Aquatic Coleoptera Distribution and Environmental Relationships

MISERENDINO, M. L; ARCHANGELSKY, M

INTERNATIONAL REVIEW OF HYDROBIOLOGY

Wiley-Iterscience

Lugar: Weinheim; Año: 2006 p. 423 - 437

1434-2944

The benthic coleopteran assemblages of the Chubut River basin were studied in order to assess themain factors affecting species composition and distribution along the upper, middle and lower catchments.A total of 13 sampling sites were selected and sampled seasonally. Eight taxa and 1,601 individualswere collected during the study. Richness was higher in the main channel of Chubut River atthe upper basin than at the middle basin. Beetles were completely absent at the lower basin. Meanmonthly density per sites varied from 0 to 85 ind m–2. Stethelmis kaszabi had a more restricted distributionwhereas Hemiosus dejeanii, Austrelmis sp. and Austrolimnius spp. were more frequent andabundant. Austrelmis sp. appears as the most tolerant species, especially to higher TSS, ammonia, andconductivity values. Luchoelmis cekalovici was absent in stations associated with urban areas. A CanonicalCorrespondence Analysis shows that conductivity, total suspended solids, wet width, watertemperature and pH were the most important variables structuring beetle assemblages. Land use relatedvariables such as NH4, TP, and NO3 were less important but still significant. An increase in TSSaffected negatively the coleopteran community; this could be related to both hydrogeological characteristicsand agricultural activities (including overgrazing).This is the first approach to the knowledge of the ecological range of distribution of the coleopteranspecies in Patagonian rivers.