1997 Progress Report: The Toxic Dinoflagellate, Pfiesteria piscicida, as a Potential Biosensor of Estuarine Stress

EPA Grant Number: R825551
Title: The Toxic Dinoflagellate, Pfiesteria piscicida, as a Potential Biosensor of Estuarine Stress
Investigators: Burkholder, Joann M. , Rublee, Parke , Shumway, Sandra E.
Institution: North Carolina State University , Long Island University - Southampton College , University of North Carolina at Greensboro
Current Institution: North Carolina State University , Long Island University - Southampton College , University of North Carolina at Greensboro
EPA Project Officer: Hiscock, Michael
Project Period: May 19, 1997 through May 18, 2000 (Extended to May 18, 2001)
Project Period Covered by this Report: May 19, 1997 through May 18, 1998
Project Amount: $500,000
RFA: Harmful Algal Blooms (1997) RFA Text |  Recipients Lists
Research Category: Aquatic Ecosystems , Water Quality , Water , Ecosystems


The objectives of this project are to: (1) examine controlling influences of both inorganic and organic N and P on growth of Pfiesteria piscicida zoospores (toxic and nontoxic), when given food resources as dissolved or particulate (algal) carbon; (2) improve detection of Pfiesteria piscicida through development of a molecular probe for this species; and (3) assess Pfiesteria's acute and sublethal/chronic impacts on life stages of commercially/ecologically valuable shellfish species.

Progress Summary:

We first obtained a research-quality clone of toxic Pfiesteria piscicida from a fish kill site on the Neuse Estuary, NC. The clone was verified as capable of toxin production using our standardized fish bioassay process (required step since there is wide variability among P. piscicida cells in toxin production capability ranging from non-inducible, or apparently incapable of toxin production, to highly toxic). This clone is a critical requirement for the research; it serves as the foundation for all of the project components. In nutrient ecology research, a set of experiments was conducted to compare organic nitrogen uptake by actively toxic zoospores, gametes, and lobose amoebae (TOX-A functional type, taken from a fish-killing condition) and temporarily nontoxic zoospores and lobose amoebae (TOX-B functional type, from the same clone, but maintained on cryptomonad algal prey without access to fish for 3 months). We found that uptake of the organic N substrate was highest for lobose amoebae on a cell number basis, and highest for gametes on a cell biovolume basis (note: cysts were tested as well, but showed minimal uptake as expected). All active toxic stages were more active in substrate uptake than the corresponding active nontoxic stages. In molecular probe development, we developed a PCR rDNA probe to P. piscicida (fluorescent in situ hybridization or FISH probe), which tested as species-specific when compared to other dinoflagellates from the GenBank. Samples from various other states (several estuaries in Maryland; estuaries in Delaware, Virginia, South Carolina, and Florida) were successfully tested for activity with our rDNA fluorescent probe including (as expected) negative tests in some sub-locations. In shellfish research, we initiated two experiments testing impacts of toxic P. piscicida on juvenile eastern oysters and northern quahogs. However, both experiments had to be shut down because of emergency conditions that occurred in the state of Maryland, where our assistance was requested by the governor and required all of the available space in the small biohazard III facility that was available for this research. The imposed delay and related circumstances prevented shellfish experiments from being re-established for nearly a year.

Future Activities:

During the next year, we will compare cell production of toxic versus nontoxic zoospores in our nutrient ecology research. In molecular probe testing/refinement, we will continue to test our fluorescent ribosomal DNA probe to P. piscicida from the Neuse Estuary on natural water samples from the Pocomoke Estuary and the Pamlico Estuary, and on isolates of various "lookalike" species. In shellfish research, we will set up an inland culture facility and use it to maintain blue crabs, bay scallops, and northern quahogs. Acute toxicity tests will be conducted on adult bay scallops and blue crabs in the presence versus absence of finfish (tilapia).

Journal Articles:

No journal articles submitted with this report: View all 19 publications for this project

Supplemental Keywords:

nutrients, estuaries., RFA, Scientific Discipline, Water, Waste, Ecosystem Protection/Environmental Exposure & Risk, Hydrology, Nutrients, Ecosystem/Assessment/Indicators, Ecosystem Protection, exploratory research environmental biology, Chemical Mixtures - Environmental Exposure & Risk, Contaminated Sediments, Environmental Microbiology, Ecological Effects - Environmental Exposure & Risk, algal blooms, Ecological Effects - Human Health, Ecological Risk Assessment, Ecology and Ecosystems, Ecological Indicators, aquatic ecosystem, nutrient supply, nutrient transport, pfiesteria piscicida, ecological exposure, dinoflagellates, estuaries, food web, watershed management, fish lesions, harmful algal blooms, contaminated sediment, estuarine stress, nutrient kinetics, phytoplankton, heterotrophic microbial prey, algal growth, pfiesteria, phytoplankton dynamics, estuarine ecosystems, nutrient cycling, phytoplankton blooms, dinoflagellate, water quality, biosensor, estuarine food web

Progress and Final Reports:

Original Abstract
  • 1998 Progress Report
  • 1999 Progress Report
  • Final Report