Fisher, C. R. The Pennsylvania State University, cfisher@psu.edu
MacDonald, I. R. Geochemical and Environmental Research Group, ian@gerg.tamu.edu
Hourdez, S. The Pennsylvania State University, hourdez@email.bio.psu.edu
Macko, S. University of Virginia, sam8f@virginia.edu
McMullin, E. The Pennsylvania State University, erm8@email.psu.edu
Joye, M. University of Georgia, mjoye@arches.uga.edu

 
HESIOCAECA METHANICOLA, A CLATHRATE DWELLING POLYCHAETE
 
Hesiocaeca methanicola lives on methane clathrates in the deep-sea. On exposed surfaces, the 2-5 cm long polychaetes occupy small depressions which cover all visible areas. Worms on the exposed surfaces of the hydrate have never been seen to leave that surface unless physically disturbed. Their fidelity to the hydrate and the fact that the mono-specific aggregation is colonizing the hydrate at densities over 2,000 animals per m2 suggests a strong nutritional tie between the worms and the hydrate. The tissue stable isotope values of the polychaete (C, N, and S) are consistent with a microbial (chemoautotrophic and not methanotrophic) nutritional source for the worm. We found no evidence of either internal or external symbionts associated with the worm. However, several lines of evidence indicate abundant bacteria are associated with the surface of the hydrate, and we hypothesize that these bacteria are the dominant food source for the clathrate polychaetes. The anaerobic tolerance of H. methanicola is at the upper end of that reported for other polychaetes, and they oxy-regulate down to about 10% of air saturation. We suggest that these animals are able to inhabit and exploit this "extreme" environment by modifying their immediate microhabitat through their behavior.
 
Day: Tuesday, Feb. 2
Time: 11:45 - 12:00pm
Location: Sweeney Center
 
Code: SS27TU1200S