North East and Yorkshire Freshwater group – INNS meeting

On 15th December the North East and Yorkshire Freshwater group organised its second annual meeting which focused on the topic of invasive non-native species. The event featured talks from a variety of organisations across the region as well as an opportunity for open discussion and knowledge exchange with regards to the work carried out on invasive species. The event had a very successful turnout, with approximately 80 attendees including researchers, academics, non-departmental bodies and ecological consultants.


Dr Stephanie Peay from AECOM discussed the current situation regarding invasive crayfish in the UK, by delineating their ecology and reasons for rapid and successful colonisation of British watercourses, and, furthermore, the future risks that these species will pose; but also some of the difficulties that invasive crayfish may encounter in the years to come in terms of natural threats, as well as the possibilities available and being researched as control measures.


Prof Jon Grey from Lancaster Uni/Wild Trout Trust talked about pieces of research done in the last few years with regards to trophic interactions between different Dikerogammarus (invasive shrimp) species as well as their effect, in terms of food webs, on native species, by using stable isotopes. He also outlined some limitations around research in invasion biology, which often tends to be focused solely on the acute phase of invasion and studies are not perpetuated to monitor the evolution of the invasion.



Scott McKenzie from Ecus discussed work that the company is doing in various Lochs in the Hebrides, which consists of ecological surveys of macrophytes, reliable indicators of environmental conditions which allow to assess whether SSSI and SACs are healthy. Particular attention was given to the plant Najas flexilis, of which the South Uist SAC holds 1/3 of the UK’s population. Surveys of this plant have been done every 6 years since 2006, and in 2010 more than 5000 individuals were present in the samples taken. In 2016, less than 20 individuals were found due to it being outcompeted by the invasive waterweed Elodea canadensis. With this information the aim is now to understand how to act upon this invasive species and maintain the UK’s population of Najas alive.


Cat Shannon from Leeds University gave an overview of the impacts of invasive species and their major pathways of dispersal, discussed the importance of biosecurity and how prevention is the most effective mode of stopping the spread of invasive species. She illustrated the importance of awareness of biosecurity and the impacts that national campaigns such as Check Clean Dry are having in altering the behaviour of waterway users. She also talked about the work she is doing as part of her PhD to create a biosecurity training package for academics and researchers, which can be assessed by anyone online either on the Secretariat’s website or on the Leeds University website.




Ailsa Henderson from the Yorkshire Wildlife Trust outlined the importance of citizen science and the great impact that is has had towards the mapping of invasive species present in the Don and Rother and the Aire and Calder catchments, even in terms of economic savings. In just four years, help from the volunteers has allowed most of this region to be mapped for the INNS present within it.



Melanie Fletcher from the FBA discussed some work that is being done on Crassula, (see header image) introduced to a mesotrophic tarn in Cumbria in 2010, previously designated as a SSSI due to the macrophytes present within it. The native species Elatine hexandra was greatly reduced in areas where Crassula had spread and become predominant due to its ease of spread (further enhanced by the action of water birds). The project also surveyed for the rare water flea Ilyocryptus acutifrons, of which three individuals were found for the first time since 1955. Melanie raised an open discussion for potential ways of dealing with Crassula within a SSSI without compromising its designation.


All the talks sparked much curiosity and interest and promoted discussion between attendees both at the break and following the session, which hopefully provided opportunity for knowledge exchange and to share ideas, which was the ultimate goal of the meeting.