Profundal oligochaete faunas (Annelida, Clitellata) in Japanese lakes

Abstract

Thirty-eight species of oligochaetes (Annelida, Clitellata) belonging to five families were recorded from profundal bottoms of 50 freshwater lakes on Japanese islands. They were mostly widely distributed species, and the composition of fauna is basically explained by the scheme of Timm (2012), with parallel replacement of European species. Oxygen, temperature and surrounding fauna could be main factors determining the profundal fauna in the lakes. The lumbriculids (Styloscolex japonicus, Yamaguchia toyensis and Lumbriculus variegatus), haplotaxids (Haplotaxis gordioides) and enchytraeids (Marionina klaskisharum) were restricted to several deep and oligotrophic lakes located in Hokkaido and northern Honshu, where Rhyacodrilus komarovi often accompanied them. Limnodrilus hoffmeisteri was the commonest species, occurring irrespective of the trophic status and bottom temperature of the lake. Tubifex tubifex also occurred in wide trophic scale, but it has never been found in shallow eutrophic lakes where the bottom temperature exceeds 15°C, where L. hoffmeisteri, Branchiura sowerbyi and several Aulodrilus species were the main representatives.