THE INFLUENCE OF FISH-EXUDED CHEMICAL SIGNALS ON THE CARBON BUDGET OFDAPHNIA

Respiration and carbon assimilation rates were measured in juvenile in stars of Daphnia magna cultivated either in fish-treated or in control medium without fish exudates. Respiration and carbon assimilation rat es increase proportionally to Daphnia body size. This relationship did not differ between fish-influenced and control daphnids throughout ju venile development. The results imply that observed Life-history shift s in Daphnia exposed to fish exudates are facultative changes and not the result of changes in the carbon budget induced by other predator-i nduced defense mechanisms or experimental setups.