The transfer of harmful aquatic organisms and pathogens with ballast water and their impacts

Abstract

The annual number of new species records world-wide has paralleled shipping and is increasing. For example, in ICES member countries a new introduction forming a new population beyond its natural range occurs approximately every 9 weeks. The introduction of non-indigenous species by ships’ ballast water is known since more than 100 years, but it was not until 1970s that the first biological samples from ballast water were taken. Since, more than 1,000 species were identified from ballast tanks, including human pathogens. It was estimated that 3,000-7,000 different species are moved each day around the globe by ships and it was concluded that shipping is the prime species introduction pathway with each vessel having the potential to introduce a species. However, not all species find a suitable situation in the new environment, but it was suggested that >2,000 aquatic non-indigenous species have been introduced world-wide, of which in minimum 850 are likely introduced by ships. Not all introduced species are considered harmful, in some cases this is quite the reverse, as some support important industries. However, a number of introduced species had almost catastrophic and seemingly irreversible impacts and all of the summed impacts amount to considerable costs of billions of Euro annually. Consequently, a precautionary approach suggests that every vessel transporting ballast water should be treated as a potential risk by enabling introductions of harmful species. This chapter summarises key aspects of the current knowledge on species transfers with vessels ballast water.