Environmental Change

Marine carbonate production and cycling

Sustainable poverty alleviation from coastal ecosystem services: the SPACES project

This recently funded (2013) project, supported through NERC-ESPA-DFiD, is exploring the complex relationships between ecosystem services and the wellbeing of the poor in coastal Kenya and Mozambique. The ultimate aim of this will be to identify realistic opportunities for the dual goals of poverty alleviation and sustainable resource use. The EC group in Geography at Exeter will be leading a specific component of this large, interdisciplinary project that will focus on quantifying various biophysical attributes of reef ecosystems in the region (carbonate production, reef growth potential, fisheries stocks) that can then be linked to specific ecosystem service chains and thus to modelled scenarios to aid poverty alleviation strategies and ecosystem service sustainability.

Recent funding:

NERC-ESPA-DFiD: Ecosystem Services for Poverty Alleviation Programme  Grant Sustainable poverty alleviation from coastal ecosystem services (SPACES): Investigating elasticities, feedbacks and tradeoffs. £805,000 (part of £2M bid with multiple EU and African partners)

Understanding coral reef development in nearshore, turbid-zone environments

A major focus of research lead by Prof Chris Perry within the EC Group has been on developing an improved understanding of the dynamics of coral reef growth with high turbidity, nearshore marine environments. This has included a substantial body of, largely NERC funded, research that has quantified rates and styles of Holocene reef-development across the inner-shelf areas of Australia’s Great Barrier Reef, identified regional patterns of reef “turn-on” and “turn-off”, and has started to establish palaeoecological baselines of coral community development associated with different phases of reef growth. Presently, this work is being extended (through the NERC) to include multibeam mapping of inner-shelf environments and to better quantify nearshore benthic community compositions.

Key publications:

Perry C.T., Smithers S.G., Gulliver P. and Browne N. (2012) Evidence of very rapid reef accretion and reef growth under high turbidity and terrigenous sedimentation. Geology 40: 719-722.

Perry, C.T. and Smithers, S.G (2011) Cycles of coral reef ‘turn-on’, rapid growth and ‘turn-off’ over the past 8,500 years: a context for understanding modern ecological states and trajectories. Global Change Biology 17: 76-86.

Perry, C.T. and Smithers, S.G (2010) Evidence for the episodic 'turn-on' and ‘turn-off' of turbid-zone, inner-shelf coral reefs during the late Holocene sea-level highstand. Geology 38: 119-122.

Recent funding:

Natural Environment Research Council (NE/J023329/1) 2013-2016. Exploring the hidden shallows: inner-shelf reef growth and future trajectories of reef geomorphic change. £521,810 with partners at James Cook University, Natural History Museum.

Natural Environment Research Council (NE/J005398/1). 2011-2012. Rapid assessments of Cyclone Yasi’s impact on nearshore coral reefs and resultant sediment records of the event. £62,014

Quantifying carbonate production rates on Caribbean coral reefs

Global-scale deteriorations in coral reef “health” have caused major shifts in species composition, and one projected consequence is a lowering of reef carbonate production rates. To quantify the impacts of these on-going reef ecological changes in the Caribbean we have been developing a new methodologies to assess reef carbonate production rates (geography.exeter.ac.uk/reefbudget). Using this approach we have, most recently, assessed reef growth potential across 19 Caribbean reefs, this work showing that on average, current production rates are reduced by at least 50%, and 37% of surveyed sites were net erosional (Perry et al. 2013). We have also used these data to identify critical live coral cover thresholds below which reefs will typically start to erode. We have also used these same budgetary approaches to model future reef budget trajectories under different management and climate change scenarios (Kennedy et al. 2013)..

Key publications:

Kennedy EV, Perry CT, Halloran PR, Fine M, Carricart-Ganivet JP, Iglesias-Prieto R, Form A, Wisshak M, Schönberg CHL, Mumby PJ. (2013) Avoiding coral reef functional collapse requires combined local and global action. Current Biology 23: 912-918

Perry C.T., Murphy G.N., Kench P.S., Smithers S.G., Edinger E.N., Steneck R.S. and Mumby P.J. (2013) Caribbean-wide decline in carbonate production threatens coral reef growth. Nature Communications. doi: http://dx.doi.org/10.1038/ncomms2409

Perry C.T., Edinger E.N., Kench, P.S., Mumby P.J., Murphy G., Steneck, R.S. and Smithers S.G. (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: 853-868

Recent funding:

The Leverhulme Trust – International Research Network (F/00426/G) 2009-2012. Development of a rapid carbonate budget assessment protocol for coral reefs. £93,619

Quantifying the contributions of fish to marine carbonate production

Through NERC funding we have undertaken highly novel work which has demonstrated that tropical marine fish produce and excrete various forms of precipitated (nonskeletal) calcium carbonate from their guts (“low” and “high” Mg-calcite and aragonite) (Perry et al. 2011) and used site specific fish biomass and carbonate excretion rate data to estimate rates of fish carbonate production across the Bahamian archipelago. Through this work we also demonstrated the huge diversity of carbonate crystallite morphologies that fish produce (Salter et al. 2013), and identify this carbonate as a potentially important (but previously unknown) source of mud-grade carbonate sediment. This research is now being extending across large latitudinal gradients to assess environmental variations in the types and fates of these carbonates.

Key publications:

Salter M.A., Perry C.T. and Wilson R.W. (2012) Production of mud-grade carbonates by marine fish: crystalline products and their sedimentary significance. Sedimentology. 59: 2172-2198.

Perry, C.T., Salter, M.A., Harborne, A.R., Crowley, S.F., Jelks H.J., Wilson, R.W., (2011) Fish as major carbonate mud producers and missing components of the tropical carbonate factory. Proceedings of the National Academy of Science 108: 3865-3869

Recent funding:

Natural Environment Research Council (NE/K003143/1) 2013-2017. Carbonate sediment production by marine fish: quantifying production across carbonate provinces and applications to global marine carbonate modelling. £577,110 with Univ. Bremen, Univ. Queensland, UK Met Office.

Natural Environment Research Council (NE/H010092/1) 2009-2013. Fish carbonates – their nature and fate within the marine inorganic carbon cycle. £501,634 with partners at UEA, Southampton.

Natural Environment Research Council (NE/G010617/1) 2009-2010. The production and fate of fish-derived carbonate crystals in tropical shallow water environments. £86,909

Assessing the development and susceptibility of reef islands to environment change

Coral reef islands are considered to be 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. Work with the EC Group is thus currently focused on developing a better understanding of the timescales and processes involved in reef island development, and on better understanding the linkages between the surrounding reefs (as sediment sources) and the islands themselves (as sediment sinks). Much of this work has, thus far, been conducted in the Maldives under the auspices of the Exeter-led IAG working group REEForm (geography.exeter.ac.uk/reeform), with recent work identifying key reef platform size thresholds that influence the timing and location of reef island “switch-on” (Perry et al. 2013).

Key publications:

Perry C.T., Kench P.S., Smithers S.G., Yamano H., O’Leary M. and Guilliver P. (2013, in press) Timescales and modes of reef lagoon infilling in the Maldives and controls on the onset of reef island formation. Geology

Perry C.T., Kench P.S., O’Leary, M., Riegl, B.R., Smithers S.G. and Yamano H. (2011) Implications of reef ecosystem change for the stability and maintenance of coral reef islands? Global Change Biology 17: 3679-3696.

Recent funding:

Natural Environment Research Council (Radiocarbon Dating Allocation 1580.0911). 2011. Rates and timescales of lagoon infilling as a control on reef island development. £27,840

Exeter Science Strategy Project Development Fund. 2013-2014. Constraining reef-reef island sediment linkages: towards integrated physical-social assessments of reef island resilience. £9,800