Towards modeling the coral reef ecosystem response to multiple environmental factors: development of a coupled coral polyp and hydrodynamic-biogeochemical model

mechanism of calcification and its relation to photosynthesis and respiration in the scleractinian Abstract Although the need for predicting coral responses to future environmental changes at the reef scale is increasing, it remains a difficult task to achieve. This is because: (1) multiple environmental factors are affecting corals, (2) biological responses to such factors are usually nonlinear, and (3) these environmental factors are changing over time. Using numerical models can be highly effective in evaluating the effects of multiple environmental factors if the dynamic responses of corals to each environmental parameter are properly incorporated into the model and the underlying mechanisms are well-understood and reproduced. To help attain this goal, we developed a “coral polyp model” which simulates the internal physical, chemical, and physiological processes within an individual coral polyp. Furthermore, to evaluate the responses of corals under a spatiotemporally vary-ing environment at the reef-scale, we coupled a hydrodynamic–biogeochemical model to the coral polyp model. The coupled model was able to accurately reproduce the main characteristics of both the reef environment and the coral metabolic responses, and can be set up to predict the coral responses under various future climate change scenarios. To obtain more accurate predictions of the impact of multiple environmental factors on coral reef ecosystems, ongoing work includes incorporating the responses to temperature, red soil, and nutrients into the coupled model.