marine biodiversity
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Biophysical dispersal models are rapidly developing into a powerful and sophisticated means of investigating the interface between oceanographic and biological processes. By coupling ocean physics with larval behaviour, it becomes possible to study expected dispersal patterns, assess the potential impact of rare and/or catastrophic events, evaluate the sensitivity of the system to changes in larval characteristics or behaviour, and project these impacts over time. Potential applications include: examining the influence of vertical movement, studying the effects of different navigational strategies, analysing the effects of a defined reproductive season, and assessing the consequences of applying different survivorship functions. The development and implementation of these types of models will be addressed, and examples from Southeast Asia and Australia will be provided.
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The Antarctic continental slope spans the depths from the shelf break (usually between 500-1000 m) to ~3000 m, is very steep, overlain by 'warm' Circumpolar Deep Water and life there is poorly studied. This study investigates whether life on Antarctica's continental slope is essentially an extension of the shelf or the deep-sea fauna, a transition zone between these or clearly distinct in its own right. Using data from several cruises to the Weddell and Scotia sea, including the ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) I-III and BIOPEARL (BIOdiversity, Phylogeny, Evolution and Adaptive Radiation of Life in Antarctica) 1 and EASIZ II cruises as well as current data bases (SOMBASE, SCAR-MarBIN), we selected four different taxa (i.e. cheilostome bryozoans, isopod and ostracod crustaceans, and echinoid echinoderms) and two areas, the Weddell and the Scotia Sea, to examine faunal composition, richness and affinities. The answer has important ramifications to the link between physical oceanography and ecology, and the potential of the slope to act as a refuge and resupply zone to the shelf during glaciations (and therefore support or not glaciological reconstructions of ice sheets covering continental shelves).
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This dataset contains species identifications of molluscs collected during survey SOL5117 (R.V. Solander, 30 July - 27 August, 2010). Animals were collected from the Joseph Bonaparte Gulf with a benthic sled (SL) and Smith McIntyre grab (GR). Specimens were lodged at Northern Territory Museum on the 27 August 2010. Species-level identifications were undertaken by Richard Willan at the Northern Territory Museum and were delivered to Geoscience Australia on the December 2010 (for large samples) and 26 June 2012 (for smaller molluscs from grabs). See GA Record 2011/08 for further details on survey methods and specimen acquisition. Data is presented here exactly as delivered by the taxonomist, and Geoscience Australia is unable to verify the accuracy of the taxonomic identifications. Comments: The following comments relate to live-taken specimens only: 1. The SOL5117 molluscan samples contain at least one new species (Talabrica sp.), one new record for Australia (Oliva rufofulgurata), and five new records for Commonwealth waters north of the Northern Territory (Strombus hickeyi, Trigonostoma textilis, Dentalium formosum, Phyllidiopsis shireeenae, Ceratosoma trilobatum). 2. Many of the molluscan species in the SOL5117 grab samples, both live individuals and dead shells, are represented only by tiny juveniles, so identification to species level is not possible because the shell characters change considerably as the species reaches maturity. 3. Clearly the majority of molluscs in the SOL5117 samples are represented by dead shells only. 4. Species richness is far higher than suggested by these samples. Judging from the range of species present in the SOL4934 and SOL5117 samples plus the accumulation of species through the samples, the molluscan biodiversity in this area would be between 400 and 500 species, the great majority micromolluscs (i.e., < 5 mm in greatest dimension). 5. The SOL5117 molluscan samples are not as comprehensive as the earlier SOL4934 samples taken in the same areas(s). 6. The SOL5117 molluscan samples provide us with hardly any picture of the composition or abundance of molluscs within or between the sites. 7. The SOL5117 molluscan samples should not be used to assess the conservation status of the submarine communities in the area(s) sampled. 8. More targeted and intensive sampling is required to appropriately measure molluscan diversity, abundance and communities in this region. ~ R Willan
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Geoscience Australia undertakes classification of biophysical datasets to create seabed habitat maps (termed 'seascapes') for the Australian margin and adjacent sea floor. Seascapes describe a layer of ecologically meaningful biophysical properties that spatially represents potential seabed habitats. Each seascape area corresponds to a region of the seabed that contains similar biophysical properties and, by association, potential habitats and communities. The lack of available standardised biological data at the national scale precludes the integration of biological information into the derivation of national seascapes. By focusing on a much smaller scale over tens of kilometres near the Glomar Shoals in Western Australia, referred to as 'local scale', available biological data were integrated into new derivations of seascapes and results compared with seascapes without these data. Using physical data as described in Whiteway et al. 2007 (GA Record 2007/11) and demersal fish data obtained from the 1967 Russian Berg-3 survey, we have derived four new local sets of seascape to compare the effects of integrating biological data: 1) Standard seascapes using only physical data, 2) Seascapes with an additional biology layer based on the Shannon diversity index, 3) Seascapes with an additional biology layer based on the Simpson diversity index, and 4) Seascapes with an additional layer of randomly-generated data. At the 'regional-scale' we derived two sets of seascapes: 1) Seascapes with an additional biology layer based on the Shannon diversity index that encompasses the entire Berg-3 survey area in northwest Australia, and 2) Standard seascapes using only physical data for the same area. This datsets is the local scale Glomar Shoals seascape produced with a biological layer called the 'Simpson Diversity Index'.
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A key component of marine bioregional planning is to map the spatial patterns of marine biodiversity, often measured as species richness, total abundance or abundance/presence of key taxa. In this study, predictive modelling approaches were used to map soft bottom benthic biodiversity on the Carnarvon Shelf, Western Australia, using a range of physical surrogates. This surrogacy approach could also explicitly link physical environmental attributes to the marine biodiversity patterns. The statistical results show that between 20% and 37% of variances on the two biodiversity measures (Species Richness and Total Abundance) were explained by the Random Forest Decision Tree models. The best statistical validation performance was found at the Point Cloates area. This was followed by the Gnaraloo area, then by the Mandu Creek area. The models identified different individual physical surrogates for the three study areas and the two biodiversity measures. However, it was found that the infaunal biodiversity at the three study areas of the Carnarvon Shelf were driven by similar ecological process. Sediment properties were the most important physical surrogates for the infaunal biodiversity. Coarser and heterogeneous sediments favour higher infaunal species richness and total abundance. The prediction maps indicate the highest infaunal biodiversity at deeper water of the Point Cloates area. In contrast, the majority of the Mandu creek area has low infaunal biodiversity. This may be due to the much narrower shelf width (e.g., ~6 km) in this part of Carnarvon Shelf than the Point Cloates and Gnaraloo areas. The narrow shelf would limit the space for oceanographic processes to work on the sediment and develop heterogeneous sediment properties that support diverse and productive infaunal species.
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The Oceanic Shoals survey (SOL5650, GA survey 339) was conducted on the R.V. Solander in collaboration with Geoscience Australia, the Australian Institute of Marine Science (AIMS), University of Western Australia and the Museum and Art Gallery of the Northern Territory between 12 September - 5 October, 2012. This dataset comprises an interpreted geomorphic map. Interpreted local-scale geomorphic maps were produced for each survey area in the Oceanic Shoals Commonwealth Marine Reserve (CMR) using multibeam bathymetry and backscatter grids at 2 m resolution and bathymetric derivatives (e.g. slope; 1-m contours). Six geomorphic units; bank, depression, mound, plain, scarp and terrace were identified and mapped using definitions suitable for interpretation at the local scale (nominally 1:10 000). Maps and polygons were manual digitised in ArcGIS using the spatial analyst and 3D analyst toolboxes. For further information on the geomorphic mapping methods please refer to Appendix N of the post-survey report, published as Geoscience Australia Record 2013/38: Nichol, S.L., Howard, F.J.F., Kool, J., Stowar, M., Bouchet, P., Radke, L., Siwabessy, J., Przeslawski, R., Picard, K., Alvarez de Glasby, B., Colquhoun, J., Letessier, T. & Heyward, A. 2013. Oceanic Shoals Commonwealth Marine Reserve (Timor Sea) Biodiversity Survey: GA0339/SOL5650 Post Survey Report. Record 2013/38. Geoscience Australia: Canberra. (GEOCAT #76658).
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Climate change is threatening tropical reefs across the world, with most scientists agreeing that the current changes in climate conditions are occurring at a much faster rate than in the past and are potentially beyond the capacity of reefs to adapt and recover. Current research in tropical ecosystems focuses largely on corals and fishes, although other benthic marine invertebrates provide crucial services to reef systems, with roles in nutrient cycling, water quality regulation, and herbivory. We review available information on the effects of environmental conditions associated with climate change on noncoral tropical benthic invertebrates, including inferences from modern and fossil records. Increasing sea surface temperatures may decrease survivorship and increase the developmental rate, as well as alter the timing of gonad development, spawning, and food availability. Environmental changes associated with climate change are linked to larger ecological processes, including changes in larval dispersal and recruitment success, shifts in community structure and range extensions, and the establishment and spread of invasive species. Loss of some species will trigger economic losses and negative effects on ecosystem function. Our review is intended to create a framework with which to predict the vulnerability of benthic invertebrates to the stressors associated with climate change, as well as their adaptive capacity. We anticipate that this review will assist scientists, managers, and policy-makers to better develop and implement regional research and management strategies, based on observed and predicted changes in environmental conditions.
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This introductory chapter provides an overview of the book's contents and definitions of key concepts including benthic habitat, potential habitat and seafloor geomorphology. The chapter concludes with a summary of commonly used habitat mapping technologies. Benthic (seafloor) habitats are physically distinct areas of seabed that are associated with particular species, communities or assemblages that consistently occur together. Benthic habitat maps are spatial representations of physically distinct areas of seabed that are associated with particular groups of plants and animals. Habitat maps can illustrate the nature, distribution and extent of distinct physical environments present and importantly they can predict the distribution of the associated species and communities.
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Physical sedimentological processes such as the mobilisation and transport of shelf sediments during extreme storm events give rise to disturbances that characterise many shelf ecosystems. The intermediate disturbance hypothesis predicts that biodiversity is controlled by the frequency of disturbance events, their spatial extent and the amount of time required for ecological succession. A review of available literature suggests that periods of ecological succession in shelf environments range from 1 to over 10 years. Physical sedimentological processes operating on continental shelves having this same return frequency include synoptic storms, eddies shed from intruding ocean currents and extreme storm events (cyclones, typhoons and hurricanes). Modelling studies that characterise the Australian continental shelf in terms of bed stress due to tides, waves and ocean currents were used here to create a map of ecological disturbance, defined as occurring when the Shield's parameter exceeds a threshold of 0.25. We also define a dimensionless ecological disturbance ratio (ED) as the rate of ecological succession divided by the recurrence interval of disturbance events. The results illustrate that on the outer part of Australia's southern, wave-dominated shelf the mean number of days between threshold events that the Shield's parameter exceeds 0.25 is several hundred days.
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This dataset contains species identifications of macro-benthic worms collected during survey SOL4934 (R.V. Solander, 27 August - 24 September, 2009). Animals were collected from the Joseph Bonaparte Gulf with a benthic sled or a Smith-McIntyre grab. Specimens were lodged at Northern Territory Museum on the 24 September 2009. Species-level identifications were undertaken by Chris Glasby at the Northern Territory Museum and were delivered to Geoscience Australia on the 26 October 2009 See GA Record 2010/09 for further details on survey methods and specimen acquisition. Data is presented here exactly as delivered by the taxonomist, and Geoscience Australia is unable to verify the accuracy of the taxonomic identifications.