Water quality related macroinvertebrate community responses to environmental gradients in the Portoviejo River (Ecuador)

¹ Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, Campus Coupure – Building F – 2nd floor, Coupure Links 653, B-9000 Ghent, Belgium
² Research Institute for Aquaculture No1, Dinh Bang, Tu Son, Bac Ninh, Vietnam
³ Provincial Centre of Environmental Research, Godshuizenlaan 95, B-9000 Ghent, Belgium
⁴ Departamento de Ingeniería Industrial, Universidad Técnica de Manabí, Av. Universitaria y Che Guevara, 130104 Portoviejo, Ecuador
⁵ Centro del Agua y Desarrollo Sustentable, Escuela Superior Politécnica del Litoral (ESPOL), Campus Gustavo Galindo, Km. 30.5 Via Perimetral, P.O. Box 09-01-5863, Guayaquil, Ecuador
⁶ Hanoi University of Science and Technology, School of Environmental Science and Technology, No 1 Dai Co Viet, Hanoi, Vietnam

^* Corresponding author: pieter.boets@oost-vlaanderen.be

Received: 6 October 2016
Accepted: 22 February 2017

Abstract

The Portoviejo River, located in the central western part of Ecuador, has been heavily impacted by damming, intensive agriculture and untreated wastewater discharge. Unfortunately, detailed information on the water quality and the ecological status of the Portoviejo River is not available, inhibiting decision-making and the development of water management plans. Therefore, the aims of this study were (1) to assess the ecological water quality, (2) to investigate the point along the environmental gradient where the most significant change in macroinvertebrate community occurs and (3) to find potential macroinvertebrate taxa that significantly change in abundance and frequency of occurrence along the Portoviejo River. To this end, macroinvertebrate and physico-chemical data were collected and hydro-morphological conditions were recorded at 31 locations during the dry season of 2015. The results showed that the ecological water quality of the sampling sites ranged from good to bad. In addition, the Threshold Indicator Taxa ANalysis was used to examine changes in macroinvertebrate communities and revealed significant community change points for sensitive taxa declining at a conductivity value of 930 (μS.cm⁻¹) and nitrate-nitrogen concentrations of 0.6 mg.L⁻¹. In addition, the thresholds estimated for tolerant taxa were set at a conductivity value of 1430 μS.cm⁻¹ and nitrate-nitrogen concentration of 2.3 mg.L. Atyidae, Corbiculidae, Thiaridae, Acari, Baetidae and Leptohyphidae can be considered indicator taxa, showing shifts in the community. This study suggests that values of conductivity and nitrate-nitrogen concentrations should not exceed the threshold levels in order to protect macroinvertebrate biodiversity in the Portoviejo River.