Aquatic Sciences Meeting, Albuquerque 2001

PC05 Zooplankton Production, Physiology, and Ecology

Date: Tuesday, February 13, 2001

Location: Southwest Hall

Hassett, R, P, Ohio University, Athens, OH, USA, hassett@ohio.edu

DIETARY CHOLESTEROL CAN LIMIT EGG PRODUCTION RATES OF COPEPODS FEEDING ON DIATOMS

Cholesterol is required for animal growth, yet cannot be biosynthesized by most zooplankton. Dietary sterols are thus necessary for copepod growth, but vary widely in concentration in phytoplankton. To explore the potential for sterol limitation of copepod growth, supplementation experiments were conducted with adult copepods feeding on diatoms with and without cholesterol supplementation. Cholesterol was added to the diet by 1) homogenizing the insoluble cholesterol with an ultrasonic disintegrator, or 2) by preparing gelatin/acacia microcapsules with and without cholesterol using triolein as a carrier. Egg production rates were measured after 3-4 days on the experimental diets. Cholesterol had a positive effect on egg production rates when added by either method. Egg production rates increased 1.5 to 2-fold for Acartia hudsonica, A. tonsa, and Calanus finamrchicus when Thalassiosira weissflogii was supplemented with 5 µg/l cholesterol. Egg production rates of A. hudsonica also increased when Chaetoceros calcitrans was supplemented, but not C. simplex. These experiments demonstrate the potential for growth limitation by dietary sterols when copepods feed exclusively on diatoms, and offer one explanation for the enhancement of growth by mixed diets.

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Aquatic Sciences Meeting, Albuquerque 2001

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