DO FIJIAN CORAL SKELETONS RECORD WATERSHED CHANGES?

The Fiji archipelago includes approximately 35% of coral reef area in the southwestern Pacific. These reefs are at risk from both global (e.g. seawater warming, ocean acidification and tropical cyclone activity) and local stressors (e.g. overfishing, poor water quality in terms of elevated levels of sediments, nutrients and pollutants). Local organizations are routinely monitoring coral reef ecosystem health, and recent studies have linked variability in inshore benthic condition and reef fish populations to catchment land use. Here we explore whether the skeletons of massive reef-building coral can be used to reconstruct records of how watershed land use and short-lived intense events such as cyclones have influenced the local inshore reef ecosystem over the last century. Coral cores from Porites sp., spanning up to ~90 years of growth, have been collected from inshore reefs that have experienced a range of different catchment environments at five locations around the island of Viti Levu (Fiji). We use an interdisciplinary approach, combining traditional geochemical techniques with skeletal imaging (SEM, UV luminescence) and computed tomography (CT) to disentangle the relationships between coral colony response to water quality and climatic events potentially affecting Fijian inshore reefs. Preliminary results suggest that corals in the vicinity of catchments with anthropogenic impact exhibit slower growth rates and relatively prolonged recovery after a stress event.