Yih, W. Kunsan National University, yih@serc.si.edu
Coats, D. Smithsonian Environmental Research Center, 301-261-7954

Parasitism of Gymnodinium sanguineum by Amoebophrya sp.: influence of nutrient environment on parasite success and host survival
Preliminary attempts to culture Amoebophrya sp. with Gymnodinium sanguineum from Chesapeake Bay indicated that parasite success may be influenced by water quality. To explore that possibility, we monitored parasite and host populations in media of differing nutrient concentrations [16 psu Chesapeake Bay water (CB); 16 psu CB f/2-Si (CBf/2); Gulf Stream water diluted to 16 psu (GS); 16 psu GS f/2-Si (GSf/2)]. Host cultures (1000 cells/ml) were inoculated with parasite infective stages (dinospores, 1/ml) and subsampled at 12 h intervals over 12 d to follow host abundance and parasite prevalence. CBf/2 without Amoebophrya supported continuous growth of hosts to 3300 cells/ml, while densities showed little increase in other media. Host abundance in CBf/2 with parasites increased to 1300 cells/ml (day 8) and then declined to less than 200. Host densities in other media declined less. Host density in parasitized cultures divided by controls was approximately 1.0 for all treatments until day 4. Thereafter, the ratio declined for all treatments, with lower values recorded for CBf/2 and higher values for CB and GS. CBf/2 also had higher numbers of infected hosts. Thus, host nutrient environment appears to influence Amoebophrya success, with parasitism most likely in eutrophic coastal settings.
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
Code: CS60WE1125S