RESPONSE OF INVERTEBRATE ASSEMBLAGES TO FLOOD DISTURBANCE IN JAPANESE LOWLAND STREAMS

Abstract

 This study aimed to clarify the response of invertebrate assemblages to flood disturbance in lowland stream s. We established 12 study sites in the Dogo Plain, Ehime Prefecture, southwestern Japan, and conducted survey on stream invertebrates and habitat characteristics before and after a flood event. As a result, while invertebrate density decreased in all study sites, taxon richess appeared to increase in three sites after the flood event. Our community structure analysis showed that tolerant taxa originally dominated in those sites, but intolerant taxa increased after the flooding. The relationship between catchment feature and the change rate of taxon richness implied that the increase in taxon richness can be attributed to new colonization by intolerant taxa during the flood from upstream, clear water segment located in mountain area.