REEForm Thematic Programme 2: Reef growth

An improved understanding of the various ‘styles’, rates and drivers of Holocene reef growth has been a long-standing goal for reef geomorphologists – as indicated by the recent publication of several reviews on the subject. These reviews focus mostly on data derived from radiometrically-dated reef and coral cores collected since the early 1970s. Records from around 1000 cores are accessible in this literature; roughly three-quarters of which are from Indo-Pacific reefs, and a quarter from the Caribbean-Atlantic province. This combined data set is impressive and of enormous value: it has underpinned our understanding of the nature and tempo of postglacial reef growth, and of the factors that influence the process. It also provides the longer-term context against which the geomorphological and ecological responses of reef systems to current and future environmental pressure can be evaluated.

However, although the dataset is remarkable, it is deficient in several key areas, limiting our ability to resolve research questions of both pure scientific and applied environmental importance. A primary issue is that the presently available data set is not geographically comprehensive with remarkably few data available for many reef regions. Moreover, most reef cores have been collected from reefs at, or very near to, sea level. Are the range of reef types – or the reef types we most urgently need to focus on – adequately represented in the dataset? Have we focused on sea-level constrained reefs that are now largely senescent and are these relevant for the most pressing scientific questions? Chronostratigraphic precision is another significant issue; many of the early reef core records have relatively low chronological resolution and the positional integrity of dated samples was often equivocal. New U-series dating techniques and improved drilling technologies significantly reduce these problems, but the data quality and intensity available in many core records is insufficient to detect more subtle temporal variations in reef-building through the Holocene, particularly the details of reef response to smaller sea-level fluctuations and the exhaustion of vertical accommodation space during the late Holocene.

This research programme will focus on:

  • Improving the coverage of quality reef accretion data – geographically, but also to improve the representation of different reef types at different morphogenetic stages;
  • Improving the coverage and quality of contemporary reef growth data to provide more meaningful baselines against which the significance of contemporary variations can be evaluated;
  • Improving data intensity in key periods during the Holocene to investigate whether coherent and consistent responses to environmental and sea level change are recorded in reef growth records.