Does consumer injury modify invasion impact?

• Published in: Biological invasions Vol. 13; no. 12; pp. 2935 - 2945
• Main Authors: Delaney, David G, Griffen, Blaine D, Leung, Brian
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer-Verlag 01.12.2011; Springer Netherlands; Springer Nature B.V
• Subjects: animal injuries; appendages; Biodiversity; Biomedical and Life Sciences; Bivalvia; Carcinus maenas; crabs; Crustaceans; Decapoda; Developmental Biology; Ecology; field experimentation; Freshwater & Marine Ecology; Hemigrapsus sanguineus; Invasive species; Life Sciences; Mollusks; mortality; mussels; Mytilus edulis; Nonnative species; Original Paper; parks; Plant Sciences; Predation; Prey; New York; Maine; Competition; Impact; Aggression; Injury; Trait-mediated effect
• ISSN: 1387-3547; 1573-1464
• DOI: 10.1007/s10530-011-9975-0

Predicting the impacts of an invasive species solely by its abundance is common, yet it ignores other potentially important moderating factors. One such factor is injury. Severe injury can lead to mortality, which can directly reduce the abundance of the invader. However, more moderate, sublethal injury can also temper the impact of invasive species. Therefore, to predict impacts, it may be useful to examine not only abundance, but also moderating factors (e.g., injury) and predictors of these factors (e.g., density, size). We documented the density, injury (i.e., limb loss), and size of two conspicuous invaders, the European green crab (Carcinus maenas) and the Asian shore crab (Hemigrapsus sanguineus), at thirty sites from Shinnecock County Park, New York to Lubec, Maine. In addition, we used a field experiment to determine how injury influenced the consumption rate of mussels (Mytilus edulis) by each crab species. 31.6% of all C. maenas (1,493/4,721) and 30.7% of H. sanguineus (2,003/6,523) were missing appendage(s). Of the crabs injured, 38.4% (573/1,493) and 30.5% (611/2,003) were missing cheliped(s) for C. maenas and H. sanguineus, respectively. In our experiments, cheliped loss reduced consumption of both species on M. edulis. Injured C. maenas consumed 21% fewer mussels than uninjured crabs. Injury completely eliminated mussel consumption by H. sanguineus. Previous studies have highlighted the detrimental impacts of these two invaders on native bivalve prey. While the loss of a single cheliped can greatly reduce or even eliminate the ability of C. maenas and H. sanguineus to consume M. edulis, our results suggest that injury has a relatively minor role in reducing overall population-level impacts on prey such as mussels. However, injury on an individual-level can play a role in moderating the consumptive impacts of these invaders.