Meeting Abstract

104.3  Saturday, Jan. 7  Turbulent mixing diminishes discrimination of food and predator risk odor sources by altering small scale structure of signals impinging on blue crab antennules. WEISSBURG, M.J.; Georgia Tech

Animals frequently are challenged with the task of responding appropriately to chemical signals when they are intermingled or mixed with odors from multiple sources. The ability of animals to navigate to attractive cues typically is examined in isolation, despite the fact that animals experiencing multiple, conflicting messages, may not be able to easily distinguish attractive substances if they co-occur with aversive cues. To examine this process, blue crabs were challenged to locate a source of food odors in the presence of a second odor source emitting cues indicative of predation risk (injured blue crab metabolites). Blue crabs easily and reliably located the attractive source under low mixing conditions, even when it was within 10 cm of the aversive source. However, increased mixing extinguished this response. Crabs no longer foraged for the attractive source, and instead displayed behaviors consistent with responses to the aversive cue only, despite the fact that they could locate the attractive source when presented alone under the same conditions. Removing input from the antennules eliminated the suppressive effects of the aversive cue, whereas removing input from chemosensors on the legs and claws did not. Qualitative flow visualization shows intermingled attractive and aversive odor filaments in low mixing conditions, whereas turbulence caused filament homogenization. Thus-small scale discreteness of odor filaments arriving at antennules is key to preserving the ability of crustaceans to operate effectively in environments with multiple and conflicting chemical signals, and is substantially affected by fluid mixing at levels that do not substantially affect navigation per se.