Abstract
The lysianassid amphipod Orchomene obtusus (Sars) is known as an epibenthic scav- enger, but it is abundant in the water column of Saanich Inlet, British Columbia, a temperate fjord with poorly oxygenated deep water. Sampling with vertically-stratified nets and baited traps indi- cates that O. obtusus is abundant within the oxycline at 100 to 140 m, is present in anoxic deep waters at low abundances, and is also abundant in the anoxic benthic environment. Shipboard incubations revealed that O. obtusus can survive between 10 and 33 h of anoxia at in situ conditions. Stable iso- tope and gut fluorescence measurements suggest that these amphipods feed on material produced in surface waters, and not on the isotopically dissimilar suspended detrital material present in the vicin- ity of the oxycline. The amphipods do not enter surface waters, and it appears that O. obtusus has adapted to oxygen gradients in this environment by feeding on surface-water-derived material in the food-rich and predator-poor anoxic benthos and subsequently migrating into the water column to conduct aerobic respiration. These vertical excursions are probably a modification of the swimming behavior exhibited by hyperbenthic amphipods in well-oxygenated environments, and may consti- tute an important mechanism for benthic-pelagic coupling.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
