Een tweede slak in het Formerumerwiel op Terschelling

The first aquatic snail Potamopyrgus antipodarum, an invasive species originally from New Zealand, was recorded in 2007 from the Formerumerwiel on Terschelling, the Netherlands. During my visit to Terschelling in the autumn of 2010 I found a second aquatic gastropod Radix balthica in that small brackish water wetland, the remains of a dike collapse which occurred in 1717.