Millimolar H2S concentrations and the near absence of oxygen make methane seep sediments one of the most toxic environments on earth, yet metazoan assemblages persist in such settings. In microbial-mat covered seeps on the upper slopes of the Pacific Northwest, these assemblages are comprised nearly exclusively of dorvilleid polychaetes. At seeps located within the oxygen minimum zone off the Oregon and California margins the PIs have identified up to 17 co-occurring dorvilleid species, including 10 in a single genus. The PIs hypothesize that this annelid group, through exceptional tolerance to low oxygen and high sulfide concentrations, has found a suite of niches which it alone has been able to exploit, and as a result has experienced evolutionary release in the absence of predators and competitors. The PIs propose to use this dorvilleid assemblage as a model system with which to investigate how metazoan communities evolve in and adapt to extreme sulfide conditions. By mapping ecological features onto a phylogenetic framework, the PIs will identify correlations among ecology, physiology, life history and evolutionary history that help elucidate the mechanisms of speciation under extreme stress. The PIs anticipate that dorvilleid polychaetes will ultimately provide a superb metazoan model for integrated extremophile research. A partnership facilitated by California COSEE (Center for Ocean Science Education Excellence) will allow the PIs to pursue a rigorous education and outreach effort. Emerging findings will be incorporated as part of a current NSF-funded Sea Floor Science project (ISE #0229063) at the Ocean Institute.
