Nutrient loading and coastal plankton blooms: seasonal/interannual successions and effects on secondary production

A 13-year field analysis of the Perdido Bay system (Gulf of Mexico) indicated that orthophosphate and ammonia loading from a pulp mill was associated with a series of plankton blooms. Bloom species (10) followed distinct seasonal and interannual trends that included the replacement of initial diatom blooms by raphidophytes and dinoflagellates. Long-term habitat changes associated with river flow rates (drought/flood cycles) defined varying susceptibility to bloom development. The initiation and proliferation of plankton blooms were also affected by seasonal changes of temperature, phosphorus and nitrogen loading, and associated nutrient concentration gradients. Plankton blooms were associated with deterioration of secondary production through food web interactions. The bivalve Rangia cuneata was an indicator of such effects. Most scientific efforts continue to overlook the world-wide impacts of anthropogenous nutrient loading and associated plankton blooms due to the lack of long-term analyses of species-specific, community-level phytoplankton assemblages and the replacement of ecosystem studies with patch-quilt ecological efforts that depend on disorganized and inadequate data acquisition and uncoordinated multidisciplinary efforts.