Anders Nielsen
Head of Department/Head of Research
Authors
Lawrence R. Kirkendall Kyrre Kausrud Martin Malmstrøm Paul Ragnar Berg Anders Bryn Kjetil Hindar Johanna Järnegren Anders Nielsen Erlend Birkeland Nilsen Brett Kevin Sandercock Eva Bonsak Thorstad Gaute VelleAbstract
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.
Authors
Lawrence Richard Kirkendall Kyrre Linné Kausrud Martin Malmstrøm Paul Ragnar Berg Anders Bryn Kjetil Hindar Johanna Järnegren Anders Nielsen Erlend Birkeland Nilsen Brett Kevin Sandercock Eva Bonsak Thorstad Gaute VelleAbstract
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. Background Bloodsucking leeches have been employed by humans for millennia. The two species Hirudo medicinalis and H. verbana have dominated the trade in medicinal leeches in Europe. Overcollection combined with loss or degradation of freshwater habitats led to a precipitous decline in European populations by the 1800s and led to a corresponding increase in imports from Turkey, North Africa, Russia and the Middle East. By the turn of the 19th century, the demand for live leeches in Europe had tapered off as contemporary medicine developed, only to have a small resurgence over the last decades as live leeches became recognized as useful for a variety of medical and cosmetic procedures, and to be the source of bioactive molecules of interest to medical researchers. As traditional medicine in Asia also uses a variety of leech products, there is a robust global market for live leeches and leech derivatives that is being met mostly by leech aquaculture, where the live leech trade seems dominated by H. verbana. There is increasing interest in commercializing production and sale of three similar leech species, H. orientalis from Central Asia, H. sulukii from a small region in Turkey, and H. troctina from North Africa. Hirudo medicinalis has been used medicinally in Norway since at least the Middle Ages when they were used by barber-surgeons for bloodletting. Leeches have been dispensed by apothecaries up until the end of the 1950s. Phylogeographic studies have treated the species as native to southern Norway and the Norwegian Biodiversity Information Centre has numerous records of H. medicinalis, with recent records primarily from the eastern coast of southern Norway. The Norwegian Red List for Species categorizes H. medicinalis as being of Least Concern in Norway. Hirudo verbana naturally occurs in southern Europe and has not been observed in Scandinavia so far (see map in Figure 2). Methods for the risk assessment VKM established a small working group with expertise in invertebrates and risk assessment. Our group combed the scientific literature and relevant websites for information on the taxonomy, natural history, ecology, and medical uses of medicinal leeches broadly and H. medicinalis and H. verbana specifically. The project group contacted major leech providers in Europe and North America to learn more about leech production and sale. Using the EICAT (Environmental Impact Classification for Alien Taxa) system developed by the IUCN, The project group identified those mechanisms (“hazards”) through which these two species could affect native biodiversity in Norway should imported specimens become established in Norwegian nature, and characterized the risk related to each of these hazards. The project group then conducted a semi-quantitative risk assessment for the species according to four categories: Low, Medium, Possibly high, and High risk. Hazards: how likely, how impactful, and overall risks In our report, VKM regard H. medicinalis as a native species, since it is so treated by Hirudo experts and is widespread in Norway. The project group regards H. verbana as non-native to Norway. The potential hazards from the EICAT system that could be associated with introducing one or both species include predation and parasitism, competition, disease transmission, and hybridization. ................................ .................................... Conclusions VKM concludes that the overall risk to biodiversity in Norway from importing live H. medicinalis and H. verbana is low.
Authors
Lawrence Richard Kirkendall Kyrre Linné Kausrud Martin Malmstrøm Paul Ragnar Berg Anders Bryn Kjetil Hindar Johanna Järnegren Anders Nielsen Erlend Birkeland Nilsen Brett Kevin Sandercock Eva Bonsak Thorstad Gaute VelleAbstract
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.
Division of Environment and Natural Resources
CANALLS Agroecological practices for sustainable transition
Agroecology covers all activities and actors involved in food systems. It also places the well-being of people (producers and consumers of crops and products) at its core. The EU-funded CANALLS project will focus on the agroecological zones and diverse farming systems in the humid tropics of Central and Eastern Africa. It will explore the complex environmental, social and economic challenges, which in some cases are exacerbated by conflict and high vulnerability. Moreover, it will advance agroecological transitions in these regions through multi-actor transdisciplinary agroecology Living Labs at eight sites in four countries. The focus will be on crops such as cocoa, coffee and cassava, which are vital for subsistence and economic development.
Division of Food Production and Society
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