Temporal Variations in Tropical Marine Inshore Fish Assemblages in a Macro-tidal estuary (Darwin Harbour): A Perturbation in Monitoring?

Temporal Variations in Tropical Marine Inshore Fish Assemblages in a Macro-tidal estuary (Darwin Harbour): A Perturbation in Monitoring?

Fri, 16/05/2014 - 10:00 to 11:00

About the Presenter

Dr Victor Gomelyuk is a Senior Marine Scientist at the Marine Ecosystems, Flora and Fauna Division within the Department of Land Resource Management since September 1999. Victor holds a BSc from the University of Latvia and a PhD from the Institute of Evolutionary Morphology and Ecology of Animals, the Soviet Academy of Science, Moscow. Victor has over 50 scientific publications covering various fields of research: ethology and microevolution, spatial and social structures of fish populations, fish fauna and abundance assessment using SCUBA techniques and environmental bio-monitoring of fish assemblages using remote visual techniques. Dr Victor Gomelyukis an Honorary Senior Fellow at the Department of Zoology at the University of Melbourne. Victor also worked as a Senior Research Fellow at the Institute of Marine Biology in Vladivostok, Russia and as a Research Fellow at the Faculty of Biology at the University of Latvia in the Baltic States.


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Assessing temporal changes and trends in fish communities can assist with management of Darwin Harbour. It can be done using baited remote underwater system (BRUVS), which uses “video fishing” - recording fish attracted to a camera by standard bait and has been shown to be an effective non-extractive survey method. The approach is useful for long-term environment monitoring because non-impact nature of visual surveys enables repetitive sampling at reference sites. Fish assemblages were compared between two surveys conducted in 2011 and 2012. Overall, annual differences were relatively small and mainly the result of re-distribution of small school pelagic and demersal species (trevallies, threadfin breams and ponyfishes) rather than an indication of decline in fish abundance and biodiversity in monitored parts of Darwin Harbour. Univariate analyses (ANOVA) of mean fish abundance and the number of species in one video sample appear to be useful, but less sensitive and provide only limited insight on the nature of changes in monitored fish assemblages compared to multivariate indices (Permutational multivariate analysis of variance (PERMANOVA), Analysis of Similarity (ANOSIM) and Similarity percentages (SIMPER). Univariate indices therefore have to be used in conjunction with multivariate indices. Further monitoring can add important information of natural temporal variability in fish assemblages of the Harbour. This will increase ability of monitoring to detect and identify changes in fish assemblages caused by adverse environmental and anthropogenic factors.

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