City Channel Chironomids-Benthic Diversity in Urban Conditions

Abstract

The study focuses on the diversity of urban channel chironomids (the Aa River, the City of Munster, North-western Germany), initially intended as a proxy of habitat structure. Three ecological key points marked the study: The channel is the discharge effluent of a eutrophic lake. It includes lotic and lentic sections. Runoff variability is high (0.02 to 4 m3 s−2). Chironomid pupal exuviae were sampled from the surface drift. Simultaneously, variable abiotic parameters (runoff, suspensoid contents and weather) were recorded. Samples were taken from September 2011 to April 2012. Communities' diversity (>64 spp.) was relatively high. Data analyses revealed that the most significant drivers of species diversity and abundance were water temperature, suspension, flow velocity, nature nearness, water depth and weather. In addition, the increase of diversity ranged significantly with the quality of suspensoids along the channel course. Considering the great complexity of ecological interrelations found on a limited physical scale, the potential of chironomids as sentinel organisms shall be discussed critically. Ongoing analyses focus on the specification of fine particulate organic matter, microhabitat structure and microhydraulics for the development of chironomid communities.