Mawson South Escarpment, Antarctica, geological map 1:250 000

An integrated analysis of biological and geoscientific data collected from the nearshore marine environment of the Vestfold Hills was used to identify benthic habitats and associated communities and examine relationships between benthic community composition and environmental characteristics. A 48 km2 area was surveyed using a multibeam echosounder system (MBES) to produce high-resolution bathymetry and backscatter intensity maps of the seabed. Epibenthic community data and in situ observations of substrate composition and seafloor bedforms and features were obtained from towed underwater video. A comparison of top-down and bottom-up approaches to defining benthic habitats was used to improve understanding of the applicability of mapping methodologies. On a broad scale, both approaches produced habitat classes distinguished largely by geomorphic features, with substrate and depth identified as the main controls of benthic community composition, however, the relationship between benthic community composition and environmental characteristics is complex with many variables contributing to differences in community composition. The top-down approach was based on geomorphic units defined using abiotic characteristics and the assemblages identified within the geomorphic were very broad did not always show clear distinction between assemblages. Conversely, the bottom-up approach generated additional habitat classes, identified clear defining taxa for each class, greater distinction between the benthic communities, and allowed identification of additional environmental factors (i.e. sea ice cover) that influence benthic community distribution that are not discernible from geomorphic information alone. The habitat types identified and mapped using the bottom-up approach include shallow boulder fields and exposed bedrock which are dominated by dense macroalgae communities, and steep slopes, muddy basins and sandy plains which are dominated by invertebrate communities. The results indicate that a bottom-up approach is preferable for benthic habitat mapping, however, where detailed information is not available, geomorphic information provides a reasonable indication of the distribution of benthic habitats and communities. This study highlights the utility of multibeam sonar for interpretation of sea floor morphology and substrate and the multibeam data provide a physical framework for understanding benthic habitats and the distribution of benthic communities. This research provides the scientific context and spatial framework for managing the Vestfold Hills nearshore marine environment and provides a baseline for assessing environmental change.

Even by Antarctic standards, the George Vth Land coast is remote and infrequently visited. A range of questions related to oceanography, biology and geology has driven renewed interest in the area. The Antarctic ice sheet contains the earth's largest reservoir of fresh water, and for this reason its growth and decay through time have been coupled to significant sea-level, climate and oceanographic variations.

Legacy product - no abstract available

Legacy product - no abstract available

An integrated analysis of geoscience information and benthos data have been used to identify seafloor habitats and associated benthic communities in the near-shore environment of the Vestfold Hills, East Antarctica. A multibeam echo-sounder was used to collect high-resolution bathymetry of the seafloor to depths of 215 m. A towed underwater video was used to identify macrobenthos along 16 transects. Abiotic variables including depth, backscatter intensity, substrate, slope, seafloor features (e.g. iceberg scours, sand ripples) and latitude were extracted from the multibeam and video datasets. Multivariate analysis of the benthos data was used to identify discrete benthic communities within the study area. Analysis of bio-physical relationships indicates that these benthic communities occur within distinct geographical regions and seafloor habitats. The habitats are distinguished primarily on the basis of depth and substrate. The two dominant seafloor habitats and associated benthic communities are: 1) deep, muddy basins with low to medium biological cover, consisting predominantly of bivalves, urchins, and seapens; and 2) shallow rocky outcrops, typically covered in dense macroalgae communities and associated invertebrates such as amphipods, spirorbid polychaetes and holothurians. In between are transition zones which provide habitat to mixed benthic communities. This study demonstrates the efficacy of using multibeam systems to survey large areas of the seafloor and collect high-resolution baseline data across previously unexplored regions. This baseline data is critical to improve our understanding of ecosystem dynamics and the relationships between biota and habitats and allows managers to make informed decisions about the effects of different activities on marine habitats.

No abstract available

No abstract available

No abstract available

No abstract available