Biomonitoreo del Arroyo Las Catonas, Cuenca Reconquista, Provincia de Buenos Aires utilizando el gasterópodo acuático nativo Biomphalaria straminea

Abstract

The study of multiple biomarkers in native bioindicator species is a useful tool to evaluate the water quality in addition to physical and chemical analysis. Biomphalaria straminea is a freshwater gastropod native of Argentina that has been selected as a bioindicator of environmental health. These snails are useful for ecotoxicity tests due to their rapid development and growth and their easy rearing conditions. Las Catonas stream is located in the middle basin of the Reconquista River, Buenos Aires Province, Argentina. The aim of this study was to evaluate the toxicity of water samples downstream a waste processing plant (site M) and downstream small orchards (site D) in B. straminea. For this purpose, water samples were taken in march, 2021 from sites M and D and from a site upstream them (site U). Water temperature and pH did not vary between sites. Snails were exposed 48 hours in standard conditions using 8 containers with 5 organisms each one per site. After the exposure neurotoxicity signs, behavior parameters and lethality were evaluated. Snails of each container were homogeneized together due to their small size (N = 8 homogenates per site). In the supernatants, protein content and cholinesterases, carboxylesterases using two substrates, glutathione S-transferase, glutathione reductase and catalase activities were measured. 60 % of the snails exposed to water from D died during the bioassay. Regarding biochemical biomarkers, a significant decrease of glutathione S-transferase (16 %) and cholinesterase activity (30 %) was observed in snails exposed to water from M and from D, respectively, in compare with those exposed to U. Water from site D caused a high toxicity in B. straminea. Lethality and inhibition of cholinesterases could be due to the presence of pesticides used in the orchards. B. straminea result a sensitive model for water biomonitoring.