Record-breaking rainfall and last winter's snow melt, combined with relatively moderate temperatures, have caused major plankton blooms in the Chesapeake Bay this year, affecting not only the Bay's ecology but also research facilities and fish farms that depend on Bay water for their operations. Nutrient runoff from rainfall has led to record concentrations of algae in the Chesapeake Bay and extensive dinoflagellate blooms, according to researchers at the University of Maryland System and the Benedict Estuarine Research Laboratory. Most of the Bay's problems with phytoplankton blooms occur when the algae die, sink into deeper water and decay, causing a precipitous drop in oxygen levels. However, she cautions that toxic blooms are not impossible as some problem species have been identified from the Bay.
Some species also feed on other microscopic creatures.
According to researcher JoAnn Burkholder at North Carolina State University, this microscopic algae can lie dormant in a cyst-like form for extended periods of time, can change shape rapidly and often, can swarm and attack schools of fish, and can release a powerful toxin that poisons and kills large numbers of fish very quickly. The dinoflagellates then feed on materials released by the dead and dying fish. Although there have been no documented cases of fish kills caused by the phantom dinoflagellate in the Bay itself, scientists have kept a watchful eye because of the organism's potential to cause dramatic die-offs. At about the same time, Denise Breitburg, a researcher at the Benedict Estuarine Research Laboratory, lost a whole tank full of fish called gobies, a die-off she says was caused by the phantom dinoflagellate. At the end of August 1996 the insidious organism apparently struck again, and Breitburg and her colleagues witnessed another dramatic die-off in her laboratory.