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Mesophotic benthic communities associated with a submerged palaeoshoreline in Western Australia5.54 MB
Published (Version of record)CC BY V4.0, Open Access
Published (Version of record)CC BY V4.0, Open
Journal article
Mesophotic benthic communities associated with a submerged palaeoshoreline in Western Australia
PloS one, Vol.18(8), e0289805
16/08/2023
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Abstract
Key ecological features (KEFs) are elements of Australia’s Commonwealth marine environment considered to be important for biodiversity or ecosystem function, yet many KEFs are poorly researched, which can impede effective decision-making about future development and conservation. This study investigates a KEF positioned over the Last Glacial Maximum (LGM) shoreline on the northwest shelf of Australia (known as the ‘Ancient Coastline at ~125m depth contour’; AC125). Seafloor bathymetry, sedimentology and benthic habitats were characterised within five study areas using multibeam sonar, sediment samples and towed video imagery. Direct evidence for the existence of a palaeoshoreline formed during the LGM was not found, however candidate areas to find palaeoshoreline material at or just below the modern seabed were discovered. Approximately 98% of the seabed surveyed was comprised of unconsolidated soft sediment habitat (mud/sand/silt) supporting negligible epibenthic biota. The prevalence of soft sediment suggests that post-glacial sediments have infilled parts of the palaeoshoreline, with cross-shelf, probably tidal currents in the northern section of the study area responsible for some of the sediment mobilisation and southern study areas more influenced by oceanic conditions. Within study areas, total biotic cover ranged from 0.02% to 1.07%. Of the biota encountered, most comprised filter feeder organisms (including gorgonians, sponges, and whip corals) whose distribution was associated with pockets of consolidated hard substrate. Benthic community composition varied with both study area and position in relation to the predicted AC125. In general, consolidated substrate was proportionally higher in water shallower than the AC125 compared to on the AC125 or deeper than the AC125. Spatially continuous maps of predicted benthic habitat classes (pre-determined benthic communities) in each study area were developed to characterise biodiversity. Spatial modelling corroborated depth and large-scale structural complexity of the seafloor as surrogates for predicting likely habitat class. This study provides an important assessment of the AC125 and shows that if a distinct coastline exists in the areas we surveyed, it is now largely buried and as such does not provide a unique hard substrate habitat. However, much work remains to fully locate and map the ancient coastline within the vast region of the AC125 and additional surveys in shallow waters adjacent to the AC125 may identify whether some sections lie outside the currently defined KEF.
Details
- Title
- Mesophotic benthic communities associated with a submerged palaeoshoreline in Western Australia
- Creators
- Mary Wakeford - University of Western AustraliaMarji Puotinen - University of Western AustraliaWilliam NicholasJamie Colquhoun - University of Western AustraliaBrigit Vaughan - Department of Biodiversity, Conservation and AttractionsSteve Whalan - Southern Cross UniversityIain Parnum - Curtin UniversityBen Radford - University of Western AustraliaMark Case - University of Western AustraliaRonen Galaiduk - University of Western AustraliaKaren Miller - University of Western Australia
- Publication Details
- PloS one, Vol.18(8), e0289805
- Publisher
- Public Library of Science
- Identifiers
- 991013137109602368
- Copyright
- © 2023 Wakeford et al. This is an open access article distributed under the terms of the Creative Commons Attribution License. (https://creativecommons.org/licenses/by/4.0/).
- Academic Unit
- Science; Faculty of Science and Engineering
- Language
- English
- Resource Type
- Journal article