Remote Sensing of Productivity and Calcification of the Florida Keys Reef Tract

Knowledge of coral reef GPP is the foundation for understanding the function of reef systems. GPP sets the maximum energy available to a reef community through autotrophic pathways and ultimately limit the biomass and secondary production of reef consumers [1-3]. Calcification, or the production of carbonate, is directly related to the value of GPP [4]. GPP describes the basic energy production of the system and is therefore important for assessing the overall vitality of the ecosystem: areas rich in algae, seagrass or coral have significantly (~10 ) higher GPP than areas covered with sand or rubble [5]. Similarly, the spatial arrangement of GPP describes the fundamental zonation of a reef, which can be interpreted as a measure reef health: healthy reefs exhibit high GPP on fore-reefs, reef-crests and reef-flats, with active sand burial in backreef areas leading to low GPP [4, 6, 7]. Thus, GPP can be affected greatly by changes in reef community structure, such as phase shifts where the benthic community changes from coral-rich to coral-poor. Typically, reef grazers and their predators move—and spatially integrate resources—at the hectare (10,000 m2) scale. Thus, a generally applicable method to measure GPP at the hectare scale, and across reefs/islands/archipelagos, would be very useful to evaluate the trophodynamic consequences of changes in community composition.