Using an integrated sampling approach to understand benthic biotopes in an Antarctic coastal marine environment (GeoHab conference, 5-9 May 2014, Lorne, Victoria)  

Authors / CoAuthors

Smith, J. | O'Brien, P.E. | Stark, J.S. | Johnstone, G. | Siwabessy, J.

Abstract

The value of integrated high-resolution data sets in understanding the marine environment has been demonstrated in numerous studies around the Australian margin, however this approach has rarely been applied to studies in East Antarctica. This integrated approach was applied to a survey in Antarctica which utilised a multibeam sonar system, underwater video and sediment sampling to aid the understanding of seabed character and benthic biotopes in the coastal waters of the Vestfold Hills, near the Australian station of Davis. The Vestfold Hills is one of the largest ice-free areas on the East Antarctic coast. The coastal area is a complex of small islands, embayments and fjords. High-resolution bathymetry and backscatter data were collected over 42km2 to depths of 215 m. Epibenthic community data and in situ observations of seafloor morphology, substrate composition and bedforms were obtained from towed underwater video. The new high resolution datasets reveal a mosaic of rocky outcrops and sediment-filled basins. Analysis of the datasets was used to identify statistically distinct benthic assemblages and describe the physical habitat characteristics related to each assemblage, with seven discrete benthic biotopes identified. The biotopes include a range of habitat types including shallow coastal embayments and rocky outcrops, which are dominated by dense macroalgae communities, and deep muddy basins which are dominated by mixed invertebrate communities. Transition zones comprising steep slopes provide habitat for sessile invertebrate communities. Flat to gently sloping plains with a thin sandy cover on shallow bedrock are relatively barren. The relationship between benthic community composition and environmental parameters is complex with many variables (e.g. depth, substrate type, longitude, latitude and slope) contributing to differences in community composition. Depth and substrate type were identified as the main controls of benthic community composition, however, depth is likely a proxy for other unmeasured depth-dependent parameters such as light availability, frequency of disturbance by ice, currents and/or food availability. Sea ice cover is an important driver of benthic community composition, with dense macroalgae communities only found where ice-free conditions persist for most of the summer. The bathymetry data shows iceberg scouring is common, however, scouring does not appear to impact benthic community composition in the study area. This is the first study that has used an integrated sampling approach to investigate benthic assemblages across a range of habitats in a coastal marine environment in East Antarctica. This study demonstrates the efficacy of using multibeam and towed video systems to survey large areas of the seafloor in Antarctica where marine sampling is often logistically difficult, and to collect non-destructive high-resolution data in the sensitive Antarctic marine environment. The multibeam data provide a physical framework for understanding benthic habitats and the distribution of benthic communities. This research provides a baseline for assessing natural variability and human-induced change across the coastal marine environment (Australian Antarctic Science Project AAS-2201), contributes to Geoscience Australia's Marine Environmental Baseline Program, and supports Australian Government objectives to manage and protect the Antarctic marine environment.

Product Type

nonGeographicDataset

eCat Id

78991

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Keywords

• External PublicationAbstract

( Theme )

• marine

( Theme )

• antarctica

( Theme )

• habitat

( Theme )

• multibeam

( Theme )

• seabed

• AQ

Australian and New Zealand Standard Research Classification (ANZSRC)

• Marine Geoscience

• Published_Internal

Publication Date

2014-01-01T00:00:00

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Australian Government Security ClassificationSystem    

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Creative Commons Attribution-NonCommercial 4.0 International Licence    

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Use - license

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geoscientificInformation

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Unknown

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[-68.7, -68.5, 77.7333, 78.1333]

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