Biophysical predictors of spatial variation in abundance and population dynamics of an invasive decapod

Abstract

Population dynamics of invasive species and their impacts on native communities vary substantially geographically and in different environmental contexts. Therefore, effective management of invasive species requires understanding how habitat characteristics, anthropogenic effects, or other perturbations can influence their abundance and impacts on native communities at multiple spatial and temporal scales. This is particularly challenging when geographically widespread, long-term data are lacking. The Asian shore crab, Hemigrapsus sanguineus, is a well-studied invader on the Atlantic North American coast. A few studies suggest that its populations may be declining in parts of its introduced range, but spatial variation in its population dynamics is considerable even among geographically proximal habitats. We explore the ability of habitat characteristics and prey availability to predict abundance of the Asian shore crab at 12 rocky intertidal sites in southern New England over 5 years (2014–2018). Overall, abundance of the Asian shore crab increased non-linearly with time, with the rate of increase declining over time, but abundance varied among sites and population dynamics were spatially asynchronous. Aspects of habitat complexity and disturbance strongly contributed to variation in abundance, but the most important predictors reflected complex and non-linear interactions among sea surface temperature, latitude, and prey abundance. The influence of prey abundance and latitude on crab abundance were modulated by the survey years, which underscores the importance of temporal variation in mediating the species–habitat relationship. Uncovering such intricate dynamics warrants long-term data on population trends and impacts of invasive species, geographically replicated at multiple sites to capture regional heterogeneity.