UC San Diego

Scientists have witnessed a profound transformation in Caribbean coral reefs since the 1980s that includes a widespread mortality of corals and a shift in coral species composition. These changes have been widely attributed to modern disturbances such as coral disease and coral bleaching that have become prevalent in the most recent decades. However, the demise of corals in the Caribbean represents the most recent chapter in a long history of human alteration of Caribbean reef ecosystems. Centuries of human over-exploitation of turtles, manatees, monk seals, and predatory and large herbivorous fishes had virtually eliminated these organisms from reefs long before the 1980s. Historical deforestation of watersheds draining onto reef habitats had likely also substantially changed reef environments prior to this time. The timing and ultimate causes of change in Caribbean coral communities remains unresolved because of a lack of quantitative information about the state of these reefs from a time period preceding the 1980s. My dissertation reconstructed coral and mollusk community composition from reefs in Caribbean Panama over approximately the past 150 years to extend the timeline of ecological change. This work showed that changes in coral and mollusk communities occurred at least 50 years ago and likely as far back as the mid 19th century, a period coinciding with rapid human population growth and deforestation in the regions of study. Data confirmed that major changes in coral and mollusk communities off the Central American coast predate the first appearance of coral disease and bleaching outbreaks and that the demise of Caribbean coral populations is likely rooted in older anthropogenic disturbances such as fishing and deforestation. This work provides a more accurate ecological baseline of Caribbean coral reefs that will provide a better frame of reference for future reef management actions