Trophic Cascades

Innocent until proven guilty

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Science  04 Mar 2016:
Vol. 351, Issue 6277, pp. 1039-1040
DOI: 10.1126/science.351.6277.1039-c

Cownose rays may have been mistakenly implicated in bivalve decline

PHOTO: © AURORA PHOTOS/ALAMY STOCK PHOTO

The existence of trophic cascades is well documented; however, characterizing such linkages is more challenging than it might appear. Grubbs et al. reanalyzed data used to support the existence of a predator-mediated cascade from sharks, to cownose rays, to bivalves in the Atlantic and argue that the original connections need to be reexamined. Specifically, they found little evidence that the ray could biologically fit the role of damaging mesopredator in this system. Since the original study was conducted, the cownose ray has been the focus of unregulated fishing pressure justified, in part, as a way to protect the commercial bivalve industry. Such unregulated pressure could have detrimental effects on the very slowly reproducing rays, and draws attention away from other human contributions to bivalve decline.

Sci. Rep. 10.1038/srep20970 (2016).

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