Abstract

The structure and composition of stream benthic communities are strongly influenced by spatial and temporal factors. This study evaluated the intra and inter-annual variations in Chironomidae communities in subtropical streams. The organisms were sampled from 10 small-order streams during the summer and winter of 2010-2012. The number of chironomid specimens sampled was 7,568, distributed in 49 genera. Chironomid abundance and richness varied intra and inter-annually and community composition varied intra-annually (2010 and 2011). Water temperature, total organic carbon, nitrogen, and rainfall were correlated with chironomid community composition. The intra-annual variation of the community was dependent on climatic variations (temperature and rainfall) and changes caused by intensive agricultural use. We conclude that the temporal variation observed in the Chironomidae community correlates with climatic variations (rainfall) and changes in the total organic carbon and total nitrogen, caused by intensive agricultural land use.

Highlights

  • The structure and composition of aquatic communities are influenced by spatial and temporal factors (SUAREZ 2008)

  • The distribution of benthic macroinvertebrates is affected by factors such as type of substrate (HEPP et al 2012), habitat characteristics (GALDEAN et al 2000, BUSS et al 2004), land use (HEPP et al 2010), and climatic variations over a timescale (SCHEFFER & VAN NES 2007)

  • In addition to climatic factors, temporal variations in the structure and composition of chironomid communities may reflect the biological characteristics of the species that compose these communities (HEINIS & DAVIDS 1993, SIQUEIRA et al 2008) or temporal changes in physical and chemical characteristics (AL-SHAMI et al 2010b)

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Summary

Introduction

The structure and composition of aquatic communities are influenced by spatial and temporal factors (SUAREZ 2008). In addition to climatic factors, temporal variations in the structure and composition of chironomid communities may reflect the biological characteristics of the species that compose these communities (HEINIS & DAVIDS 1993, SIQUEIRA et al 2008) or temporal changes in physical and chemical characteristics (AL-SHAMI et al 2010b). Natural disturbances, such as spates caused by increased rainfall in human-impacted areas may carry chemicals from adjacent areas to the streams, affecting chironomid communities (GRESENS et al 2007). The objectives of this study were (1) to evaluate the intra and inter-annual variations in Chironomidae communities and (2) to determine whether these temporal variations are associated with environmental factors

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