Post-invasion demography and persistence of a novel functional species in an estuarine system

Long-term population data of marine invaders are rarely collected although it provides fundamental knowledge of the invasion dynamics that is important for evaluating the impacts, interactions and range expansion of the invader and for management purposes. During a 6-year monitoring period, we studied the dynamics and population demographic characteristics of the newly introduced mud crab Rhithropanopeus harrisii. The overall abundance of R. harrisii appeared to follow the boom and bust pattern with a rapid initial abundance increase and subsequent decline. The recruitment and growth of juveniles were correlated with the temperature during the larval period indicating that the increase in water temperature caused by climate change could have a positive effect on the recruitment and have potentially facilitated the establishment of R. harrisii in the northern Baltic Sea. The changes in the survival of reproductive females influence most the growth rate of the studied population. Hence, native predators feeding on benthic fauna such as fish could regulate the population growth of R. harrisii in the study area by reducing female survival. Although the population size seems to be stabilized at the monitoring locations, R. harrisii continues to expand its distribution range, and the rapid initial population increase is likely occurring at newly invaded sites.