A behaviour-mediated trophic cascade involving Dugongs, Sea turtles and Tiger sharks.

‘Patterns of top-down control in a seagrass ecosystem: could a roving apex predator (Galeocerdo cuvier) induce a behaviour-mediated trophic cascade?’
By: Derek Burkholder, Michael Heithaus, James Fourqurean, Aaron Wirsing, Lawrence Dill
onlinelibrary.wiley.com/doi/10.1111/1365-2656.12097/abstract

This manuscript presents data from a multi-year exclosure study to test a priori hypotheses regarding a behavior-mediated trophic cascade initiated by tiger sharks in a pristine seagrass ecosystem. We present evidence that seagrass communities are heavily influenced by large-bodied grazers, but only in areas where they can graze at lower risk from tiger shark predation. Although recent studies have suggested that roving predators, like tiger sharks, should be unlikely to trigger behavior-mediated cascades our work suggests that spatial heterogeneity can lead to such cascades. This study also suggests that the removal of large bodied predators could have wide-ranging consequeces for foundational species like seagrasses. Therefore, we believe that this manuscript should be of general interest to ecologists working in diverse marine, terrestrial, and freshwater ecosystems.

A behaviour-mediated trophic cascade from Journal of Animal Ecology on Vimeo.

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