The European project RINSE (Reducing the Impacts of Non-native Species in Europe) investigates the best strategies for managing invasive non-native species across the Two Seas Programme area (i.e. area comprising the British Channel and the southern part of the North Sea).
The RINSE project specifically aims to develop cross-border tools to improve the prioritisation and targeting of invasive non-native species, so that resources can be directed towards the species and sites of greatest concern.
As part of RINSE, the main objective of this project is to audit the current state of biological invasions in the RINSE study area and to provide a prioritised list of INS that may pose a threat to local ecosystems in the future. This will be achieved in a series of three inter-related stages:
Registry of Non-Native Species (NNS) in the four RINSE countries (Great Britain, France, Belgium and The Netherlands) with information on their taxonomic classification, current distribution and environment inhabited.
Horizon scanning of Invasive Non-native Species (INS). Screening of the ‘worst’ invaders according to national and international organizations. Species will be divided into two groups depending on their presence (Black List) or absence (Alert List) in any of the four RINSE countries. Expert consultation will be used to rank species in each list according to their actual or potential impacts in the region.
Distribution modelling of INS. Species distribution Models (SDM) will be developed for a representative number of Black and Alert INS, using a combination of environmental and socio-economic predictors.
The non-native species registry
The RINSE Registry compiled information from 3,454 non-native species, representing approximately 30% of all known non-native species (NNS) in Europe.
Great Britain features the largest number of reported non-native species, followed by France, The Netherlands and finally, Belgium.
The largest number of NNS in the Registry belongs to the phylum of Arthropoda, accounting for about three times as many NNS as Chordata, and four times as many as Angiospermae.
Over three quarters of NNS reported in the RINSE countries inhabit terrestrial habitats.
Almost all Anseriformes (e.g. geese, ducks, and swans), mammals, bony fish and flowering plants were deliberately introduced into RINSE countries, and mostly for ornamental reasons or leisure activities such as fishing.
Horizon scanning of invasive non-native species
Most of the species identified as the world’s worst invaders were already present in at least one of the RINSE countries (77%) and were therefore assigned to the Black List of INS. The remaining 23% of species formed the Alert List of INS, being absent from all the RINSE areas.
The top 12 Alert INS with highest risk scores according to the consulted experts included a mix of primary producers: blady grass (Imperata cylindrica), melaleuca (Melaleuca quinquenervia) and Kudzu (Pueraria montana lobata); herbivores: emerald ash borer (Agrilus plannipenis), Canadian castor (C. Canadensis) and apple snail (P. canaliculata); predators: Japanese sea star (Asterias amurensis), racer goby (Neogobius gymnotrachelus), Amur sleeper (Perccottus glenii), nomad jellyfish (Rhopilema nomadica) and red fire ant (Solenopsis invicta); and the filter-feeding Amur clam (Potamocorbula amurensis).
Most of the Black List INS (56%) were present in the four RINSE countries, which exemplify the high level of biological interchange among them resulting from the intensive trade, transport and travel.
From The Netherlands, several aquatic inland species may pose a threat to Great Britain: Chattonella (Chattonella verruculosa), two Ponto-Caspian amphipods (Chelicorophium robustum and Dikerogammarus bispinosus), marmokrebs crayfish (Procambarus fallax) and tubenose goby (Proterorhinus marmoratus). From Belgium, an amphibian (Bufo marinus) and two insects (Latrodectus geometricus and L. hasselti) may affect other RINSE countries.
The top 12 Black INS raising the greatest concern amongst RINSE experts were dominated by primary producers such as the New Zealand pigmyweed (Crassula helmsii), floating pennywort (Hydrocotyle ranunculoides), killer algae (Caulerpa taxifolia), green sea fingers (Codium fragile), Japanese knotweed (Fallopia japonica) and giant hogweed (Heracleum mantegazzianum). Other type of organisms in the list included predators: harlequin ladybird (Harmonia axyridis), American mink (Mustela vison); herbivores: Canada goose (Branta canadensis) and grey squirrel (Sciurus carolinensis); and the omnivorous killer shrimp (Dikerogammarus villosus).
Distribution modelling of invasive non-native species
Species distribution models displayed high performance for all Alert and Black INS modelled, and allowed investigation of the partial influence of environmental and socio-economic drivers on the current global distribution of the worst INS.
The permutation importance of environmental variables ranged between 70 and 82% for inland species (i.e. terrestrial plus freshwater species), and reached 99% for marine organisms.
Temperature-related variables were the most important driver of inland species distribution since it affects the body size, reproduction, growth, ecological role and survival of species, as well as determining the context for establishment (e.g. habitat and resources available, pool of interacting species).
In the marine environment, water temperature was also a primary driver of biological invasions, followed in importance by nitrate and chlorophyll-a concentration, which reflect the availability of resources and can also indicate human disturbance (eutrophication).
Several of the INS modelled featured distributions clearly influenced by the location of transport routes. This included invasive plants such as the water hyacinth (Eichhornia crassipes), Kudzu (P. montana lobata) and Kahili ginger (Hedychium gardnerianum).
Insects were predominantly affected by the Human Influence Index, including the silverleaf whitefly (Bemisia tabaci), Mediterranean fruitfly (Ceratitis capitata), Argentine ant (Linophitema humile) and oak processionary (Thaumetopoea processionea).
Closeness to ports was identified as an important predictor for aquatic inland species (e.g. Aphanius dispar, Clarias batrachus, Gammarus fasciatus, Dreissena r. bugensis, Myriophyllum heterophyllum, P. marmoratus, Anguillicola crassus), which are involuntarily transported as contaminants or stowaways.
The SE of England and NE of Belgium and the Netherlands (urban areas adjacent to major ports like London, Portsmouth, Calais, Oostende, Zeebrudge, Rotterdam and Antwerp) are under the highest risk of multiple invasions. Risk progressively decreases outwards, i.e. north and westwards in Great Britain, and south and eastwards in the continent.
Recommendations
Halting the pathways of introduction:
The ornamental/pet trade is one of the most important vectors of invasive species into the RINSE region and could be controlled by a better enforcement of existing laws and coordination of neighbouring countries. Especial attention should be paid to Internet commerce that has facilitated the import of plants and animals.
Unintentional introduction as ship foulants or contaminant of commodities is the second major pathway of invasion. INS prevention may improve through continued ballast water control, ship inspections and control of imports (especially forest products). Educational outreach programs are needed to raise awareness amongst the general public and to promote the early detection of newcomers.
Strengthen cross-border communication and cooperation in sharing, linking and integrating INS databases and management strategies.
Species of special concern:
Four of the top Alert INS are present in countries as close as Germany and Poland: the racer goby (N. gymnotrachelus), Amur sleeper (P. glenii), Canadian beaver (C. canadensis) and blady grass (I. cylindrica).
Amongst Alert plants, the Asian wild raspberry (Rubus ellipticus), South-American Brazilian holly (Schinus terebinthifolius) and Asian salt cedar (Tamarix ramossisima) feature high invasive potential and a high suitability scores across RINSE.
In Great Britain, Black aquatic inland species present in The Netherlands and Belgium are of special concern: Chattonella (C. verruculosai), two Ponto-Caspian amphipods (C. robustum and D. bispinosus), marmokrebs (P. fallax), tubenose goby (P. marmoratus) and cane toad (B. marinus).
Three of the modelled Black terrestrial animals matched high suitability scores across RINSE while at the same time being flagged as one of the worst existing invaders in the region: the grey squirrel (S. carolinensis), Asian hornet (Vespa velutina) and oak processionary (T. procesionea)
Amongst aquatic inland INS showing high suitability scores in RINSE, high risk species include the racer goby (N. gymnotrachelus), water milfoil (M. heterophyllum) and quagga mussel (D. r. bugensis)
The importance of minimum annual temperature in our models suggests that global warming could expand the potential distribution of some of the assessed species northwards by increasing minimum winter records. The interaction of climate change and invasive species should be considered when developing long-term strategies of environmental management.
Given the importance of the Human Influence Index in our insect models, future studies of invasive insects’ potential distribution should consider using this or other similar indicators of the intensity of human disturbance to improve their predictions.
The Alert and Black lists of INS are not fixed and require continuous update through a wider screening of published lists of INS combined with expert consultation.
Likewise, distribution models need to be updated should the species expand their distribution towards new areas. In addition, modelling the potential distribution of a larger set of Alert species would provide environmental practitioners with a more complete scenario to inform decisions.