Reports of INNS (invasive non-native species) always create a lot of interest. Non more so than the recent discovery of the quagga mussel in the Wraysbury River, a tributary of the Thames. Media headlines have highlighted concerns about potential impacts on native species and water supply infrastructure. So I was keen to join scientists from the Zoological Society of London (ZSL) when they carried out their annual survey of the Thames near Twickenham this week.
Scientists believe that the Thames is now one of the most heavily invaded river systems in the world due to the amount of marine traffic and dense human populations. Long term surveys such as this provide important information on the numbers and distribution of non-natives. This survey was led by Joe Pecorelli of ZSL. Joe began by briefing his colleagues and volunteers on what to expect and how to identify the species they were likely to find.
What's a few bivalve molluscs between friends?
After marking out the survey site, small plots or quadrats are used to sample areas within it and results recorded.
Typical results from a single quadrat.
Some of the species can be very hard to identify, even testing some of the experts.
Initial observations on the 2014 survey: The good news is that no quagga mussels were found on this occasion. Joe said 'Recent rainfall in the catchment meant we couldn't access as much of the riverbed as we wanted. Where we could survey we observed a similar pattern to previous years with the Asiatic clam being the most abundant species'.
Greater analysis of the data in relation to the historic data is needed to detect population changes of the target species. A report on this will be written by ZSL. My thanks to Joe and his colleagues for allowing me to join them. ZSL do great work promoting citizen science. You can find out more about ZSL and their projects here http://www.zsl.org.