Statistical Analysis and Assessment of Water Quality Parameters in Relation to the Use of Algae as Bioindicators in Contaminated Reservoirs

One of the most important water bodies in Mexico is the Purisima Reservoir. It has been declared a protected natural area and provides ecosystem services. The aim of the present study was to assess the water quality and the degree of contamination in the reservoir using an integrated methodological approach to obtain a comprehensive knowledge of the environmental status of the reservoir. Physicochemical analyses, metal/metalloid determination and biomonitoring techniques were carried out. Algae were identified as the most feasible bioindicator. Data were processed using WAWQI, PAST 4.03, JMP15.2 and QGIs 3.26.3. The main elements identified in the reservoir were Cd, Cr, Hg, Pb and As (0.002–0.1 mg L −1 ). The element pairs with high correlation ( p < 0.05) were Cd and Pb; Cr with Hg and Pb; Hg with Pb and Zn; and Pb and As. The taxonomic divisions of the algae observed were Bacillariophyta, Cyanobacteria, Charophyta and Chlorophyta. The results obtained classify the water quality of the Purisima Reservoir as “poor”, while the biomonitoring analyses classify it as “moderately polluted”. As a future perspective, a DNA meta-coding study of algal genera is recommended as it would increase the effectiveness of future biomonitoring programmes as well as the development of mapping techniques that correlate the degree of eutrophication with the population of bioindicators in order to design and implement effective protection and restoration policies. Finally, it should be noted that this is the first reported work on the study of the algae present in the Purisima Reservoir.