GRIP: Global Reef Impact Projections

Lead Research Organisation: University of Exeter
Department Name: Geography


This project seeks to bring together UK, US and Australian scientists to establish a set of proto-operational tools for predicting and projecting stress on global coral reefs, and deliver a long-term partnership to provide coral reef managers with a step-change in decision-making support.

Warm water corals are large colonies of individual organisms, coral polyps, which act as hosts to photosynthesising unicellular organisms known as zooxanthellae. The zooxanthellae and polyp symbiosis are mutually beneficial, with the zooxanthellae providing the polyp with oxygen and nutrients, and the polyps providing physical protection and supplying carbon dioxide from respiration. When stressed, zooxanthellae die or leave the polyp, in turn stressing the polyp, potentially leading to the coral's mortality (Baird and Marshall, 2002). Zooxanthellae are very sensitive to high temperatures, and while different zooxanthellae have different temperature thresholds (Hume et al., 2015), a simple metric known as Degree Heating Weeks has proved to be a very effective way of identifying when corals are likely to bleach (Skirving et al., 2019).

For more than 20 years, Coral Reef Watch has utilized remote sensing, modelling and in-situ data to observe, predict and alert its users to coral reef threats worldwide. ~1,000 resource managers, scientists, elected officials, educators, and the public subscribe to Coral Reef Watch's automated satellite coral bleaching alert system. Coral Reef Watch's DHW based alerts allow reef managers to mitigate some of the worse effects of temperature extremes by guiding when they should be making in situ temperature measurements to identify if their reefs are under imminent threat, checking for initial evidence of bleaching, then protecting herbivore populations, protecting water quality and restricting development and recreational use of at-risk areas (

Coral Reef Watch is made up of a world leading team of remote sensing scientists, biologists and ecologists. Their state-of-the-art tools have been built to take advantage of these expertise. As user requirements become increasingly sophisticated, and baselines shift in response to climate change, there is a need to move beyond what can be directly observed. This project builds a new partnership to bring climate and coastal modelling expertise and approaches into the Coral Reef Watch toolkit.

This partnership will collaboratively generate and verify a large set of reduced-complexity coastal model simulations spanning the entirety of the global tropical oceans. These model simulations will provide not only semi-dynamical downscaling or future projections, but also, using state-of-the art atmospheric reanalyses, push back in time and supplement satellite observations with subsurface information. Working together this partnership will develop coral reef stress products based on this data, but will do so by building on the more than 20 years of experience NOAA Coral Reef Watch have in developing and distributing the results from such tools. Finally, this project will identify the optimal pathway for transition these new tools into operationally produced outputs delivered directly into the hands of managers and decision makers.


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