Spatial and Temporal Variation in Benthic Macroinvertebrate Assemblages Structure in Salinized Reaches of the Pecos River

Authors: Connor L. Brown, Kelbi D. Delaune, Allison A. Pease

Year: 2018

Abstract

In the Permian Basin region of Texas, salinization has occurred in the Pecos River as natural saline inputs have been exacerbated by flow-regime change and other anthropogenic impacts. Recent studies have shown that fish diversity has declined with salinization in the Pecos River, but impacts on benthic macroinvertebrate assemblages have not been examined in recent decades as salinization has intensified. In this study, we deployed Hester-Dendy multi-plate samplers for 6-8 weeks in summer and fall 2017 to assess the structure of colonizing benthic macroinvertebrate assemblages at three sites in the lower Pecos River (two in the salinized Permian Basin region, one in the Edwards Plateau region). Invertebrate biomass and taxonomic richness was lowest in the salinized Permian Basin sites, with assemblages dominated by dipteran taxa. As specific conductance decreased and habitat heterogeneity increased in the Edwards Plateau reach, more diverse benthic macroinvertebrate assemblages colonized the samplers. Additionally, diversity of benthic macroinvertebrates and biomass increased from summer to fall. Results of this work add to our understanding of how river salinization affects ecological communities. Because river salinization is a common issue in dryland regions, and it is expected to increase with climate change, such information is important for conservation and management.