Macrobenthic faunas of two brackish lagoons with different salinity in Kamikoshiki Island, Kagoshima Prefecture.

Quantitative seasonal samplings of macrobenthos were carried out in two brackish lakes with different salinity in Kamikoshiki Island, Kagoshima Prefecture.At Lake Kazakiike, where chlorinity of the water was around 1 ‰ macrobenthic fauna was constructed mostly with chironomid larvae and oligochaetes, which were presumably fresh form, and some brackish and one marine species were added to the fauna. At Lake Kaiike, where surface water usually showed 10 ‰ chlorinity, all species were marine.The population density of macrobenthos was high in autumn and low in summer in both lakes. Dominant species changed at each depth among bivalves and polychaetes in Lake Kaiike.Common brackish species were characteristically absent in both Lake Kazakiike and Lake Kaiike. The author assumed that the absence of open waterways from the lakes into both fresh and marine region was responsible for the lack of brackish species in both lakes.