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

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

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Abstract

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 Type: Article
Journal or Publication Title: PNAS - National Academy of Sciences of the United States. Proceedings
Page Range: pp. 18256-18261
ISSN: 0027-8424
Identification Number - DOI: 10.1073/pnas.0908012107
Additional Information:

Copyright ©2010 by the National Academy of Sciences

Date Deposited: 21 Dec 2010 22:38
Last Modified: 18 Nov 2014 04:15
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