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Metazoan Life at Extreme Sulfide Concentrations:
The ecology and evolution of Dorvilleidae at methane seeps

Support: National Science Foundation, West Coast National Undersea Research Center

Collaborative Research:
Metazoan Life at Extreme Sulfide Concentrations:
The Ecology and Evolution of Dorvilleidae at Methane Seeps

Project Summary
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 we have identified up to 17 co-occurring dorvilleid species, including 10 in a single genus. We 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. Here we 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. Integrated studies of the geochemical environment with dorvilleid ecology and physiology will address mechanisms of niche partitioning and explore how communities are organized under conditions of extreme sulfide stress. Coordinated studies will be made of oxygen and sulfide concentration in sediments, dorvilleid species distributions, reproductive biology, and isotope- and molecular-based diet analyses. We will conduct species-level physiological tests of sulfide tolerance and thiotrophic bacterial activity, and in situ experiments to examine responses to sulfide gradients. Studies of seep dorvilleid phylogeny at several hierarchical levels will determine the evolutionary capabilities of these metazoans to adapt to an extreme environment. By mapping ecological features onto a phylogenetic framework, we will identify correlations among ecology, physiology, life history and evolutionary history that help elucidate the mechanisms of speciation under extreme stress. We anticipate that dorvilleid polychaetes will ultimately provide a superb metazoan model for integrated extremophile research.

Broader Impacts:
This groundbreaking research on how metazoans adapt and survive in extreme sulfidic environments will further understanding of both early metazoan evolution and the limits at which complex life can survive on this planet (and perhaps elsewhere). This multidisciplinary project will introduce undergraduate, graduate and postdoctoral students and new faculty to other disciplines within biology by blending original methods and questions in physiology, ecology, molecular biology and phylogeny. Students will gain experience at sea and share in the process of discovery. New partnerships will be established among 4 universities and 5 PIs, most of whom have not worked together previously. Results will be highlighted in a broad range of undergraduate and graduate courses. The project involves several young academicians and a hearing-disabled graduate student in the field of deep-sea biology as well as undergraduates recruited through diversity programs. A partnership facilitated by California COSEE (Center for Ocean Science Education Excellence) will allow us 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.

Colonization tray installed in a clam bed at Hydrate Ridge. The central cup contains sulfide treatments designed to examine response of settling macrofauna to varying sulfide concentrations.

Anthomastus ritteri (Cnidaria) on carbonate rocks at the Eel R. Methane Seep (500 m)

Ghost net and a rockfish near Hydrate Ridge methane seeps, 800 m Oregon Margin

Snail caravan, Hydrate Ridge methane seeps, 900 m Oregon Margin

Neptunia amianta laying egg towers on carbonate rocks, Hydrate Ridge methane seeps, Oregon Margin

Parougia sp. nov. (Dorvilleidae: Polychaeta) Eel R. Methane Seeps


Colonization trayson a gear elevator, prior to deployment at Pacific methane seeps

Seep Ampharetidae, Hydrate Ridge

ALVIN Recovery

AT-7 Scientific Party, July 2006

Seep mudwashers, July 2006

Some of the Levin Lab at Sea

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