OSTERBERG, J.S.; Duke University Marine Lab: Scavenging by Shrimp and Crabs at a Hydrothermal Vent on the Mid-Atlantic Ridge

Hydrothermal vents are located on the seafloor well within the aphotic zone. Accordingly, chemoreception rather than vision is hypothesized to be the primary method by which predators and scavengers locate food. In a first step towards identifying the cues vent scavengers use to locate food, I determined their scavenging responses in an in situ pilot study. Using the Russian MIR submersibles, minced vent mussel (Bathymodiolus azoricus), crushed whole vent shrimp (Rimicaris exoculata), and a seawater control were placed and video recorded on the Eiffel Tower vent (1700m) in the Lucky Strike hydrothermal vent field on the Mid-Atlantic Ridge. Each odor source was released from a group of three perforated 50 ml conical tubes wrapped in a diffusing cloth and covered by a protective plastic mesh. The bythograeid crab, Segonzacia mesatlantica and the vent endemic shrimp Mirocaris fortunata arrived at the bait within two minutes. Both S. mesatlantica and M. fortunata were more attracted to mussels than to shrimp; during observation more individuals of both species explored the mussel compared to the shrimp and control. Both baits retained their attractiveness for at least 35 minutes after placement. Upon returning to the site five hours after placement, no crabs and two shrimp were seen exploring the bait packages. Future studies will focus on characterization of the complex mixtures of molecules to which these scavengers cue. This study was supported by the Blue Planet Marine Research Foundation.