Quantifying rates and trends in endolithic bioerosion on coral reefs

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Active

NERC
NERC
NERC
NERC
NERC

No funds listed.

Sept. 30, 2022

March 31, 2026

Project Background

Tropical coral reef ecosystems sustain not only high levels of biodiversity, but also provide numerous ecosystem goods and services that directly benefit society. Some of these goods and services are well documented and can be quantified with increasing reliability (e.g., food resource provisioning, coastal protection). However, far more poorly quantified are rates of carbonate sand production - a process strongly influenced by reef ecology because most reef sediment derives from the fauna and flora living on reefs e.g., as a by-product of parrotfish and urchin feeding, from skeletal organisms such as molluscs and foraminifera, and from carbonate-secreting algae such as Halimeda. Data on the rates at which these producers generate sediment on reefs is generally sparse, and is especially poorly understood in relation to different types of reef settings that differ in their environmental conditions and reef community composition. This is a major knowledge gap because the quantity and grade (size) of sedimentary material produced on reefs impacts upon reef growth and is essential for proximal beach and island building.

Numerous reef species, including parrotfish, play a key role in generating

carbonate sediment on reefs.

Project Aims and Methods

The aim of this project is to parameterise and then apply methodologies for quantifying sediment generation rates, with a specific focus on remote reef-reef islands systems in Western Australia (WA). The project will build on recent approaches that have piloted methods for quantifying sediment generation based on ecological census approaches (Perry et al. 2015, 2017, 2019), and which have also started to explore the influence of disturbance events on ecologically-driven sand production (Perry et al. 2020). The student will firstly establish a set of empirical datasets to quantify rates of biological sand production for a range of sediment producing reef species (parrotfish, sea urchins, Halimeda, foraminifera) across a range of both clear-water and turbid reefs of WA (the intention being that this will include sites in Exmouth Gulf and on Ningaloo Reef). This phase of the project will include testing of AI-based tools to support auto-analysis of reef sediments for quantifying the abundance of common producers groups such as benthic foraminifera. Resultant datasets will then be used to quantify and map reef-level sand generation rates from census data across these sites. Benthic ecology and environmental conditions (light, turbidity, temperature, wave energy) are known to differ markedly between these reef systems and thus so too, we hypothesise, will rates and sources of reef-derived sediment. This project will thus add significantly to our currently limited understanding of, and capacity to quantify, rates of ecologically-driven reef sediment generation - data that is needed to support enhanced coastal and reef island vulnerability modelling.

Project partners

In addition to the U. Exeter based supervisors (Prof Chris Perry & Dr Ines Lange) the student will be co-supervised by two external academic partners. Dr Ken Johnson (Natural History Museum, London) has worked extensively in the past with supervisor Chris Perry on the ecology and sedimentology of turbid-zone coral reefs in Borneo and Eastern Australia. In addition to his expertise on turbid reefs he will offer support on the AI-based sediment analysis. The student will also work closely with the team led by overseas supervisor Dr Nikki Browne at Curtin University, whose group have undertaken wide ranging work on the ecology of the study systems and will support the proposed fieldwork in WA.