great Barrier Reef, Australia. Coral Reefs, 28(4), 941-948.
Perry CT, Smithers SG (2009). Stabilisation of intertidal cobbles and gravels by Goniastrea aspera: an analogue for substrate colonisation during marine transgressions?. Coral Reefs, 28(3), 805-806.
Berkeley A, Perry CT, Smithers SG (2009). Taphonomic signatures and patterns of test degradation on tropical, intertidal benthic foraminifera. Marine Micropaleontology, 73(3-4), 148-163.
O'Leary MJ, Perry CT, Beavington-Penney SJ, Turner JR (2009). The significant role of sediment bio-retexturing within a contemporary carbonate platform system: Implications for carbonate microfacies development. Sedimentary Geology, 219(1-4), 169-179.
2008
Perry CT, Smithers SG, Palmer SE, Larcombe P, Johnson KG (2008). 1200 year paleoecological record of coral community development from the terrigenous inner shelf of the Great Barrier Reef. Geology, 36(9), 691-691.
Perry CT, Spencer T, Kench PS (2008). Carbonate budgets and reef production states: a geomorphic perspective on the ecological phase-shift concept. Coral Reefs, 27(4), 853-866.
Perry CT, Berkeley A, Smithers SG (2008). Microfacies characteristics of a tropical, mangrove-fringed shoreline, Cleveland Bay, central Great Barrier Reef, Australia: mangrove sequence development and facies preservation. Journal of Sedimentary Research, 78, 77-97.
Perry CT, Hepburn LJ (2008). Syn-depositional alteration of coral reef framework through bioerosion, encrustation and cementation: Taphonomic signatures of reef accretion and reef depositional events. Earth-Science Reviews, 86(1-4), 106-144.
Berkeley A, Perry CT, Smithers SG, Horton BP (2008). The spatial and vertical distribution of living (stained) benthic foraminifera from a tropical, intertidal environment, north Queensland, Australia. Marine Micropaleontology, 69(2), 240-261.
2007
Berkeley A, Perry CT, Smithers SG, Horton BP, Taylor KG (2007). A review of the ecological and taphonomic controls on foraminiferal assemblage development in intertidal environments. Earth-Science Reviews, 83(3-4), 205-230.
Taylor KG, Perry CT, Greenaway AM, Machent PG (2007). Bacterial iron oxide reduction in a terrigenous sediment-impacted tropical shallow marine carbonate system, north Jamaica. Marine Chemistry, 107(4), 449-463.
2006
Mallela J, Perry CT (2006). Calcium carbonate budgets for two coral reefs affected by different terrestrial runoff regimes, Rio Bueno, Jamaica. Coral Reefs, 26(1), 129-145.
PERRY CT, TAYLOR KG (2006). Inhibition of dissolution within shallow water carbonate sediments: impacts of terrigenous sediment input on syn‐depositional carbonate diagenesis.
Sedimentology,
53(3), 495-513.
Abstract:
Inhibition of dissolution within shallow water carbonate sediments: impacts of terrigenous sediment input on syn‐depositional carbonate diagenesis
AbstractThe early diagenetic chemical dissolution of skeletal carbonates has previously been documented as taking place within bioturbated, shallow water, tropical carbonate sediments. The diagenetic reactions operating within carbonate sediments that fall under the influence of iron‐rich (terrigenous) sediment input are less clearly understood. Such inputs should modify carbonate diagenetic reactions both by minimizing bacterial sulphate reduction in favour of bacterial iron reduction, and by the reaction of any pore‐water sulphide with iron oxides, thereby minimizing sulphide oxidation and associated acidity. To test this hypothesis sediment cores were taken from sites within Discovery Bay (north Jamaica), which exhibit varying levels of Fe‐rich bauxite sediment contamination. At non‐impacted sites sediments are dominated by CaCO3 (up to 99% by weight). Pore waters from the upper few centimetres of cores show evidence for active sulphate reduction (reduced SO4/Cl− ratios) and minor CaCO3 dissolution (increased Ca2+/Cl− ratios). Petrographic observations of carbonate grains (specifically Halimeda and Amphiroa) show clear morphological evidence for dissolution throughout the sediment column. In contrast, at bauxite‐impacted sites, the sediment is composed of up to 15% non‐carbonate and contains up to 6000 μg g−1 Fe. Pore waters show no evidence for sulphate reduction, but marked levels of Fe(II), suggesting that bacterial Fe(III) reduction is active. Carbonate grains show little evidence for dissolution, often exhibiting pristine surface morphologies. Samples from the deeper sections of these cores, which pre‐date bauxite influence, commonly exhibit morphological evidence for dissolution implying that this was a significant process prior to bauxite input. Previous studies have suggested that dissolution, driven by sulphate reduction and sulphide oxidation, can account for the loss of as much as 50% of primary carbonate production in localized platform environments. The finding that chemical dissolution is minor in a terrigenous‐impacted carbonate environment, therefore, has significant implications for carbonate budgets and cycling, and the preservation of carbonate grains in such sediment systems.
Abstract.
Perry CT, Smithers SG (2006). Taphonomic signatures of turbid-zone reef development: Examples from Paluma Shoals and Lugger Shoal, inshore central Great Barrier Reef, Australia. Palaeogeography, Palaeoclimatology, Palaeoecology, 242(1-2), 1-20.
Perry CT, Taylor KG, Machent PG (2006). Temporal shifts in reef lagoon sediment composition, Discovery Bay, Jamaica. Estuarine, Coastal and Shelf Science, 67(1-2), 133-144.
2005
MACDONALD I, PERRY C, LARCOMBE P (2005). Comment on ?Rivers, runoff, and reefs? by McLaughlin et al. [Global Planetary Change 39 (2003) 191?199]. Global and Planetary Change, 45(4), 333-337.
Perry CT, Beavington-Penney SJ (2005). Epiphytic calcium carbonate production and facies development within sub-tropical seagrass beds, Inhaca Island, Mozambique. Sedimentary Geology, 174(3-4), 161-176.
Perry CT (2005). Morphology and occurrence of rhodoliths in siliciclastic, intertidal environments from a high latitude reef setting, southern Mozambique. Coral Reefs, 24(2), 201-207.
Perry CT (2005). Structure and development of detrital reef deposits in turbid nearshore environments, Inhaca Island, Mozambique. Marine Geology, 214(1-3), 143-161.
