Evaluación ecotoxicológica de arroyos de la reserva San Rafael y su zona de amortiguamiento mediante bioensayos con Daphnia magna y Lactuca sativa

Abstract

The ecotoxicological effects of agricultural activity on streams of the San Rafael Reserve and its buffer zone were assessed through bioassays, determination of pesticides and physicochemical parameters. Seven sampling campaigns were carried out between the years 2012 and 2013, taking water and sediment samples from five streams, two of which are water springs in a primary forest zone; the remaining three samples were taken from agroecosystems located within the buffer zone. Acute and chronic toxicity tests were carried out with Daphnia magna , in addition to acute toxicity assays with Lactuca sativa . No acute toxicity was recorded in D. magna or L. sativa , but slight chronic toxic effects were observed on their rates of reproduction. The pesticide screening for chlorpyrifos and cypermethrin determined that neither was present in the samples. Physicochemical parameters indicate that the waters are in good condition, classified as Class I according to the standards of the Secretariat of the Environment (SEAM by its Spanish acronym). However, increases were detected mainly in the levels of nitrates and total phosphorus when comparing the controls to waters from agroecosystems. Keywords: toxicity, bioassays, pesticid