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The Journal of Experimental Biology 205, 1669-1681 (2002)
© 2002 The Company of Biologists Limited

Respiratory adaptations in a deep-sea orbiniid polychaete from Gulf of Mexico brine pool NR-1: metabolic rates and hemoglobin structure/function relationships

Stéphane Hourdez1,2,*, Roy E. Weber3, Brian N. Green4, John M. Kenney5 and Charles R. Fisher1

1 Department of Biology, 208 Mueller Lab, Pennsylvania State University, University Park, PA 16802, USA
2 Station Biologique de Roscoff, BP74, CNRS-UPMC-INSU, 29682 Roscoff cedex, France
3 Center for Respiratory Adaptation (CRA), Department of Zoophysiology, University of Aarhus, 8000 Aarhus C, Denmark
4 Micromass Ltd, Tudor Road, Altrincham, Cheshire WA14 5RZ, UK
5 Institute for Storage Ring Facilities — Aarhus (ISA), University of Aarhus, 8000 Aarhus C, Denmark
* Present address: Department of Biology, 208 Mueller Lab, Pennsylvania State University, University Park, PA 16802, USA

(e-mail: hourdez{at}psu.edu )

Accepted 20 March 2002

Methanoaricia dendrobranchiata Blake (Polychaeta; Orbiniidae) occurs in large numbers in association with communities of the mussel Bathymodiolus childressi at hydrocarbon seeps on the Louisiana Slope of the Gulf of Mexico. Its microhabitat can be strongly hypoxic (oxygen is often undetectable) and sulfidic (sulfide concentrations can reach millimolar levels), which may seriously challenge aerobic metabolism. We describe a suite of adaptations to its low-oxygen environment. The worms are capable of regulating their rate of oxygen consumption down to partial pressures of approximately 870 Pa oxygen. This capability correlates with a large gill surface area, a small diffusion distance from sea water to blood, a very high hemoglobin oxygen-affinity (P50=27.8 Pa at 10°C and pH 7.6) and a Bohr effect that is pronounced at high oxygen saturations. When fully saturated, the hemoglobin binds sufficient oxygen for only 31 min of aerobic metabolism. However, these polychaetes can withstand extended periods of anoxia both in the absence and presence of 1 mmoll-1 sulfide (TL50=approx. 5.5 and 4 days, respectively).

Key words: hypoxia, anoxia-tolerance, sulphide-tolerance, functional properties, cold seep, oxygen consumption, physiology, haemoglobin, orbiniid, polychaete, Methanoaricia dendrobranchiata






© The Company of Biologists Ltd 2002