How are coral reef ecosystems changing? Nick Graham is quantifying differences in how their species function and in the benefits that humans derive from them
My research tackles large-scale issues related to the pressures faced by coral reef ecosystems. This has included investigating how climate change driven loss in coral cover influences reef fish assemblages, how fishing influences the ecosystem, and how differing types of management can chart a way towards a more sustainable future.
This research and that of many others has highlighted that the types and abundances of corals and fish are changing dramatically on coral reefs. These changes in composition are due to the differential susceptibility and recovery potential of species to climate change and other human impacts such as fishing and nutrient inputs. The scientific community is rushing to understand this large-scale reorganisation of species.
My Philip Leverhulme Prize will help me to study changes to coral reefs across the Indian Ocean, that represent large gradients in climate change impacts and human use. I already have an understanding of the changes in species make-up in many of these locations, and will now move towards quantifying differences in how the ecosystems function and how the benefits people derive from coral reefs (e.g. fisheries, tourism, shoreline protection) are changing.
I will quantify differences in ecosystem function in two ways. Firstly, I will link changes in species composition to changes in functions, based on the specific characteristics (or “traits”) that species have. These characteristics may include diet, body size, mouth size, swimming speed, and home range. Secondly, I will measure the magnitude of key ecosystem functions, and identify the species performing the functions. This may involve filming fish feeding on algae, measuring coral growth rates, and assessing predator success rates.
I will assess how benefits to people are likely to change using a range of proxies. I will estimate the benefits to fisheries based on the amount of fish surveyed on reefs underwater and through a fish productivity model. For coastal protection, I will use a model of wave energy at different locations. Tourism benefits will be based on attributes known to be important to tourist satisfaction, such as the presence of iconic marine organisms (e.g. sharks) and high coral cover. Interviews with stakeholders will compare if these proxies capture differences in benefits perceived by people.
Collectively, this research, funded by a Philip Leverhulme Prize, will enable me and my research group to gain a better understanding of how coral reefs in the Indian Ocean are changing, how this influences the way they function, and the benefits derived from reefs by people.