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Effects of marine reserves versus nursery habitat availability on structure of reef fish communities.

Nagelkerken I, Grol MG, Mumby PJ - PLoS ONE (2012)

Bottom Line: Reserves had no effect on fish community composition, while proximity to nursery habitat only had a significant effect on community structure of species that use mangroves or seagrass beds as nurseries.For large-bodied individuals of nursery species (>25 cm total length), an additive effect was present for these two factors, although fish benefited more from fishing protection (203% higher biomass) than from proximity to nurseries (139% higher).As a result, conservation of nursery habitats gains importance and more consideration should be given to the ecological processes that occur along nursery-reef boundaries that connect neighboring ecosystems.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal Ecology and Ecophysiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Nijmegen, The Netherlands. ivan.nagelkerken@adelaide.edu.au

ABSTRACT
No-take marine fishery reserves sustain commercial stocks by acting as buffers against overexploitation and enhancing fishery catches in adjacent areas through spillover. Likewise, nursery habitats such as mangroves enhance populations of some species in adjacent habitats. However, there is lack of understanding of the magnitude of stock enhancement and the effects on community structure when both protection from fishing and access to nurseries concurrently act as drivers of fish population dynamics. In this study we test the separate as well as interactive effects of marine reserves and nursery habitat proximity on structure and abundance of coral reef fish communities. Reserves had no effect on fish community composition, while proximity to nursery habitat only had a significant effect on community structure of species that use mangroves or seagrass beds as nurseries. In terms of reef fish biomass, proximity to nursery habitat by far outweighed (biomass 249% higher than that in areas with no nursery access) the effects of protection from fishing in reserves (biomass 21% lower than non-reserve areas) for small nursery fish (≤ 25 cm total length). For large-bodied individuals of nursery species (>25 cm total length), an additive effect was present for these two factors, although fish benefited more from fishing protection (203% higher biomass) than from proximity to nurseries (139% higher). The magnitude of elevated biomass for small fish on coral reefs due to proximity to nurseries was such that nursery habitats seem able to overrule the usually positive effects on fish biomass by reef reserves. As a result, conservation of nursery habitats gains importance and more consideration should be given to the ecological processes that occur along nursery-reef boundaries that connect neighboring ecosystems.

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Fish biomass in marine reserves vs. fished areas with different proximity to nurseries (close vs. isolated).Mean total biomass per 100 m2 (±standard error) across reef sites is shown for the entire size range (A) of nursery species and all species, and split (B, C) for small (≤25 cm total length) and large (>25 cm total length) fish. The black arrow indicates the reserve effect in absence of nurseries, whereas the dashed arrow indicates the nursery habitat effect in fished areas on small individuals of nursery species.
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pone-0036906-g003: Fish biomass in marine reserves vs. fished areas with different proximity to nurseries (close vs. isolated).Mean total biomass per 100 m2 (±standard error) across reef sites is shown for the entire size range (A) of nursery species and all species, and split (B, C) for small (≤25 cm total length) and large (>25 cm total length) fish. The black arrow indicates the reserve effect in absence of nurseries, whereas the dashed arrow indicates the nursery habitat effect in fished areas on small individuals of nursery species.

Mentions: For the structure of the entire fish assemblage, nursery habitat proximity was not significant (p = 0.07), but had a moderately strong effect (Rho) of 0.5, whereas reserve presence had no significant effect and a low R value (2-way ANOSIM, R = 0.19, p = 0.33). For reef fish that use mangrove/seagrass nurseries as juveniles (nursery species), the effects were much stronger such that nursery proximity had a very strong effect on their structure (Fig. 2; R = 0.94, p = 0.03) and total biomass (see Fig. 3b), whereas reserve presence had no overall effect on community structure (R = 0.46, p = 0.13). Even though the reef sites were located at different parts of the island, sites close to nurseries were more similar to one another in their community structure than to the isolated sites (Fig. 2). In decreasing order of importance, Haemulon flavolineatum, Lutjanus apodus, L. analis, H. sciurus, L. mahogoni, Ocyurus chrysurus, H. plumierii, Scarus iseri, and S. guacamaia contributed most (SIMPER analysis, cumulative contribution: 91%) to the differences in assemblage structure (n = 17 spp.), with their biomass being higher at sites close to vs. isolated from nurseries, except L. analis which showed the opposite pattern (Table 1). Considering species presence/absence alone, nursery species were observed at reserve as well as fished reef sites, and at sites close to nurseries as well as on isolated reefs.


Effects of marine reserves versus nursery habitat availability on structure of reef fish communities.

Nagelkerken I, Grol MG, Mumby PJ - PLoS ONE (2012)

Fish biomass in marine reserves vs. fished areas with different proximity to nurseries (close vs. isolated).Mean total biomass per 100 m2 (±standard error) across reef sites is shown for the entire size range (A) of nursery species and all species, and split (B, C) for small (≤25 cm total length) and large (>25 cm total length) fish. The black arrow indicates the reserve effect in absence of nurseries, whereas the dashed arrow indicates the nursery habitat effect in fished areas on small individuals of nursery species.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3366965&req=5

pone-0036906-g003: Fish biomass in marine reserves vs. fished areas with different proximity to nurseries (close vs. isolated).Mean total biomass per 100 m2 (±standard error) across reef sites is shown for the entire size range (A) of nursery species and all species, and split (B, C) for small (≤25 cm total length) and large (>25 cm total length) fish. The black arrow indicates the reserve effect in absence of nurseries, whereas the dashed arrow indicates the nursery habitat effect in fished areas on small individuals of nursery species.
Mentions: For the structure of the entire fish assemblage, nursery habitat proximity was not significant (p = 0.07), but had a moderately strong effect (Rho) of 0.5, whereas reserve presence had no significant effect and a low R value (2-way ANOSIM, R = 0.19, p = 0.33). For reef fish that use mangrove/seagrass nurseries as juveniles (nursery species), the effects were much stronger such that nursery proximity had a very strong effect on their structure (Fig. 2; R = 0.94, p = 0.03) and total biomass (see Fig. 3b), whereas reserve presence had no overall effect on community structure (R = 0.46, p = 0.13). Even though the reef sites were located at different parts of the island, sites close to nurseries were more similar to one another in their community structure than to the isolated sites (Fig. 2). In decreasing order of importance, Haemulon flavolineatum, Lutjanus apodus, L. analis, H. sciurus, L. mahogoni, Ocyurus chrysurus, H. plumierii, Scarus iseri, and S. guacamaia contributed most (SIMPER analysis, cumulative contribution: 91%) to the differences in assemblage structure (n = 17 spp.), with their biomass being higher at sites close to vs. isolated from nurseries, except L. analis which showed the opposite pattern (Table 1). Considering species presence/absence alone, nursery species were observed at reserve as well as fished reef sites, and at sites close to nurseries as well as on isolated reefs.

Bottom Line: Reserves had no effect on fish community composition, while proximity to nursery habitat only had a significant effect on community structure of species that use mangroves or seagrass beds as nurseries.For large-bodied individuals of nursery species (>25 cm total length), an additive effect was present for these two factors, although fish benefited more from fishing protection (203% higher biomass) than from proximity to nurseries (139% higher).As a result, conservation of nursery habitats gains importance and more consideration should be given to the ecological processes that occur along nursery-reef boundaries that connect neighboring ecosystems.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal Ecology and Ecophysiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Nijmegen, The Netherlands. ivan.nagelkerken@adelaide.edu.au

ABSTRACT
No-take marine fishery reserves sustain commercial stocks by acting as buffers against overexploitation and enhancing fishery catches in adjacent areas through spillover. Likewise, nursery habitats such as mangroves enhance populations of some species in adjacent habitats. However, there is lack of understanding of the magnitude of stock enhancement and the effects on community structure when both protection from fishing and access to nurseries concurrently act as drivers of fish population dynamics. In this study we test the separate as well as interactive effects of marine reserves and nursery habitat proximity on structure and abundance of coral reef fish communities. Reserves had no effect on fish community composition, while proximity to nursery habitat only had a significant effect on community structure of species that use mangroves or seagrass beds as nurseries. In terms of reef fish biomass, proximity to nursery habitat by far outweighed (biomass 249% higher than that in areas with no nursery access) the effects of protection from fishing in reserves (biomass 21% lower than non-reserve areas) for small nursery fish (≤ 25 cm total length). For large-bodied individuals of nursery species (>25 cm total length), an additive effect was present for these two factors, although fish benefited more from fishing protection (203% higher biomass) than from proximity to nurseries (139% higher). The magnitude of elevated biomass for small fish on coral reefs due to proximity to nurseries was such that nursery habitats seem able to overrule the usually positive effects on fish biomass by reef reserves. As a result, conservation of nursery habitats gains importance and more consideration should be given to the ecological processes that occur along nursery-reef boundaries that connect neighboring ecosystems.

Show MeSH
Related in: MedlinePlus