Ocean Response Coastal Analysis System (ORCAS)

Phytoplankton populations and communities respond to nutrient inputs on time scales from days to weeks. This short-term variability is superimposed on the long-term seasonal, annual and interannual variability in estuarine biogeochemical cycling that together regulate food web dynamics and ecosystem responses to nutrient loadings. Quantifying this short-term variability within the context of long-term changes in phytoplankton community structure (including harmful algal blooms), growth and production, relationship(s) to physico-chemical factors, food web efficiency and ecosystem ascendancy will provide critical information to assess nutrient thresholds for hypoxia and food web shifts. One of the long-term goals of the Gulf Ecology Division is to support EPA’s efforts under the Clean Water Action Plan by establishing the scientific basis developing nutrient criteria for the Nation’s coastal receiving waters.