Hazard Analysis of Aquatic Species Invasions

Abstract

Anthropogenically supported invasions of nonindigenous species (NIS) in aquatic ecosystems seem to increase worldwide. Many aspects of invasions remain nearly unpredictable. Among them, unfortunately, are the most wanted answers to: Which species will invade, when will it arrive, where will the species invade and what impact may be caused by this new invader? Until today these questions can be answered only on a theoretical or broad scale. Accordingly an indication of habitats at risk can be given only on a limited base. We know that certain areas such as estuaries and areas with high input of NIS, such as ports, waterways and aquaculture sites, are high-risk areas for further human mediated species introductions. Matching salinity and climate conditions in donor and recipient region enable a first but incomplete estimation of the species’ potential to survive in new habitats. Taking into account the voyage duration of a ship (short term voyages support the survival rate of specimens in the ballast tank) the picture comes clearer, but still is far from prediction. The need for an improved risk assessment becomes clear as one introduced species can cause severe damage to economy or environment.