Glasgow, H. B. North Carolina State University, howard_glasgow@ncsu.edu
Burkholder, J. M. NCSU, joann_burkholder@ncsu.edu
Lewitus, A. J. USC, LEWITUS@BELLE.BARUCH.SC.EDU

 
STIMULATION OF PFIESTERIA PISCICIDA AND A SECOND TOXIC PFIESTERIA-LIKE SPECIES BY N AND P ENRICHMENTS
 
We compared the response to N and P enrichments of the toxic dinoflagellate, Pfiesteria piscicida and a second more weakly toxic Pfiesteria-like species (species "B," not yet formally named) in clones that were isolated from two known fish kill sites in the Neuse Estuary, NC and the Pocomoke Estuary, MD. For 2 months prior to the experiments, both species were acclimated under similar conditions in separate cultures where they were grown with fish or with cryptomonad prey. Nontoxic zoospore (NTZ) production was then evaluated for each species. The trials were conducted across gradients of inorganic phos-phate, organic phosphate, nitrate, or ammonium enrichments in short-term batch cultures (10 days), with vs. without N/P-starved cryptomonad algal prey (initial prey densities of 5,000 or 25,000 cells/mL). When given algal prey, NTZ production by species "B" from both estuaries was significantly higher than cell production by P. piscicida. Lowest zoospore densities were attained by P. piscicida isolates that previously had been grown with live fish in an actively toxic mode. For both species, highest NTZ pro-duction occurred with nitrate stimulation and tracked cryptomonad prey abundance.
 
Day: Thursday, Feb. 4
Time:
Location: Sweeney Center
 
Code: SS42TH1189S