Aquatic Sciences Meeting, Albuquerque 2001

CS37 Zooplankton

Date: Tuesday, February 13, 2001, Time: 11:15:00 AM

Location: Aztec

Kreeger, D, A, Academy of Natural Sciences, Philadelphia, USA, kreeger@acnatsci.org

Lanka, S, G, Academy of Natural Sciences, Philadelphia, USA, lanka@acnatsci.org

Kilham, S, S, Drexel University, Philadelphia, USA, kilhams@drexel.edu

DEVELOPMENT OF PHOSPHORUS MICROCAPSULES FOR MANIPULATING DIETARY C:P FOR AQUATIC SUSPENSION-FEEDERS

The fitness of aquatic suspension-feeders is governed largely by food quality. Dietary C:P, proteins, fatty acids and other factors have been correlated with productivity in zooplankton and bivalves, for example. Our understanding of the specific nutritional demands of these key aquatic consumers is still rudimentary however, because of technical difficulties in manipulating the composition of their microparticulate diet in defined ways; i.e., adjusting specific elemental or biochemical constituents without altering others. In preparation for studies with freshwater Cladocera, we microencapsulated carbohydrates (maltodextrin, potato starch, carboxymethyl cellulose) and P-containing compounds (sodium hexametaphosphate, calcium phosphate, tripolyphosphate) in various mixtures to produce >20 types of microparticles. For nutritional research, microcapsules must be susceptible to animal digestive enzymes but not leaky in water. Leakage rates for most types were low (<5% per day). Adding amylase more than doubled rates of capsule breakdown, and so all were susceptible to this common digestive enzyme. Capsules prepared from 80% maltodextrin and 20% sodium hexametaphosphate (C:P = 1.8) were the most digestible in vitro, being degraded by amylase >7-fold faster than their leakage rates. With low leakiness and high digestibility, cross-linked walled microcapsules represent promising tools for manipulating dietary C:P for suspension feeders.

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Aquatic Sciences Meeting, Albuquerque 2001

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