Coastal ecosystems are subject to a wide variety of abiotic variation including seasonal fluctuations and hydrodynamic disturbance, which can influence species distributions. Additionally, introductions of invasive species are creating biotic pressures within coastal ecosystems, which can influence biological interactions. With the recent development of combining comparative functional responses, prey switching and biotic resistance theory in invasion ecology, invasion success and ecological impacts of invaders can be better quantified. Further, the incorporation of environmental contexts with these approaches allows predictions of invader success under a range of ecological scenarios. We examined the functional responses and prey switching propensities of the native European green crab, Carcinus maenas (Linnaeus, 1758), towards native blue mussels, Mytilus edulis (Linnaeus, 1758), and invasive Pacific oysters, Crassostrea (Magallana) gigas (Thunberg, 1793), under the abiotic contexts of season (winter vs summer) and hydrodynamic disturbance level (high vs low). In general, when each prey species was offered separately, C. maenas maximum feeding rates were higher towards native M. edulis compared to invasive C. gigas. In addition, handling times were lower, and thus maximum feeding rates were higher, in summer compared to winter. Hydrodynamic disturbance level had no significant influence on handling times or maximum feeding rates towards either prey species. When prey species were offered simultaneously, C. maenas disproportionately consumed native M. edulis over invasive C. gigas irrespective of proportional availability. In addition, increased hydrodynamic disturbance further increased the disproportionate consumption of M. edulis over C. gigas. We thus demonstrate that C. maenas offers little biotic resistance to invasions of C. gigas under a range of abiotic contexts, and indeed some of these contexts may exacerbate the invasion. We suggest that combined functional response and prey switching studies provide a wealth of information regarding invasion success and biotic resistance towards invasive species under environmental variation.
|Journal||Journal of Experimental Marine Biology and Ecology|
|Publication status||Published - 11 May 2020|