Accidental introductions of non-native species has been of increasing concern since the 1980s when human-mediated transportation, mainly related to ships' ballast water, was recognized as a major route by which species are transported and spread.
A review just published by PML Applications Ltd and the University of Plymouth, brings together and updates evidence on invasive species for the NE and SW Atlantic Ocean, in order to assess the risk represented by the shipping trade between these two regions.
The study found that the pathways most frequently recorded as transporting invasive species are ballast water and biofouling for both regions, while aquaculture has also been a very significant route of introduction and spread of invasive species in the NE Atlantic. It also established that the number of non-native species that have become invasive with high ecological impacts are 44 in the NE Atlantic and 15 in the less well studied south-western Atlantic.
Cecilia de Castro, lead author of the review, commented:
“This study comes at a pertinent time, providing further evidence to highlight the importance of the IMO Ballast Water Convention, which has recently reached 53 per cent of world merchant shipping tonnage and will enter into force on 8/09/2017. Though countries such as the UK have yet to sign up, the convention remains a landmark step towards halting the spread of invasive aquatic species, which can damage biodiversity and local ecosystems, as well as potential economic problems.”
Non-native species are a crucial issue that needs to be addressed to raise general awareness and publicity, alongside scientific surveys and monitoring, improved data availability, regulations, management tools, risk assessment, stakeholders' commitment, enforcement, best practices and constant surveillance.
For example, Chinese mitten crabs are officially listed as one of the World's 100 worst invasive species. They can cause damage to fishing gear and river banks, block intake screens, modify natural habitats and compete with native species, and it is this economic and ecological damage that makes this crab such an unwelcome arrival.
The full extent of these exotic pests in English and Welsh waters is currently unclear and a consortium of research institutes is requesting mitten crab sightings from members of the public, anglers and waterway workers, to clarify the distribution of this species.
Plymouth University’s Professor Jason Hall-Spencer is coordinating the UK-Brazil collaboration. He says:
“An estimated 10,000 marine species are transported around the world in ballast water every day. This sometimes causes outbreaks of diseases such as Cholera in which 1000s of people die, and commonly introduces toxic algae which can cause massive kills of aquatic life. I would hope the UK signs up to the United Nations ballast water regulations to help secure healthy productive seas.”
You can read the paper ‘Invasive species in the North-eastern and Southwestern Atlantic Ocean: A review’ here.