Aquatic Sciences Meeting, Albuquerque 2001

SS20 Biological Control of Harmful Algal Blooms: Role of Grazers, Parasites, Viruses and Bacteria

Date: Monday, February 12, 2001, Time: 3:00:00 PM

Location: Cochiti/Taos

Setala, O, , Finnish Environmental Institute, PO Box 140, Helsinki 00251, Finland, outi.setala@vyh.fi

Autio, R, , Finnish Institute Marine Research, PO Box 33, Helsinki 00931, Finland,

Gustafson, D, , UMCES, Horn Point Lab, Cambridge, MD 21613, USA,

Stoecker, D, , UMCES, Horn Point Lab, Cambridge, MD 21613, USA,

GRAZING BY THE PLANKTONIC CILIATE, STROMBIDINOPSIS SP., ON PFIESTERIA PISCICIDA

Grazing by the planktonic ciliate, Strombidinopsis sp., on cultured non-toxic zoospores of the dinoflagellate P. piscicida (strain FDEPMDR23, a non-inducible strain) was measured as a function of prey concentration. The ciliate was from Chesapeake Bay water samples. P. piscicida were stained with the fluorescent dye 5-chloromethylfluorscein diacetate (CMFDA) and added live at concentrations ranging from 0 to 4000 cells/ml to duplicate incubation bottles containing the ciliates. The samples were then incubated for 45 minutes in the dark and subsamples taken at 0, 15, 25 and 45 minutes and fixed with 1% glutaraldehyde for epifluorescence microscopy. The number of ingested Pfiesteria cells inside ciliates as well as the disappearance of Pfiesteria from the water samples were determined. Strombidinopsis sp. was found to be an effective grazer on Pfiesteria. No saturation of the ingestion was found during the experiment. The maximum observed ingestion was 10 Pfiesteria/ciliate/h found at the highest prey concentration.

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Aquatic Sciences Meeting, Albuquerque 2001

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