Mobility and Habitat Colonization in Stream Invertebrates: an Experimental Study

Abstract

A set of field experiments was conducted in the Takami River, a tributary of the Yoshino River in Nara Prefecture, to assess differences in mobility among invertebrate taxa.
Four experimental designs (drift nets, fall traps, colonization trays with or without gaps) plus a core sampler were used to sample invertebrates and to compare their taxonomic composition. Taxonomic composition was significantly different for all pairwise comparisons of samples except for colonization trays with and without gaps. In terms of the abundance of different taxa, five sampling methods revealed some notable differences. There were more non-chironomid dipterans and less Acarina in drift nets, more Trichoptera and Chironominae in fall traps, more Tanypodinae in colonization trays, and more Ephemeroptera and fewer non-chironomid dipterans in the natural substrate. Consideration was given to the behavioural characteristics of different taxa and to the possibility of interspecific interactions which may have contributed to the observed differences in colonization pattern.