Reports of declining summer ice coverage and drowning polar bears in the Arctic illustrate dramatic ecosystem responses to global climate change occurring in Earth’s polar regions. Now, in a first-ever account of a long-term project in the southern Caribbean Sea, a SOMAS professor and his colleagues report in this week’s Proceedings of the National Academy of Sciences U.S.A that tropical ecosystems are also affected by global climatic trends—and with accompanying economic impacts.
In an article entitled “Ecosystem responses in the southern Caribbean Sea to global climate change,” Dr. Gordon Taylor and colleagues from SoMAS, as well as the University of South Florida, University of South Carolina and two Venezuelan institutions (EDIMAR, Fundación de la Salle de Ciencias Naturales and Universidad de Oriente) provide an analysis of 14 years of continuous monthly oceanographic observations in the southern Caribbean off the coast of Venezuela.
The researchers report that the complex food web overlying the Cariaco Basin has changed in this relatively short time frame. Microscopic plankton production has steadily declined and the assemblage of plant species in the food web has shifted. These ecosystem changes have affected the way this region exchanges carbon dioxide (CO2) with the atmosphere and contributed to the collapse of the local sardine fishery, with substantial impacts to the economy of Margarita Island. Fishermen from the island harvest 70% of the sardines consumed in Venezuela.
Taylor and colleagues link these ecosystem changes to declining upwelling of nutrient-rich waters caused by weakening trade winds in the region and an average sea surface warming of 1°C during the period of their observations. According to the authors, all these changes trace back to the global heat budget, corresponding to climatic shifts in well-known indices of atmospheric circulation. This is the first report to link long-term, shipboard time-series oceanographic and local meteorological observations in the tropics with global scale climatic changes