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(80-53) Baseline Conditions in the Caspian Sea: A Worm's Eye View. Tait, Russell*,1, Germano, Joseph2, 1 ExxonMobil Production Company, Houston, Texas2 Germano and Associates, Inc., Bellevue, Washington ABSTRACT- A Sediment Profile Imaging (SPI) survey was conducted in May, 2000 along four transects in the deeper southern basin of the Caspian Sea, offshore Azerbaijan. The SPI survey was included as part of a comprehensive baseline environmental assessment in and around three Production Sharing Contract Areas for ExxonMobil affiliates. The objectives of the SPI survey were to document sediment type and benthic ecological conditions at each location, and evaluate the system as a potential tool to assess impacts from exploration drilling discharges. Four survey transects ranged in water depth from 20 to 900 metres. The sediment profile images strongly suggest that the deeper regions of the survey area are primarily depositional with few and scattered stations showing any evidence of physical disturbance. These exhibited discrete rhythmic laminae corresponding to successive depositional events. Laminae were not observed within the shallow water sediments. Although there was variability in environmental parameters between transects, a general, site-wide pattern of sediment type, sediment features, and biological conditions was evident. In all transects, the stations located in shallow-water areas exhibit the most biologically-rich sediments. These areas consist of bivalves, epizoans and polychaete worms that actively bioturbate and irrigate the sediment column to depth and represent the regions of greatest benthic habitat quality. The deep-water sediments were very porous, soft silts and clays with well-defined laminations at depth within the sediment column. The infaunal communities at these deep-water stations exhibit low-order successional seres with minimal bioturbation of the sediment column. This strongly suggests that these deep-water areas have historically been regions of low benthic successional development and infrequently disturbed. Key words: sediment profile imaging, benthic community, Caspian Sea |
