Aquatic macroinvertebrates as indicators of water quality in areas of residual discharge to the Quevedo River, Ecuador

Abstract

The objective of this paper was to characterize physical and chemical conditions of water, to identify the diversity of benthic macroinvertebrates, and to determine water quality in two urban monitoring sites of the river in the city of Quevedo. Samplings were carried out from September to November 2015, at sites influenced by residential (RE) and agricultural-industrial (EAI) discharges. Physio-chemical parameters of water quality were measured: dissolved oxygen, biochemical oxygen demand, chemical oxygen demand and total dissolved solids. Chao2 richness indexes, Shannon-Weiner diversity (H), Simpson dominance (1-D) and Bray-Curtis dissimilarity were estimated. Water quality was estimated using the Biological Monitoring Working Party (BMWP-Col) index. The values of the physical-chemical parameters did not show differences between RE and IAS. There were no statistical differences between the expected family richness (Chao 2) and the observed richness. The Tubificidae family showed the highest total abundance with 4574 individuals (90.48%), for ER - 3918 individuals (93%), and EAI - 656 (76%). H-diversity in ER and IAC was low: 0.49±0.22; 1.009±0.21 respectively, and differed significantly. The highest dominance was shown by ER (0.78±0.1), and it differed from IAC (0.58±0.096). The BMWP-Col index indicated that ER recorded “critical” water quality (20±7.52), as compared to “uncertain” water quality (37±6.27). The water body that crosses the urban area of Quevedo was found heavily polluted due to urbanism, agricultural and industrial activities, negatively influencing the structure of aquatic macroinvertebrate communities.