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Can marine reserves restore lost ecosystem functioning? A global synthesis
Author(s) -
Cheng Brian S.,
Altieri Andrew H.,
Torchin Mark E.,
Ruiz Gregory M.
Publication year - 2019
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1002/ecy.2617
Subject(s) - ecology , ecosystem , environmental science , marine ecosystem , biology
Marine protected areas ( MPA s) have grown exponentially, emerging as a widespread tool to conserve biodiversity and enhance fisheries production. Although numerous empirical studies and global syntheses have evaluated the effects of MPA s on community structure (e.g., biodiversity), no broad assessment concerning their capacity to influence ecological processes (e.g., species interactions) exists. Here, we present meta‐analyses that compare rates of predation and herbivory on a combined 32 species across 30 MPA s spanning 85° of latitude. Our analyses synthesize the fate of 15,225 field experiment assays, and demonstrate that MPA s greatly increased predation intensity on animals but not herbivory on macroalgae or seagrass. Predation risk, quantified as the odds of prey being eaten, was largely determined by predator abundance and biomass within reserves. At MPA s with the greatest predator accumulation, the odds of predation increased to nearly 49:1, as opposed to 1:1 at MPA s where predators actually declined. Surprisingly, we also found evidence that predation risk declined with increased sea‐surface temperature. Greater predation risk within MPA s was consistent with predator and prey population abundance estimates, where predators increased 4.4‐fold within MPA s, whereas prey decreased 2.2‐fold. For herbivory, the lack of change may have been driven by functional redundancy and the inability of reserves to increase herbivore abundance relative to fished zones in our sample. Overall, this work highlights the capacity of MPA s to restore a critical ecosystem function such as predation, which mediates energy flows and community assembly within natural systems. However, our review of the literature also uncovers relatively few studies that have quantified the effects of MPA s on ecosystem function, highlighting a key gap in our understanding of how protected areas may alter ecological processes and deliver ecosystem services. From a historical perspective, these findings suggest that modern levels of predation in the coastal oceans may currently only be a fraction of the baseline prior to human exploitation.