Functional roles of coral reef primary producers examined with stable isotopes

Context Primary production on coral reefs varies under changing conditions such as light and nutrient availability. This variation causes changes in basal stable isotopes photosynthetic pathways change.Aims study provides a preliminary baseline of nitrogen (δ15N) carbon (δ13C) isotope profiles Symbiodinium macroalgae at spatial scale along depth gradient around an island.Methods Coral fragments were collected depths from the surface to 26m. δ15N δ13C values assessed for relative cell density per area.Key results showed uniform profile across primary producers. However, chlorophyll-a Montipora stellata had higher concentrations southern side island. Stylophora pistillata did not change with depth. Depth was associated significant decrease density, macroalgae.Conclusions We attribute these findings S. increases, decreasing but maintaining concentration satisfy coral-host requirements.Implications sets scene future, more comprehensive research detecting producers reefs.