Spatial scale effects on Chironomidae diversity and distribution in a Mediterranean River Basin

Abstract

Chironomidae are a very common insect group in running waters of Greece; however, they have been rarely studied. The aim of this work was to investigate Chironomidae distribution and abundance in a Mediterranean intermittent river basin, identify the environmental factors that are linked to variation in their assemblages and to partition the influence of environmental and spatial components, alone and in combination, on Chironomidae community composition. Multivariate ordination techniques were used to assess the association between environmental variables and species abundance, while variation partitioning was performed using partial canonical correspondence analysis to understand the importance of different explanatory variables in Chironomidae variation. Chironomidae variation was divided into independent and joint effects of micro-scale (physical and chemical variables, microhabitat composition, etc.), meso-scale (land use/cover) and macro-scale (altitude and distance to source, etc.) variables. Stream width and depth, water discharge, land uses, pH, and ecological quality were the most important factors structuring Chironomidae assemblages. Micro-scale variables accounted for 55.6% of the total explained variation followed by meso-scale (10.7%) and macro-scale (10.4%) variables. The results of partial constraint analyses suggest that micro-scale variables play a major role in Chironomidae assemblages.