The impact of marine reserves on nekton diversity and community composition in subtropical eastern Australia

Published source details Pillans S., Pillans R.D. & Possingham H.P. (2007) The impact of marine reserves on nekton diversity and community composition in subtropical eastern Australia. Biological Conservation, 136, 455-469.
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Summary

Moreton Bay, located along the southeast coast of Queensland (Australia), is a coastal area heavily impacted by anthropogenic pressure, including commercial fishing. The objective of this study was to assess if the 'no-take' marine reserves in Moreton Bay were effective in protecting marine biodiversity. The effectiveness of two small coastal marine reserves in the bay were assessed by comparing the diversity and community composition of nekton (i.e. fish and invertebrates) with nearby non-reserve 'fished' areas.

Study sites: The study was undertaken in the Moreton Bay Marine Park (27º25′S, 153º20′E) a subtropical bay covering an area of approximately 3,400 kmÂ². Marine reserves were established within the bay in 1997 and are designated no-take areas but amount to less than 1% of the area of the Marine Park. Two reserves were surveyed, Tripcony Bight (5.7 kmÂ²) and Willes Island (1.9 kmÂ²). These two reserves and four non-reserves (sampled for comparison) were located in different locations within the bay (north and south). Non-reserve comprised two situated on the reserve boundaries, and two further away; the northern pair was subject to recreational fishing and the south pair subject to commercial net fishing or recreational fishing.

Sampling: Sites were surveyed with multiple hauls of a seine net. Netting was carried out in each area during the summers and winters of 2002 and 2003. Species richness, evenness*, density and mean size of the inshore communities were compared between the reserves and non-reserves.

Note: *Species evenesss is the relationship between the relative abundance of the different species, defined as how evenly the total number of individuals of a community are divided between the different species.

During the surveys 168 sampling hauls were made; a total of 65,708 individuals including 90 fish species and 11 invertebrate species, were caught. Whilst species richness was similar between areas, species evenness was significantly lower in the one non-reserve site subject to commercial net fishing. Average nekton size was greater in the no-take reserves (average length 5.4 cm) compared to boundary non-reserves (5.3 cm) and far non-reserves (5.2 cm); density of nekton between sites was similar (c.17.5-20 individuals/haul).

Differences in community composition were apparent, particularly between geographical locations and differently fished sites, results highlighting how commercial fishing can impact on entire nekton assemblages (not just targeted species as non-target species may respond in different ways to fishing disturbance).

The authors conclude that the two small marine no-take reserves in Moreton Bay are enhancing marine biodiversity.

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http://www.sciencedirect.com/science/journal/00063207