Influence of the seasons on the water quality of the Marmeleiro River (Paraná, Brazil) using different bioindicators

The use of environmental bioindicators and biomarkers has shown promising to evaluate water quality. In this study, the biological indicators Lactuca sativa L., Allium cepa L., and Artemia salina L. were used to verify the water quality of the Marmeleiro River (Paraná, Brazil). Water samples were collected at six points along the river, covering urban and rural areas over the four seasons. The experiment of germination and initial growth of the A. cepa seeds showed changes between seasons, but no difference between the collection points. Regarding L. sativa seeds, the results showed changes between the points and the seasons. In general, it was possible to correlate the highest numbers of germinated seeds, size of the germinated roots, percentage, and germination speed with the highest levels of phosphorus and lowest levels of chemical demand for oxygen, oils and greases, and total solids. The results of the cytotoxicity test with A. cepa showed an increase in the mitotic indices of Points 3 (spring, summer, and winter), 4 (spring and winter), 5, and 6 (summer and autumn) correlated with higher levels of phosphorus and chemical oxygen demand in water samples. For the immobility/mortality test with A. salina , in the spring and summer, all collection points were toxic, possibly due to the lower levels of dissolved oxygen in these samples. Therefore, bioindicators proved to be efficient to determine and monitor the Marmeleiro River toxicity and indicate that preservation actions should be implemented for this watershed.