Coral reefs are important for human societies and economies (Moberg and Folke, 1999; Costanza et al., 2014). These ecosystems provide a wide variety of ecological and economic services (worth trillion of dollars) such as coastal protection, habitat provisioning, nutrient recycling and food security (Moberg and Folke 1999; Burke et al. 2011; Costanza et al. 2014; Spalding et al. 2017). To a certain extent, each of these ecosystem services depends on the growth and calcification of the reef builders – especially corals themselves (Cooley et al. 2009; Glynn and Manzello 2015). Reef health and function is also closely linked to coral feeding (heterotrophy; e.g. Conti-Jerpe et al., 2020), which can be assessed using stable isotope analyses of tissue samples. Many studies have demonstrated that calcification rates are diminishing around the world largely due to global climate change and anthropogenic stressors such as sedimentation. The broad aim of this project is to understand how reef function (e.g., net ecosystem calcification, heterotrophy) may change across gradients of varying human pressure. Ecosystem calcification will be assessed using the Total Alkalinity (AT) anomaly approach (Smith and Kinsey, 1978), with AT measured in replicate water samples using potentiometric titration with standard protocols (SOP6A, Dickson et al., 2007). Heterotrophy will be assessed using compound-specific isotope analysis of amino acids (CSIA-AA) in organisms’ tissues (Ohkouchi et al., 2017).