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 distr ibution. Four taxon-abundance-based benthic station groups were identi fied by cluster analysis and ordination techniques. These groups are e xplained, using stepwise multiple discriminant analysis, by the gravel -sand-mud and water content of bottom sediments, and the organic carbo n/nitrogen (OC/N) ratio. In contrast to previous benthic investigation s in the northeastern Bering and southeastern Chukchi Seas, faunal div ersity between inshore and offshore regions in our study area were not related to differences in sediment sorting. Instead, regional diversi ty 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 h igh benthic biomass north of Icy Cape in the vicinity of Point Frankli n and seaward of a hydrographic front is presumably related to an enha nced local depositional flux of particulate organic carbon (POC) in th e area. We postulate that POC-rich waters derived from the northern Be ring and northwestern Chukchi Seas extend to our study area and the fl ux of the entrained POC provides a persistent source of carbon to sust ain the high benthic biomass. Annual POC enrichment of the coastal reg ion 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 divergens and gray whales Eschrichtius ro bustus that feed on these invertebrates. This study demonstrates that there can be high standing stocks of benthos in arctic regions with re latively low annual primary production if local carbon is augmented by POC advected from highly productive areas.