David Kimbro Research

Invasive species cause large-scale loss of native California oysters by disrupting trophic cacades.

By moving species beyond their native ranges, humans are rapidly filling coastal habitats with invasive species. Although invasive species may resemble their native counterparts, invaders typically do not share an evolutionary history with native species. Consequently, important recognition and behavioral responses displayed by native predators and prey may be absent from food webs containing invasive species. With colleagues from UC Davis and its Bodega Marine Laboratory, I showed that half of a California estuary contains native rock crabs that indirectly protect oysters by both consuming and altering the behavior of native snails (i.e., these snails spend more time and energy hiding rather than consuming oysters). In contrast, the other half of the estuary contains invasive European green crabs that do not protect native oysters because they fail to consume and alter the feeding behavior of Atlantic coast oyster drills. This dysfunctional predator-prey relationship occurs because green crabs use only brute force (crushing) to consume these relatively large snails as opposed to larger native crabs that use brute force and a relatively delicate peeling method for larger snails. In addition, Atlantic oyster drills continue to consume oysters in the presence of crabs because they originated from an east coast estuary that lacked large and effective predatory crabs that would be needed to favor the presence of anti-predator behavior. While this naiveté allows Atlantic oyster drills to decimate one half of the estuary's oyster habitat, it actually prevents its invasion throughout the entire estuary by making it highly susceptible to native rock crabs. These results represent an important but under-appreciated mechanism by which biological invasions can degrade coastal habitats. Read news release

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Kimbro, D. L. E. D. Grosholz, A. Baukus, N. Nesbitt, N. Travis, S. Attoe, and C. Coleman-Hulbert. 2009. Invasive species cause large-scale loss of native California oysters by disrupting trophic cacades. Oecologia 160: 563-575.