Functional diversity of benthic macroinvertebrates regarding hydrological and land use disturbances in a heavily impaired lowland river

Abstract

This paper proposes the exploration functional diversity of benthic macroinvertebrates to evaluate their response to hydrological and land use stressors in a semi-arid lowland river. We aim to assess dominant functional traits and their sensitivity to environmental drivers, and how functional diversity respond to anthropogenic ecosystem impacts. Environment was evaluated through physical-chemical characterization of water, substrate and hydrological indices. For riparian condition assessment, we applied the QBR index for riparian forest quality and hemeroby index for level of anthropogenic intervention on the landscape. Links between environmental variables (R), taxa distribution (L) and trait composition (Q) were examined with RLQ and combined with fourth-corner analysis. The principal disturbance gradient was related to discharge regulation overlapping with land use represented by hemeroby index. There was also a gradient related to the hydrological regime which alternates seasonal floods with low flow periods. Traits related to reproductive and dispersal strategies were the most influenced by disturbance gradients, both natural and anthropogenic. Functional diversity decrease in sites subject to water abstraction and with higher hemeroby levels. Our findings have been promising in order to the application of functional diversity for biomonitoring in the Dulce River. Hemeroby enables the identification of trending changes between land uses, as well as to identify threat contexts. Furthermore, hemeroby could be useful in diagnostic stages to propose biomonitoring sites, by setting areas with different anthropogenic intervention on the ecosystem.