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Characteristics of the fish fauna of the Mandurah artificial reef

Ramm, Lachlan A.W. (2020) Characteristics of the fish fauna of the Mandurah artificial reef. Honours thesis, Murdoch University.

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Abstract

Artificial reefs have been deployed throughout the world for a range of different purposes and thus differ in their characteristics. To better understand how their designs and implementation differ spatially, temporally and according to their stated purpose, an extensive collation of information on artificial reefs is needed. Furthermore, in Australia and particularly Western Australia, artificial reefs are increasingly being deployed to enhance recreational fishing experiences and catch rates of key species. To address these topics, this thesis aimed to conduct a systematic literature review on existing artificial reefs around the world and describe their characteristics. It also aimed to compare and describe the characteristics of the fish fauna on the recently deployed Mandurah artificial reef (south-western Australia) to those on nearby natural habitat. Finally, a comparison of the fish community of the three ‘Fish Box’ artificial reefs in Mandurah, Bunbury and Dunsborough was conducted.

The literature review identified 1,074 unique artificial reefs from 71 countries, with 89% located in the northern hemisphere, but with an equal distribution between east and west. A more in-depth investigation of artificial reefs that were intentionally deployed found that these deployments increased markedly after 1965 and were most commonly sunk between depths of 10 and 30 m. Most reefs were designed to enhance faunal communities and/or fisheries. More affluent countries have monitored artificial reefs using more technologically advanced methods including video systems over recent decades. However, many reef deployments have not had an associated monitoring program and those that do are generally too short to detect long-term temporal changes.

Fish and the associated faunal assemblages were monitored on an artificial reef and natural (control) site using Baited Remote Underwater Video (BRUVs) between February 2019 and July 2020. A far greater number of species and individuals were observed on the artificial reef than the control site. Additionally, three key recreational fishing species, i.e. Chrysophrys auratus, Seriola hippos and Pseudocaranx dentex, were also found in far greater abundances on the artificial reef. Pelagic fish were also more common on the artificial habitat, likely due to the upward flow diversion produced by the modules and the subsequent increased availability of plankton. While community composition was mainly driven by differences between the artificial reef and control site, the faunas of both sites did change temporally, albeit to a lesser extent. There was a general decrease in the number of species of fish in winter and increase in summer.

An aim of this study was to develop a standardized protocol for describing artificial reefs, which is hoped to be adopted globally. If successful, this will allow comparisons between artificial reefs and their outcomes to be made thus increasing our understanding of these reefs and improving their designs. The study also demonstrates that the Mandurah artificial reef supports a distinct faunal community compared with an adjacent natural habitat with no reef, including species that are of recreational importance. A comparison of three ‘Fish Box’ artificial reefs demonstrated that the fauna on the Mandurah reef was the most speciose and harboured the greater number of fish, indicating that site selection has a major influence on the resultant fish community composition and thus should be considered in future reef deployments.

Item Type: Thesis (Honours)
Murdoch Affiliation(s): Environmental and Conservation Sciences
Supervisor(s): Tweedley, James, Florisson, James and Watts, Stephanie
URI: http://researchrepository.murdoch.edu.au/id/eprint/59673
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