Pelagic-benthic coupling on the shelf of the northern Bering and Chukchi Seas. Ill Benthic food supply and carbon cycling

Abstract

Benthic carbon c y c h g in the northern Bering and Chukchi Seas was hypothesized to be regulated by variable primary production regimes in the overlying water: the highly productive (-250 to 300 g C m-2 yr-l) Bering Shelf-Anadyr Water (BSAW) and the less productive (-50 g C m-2 yr-l) Alaska Coastal Water (ACW).Sediment oxygen uptake was correlated with water column parameters and surface sediment C/N ratios characteristic of each water type.Total sediment oxygen uptake rates decreased from a mean 19.2 mm01 O2 m-2 d-' in BSAW to a mean 8.7 mm01 O2 m-' d-' in ACW.Mean benthic aerobic respiration rates significantly varied interannually in BSAW, although they were consistently 2 to 3 times greater in BSAW than in ACW within any one year, indicating that interannual variability in water column primary production may have a direct influence on the availability of organic carbon to the benthos.The explanation for higher respiration rates in the benthos beneath BSAW negates an expected reduction due to colder temperatures.A reduction in organic matter to the benthos in ACW apparently limits benthic metabolism even at higher temperatures.Macrofaunal respiration and bioturbation in high benthic biomass regions were important components in benthic carbon cycling.