Human impacts on water systems: Biological assessment of water quality in the Bosque Protector Río Guajalito (BPRG) using aquatic macroinvertebrates

Benthic macroinvertebrates have been extensively used as bioindicators for water quality due to their varying sensitivity to a diverse range of impacts on hydrographic sources. In this study a sampling of macroinvertebrates was carried out in the Guajalito and Brincador rivers and a small creek that runs through the private reserve Bosque Protector Rio Guajalito in order to analyze if the health of the rivers has changed in relation to previous studies. The sampling stations were located upstream and downstream of potential sources of disturbance in each of the three streams sampled in order to determine what level of impact the disturbance had on the stream. Additionally basic physiochemical parameters were characterized at each sampling station to validate the biological data. Significant differences were observed in the water quality biotic indexes of BMWP and IBMWP between the three streams sampled. There were no significant differences, however, in the abundance, richness, biological index scores, and diversity measures between the upstream and downstream stations. According to the biological index scores of BMWP and IBMWP, the three streams sampled have fair and good water quality. According to the BMWP/Col, Sensibilidad, FBI and %EPT indexes, however, the streams rank as good, very good, and excellent. These results are consistent with the previous study conducted by Arroyo (2007) and indicate that the water quality conditions have not significantly changed in the time since that study