Cue hierarchy and foraging in calanoid copepods: ecological implications of oceanographic structure

摘要: Fine-scale water column structure was mimicked in a laboratory plane jet flume to examine responses of the calanoid copepods Temora longicornis and Acartia tonsa layers consist- ing velocity gradient, density phytoplankton exudates food (phytoplankton). Cope- pods were exposed isolated combinations cues as defined by situ conditions. Behaviors elicited gradient chemical exudate included increased swim- ming speed turn frequency consistent with excited area-restricted search behavior, which led proportional residence time layers. Both species had significant gradients exudates, T. responding more intensely than A. equally both. Combined fluid mechanical species-specific responses. For longicornis, pres- ence induced that strengthened or cancelled initial reactions gradient. These results suggest cue hierarchy where acts an for narrowing regions, presence determine consequent tonsa, combining same effect on copepod behavior indi- vidual cues, suggests both are equal sources information but not closely associated. In species, physical contact particles cells initiated feeding resulting lower swimming speeds. Fluid potentially aversive effect, neither responded response individuals rarely crossed strong Observed behaviors may lead aggregation, especially when superimposed rhythmic move- ments such diel vertical migration.