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: 3:45:00 PM |
| Location: Cochiti/Taos |
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| Stoecker, D, K, University of Maryland Center for Environmental Science, Horn Point Laboratory, Cambridge, USA, stoecker@hpl.umces.edu |
| Parrow, M, W, Center for Applied Aquatic Ecology, NCSU, Raleigh, USA, mwparrow@unity.ncsu.edu |
| Burkholder, J, M, Center for Applied Aquatic Ecology, NCSU, Raleigh, USA, joann_burkholder@ncsu.edu |
| Glasgow, H, B, Center for Applied Aquatic Ecology, NCSU, Raleigh, USA, howard_glasgow@ncsu.edu |
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| COMPARISON OF GRAZING BY MICROZOOPLANKTON ON TOX-A, TOX-B AND NON-INDUCIBLE ZOOSPORES OF PFIESTERIA PISCICIDA |
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| Grazing by microzooplankton on 5-chloromethylfluorescein diacetate stained zoospores that varied in their culture history were compared in 6 h incubations. TOX-A (actively toxic), TOX-B (temporarily nontoxic in the absence of live fish, but capable of toxicity) and NON-IND (non-inducible, with negligible or undetectable toxin production in the presence or absence of fish) were used. TOX-A, TOX-B, and NON-IND zoospores had been last exposed to fish 2 days, 2 weeks, and 2 months, respectively, before the experiment.
There were no significant differences in grazing by three assemblages of mesohaline microzooplankton on the added zoospores. Zoospores from all cultures were ingested by tintinnids and oligotrichous ciliates, but the grazing coefficients varied significantly among cultures. The mean (+/- std dev) grazing coefficients for TOX-A, TOX-B and NON-IND cultures were 0.9 +/- 1.10, 5.0 +/- 1.01, and 5.8 +/- 2.32 /d, respectively. Grazing was significantly lower on TOX-A than on TOX-B or NON-IND zoospores. These data suggest that although microzooplankton grazing on nontoxic zoospores can be a significant source of mortality to P. piscicida, grazing on toxic or very recently toxic zoospores is relatively low. |
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