Benthos of the Cariaco Basin: Is the Eukaryotic Community Similar to that of the Santa Barbara Basin?

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Benthos of the Cariaco Basin:Is the Eukaryotic Community Similar to that of the Santa Barbara Basin?The Cariaco Basin, the second largest known anoxic body of water known on Earth, has been extensively studied for its water-column processes and sedimentary record, but virtually nothing is known about the benthos of the oxygen-depleted and anoxic regions of the basin. An abundant community of metazoans and protists has been described from the sedimentary anoxic-oxic interface in the Santa Barbara Basin, and this study will examine the possibility that the Cariaco Basin supports a similarly rich benthic consortium. The broad objective of the proposed project is to describe the eukaryotic benthos of the Cariaco Basin. We will: 1) quantify the eukaryotic community using Percoll gradient extraction and fluorogenic staining; 2) examine the eukaryotes for prokaryotic associates using DAPI staining and ultrastructural examination; 3) identify the benthic foraminiferal assemblage using various viability indicators (i.e., fluorogenic probes, ultrastructure, conventional rose Bengal staining); and 4) determine changes in the benthic foraminiferal community composition across the anoxic / oxic interface. These specific aims will be addressed using material collected on one short cruise to sample the Cariaco Basin using the Venezuelan ship RV Hermano Gines in May 2001. Replicate multicores will be taken at each of 8 sites in the northeastern sector, at one site located in the eastern sub-basin, and at one site on the saddle between the two sub-basins. Bottom-water oxygen concentrations will be determined with microwinkler analysis. Results will impact the areas of benthic ecology, biodiversity and biogeography, and paleoceanography. Cell biology and evolutionary biology may also benefit if novel symbioses or adaptations to this extreme environment are identified.