McManus, G. B.. Dept Marine Sciences University of Connecticut, mcmanus@uconnvm.uconn.edu
Fagin, S. B.. Dept. Marine Sciences University of Connecticut, sjf47@columbia.edu

 
FEEDING OF OLIGOTRICH CILIATES ON THE HARMFUL ALGAL BLOOM SPECIES PROROCENTRUM MINIMUM AND HETEROSIGMA CARTERAE.
 
As part of a larger study that is attempting to assess the role of benthic and planktonic grazers in the initiation and termination of harmful algal blooms (HAB), we measured feeding by oligotrich ciliates, the principal planktonic grazers in many coastal systems, on two HAB species, Prorocentrum minimum (a dinoflagellate) and Heterosigma carterae (a raphidophyte). Our goals were to assess the quality of these algae as food for oligotrichs isolated from waters where blooms are known to occur, and to evaluate whether poor ciliate growth could be attributed to toxins rather than to nutritional quality alone. For the ciliate Strombidinopsis sp. feeding on Prorocentrum, maximum growth rate was 0.84 per day, more than twice as high as that observed for a control food, the dinoflagellate Heterocapsa triquetra, which is commonly used in the cultivation of oligotrichs. Growth rate was half the maximum rate at a food concentration of 2000 cells per ml Two other oligotrichs we studied also grew well on Prorocentrum. By contrast, Heterosigma did not support the growth of Strombidinopsis nor that of another oligotrich with which it was tested. Observations of poor growth and detrimental morphological changes in ciliates fed high concentrations (>50000 cells per ml) of several algal species, including non-toxic ones, suggest that their grazing is not likely to be important in bloom termination once high concentrations are reached.
 
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
 
Code: SS42TH0932S