CHANGES IN BIVALVE ASSEMBLAGES THROUGH TIME INDICATE LONG-TERM ECOSYSTEM CHANGE IN CORAL REEFS OF BELIZE

Caribbean coral reef ecosystem health has drastically declined since large-scale monitoring began in the 1970s, due to local human stressors and climate change. However, we know less about anthropogenic change on Caribbean reefs before monitoring began. Reef sediment cores can help provide context for understanding the causes and consequences of changes in reef ecosystems as they can provide a millennial-scale record of reef communities and environments. For example, reef sediment cores from Panama suggest that coral reef decline began as early as the 17th century and was closely linked to land use change. We utilized bivalve subfossils preserved within a 4m-long sediment core collected from a lagoonal reef in central Belize to track changes in reef environmental conditions from the mid 1500s to 1938. In the bottom of the core, dating to the mid 1500s, the percent of infaunal bivalves is 0.48%. In the top of the core, dating to 1938, the percent of infaunal bivalves increased to 39.13%. The increase of infaunal bivalve species suggests a loss of hard substrate in the reef ecosystem. This trend has been observed in other places around the Caribbean, and suggests a loss in coral reef substrate, possibly due to changes in water quality and/or a loss of reef herbivory from fishing.