EXCRETION OF HEPTADECENE-1 INTO LAKE WATER BY SWARMS OF POLYPHEMUS-PEDICULUS (CRUSTACEA)

1. In the littoral zone of a mesotrophic freshwater lake (Lake Selent, Northern Germany) much higher concentrations of heptadecene-1 were fo und within a swarm of Polyphemus pediculus than in lake water at some distance from the swarm. Polyphemus collected in the field produced la rge amounts of heptadecene-1 when exposed to osmotic shock. Other vola tile compounds were not detected. 2. Heptadecene-1 could be involved i n the formation, maintenance and recognition of swarms of Polyphemus. It is the first report of the release of a volatile organic compound f rom a freshwater crustacean.