Studies on Bottom Fauna in River in Fukuoka City

In order to evaluate the water pollution of Mikasa River, the benthic
animal phase was investigated. As for the fresh water area it was
thought that Miura Bridge of the upper stream was the most clear and
the lower stream, a little muddy. Compared with 1994 the environmental
change near the middle was not fully grasped and no significant change
was observed at the upper stream. Between the investigations of May
and October at the estuary, the change of the community composition
was bigger in going from the lower stream to the upper
stream. Compared with 1974, the change was not sufficiently grasped at
the upper stream of the estuary, but the environment is thought to be
a little improved at the middle stream and the diversity and
complexity of biotic community was decreased at the lower stream.