Benthic Foraminifera as Environmental Indicators in Torres Strait - Gulf of Papua: In Todd, B.J., and Greene, H.G., eds., Mapping the Seafloor for Habitat Characterization

Brief description

Three areas in the Torres Strait-Gulf of Papua region were selected for detailed study of sediments and benthic fossil biota. These areas form a transect across the shelf from the Fly River Delta to the shelf edge, near the northern extremity of the Great Barrier Reef. The Torres Strait-Gulf of Papua shelf is a shallow, low-gradient platform, where the shelf edge occurs between 120 and 140 m depth. In the study area, where the sediments range from muddy to gravelly carbonate sands, the sediment deposition rates are low and the relict content of sediment is often high.

The three areas show distinct differences in benthic foraminiferal assemblages as indicated by relative abundances at the order level, as well as distribution patterns of individual species; these differences are also reflected in the total microbiotic communities. Given the high relict content in the surface material across these sites, a foraminiferal preservation scale was developed to assess the extent of reworking. Taphonomic features indicate that abrasion is the main factor affecting preservation.

Despite poor preservation of the foraminiferal tests, the benthic foraminiferal species have a strong correlation to water depth, indicating that transportation pathways are short. Application of multivariate statistics to analyze the relationship between environmental attributes and the distributions of the microbiota and foraminiferal species indicates the additional importance of factors including percent carbonate mud, percent gravel, organic carbon flux, temperature, salinity and mean grain size. The benthic foraminifera produce a much stronger correlation to the environmental variables than the microbiota, indicating that these organisms can provide a detailed assessment of habitat types.

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