Biomarcadores de daño temprano en Ankistrodesmus falcatus y Hyalella azteca como indicadores de estrés en tres áreas (urbana, turística y agrícola), de la zona lacustre de Xochimilco

Abstract

Pollution of freshwater by the discharge of industrial and domestic wastes provokes, damage to the aquatic biota and endanger the ecosystems biodiversity. Lake Xochimilco, have been affected by wastewater previously treated and agricultural wastes, pouring pesticides, heavy metals, and a great number of pathogens. These pollutants generate complex mixtures that may damage resident organisms. The aim of this study was to assess the oxidative stress damage in the microalgae Ankistrodesmus falcatus and the amphipod Hyalella azteca by exposure to water from three sites from the lake Xochimilco zones (urban, tourist and agricultural) during an annual cycle. We used early warning biomarkers as the level of lipid peroxidation and antioxidant activity of superoxide dismutase, catalase and glutathione peroxidase. Additionally, we determined the inhibition of acetylcholinesterase in H. azteca. Water quality analysis and some heavy metals and static bioassays were carried out to evaluate the inhibition/stimulation of the algal growth potential in A. falcatus. The results show seasonal and temporary variations, the higher values of the level of LPO in the alga were in the urban and agricultural zones during May and August. The high antioxidant activity was observed in the urban and tourist zones in the rainy season. In the amphipod lipid peroxidation level was high in urban and tourist zones, mainly during the rainy months, persisting until November and the high antioxidant activity was observed in the tourist and agricultural zones in May, November and February. Moreover, inhibition of acetylcholinesterase was higher in August and November in the three study sites. The analysis show that the mixture of pollutants that is found circulating and entering the lake, generate free radicals that damage the organisms of the first and second trophic level. Additionally, neurotoxic damage in H. azteca was detected. Results show that the conditions prevailing in the Xochimilco lake system can cause alterations in the first levels of the food chain.