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Although Harmful Algal Blooms (HABs) have long impacted coastal ecosystems, in the past several decades there appear to be increases in both their frequency and severity. Such outbreaks can cause public health problems and considerable economic loss. A large majority of HABs involve dinoflagellates, many of which can be toxic during certain stages of their life cycle. Such is the case with Pfiesteria.
Pfiesteria piscicida, and its related species Pfiesteria shumwayae, are toxic dinoflagellates that have been associated with fish kills in estuarine and brackish water from Delaware to North Carolina. Pfiesteria normally feeds on bacteria and small algae near the sediment, but can be triggered to transform into a toxic planktonic stage. The presence of fish and their excreta/secreta may stimulate this transformation. Factors we are currently investigating that appear to stimulate the growth of Pfiesteria include warm water temperatures, poor flushing and high nutrient levels. Many of the regions impacted by Pfiesteria receive nutrient loading from agricultural or animal operation runoff.
The Ecology of Harmful Algal Blooms (ECOHAB) Program is a national effort aimed at addressing the fundamental physical, biological, and chemical oceanographic questions critical to scientifically based management of fisheries resources, public health, and ecosystem health in regions threatened by toxic and harmful algae. The ECOHAB Program, administered through NOAA, is jointly sponsored by NOAA, NSF, EPA, NASA and ONR.
The
University of Maryland
Center for Environmental Science's (UMCES) ECOHAB-sponsored
Pfiesteria research program, Toxic Dinoflagellates and Nutrients,
is a regional, comparative study of the physical nutritional and
trophodynamic mechanisms that contribute to blooms of Pfiesteria. The four comparative study sites
are the Neuse-Pamlico Estuaries, NC; the Pocomoke River, MD;
Indian River, DE; and North Inlet, SC. We hypothesize that certain
adaptive mechanisms are interdependent, and together contribute to the
development and persistence of these blooms. Through comparative
field sampling, spanning a range of conditions under which Pfiesteria
and other toxic Pfiesteria-like species are found to occur or
to bloom, we aim to describe the environmental conditions and factors
that contribute to their success. Our laboratory and field results
will are being incorporated into a model that can be used to understand
the biology of Pfiesteria.
