ZMT - Leibniz Zentrum für Marine Tropenforschung

Coral reef framework production and sediment generation are key controls on reef island formation and maintenance. However, quantitative data on these geo-ecological functions remain scarce, particularly within shallow habitats that mediate wave energy and sediment supply to shorelines. We quantified carbonate framework and sediment budgets across shallow lagoon, shallow fore reef and deep fore reef habitats surrounding six islands in the remote Chagos Archipelago, Central Indian Ocean. Half of these islands support dense seabird colonies that deliver natural nutrient subsidies via guano run-off, enabling assessment of nutrient impacts on reef carbonate dynamics. Benthic surveys (ReefBudget and SedBudget) were combined with sediment composition analyses from shallow reefs and adjacent beaches. Carbonate production rates can then be used to calculate reef accretion and sediment delivery potential to islands, which strongly link reef ecology to island resilience. In this talk I want to share some results from my current project, investigating spatial variability in carbonate production rates and the benefits of seabird-derived nutrient subsidies on reef geo-ecological functions.