The northeastern Chukchi Sea: benthos-environmental interactions

Benthic faunal abundance, diversity, and biomass were examined in the northeastern Chukchi Sea to determine factors influencing faunal distribution.Four taxon-abundance-based benthic station groups were identified by cluster analysis and ordination techniques.These groups are explained, using stepwise multiple discriminant analysis, by the gravel-sand-mud and water content of bottom sediments, and the organic carbon/nitrogen (OC/N) ratio.In contrast to previous benthic investigations in the northeastern Bering and southeastern Chukchi Seas, faunal diversity between inshore and offshore regions in our study area were not related to differences in sediment sorting.Instead, regional diversity differences in the northeastern Chukchi Sea were related to greater environmental stresses (e.g.ice gouging, wave-current action, marine-mammal feeding activities) inshore than offshore.The presence of a high benthic biomass north of Icy Cape in the vicinity of Point Franklin and seaward of a hydrographic front is presumably related to an enhanced local depositional flux of particulate organic carbon (POC) in the area.We postulate that POC-rich waters derived from the northern Bering and northwestern Chukchi Seas extend to our study area and the flux of the entrained POC provides a persistent source of carbon to sustain the high benthic biomass.Annual POC enrichment of the coastal region north of Icy Cape is reflected by the great abundance of amphipods and other invertebrates present there and the concentration in summer of walrus Odobenus rosmarus djvergens and gray whales Eschrichtius robustus that feed on these invertebrates.This study demonstrates that there can be high standing stocks of benthos in arctic regions with relatively low annual primary production if local carbon is augmented by POC advected from highly productive areas.