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Blake Ridge Seep: Biodiversity, Foraminiferal Studies, and Food Webs

Join the Deep East Cruise by NOAA-NURP, UNC-Wilmington, and NOAA Ocean Exploration to explore the fascinating Blake Ridge Seep. Discover the quantitative mussel bed diversity, foraminiferal studies, coring, sediment profiling, mapping, and food web dynamics of this unique ecosystem. Don't miss this exciting scientific expedition!

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Blake Ridge Seep: Biodiversity, Foraminiferal Studies, and Food Webs

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  1. Blake Ridge Seep • Deep East Cruise • sponsored by NOAA-NURP UNC-Wilmington and NOAA Ocean Exploration • CL Van Dover, Chief Scientist College of William & Mary ecology • C. Ruppel Georgia Tech. geophysics • B. Sen Gupta Louisiana State U. foraminifera • J. Bernhard U. South Carolina foraminifera • P. Aharon U. Alabama geology • S. Macko U. Virginia stable isotopes • R. Seitz College of William & Mary (VIMS) food webs • P. Keener-Chavis U. Charleston web site • 4 Alvin dives (September 2001)

  2. Blake Ridge Seep • Primary Objectives: • quantitative mussel bed sampling for comparative diversity studies (Van Dover) • foraminiferal studies (Bernhard, Sen Gupta) • coring and sediment profiling (Ruppel) • mapping (seabeam) (Ruppel) • Other Objectives: • site reconnaissance • foodweb studies (Van Dover, Macko, Seitz) • outreach (website)

  3. Blake Ridge Seep

  4. Blake Ridge Seep Sarsiaster greigi cake urchin Bathymodiolus heckerae mussels Vesicomya cf. venusta clams green commensal polychaete family Nautiliniellidae

  5. Blake Ridge Seep Alvinocaris muricola and Alvinocaris new species

  6. Van Dover et al., Mar 2002 unpublished data Blake Ridge Seep brisingid seastar Syringammina xenophyophore (Protozoa) “tubeworms” pogonophorans or vestimentiferans? sipunculid

  7. Blake Ridge Seep

  8. Blake Ridge Seep

  9. Blake Ridge Seep Mussel gill symbionts methanotrophs & thiotrophs Clam gill symbionts thiotrophs N

  10. Blake Ridge Seep

  11. Blake Ridge Seep

  12. Blake Ridge Seep 34Smussel = f (34Ssulfide) + (1 - f ) 34Sseawater sulfate ~80% sulfide ~20% seawater sulfate Mixing Models Carbon: source methane (from Paull et al. 2000): -68 ‰ thiotrophic carbon (this study): -36 ‰ 13Cmussel = f (13Cmethane) + (1 - f ) 13Cthiotrophic C ~60% methanotrophic carbon ~40% thiotrophic carbon Sulfur: sulfide (inferred from clams): -15 ‰ seawater sulfate: +20 ‰

  13. Blake Ridge Seep Summary 1. Blake Ridge seeps share some species with Florida Escarpment and Barbados seep sites; i.e., the fauna is not strictly endemic to this site. 2. The large size of the mussels at Blake suggests more rapid growth and/or a relatively greater duration of the Blake seepage. 3. There has been substantial mortality in the bivalve populations, but the cause(s) are unknown. 4. Blake mussels have a dual symbiosis (methanotrophs and thiotrophs); Blake clams have only thiotrophic symbionts. 5. Mussels are the biomass dominants and derive their organic carbon ~60% from methanotrophs, 40% thiotrophs. 6. The Blake food web is dominated more by thiotrophic carbon than by methanotrophic carbon. 7. There is no evidence for a significant role of photosynthetically derived organic carbon in the Blake food web.

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