Assessment the water quality and the riparian quality in the Margaritas river basin, Chiapas, Mexico

Deteriorating water quality is a worldwide problem, so that good quality water resources may become scarce in the future, putting their use for drinking clear water and economic development at risk. In the Margaritas river basin, anthropogenic activities such as agriculture and livestock may be influencing the quality of the water and the banks, so we aimed to assess the quality of the riverbank and the water quality in this basin. The Riparian Quality Index (RQI) and the Index of the Biological Monitoring Working Group (BMWP) adapted for Costa Rica (BMWP_CR) were used; also physical and chemical parameters of the water (pH, dissolved oxygen, temperature and conductivity) and hydrological parameters (current speed and flow) in dry and rainy seasons were determined. The riparian quality ranged from "bad" to "very good". The attributes of the index with the greatest affectations were the natural regeneration, the composition and structure of the riparian vegetation. The BMWP_CR water quality index showed that water quality decreased in the rainy season. A total of 17 676 macroinvertebrate individuals were counted, belonging to 13 orders and 50 families. Baetidae was the family with the largest number of collected individuals, followed by Hydropsychidae and Elmidae. The richness and diversity (H') values were higher in the dry season. This work is the first to integrate the quality of the water, the quality of the banks and the biodiversity of macroinvertebrates at the local and regional scales, which represents the baseline for future water management in the area and the creation of a BMWP index adapted to this region of southeastern Mexico.