American Mink in the River Dodder

Yesterday students from my undergraduate freshwater biology course and myself were out surveying the River Dodder in the heart of suburban Dublin. To our surprise we were able to observe mature American Mink patrolling the opposite bank completely at home and oblivious to all the activity going on. I have very rarely seen mink in the wild and was surprised to see it so well adapted to its urban environment. This voracious predator has had devastating impact on river wildlife, especially water voles, which are now classed as endangered, as well as wildfowl (e.g. moorhens, coots, widgeon and teal) and of course fish. It is perhaps our most problematic invasive species. This sighting comes at a time when the University of Aberdeen is leading a major eradication scheme in a number of Scottish rivers. So far 10,000 sq km of land in north-east Scotland has been cleared of mink. Below is an excellent video from the BBC of biologist Jamie Urquhart (River Don Trust) showing science reporter Rebecca Morelle how the mink are caught.

Ballast Water and the Control of Invasive Species and Pathogens

Following on from Don's comment below there is now a large body of evidence that both invasive species and pathogens can be transferred by ballast water between ports. My previous comment really referred to the acceptance of this problem and making it part our existing barrier approach to pathogen control. There is an excellent website operated by the GEF/UNDP/IMO Global Ballast Water Management Programme (GloBallast) which is supported by the International Maritime Organization. It looks at the evidence and up to date research, including international regulations, concerning ballast water treatment and management. The site provides numerous technical reports and guidelines that can be downloaded. Link

Another Alien Alert - Killer Shrimp in the UK



The predatory shrimp Dikerogammarus villosus

 Another invasive species has hit the headlines in the past weeks, the predatory shrimp Dikerogammarus villosus, which preys on a wide range of macro-invertebrates and even small fish. It comes from the Steppe region between the Black Sea and the Caspian Sea. The shrimp is much larger (up to 30mm) than the native shrimps such as Gammarus and has obvious strips making it easy to identify.  The shrimp, described by the Environment Agency as 'particularly vicious and destructive'  was discovered by anglers in Grafham Water, a large reservoir in Cambridgeshire. It has rapidly been moving throughout Europe mainly via the River Danube, but it was a shock when it turned up in the UK.  A containment strategy has been put into place with the water leaving the  reservoir passing thorough a double set of coarse and fine mesh, although it is inevitable that the species will escape into the adjacent River Ouse.  All boat movements are being closely monitored.  The Environment Agency have moved very quickly to control this invader and it will be interesting if the strategy succeeds. Link

Asian Clam invades Irish Freshwaters

Recent reports have shown that the aquatic invasive species Asian Clam (Corbicula fluminea), which was recorded for the first time in Ireland in April this year in the River Barrow in County Carlow,  is more widespread than previously thought. The mollusc has also been recorded in Lough Corrib and the Grand Canal. Canals are trans-catchment waterways that have significantly accelerated the spread of invasive species in other countries.

The clam originally comes from south-eastern Asia and grows very rapidly reaching high densities in a short period of time. Like the Zebra Mussel (Dreissena polymorpha) it significantly damages the food web and excludes the native mussel species. In the US the mussel is estimated to cause in excess of a $1 billion of damage each year. The National Invasive Species Database has asked that any suspected sightings be reported to them with a photograph if possible so that identification can be confirmed. Link