Algal growth potential and water quality of La Culebra stream in the Guadalajara Metropolitan Area (México)

Abstract

Background. La Culebra stream originates in Los Colomos Urban Forest (LCUF) within the Guadalajara Metropolitan Area (GMA), which is preserved almost naturally with few human interventions in the studied section. The stream flows from springs that emerge within the LCUF. There are no records of the water quality of La Culebra stream. It is of great interest to know its characteristics to propose management alternatives.

Methods. Using physicochemical techniques and test organisms, the behavior of macronutrients in the water, the existence of inhibition factors and the presence of coliforms were investigated during six months representative of the seasonality of the year 2018. Results. The stream was found with low concentration of nutrients and with a variability in its physicochemistry and biology depending on the seasonal cycle. The system maintains adequate levels of dissolved oxygen to support the respiration of organisms in the water column, and particularly the upper layer of the sediments. Using test algae, it was revealed the presence of an inhibition factor. Although coliform levels were high in all samples, their presence is not from human origin, but of ducks and small mammals that normally inhabit the urban forest.

Conclusions. Nevertheless, the stream presents ecological functionality, we recommend conducting microbiological studies of groundwater to confirm the natural origin of coliforms. Likewise, it is recommended that studies be implemented to characterize the nature of the inhibiting agent that we have detected. Finally, it is recommended that the administrative authority of the LCUF manage funds for the dissemination and preservation of La Culebra stream as a subject of high environmental and cultural value in the GMA.