Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
Feeding on the Bottom at the Top of the World
Katrin B. Iken1, Bodil A. Bluhm2, Rolf R. Gradinger3
1School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 245 O'Neill Bldg, Fairbanks, AK, 99775, USA, Phone 907-474-5192, Fax 907-474-7204, iken@ims.uaf.edu
2School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 245 O'Neill, Fairbanks, AK, 99775, USA, Phone 907-474-6332, Fax 907-474-7204, bluhm@ims.uaf.edu
3School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 245 O'Neill Bldg, Fairbanks, AK, 99775, USA, Phone 907-474-7407, Fax 907-474-7204, rgradinger@ims.uaf.edu
The trophic structure of the benthic community of the deep Canadian Basin in the Arctic was investigated. We used stable isotope analysis to elucidate how closely linked deep-sea benthos is to the pelagic and ice-associated production. d15N ratios are indicative of relative trophic relationships with a stepwise enrichment between trophic levels (TL) of about 4‰. Mean d15N isotopic values for water column POM was 5.1‰. Benthic animals ranged from 10.2‰ to 17.7‰ in their d15N isotopic values with most of the organisms falling into the second and third TL with respect to the POM values. This suggests that little fresh phytodetritus is reaching the seafloor.
The benthic community consists mainly of deposit feeders consuming refractory material, e.g. many polychaetes, and of scavengers, predators or omnivores. In contrast to the benthic system, distinctive herbivores (TL1) and 1st order predators (TL2) were present at the sea ice and the upper water column, with d15N values between 5-7‰ and 10-13‰, respectively. Few pelagic/ice organisms fell within the third TL suggesting that the link between the pelagic/sea ice and the benthic system is through sinking of grazers and their products (e.g. fecal pellets, molts, dead animals) to the seafloor rather than through direct input of algal material to the benthos.
Abstract Categories: Biological Feedbacks
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