Alien invasive species
Non-indigenous species (NIS) introduced by humans, both intentionally and un-intentionally, can have both significant ecological and economic impacts and their increasing spread is a major concern for many world and European seas. NIS can represent very large numbers (e.g. approx 1000 species in the Mediterranean) of very different taxa ranging from parasites to fish. A subset of NIS is the Invasive Alien Species (IAS) which have spread, can spread or have demonstrated the ability to do so and have the potential to impact biodiversity, communities, habitats and ecosystem functioning.
Although the term biopollution has been used in connection to IAS, IAS do not respond in the same way as classic chemical pollution, which can be tackled at source with appropriate local measures. Arrival, distribution and spread of an IAS can involve a suit of vectors and pathways, although main pathways linked to arrival are shipping (through ballast water & fouling), canals and the mariculture and aquaria trade. Established NIS may expand their distribution and increase their abundance beyond a local starting point through processes, which may not be controllable.
Further, vectors and pathways will change over time, impacting the spatial extent of the NIS (and further facilitating secondary spread) which depends on both species life history traits and the state of the receiving ecosystem upon arrival. Equally complex and varied is the timescale component of an invasion event, as this will depend on the species life cycles and can vary from days to decades, and have a permanent or seasonal nature.
In addition, climate warming has been reported as an additional stressor modifying marine ecosystems and enabling and enhancing biological invasions. While mitigating the spread or eradicating existing IAS is currently very challenging, the risk of new biological invasions can be reduced by controlling vectors and implementing pathway-relevant precautionary measures e.g. aquariology prohibitions or the Ship’s Ballast Water Convention.
Consequently, the best management strategy regarding invasive alien species is to avoid new invasions as targets for biopollution levels are not possible to set. Therefore, the work on invasive alien species in MEECE has focused on understanding ecosystem responses to this driver and related parameterizations to include alien species in ecosystem models (D1.4; 2.1, 2.13), estimating biopollution levels and their impacts on ecosystems (e.g. Zaiko et al. 2011) and incorporating these to expert systems (D5.2).
Fact sheet describing how MEECE science can support the Marine Strategy Framework Directive descriptor on Non-indigenous species