Relationships between polychaete community composition and environmental factors in the Gulf of Carpentaria, northern Australia

Hocknull, Shona A. (2010). Relationships between polychaete community composition and environmental factors in the Gulf of Carpentaria, northern Australia M.Sc Thesis, Centre for Marine Studies, The University of Queensland.

       
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Author Hocknull, Shona A.
Thesis Title Relationships between polychaete community composition and environmental factors in the Gulf of Carpentaria, northern Australia
School, Centre or Institute Centre for Marine Studies
Institution The University of Queensland
Publication date 2010-08
Thesis type M.Sc Thesis
Supervisor Ian Tibbetts
Anthony Richardson
Chris Glasby
Rodrigo Bustamante
Total pages 138
Total colour pages 31
Total black and white pages 107
Language eng
Subjects 05 Environmental Sciences
Abstract/Summary Abstract Polychaetes are an important component of benthic ecosystems, both from an environmental and from an economic perspective. Polychaetes play a role in the environment by assisting in nutrient cycles, bioturbation and aeration of the sediment. Polychaetes are strongly linked within food webs with birds, fish, crustaceans and gastropods all having been recorded feeding on them. Polychaetes are among the best indicators of pollution and disturbance in environmental management and monitoring. They are well known as first stage colonisers of anthropogenic and naturally damaged marine ecosystems. All these roles that polychaetes play in marine ecosystems make them important in sustainable fisheries, aquaculture and environmental monitoring research. In this thesis, data on the diversity, abundance and richness of polychaete communities in the Gulf of Carpentaria (GoC) are presented and correlated with environmental predictors. Correlations of feeding guild diversity and richness to environmental data are also presented. Data are collated from four surveys conducted over the past twenty years. These surveys are the Gulf of Carpentaria Fish and Megabenthos Project SS03/1990 (GoCFM); the Northern Prawn Fisheries Benthic Spatial MSE Project SS03/2005 (MPFB); Arafura Sea Biological Survey SS05/2005; and the Northern Territory Museum (NTM) benthic baseline survey. Benthic samples were collected via different equipment for each survey, mainly a Smith-McIntyre, Box Core and Petersen Grab. Statistical analysis was conducted as part of three case studies: the 1990 dataset from the Gulf of Carpentaria Fish and Megabenthos Project; the 2005 dataset collected from the Southwest region of the GoC in the Northern Prawn Fisheries Benthic Spatial MSE Project; and the species level analysis of the Pilargidae family ecology, which combined data from the Northern Prawn Fisheries Benthic Spatial MSE Project SS03/2005; Arafura Sea Biological Survey SS05/2005; and the Northern Territory Museum (NTM) benthic baseline survey. Statistical analysis was conducted at the family level, due to time restrictions in the project. Only one family, the Pilargidae, was identified to the species level for a more detailed assessment of distribution and ecology. This detailed assessment found five new species to science and five new species records for Australia. A total of 10,044 individual polychaetes from forty-four families were collected during all four surveys. All these families are commonly collected from waters around Australia. The density of polychaetes in the 1990 GoC ranged from 10 – 2,010 ind/m2, = 130 ind/m2. In 2005 the density of polychaetes ranged from 100 – 2,880 ind/m2, = 820 ind/m2. The three dominant families in the GoC have remained the same between 1990 and 2005. However the top ranked family has changed between the two surveys. In 1990 Eunicidae was the top ranked family, followed by Capitellidae and Spionidae, whereas in 2005 Capitellidae was the top ranked, followed by Spionidae and Eunicidae. This may be due to a seasonal effect on polychaete groups, as the GoCFM survey was conducted at the start of the wet-season (Nov-Dec) and the NPFB survey was conducted at the end of the wet season (Feb-Mar). In 1990 and 2005 the same pattern in polychaete diversity, abundance and richness was observed across the GoC. In general there was a distinctly higher diversity and richness in the south-eastern region of the GoC, with a trend of reduction in a diagonal direction to the north-west GoC and into the Arafura Sea. This same pattern was observed in the feeding guild diversity and richness, except for the filter feeding guild. This guild did not show a reduction in abundance across the GoC sites. The best predictor for the relationship of polychaete community composition to environmental predictors, for both 1990 and 2005 was firstly the percentage sand content of the sediments and secondly the salinity of surrounding water. Polychaetes guild showed the same correlation with sand being the best predictor for guild diversity and richness. Species level analyses of the Pilargidae suggest that individual species have sediment grain size preferences. Overall the findings demonstrate that within the GoC higher sand content of the sediments supports a higher polychaetes diversity, abundance and richness.
Keyword Polychaeta -- Gulf of Carpentaria
Annelida
water temperature
salinity
turbidity
particle grain size
polychaete feeding guilds
systematics
diversity
richness
Additional Notes Colour Pages: 19; 31; 32; 48–56; 59; 60; 63-68; 73-75; 79-83; 88; 95-96; A4 pages-Landscape – 119-127; 131-136 A3 pages – None CD case not required

 
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Created: Thu, 07 Oct 2010, 22:53:03 EST by Mrs Shona Hocknull on behalf of Library - Information Access Service