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Marine reserves reduce risk of climate-driven phase shift by reinstating size- and habitat-specific trophic interactions


Ling, SD and Johnson, CR, Marine reserves reduce risk of climate-driven phase shift by reinstating size- and habitat-specific trophic interactions, Ecological Applications, 22, (4) pp. 1232-1245. ISSN 1051-0761 (2012) [Refereed Article]

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Copyright Statement

Copyright 2012 Ecological Society of America.

DOI: doi:10.1890/11-1587.1


Spatial closures in the marine environment are widely accepted as effective conservation and fisheries management tools. Given increasing human-derived stressors acting on marine ecosystems, the need for such effective action is urgently clear. Here we explore mechanisms underlying the utility of marine reserves to reinstate trophic dynamics and to increase resilience of kelp beds against climate-driven phase shift to sea urchin barrens on the rapidly warming Tasmanian east coast. Tethering and tagging experiments were used to examine size- and shelter-specific survival of the range-extending sea urchin Centrostephanus rodgersii (Diadematidae) translocated to reefs inside and outside no-take Tasmanian marine reserves. Results show that survival rates of C. rodgersii exposed on flat reef substratum by tethering were approximately seven times (small urchins 10.1 times; large urchins 6.1 times) lower on protected reef within marine reserve boundaries (high abundance of large predatorycapable lobsters) compared to fished reef (large predatory lobsters absent). When able to seek crevice shelter, tag-resighting models estimated that mortality rates of C. rodgersii were lower overall but remained 3.3 times (small urchins 2.1 times; large urchins 6.4 times) higher in the presence of large lobsters inside marine reserves, with higher survival of small urchins owing to greater access to crevices relative to large urchins. Indeed, shelter was 6.3 times and 3.1 times more important to survival of small and large urchins, respectively, on reserved relative to fished reef. Experimental results corroborate with surveys throughout the range extension region, showing greater occurrence of overgrazing on high-relief rocky habitats where shelter for C. rodgersii is readily available. This shows that ecosystem impacts mediated by range extension of such habitat-modifying organisms will be heterogeneous in space, and that marine systems with a more natural complement of large and thus functional predators, as achievable within no-take reserves, will minimize local risk of phase shifts by reinstating size and habitat-specific predator–prey dynamics eroded by fishing. Importantly, our findings also highlight the crucial need to account for the influence of size dynamics and habitat complexity on rates of key predator–prey interactions when managing expectations of ecosystem-level responses within marine reserve boundaries.

Item Details

Item Type:Refereed Article
Keywords:Centrostephanus rodgersii, climate change, fishing, kelp beds, marine protected areas, predation, range extension, resilience, sea urchin, spatial refuge, Tasmanian temperate reefs, urchin barrens
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Marine and estuarine ecology (incl. marine ichthyology)
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Effects of climate change on Australia (excl. social impacts)
UTAS Author:Ling, SD (Dr Scott Ling)
UTAS Author:Johnson, CR (Professor Craig Johnson)
ID Code:80070
Year Published:2012
Web of Science® Times Cited:75
Deposited By:IMAS Research and Education Centre
Deposited On:2012-10-21
Last Modified:2013-05-03
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