T6 AM Environmental Hypoxia
Tuesday, 15 November 2005: 8:00 AM - 11:40 AM in 324-326

(MAX-1117-825477) Effects of hypoxia and anoxia on benthic infauna of the deep Caspian Sea.

Tait, R.¹, Maxon, C.², Parr, T.³, Germano, J.⁴, Newton III, F.⁵, ¹ ExxonMobil Production Company, Houston, TX, USA² CH2M Hill, San Diego, CA, USA³ Terry Parr Consulting, San Diego, CA, USA⁴ Germano and Associates, Bellevue, WA, USA⁵ Battelle Memorial Institute, Carlsbad, CA, USA

ABSTRACT- Deepwater sediment studies were conducted in the south Caspian Sea in support of oil and gas exploration and production over a four year period. Results document the transformation of sediments from hypoxic to possible anoxic conditions with concomitant increases in stratification of the water column, organic carbon concentrations, and laminar banding at the sediment surface independent of exploration or other anthropogenic activities. This study examines the effect of these physical changes on the resident infauna, which was initially dominated by segmented annelid worms, common in oxygen minimum zones. Decreases in abundance, species density, and biomass were attributed to increases in biological oxygen demand at the sediment surface, suggesting that various stages of hypoxia can be identified and used to predict azoic thresholds for deepwater infauna in the Caspian Sea.

Key words: hypoxia, anoxia, Caspian Sea, infauna