Invasive Non-Native Species (INNS)
Invasive non-native species (INNS) are defined as species that have been introduced to an area outside their natural past or present distribution that have a negative environmental, economic or social impact. Introductions of marine INNS are occurring with increasing frequency; the key pathways responsible for the transfer of marine INNS from one region to another are
- commercial shipping - through expulsion of ship ballast water/sediments and hull-fouling
- recreational shipping - hull-fouling
- aquaculture and fishery practices - culture of species and transfer of material
Marine INNS pose a significant threat to global, local and regional biodiversity and ecosystem health and their continued spread is believed to be one of the four greatest threats to the world's oceans. They can have a detrimental economic impact on aquaculture, fishing and shipping industries, with a recent study indicating that the direct cost of INNS to marine industries in Great Britain is in the region of £40 million per year (Williams et al., 2010).
INNS of International Concern
Members of academic staff here at Bangor University are actively involved in researching problematic INNS and more recently we have become involved in researching the more practical issues of biosecurity.
Didemnum vexillum (Kott, 2002), commonly referred to as the carpet sea squirt, is a colonial ascidian species (native to the Northwest Pacific Ocean) that has attracted considerable global attention as a nuisance INNS. The introduction of D. vexillum can have profound impacts on marine systems as it can rapidly outgrow and displace native species; it can also extensively foul aquaculture and maritime structures, substantially increasing maintenance costs of such facilities. In September 2008, an MSc student from Bangor University made the first recording in Great Britain of an established population D. vexillum within Holyhead Harbour (Griffith et al., 2009). The proximity of this organism to nearby Special Areas of Conservation (SACs) and aquaculture fisheries in the Menai Strait lead to eradication procedures by the Countryside Council for Wales (now Natural Resources Wales, NRW), which to date have been unsuccessful. Since the initial discovery of this species Bangor University has undertaken research to investigate the ecological tolerances of this species in an effort to understand what environmental factors may limit the spread of the species (e.g. Groner et al., 2011). We believe that understanding the processes that drive the recruitment and survival of INNS is of critical importance in evaluating their potential to colonise previously unoccupied habitats.
Crepidula fornicata is a slipper limpet native to the east coast of the Americas that has been introduced to locations around the world through transfer of aquaculture stock. In introduced regions C. fornicata is a pest of commercial oyster and mussel beds as the limpets directly compete with the aquaculture stock and can also modify the substratum making it unsuitable for the settlement of spat. In 2006 this INNS was accidentally introduced into a mussel fishery within the Menai Strait, posing a serious threat to the success of the fishery. Fortunately, an intervention by the Countryside Council for Wales (now NRW) and the Bangor Mussel Producers Association meant C. fornicata did not successfully establish a population. The temporary arrival of this INNS prompted some extensive research by a PhD student at Bangor University which investigated the factors limiting the northward spread of Crepidula (Bohn et al. 2012; Bohn et al. 2013a; Bohn et al. 2013b).
How is Bangor University Helping to Stop the Spread of INNS?
The failed eradication attempts by NRW to eliminate D. vexillum from Holyhead harbour (Sambrook et al., 2014) emphasizes the difficulty of managing marine INNS once introduced. Here at Bangor University we believe a focus on biosecurity is paramount to tacking these problematic species. One such approach is the development of an in-water quarantine facility, known as a decontamination berth, designed to limit transfer of marine non-natives (Roche et al. 2014). Research into this new and novel technique is on-going and will hopefully contribute significantly to the management of INNS around the UK. Bangor University is also developing techniques to enable early detection of INNS at introduction hotspots, such as marinas and aquaculture sites. Earlier detection means we have a wider range of management options, which increases our capacity to rapidly respond to new marine invasions successfully and in turn reduce economic and environmental costs.