Benthic Macroinvertebrates as Bioindicators for Assessing Water Quality in the Cañipia River, Cusco, Peru

Introduction. Benthic macroinvertebrates (BMIs) are widely used as bioindicators of water quality due to their sensitivity to physicochemical alterations caused by pollution. Their presence and community composition provide a comprehensive assessment of the ecological status of aquatic ecosystems. Objective. This study aimed to assess the water quality of the Cañipia River, located in Cusco, Peru, using three biotic indices: BMWP/ Col, ABI, and EPT. Materials and Methods. Sampling was conducted at four stations during the dry and wet seasons. BMIs were identified at the family level to calculate diversity and biotic indices. Additionally, physicochemical parameters were analyzed, and heavy metal concentrations in water and sediments were determined. Results. The families Elmidae and Chironomidae were the most abundant. According to the BMWP/ Col index, water quality ranged from critical to doubtful, while the ABI index indicated a poor to good status. The EPT index classified water quality as poor to moderate. Simpson’s index revealed fluctuating diversity, ranging from low to high during the dry season and from moderate to high during the wet season, whereas Shannon’s index indicated low to moderate diversity. Margalef ’s index (DMg) was higher in the wet season. Regarding metal contamination, only station RCañi1, located upstream of the formal mining area, exceeded Peruvian regulatory limits for Ba, Cu, Mn, and Zn in water. Canonical Correspondence Analysis (CCA) showed seasonal relationships between metal concentrations and biotic indices. Conclusions. The three biotic indices suggest a moderate impact on the water quality of the Cañipia River, likely influenced by anthropogenic factors.