AQUATIC MACROINVERTEBRATES OF THE LERMA RIVER, MEXICAN HIGHLANDS: HIGH WATER REGULATION AND POLLUTION

• DOI: https://doi.org/10.22533/at.ed.813432421038

• Palavras-chave: río regulado, presas, fertilizantes, hipoxia, lentico

• Keywords: regulated river, dams, fertilizers, hipoxia, lentic

• Abstract: In this study, the benthic macroinvertebrate community as a bioindicator and the physicochemical conditions of the Lerma River basin are used to evaluate its environmental quality and organic contamination. The applied BMWP Index with the macroinvertebrate community includes parallel water temperature, pH, dissolved oxygen, nitrogen, and total phosphorus records. During May (dry), the river water showed critical water quality with severe contamination; in August (rains), the upper basin presented a range of light to severe contamination, while the middle and lower basin maintained critical quality and highly contaminated water. Dissolved oxygen, pH, total Nitrogen, and Phosphorus with high variability in each site; hypoxia and anoxia conditions related to lentic conditions, as well as values up to 7 mg/L in lotic conditions, alkaline to slightly acidic waters and average nutrients of 4 to 12 mg/L and extremely high in the lower basin. Water quality is in a condition of degradation from the upper basin; macroinvertebrates are pollution indicators that reflect the environmental quality and pollution along the river and in dry and rainy conditions. It also shows the contribution of fertilizers from agricultural activity and nutrient enrichment conditions.