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- Title
Random movement of predators can eliminate trophic cascades in marine protected areas.
- Authors
Jiao, Jing; Pilyugin, Sergei S.; Osenberg, Craig W.
- Abstract
The protection of predators inside marine reserves is expected to generate trophic cascades with predator density increasing but prey density decreasing; however, predators and prey often both increase inside reserves. This mismatch between the expected and observed change in prey density has been explained because prey also are harvested; that is, the protection of prey compensates for the additional predation inside the reserve. Here, we show that this mechanism alone cannot increase densities of predator and prey; other mechanisms are required, and we hypothesized that movement of predator and/or prey might provide such a mechanism. We therefore built two spatially implicit two-patch predator--prey models with movement of predator and prey between reserve and fishing grounds. We show that post-settlement movement of predators (but not prey) altered the strength of trophic cascades and could increase densities of both predator and focal prey. We further built a more general model that shows that predator post-settlement movement can reinforce and even supplement the effect of two previously investigated mechanisms producing trophic cascades: a prey size refuge and predator density-dependent mortality. Our study increases understanding of mechanisms that can alter the strength (and direction) of prey responses inside marine reserves and highlights the importance of movement in human-induced heterogeneous systems.
- Subjects
MARINE parks &; reserves; ECOLOGICAL models; MARINE ecological models; PREDATION; FOOD chains
- Publication
Ecosphere, 2016, Vol 7, Issue 8, p1
- ISSN
2150-8925
- Publication type
Article
- DOI
10.1002/ecs2.1421