Treacherously beautiful

Have you ever gone swimming in a lake, and come out of the water covered with a thin layer of mucus that itches? Then you might have been subjected to gonyostomum semen – freshwater algae that previously only existed in forest ponds and swamps, but that are now invading other lakes in northern Europe. Ingrid Sassehagen at Lund University has shown that the algae – which consist of only one cell – can easily spread to new lakes over great distances. Gonyostomum semen that already exist in lakes, however, can prevent new cells from settling down there. The algae presumably spread with the help of birds and other animals.