EFFECT OF HEAVY METALS ON STRUCTURES OF BENTHIC INVERTEBRATE COMMUNITIES IN KASUKAWA RIVER

Abstract

 I conducted field surveys in Kasukawa river once a month to examine the influence of heavy metals from industrial factories on benthic invertebrate communities. I selected one reference site and one metal polluted site that had a difference in heavy metal concentration and approximately equality in flow velocity, water depth and riverbed structure. I evaluated the toxic effects among copper, nickel and zinc additively. I compared the time series data of river environmental variables and benthic invertebrate indicators at the two sites using generalized linear mixed model. The difference in electric conductivity, transparency, cumulative criterion unit of these three metals, taxonomic species richness, the abundance, wet biomass, the abundance of Baetis thermicus, and the abundance of Chironomidae was statistically significant. I inferred that the effect of heavy metals on the structure of benthic invertebrate communities was that compositional changes of species caused by increasing heavy metal pollutions were simply a shift from communities composed of susceptible species to those composed only of tolerant species (Chironomidae) in Kasukawa river.