Anders Nielsen

Head of Department/Head of Research

(+47) 913 50 435
anders.nielsen@nibio.no

Place
Ås O43

Visiting address
Oluf Thesens vei 43, 1433 Ås

To document

Abstract

The Norwegian Environment Agency has asked VKM to evaluate the risks to biodiversity associated with the import of two species of leeches to Norway, Hirudo medicinalis and H. verbana (so-called medicinal leeches). In addition, they ask that the project group suggest mitigating measures that could reduce any potential risks, should import of the two species be granted.

Abstract

Import of leeches for medical use and hobby keeping poses a low risk of negative effects on Norwegian biodiversity. This is the key message in a risk assessment of two species of blood-sucking leeches conducted by VKM for the Norwegian Environment Agency. Background The two species of leeches (Hirudo medicinalis and H. verbana) have in recent years become more commonly used in Western medicine for various procedures where maintaining good blood flow is important. Hirudo medicinalis is considered native to Norway and is found in scattered populations in southern Norway. There is uncertainty about the genetic impact on these populations if imported leeches were to be released into the wild. Hirudo verbana is not registered in Norway but may have been imported as H. medicinalis in the past. Both species are listed under Appendix I, List B of the Norwegian CITES regulations. Methods VKM reviewed scientific literature to uncover potential negative effects in light of the leeches’ ecology under Norwegian conditions. VKM also investigated how the trade in live leeches is conducted, where they originate from, and outlined possible risk-reducing measures. VKM assessed four factors of potential relevance for negative impacts on biodiversity and conducted risk assessments for each: Hybridisation or other negative genetic impacts on local populations Competition with other leech species Parasitism or predation on amphibian populations Transmission of diseases Additionally, VKM assessed the extent of such imports and the likelihood of imported leeches ending up in Norwegian nature. Results VKM concluded that it is moderately likely that H. medicinalis will genetically affect Norwegian populations, but this will have minimal negative effects. Hybridisation between H. verbana and H. medicinalis is considered unlikely and would have little effect if it occurs. ”The leeches already present in Norway mainly originate from leeches imported from Europe in the 1800s. The introduction of new genes from the same areas now will therefore have minimal impact. The risk is therefore low,” says Lawrence Kirkendall, the scientific leader of the work. For parasitism or predation, amphibians are the main species that could theoretically be negatively affected by the leeches. VKM concludes that such negative effects are very unlikely and would have little or minimal impact. This implies low risk. Regarding competition and disease transmission, VKM assesses that these factors have little or minimal effect on biodiversity and are very unlikely. "We assess that the effects on biodiversity in Norway, if imported leeches were to end up in an environment where they thrive, are very small. At the same time, it is very unlikely that leeches used for medical procedures will end up in nature. The overall assessment is therefore that both species are associated with low risk of negative impact on biodiversity," says Kirkendall. The risk assessment is approved by the VKM Panel for Biodiversity.

Abstract

The Norwegian Environment Agency asked VKM to evaluate the risks to biodiversity associated with the importation of eight species of live crabs intended for human consumption. Background Invasive crab species represent a significant threat to biodiversity globally due to their omnivory, adaptability to diverse habitats, high reproductive output, and aggressive behaviour. The Norwegian Environment Agency has raised concerns about the potential ecological risks posed by the import of live crabs to Norway intended for human consumption. This report provides a risk assessment of eight species of crabs that could have negative effects on native biodiversity. The species include Chinese mitten crab (Eriocheir sinensis), Japanese mitten crab (E. japonica), blue crab (Callinectes sapidus), Atlantic rock crab (Cancer irroratus), Asian paddle crab (Charybdis japonica), common moon crab (Matuta victor), African blue swimming crab (Portunus segnis), and Harris mud crab (Rhithropanopeus harrisii). Three of the assessed species were recently confiscated at Norway's border. This suggests a market demand that could increase the frequency of introductions to Norway. Methods VKM established a working group with expertise in invertebrates and risk assessment. The group searched scientific literature for information on the taxonomy, natural history, invasiveness, and ecology for each crab species. If scientific literature was lacking, supplemental google searches allowed for a broader understanding of species with limited research or on the use and transportation of live crabs as food. The assessment utilized the EICAT framework (Environmental Impact Classification for Alien Taxa) to identify potential mechanisms by which each species could harm native biodiversity, should imported specimens become established in Norwegian nature. Key mechanisms include competition, predation, pathogen transmission, and hybridization. The relevant mechanisms were analysed for each species by rating the potential magnitude of impact on biodiversity from minimal to massive. The likelihood of each impact was assessed from very unlikely to very likely. A combination of magnitude of impact and likelihood resulted in final risk levels ranging from low and medium to possibly high and high. Confidence levels for each assessment were also categorized as low, medium, or high based on expert opinion. Results The potential hazards evaluated under the EICAT framework include competition, predation, and transmission of disease for all species, grazing for four species and structural impacts on the ecosystem for three species. The conditions required for crabs imported live for human consumption to reach a natural ecosystem in Norway include a commercial demand for crabs, survival during transport and handling, and the possibility of release or escape. If these conditions for reaching a natural ecosystem are met, the species must then be capable of establishment in the new ecosystem. There are several examples of species imported live for human consumption becoming established in the wild, most likely due to intentional release. The risk assessments indicate varied levels of risk across the five hazards. Competition from E. sinensis or E. japonica was assessed to pose a high risk, while competition from C. sapidus, C. irroratus, M. victor, P. segnis, or R. harrisii was assessed to pose a medium risk. Predation by E. sinensis or E. japonica was assessed to pose a high risk and predation from R. harrisii, C. sapidus, C. irroratus, M. victor, or P. segnis was assessed to pose a medium risk. Transmission of disease from either E. sinensis or E. japonica was assessed to pose a high risk, while there was a possibly high risk of disease transmission from C. irroratus. The diseases of highest concern include the crayfish plague (Aphanomyces astaci) and gaffkaemia (Aerococcus viridans var. homari). Finally, there was a moderate risk of ......