Parasite fauna of Lake Biwa water system: A review on parasites using aquatic host organisms in their life cycle

Lake Biwa, with its long geological history, has given rise to many endemic species, but only four endemic parasites are known from Lake Biwa and connected water areas. They are considered to have co-evolved with their endemic host species or to have become adapted to the pelagic ecosystem unique to Lake Biwa. The number of parasite species introduced into this water system is rising, facilitated not only by the introduction of new species but also through genetic analyses that have revealed new information about previously known species. In addition, a few species are considered to have become extinct in the lake recently. Parasitological surveys of under-studied host taxa and more genetic studies are essential not only to understand the fauna of the Lake Biwa water system, but also to investigate parasite life cycles and host-parasite coevolution.