Coral Reef Resilience

Monitoring Coral Reefs in the Indian Ocean

Principal Investigators
Prof.
John Turner
Dr.
Ronan Roche
Other Scientists

Project Overview

Context

The degree to which a coral reef is considered to be ‘functioning’ is determined by a combination of measures such as coral cover, biomass, diversity, calcification rate and growth.

A key metric in determining reef status and resilience to future stressors is the balance between calcification and erosion which indicates if a reef is growing or eroding.

Monitoring BIOT’s benthic community is essential to the prognosis of the condition of its reef in the near future. It is believed that the back-to-back bleaching events in 2015 and 2016 have greatly altered the reefs’ trajectory.

Funded by

Our research on the coral reefs of the British Indian Ocean Territory (BIOT) is providing an increased understanding of their vulnerability in the face of climate change and helping to better inform management practices for the Marine Protected Area (MPA) and beyond.

Specifically, our research is extending the existing long-term assessments of coral reef growth, cover, recruitment and functionally extinct corals that have been monitored since 1978 and are of crucial importance to the ecological health of the reefs.

A video archive has been established to assess long term changes in the benthic community resulting from a warming ocean. The increase in ocean temperature results in more frequent disease and bleaching events which impair the health and reproductive capacity of corals and often leads to death of coral. These events cause significant changes in coral community structure and reduces the reefs’ ability to prevent shoreline erosion. Impacts of increased sea temperature can also be observed in species of connected ecosystems. To understand coral resilience to climate change, we are investigating the innate immune response of corals, and integrating long-term sea surface temperature trends into coral reef resilience models. Additionally, the coral reefs of BIOT vary considerably in their aspect, topography and hydrography due to the structure of the different atolls, banks, sea mounts and islands. These factors impact the benthic community and reef resilience and so we are also studying how internal wave-driven upwelling affects the shallow reefs’ resilience to bleaching. These studies will enable us to better understand why some corals are more resilient to bleaching than others.

Coral condition is one of the leading guides to the future condition and trajectory of the BIOT marine environment in our warming world. The British Indian Ocean Territory is an important ocean observatory due to its remote location which shelters it from direct human impact. The Territory acts as a benchmark against which other reefs can be assessed and demonstrates how undisturbed reefs function and respond to climate change, pollution and over-exploitation. This helps to demonstrate the value of BIOT’s MPA and can inform effective improvements in the management of degraded coral reefs in the Indian Ocean and beyond.

The resilience of coral reefs in the Chagos Archipelago to rising sea temperatures has been remarkable. But as the warming events become more severe and more frequent will they keep recovering?

Prof. John Turner

Key Facts

60,000
km2 of shallow banks and reefs in BIOT
990 Million $
worth good and services from the BIOT MPA
70%
of hard corals in the central Indian Ocean died between 2015-2017
  • Pachyseris coral covering the reef's edge.
  • Sprouting juvenile corals.
  • Dan Bayley recording for the coral video archive.
  • Dead branching coral.
  • The Chagos brain coral, (Ctenella chagius).
  • Three divers assessing the coral reef.
  • Dead Corals.
  • Bluestripe snapper, (Lutjanus kasmira) schooling over plating coral.
  • Starfish (Linckia laevigata), on eroded coral.

Publications

Application of Earth Observation Data and Google Earth Engine for Monitoring Coral Reef Exposure to Environmental Stressors

Williamson, M.J., Tebbs, E.J., Thompson, H.J., Dawson, T.P., Head, C.E.I. and Jacoby, D.M.P. (2021) Application of earth observation data and Google Earth Engine for monitoring coral reef exposure to environmental stressors. Remote Sensing.

A Protocol for the Large-Scale Analysis of Reefs Using Structure From Motion Photogrammetry

Bayley, D.T.I. and Mogg, A.O.M. (2020) A protocol for the large-scale analysis of reefs using structure from motion photogrammetry. Methods in Ecology and Evolution.

Coral Mass Mortalities in the Chagos Archipelago Over 40 Years: Regional Species and Assemblage Extinctions and Indications of Positive Feedbacks

Sheppard, C., Sheppard, A. and Fenner, D. (2020) Coral mass mortalities in the Chagos Archipelago over 40 years: Regional species and assemblage extinctions and indications of positive feedbacks. Marine Pollution Bulletin.

Bleaching-Driven Reef Community Shifts Drive Pulses of Increased Reef Sediment Generation

Perry, C.T., Morgan, K.M., Lange, I.D. and Yarlett, R.T. (2020) Bleaching-driven reef community shifts drive pulses of increased reef sediment generation. Royal Society Open Science. 7:192153.

A Quick, Easy and Non-Invasive Method to Quantify Coral Growth Rates Using Photogrammetry and 3D Model Comparisons

Lange, I.D. and Perry, C.T. (2020) A quick, easy and non-invasive method to quantify coral growth rates using photogrammetry and 3D model comparisons. Methods in Ecology and Evolution.

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