Artificial Substrate Transfer Technique to Detect Impact of Urbanization on Colonized Macroinvertebrates from a Minimally Impacted Stream

Abstract

ABSTRACT The colonization patterns of benthic macroinvertebrates were compared on artificial substrates between a best available strcarn reference site and an urban stream site, and then the colonized artificial substrates from the reference site were transferred to the urban site. Statistical comparisons for non-transferred samplers indicated a significant difference (p < 0.05) in taxa abundance of colonized benthic samplers between the reference and urban sites. Significantly (p < 0.05) higher numbers of Nais spp., Ablabesmyia spp., Tanytarsus spp., Parakiefferiella spp., and Ceratopogonidae occurred at the reference site. At the urban site, colonization was characterized by significantly (p < 0.01) higher numbers of Aphanonerua spp., Dero spp., Ancylidae, Larsia spp., Chironomus spp., Dicrotendipes spp., and Polypedilum spp. Caenis spp. were common to both sites. Identification of chironomids to the subfamily level had enough statistical power (except for Tanypodinae) to detect differences between sites. The comparison of reference and transferred benthic samplers at the urban site indicated a significant number of invasions by local taxa and a reduction in number (or disappearance) of taxa colonized from the reference site. This experimental technique was effective in detecting differences in benthic community structure between reference and urban sites.