A hazardous place to live: spatial and temporal patterns of species introduction in a hot spot of biological invasions

Globally, the spread of non-indigenous species in marine ecosystems is a major ecological and socio-economical concern. The need for long-term assessment on a large scale is a pre-requisite for understanding the drivers associated with their establishment and expansion. Here, the patterns of invasions of subtidal soft-bottom assemblages of shelled molluscs have been quantified based on a unique dataset collected between 2005 and 2012 along the coast of Israel (SE Mediterranean Sea), a hotspot of bioinvasion. Overall, the number of non-indigenous species doubled between 2005 and 2012. Significant differences in terms of species richness and relative abundance were observed in space and time in both native and non-indigenous species. A combination of enduring disturbance regimes related to human activities and site-specific environmental conditions seem to have a critical role in promoting the observed patterns. Our results emphasize the value of long term broad-scale systematic surveys to the development of effective environmental policies for the control of bioinvasions.