Functional response of Atlantic halibut larvae related to prey density and distribution

Abstract

Two experiments were conducted in order to elucidate the relationship between prey density and feeding success of Atlantic halibut larvae ( Hippoglossus hippoglossus L.) in terms of a functional response. One experiment was designed for the purpose of controlling zooplankton swarming, which otherwise would have complicated the interpretation of a response. Another experiment investigated the response in numbers of prey eaten by each larva. An inflection point referred to in the literature as an incipient limiting level, should indicate the optimal prey density to be offered. This work concludes that rotifers ( Brachionus plicatilis) can be prevented from horizontal patching simply by providing diffused light; hunger motivation is seemingly without effect. Brine shrimp ( Artemia sp.), on the other hand, appear to be less well controlled. Halibut seem to have an optimal feeding response at approximately 12 rotifers per ml, whereas the majority feed above a level of 2.5 ml.