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Decadal trends in marine reserves reveal differential rates of change in direct and indirect effects


Babcock, RC and Shears, NT and Alcala, AC and Barrett, NS and Edgar, GJ and Lafferty, KD and McClanahan, TR and Russ, GR, Decadal trends in marine reserves reveal differential rates of change in direct and indirect effects, Proceedings of the National Academy of Sciences of the United States of America, 107, (43) pp. 18256-18261. ISSN 0027-8424 (2010) [Refereed Article]

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Copyright © 2010 by the National Academy of Sciences

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DOI: doi:10.1073/pnas.0908012107


Decadal-scale observations of marine reserves suggest that indirect effects on taxa that occur through cascading trophic interactions take longer to develop than direct effects on target species. Combining and analyzing a unique set of long-term time series of ecologic data in and out of fisheries closures from disparate regions, we found that the time to initial detection of direct effects on target species (±SE) was 5.13 ± 1.9 years, whereas initial detection of indirect effects on other taxa, which were often trait mediated, took significantly longer (13.1 ± 2.0 years). Most target species showed initial direct effects, but their trajectories over time were highly variable. Many target species continued to increase, some leveled off, and others decreased. Decreases were due to natural fluctuations, fishing impacts from outside reserves, or indirect effects from target species at higher trophic levels. The average duration of stable periods for direct effects was 6.2 ± 1.2 years, even in studies of more than 15 years. For indirect effects, stable periods averaged 9.1 ± 1.6 years, although this was not significantly different from direct effects. Populations of directly targeted species were more stable in reserves than in fished areas, suggesting increased ecologic resilience. This is an important benefit of marine reserves with respect to their function as a tool for conservation and restoration.

Item Details

Item Type:Refereed Article
Keywords:fishing effects; interactions; time lags; trophic cascade; marine protected area
Research Division:Environmental Sciences
Research Group:Environmental management
Research Field:Conservation and biodiversity
Objective Division:Environmental Management
Objective Group:Terrestrial systems and management
Objective Field:Assessment and management of terrestrial ecosystems
UTAS Author:Barrett, NS (Associate Professor Neville Barrett)
UTAS Author:Edgar, GJ (Professor Graham Edgar)
ID Code:66981
Year Published:2010
Web of Science® Times Cited:400
Deposited By:TAFI - Marine Research Laboratory
Deposited On:2011-02-22
Last Modified:2011-03-22

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