Primera caracterización de un reservorio tropical somero en riesgo en el norte de la Argentina

Abstract

The study of shallow tropical environments in northwestern Argentina is poorly developed. The Itiyuro reservoir is of major importance for supplying drinking water to more than 100000 people in the San Martin department. The development of cyanobacterial blooms with cyanotoxin-producing species in the reservoir constitutes a health problem. The present study explores the relationship between phytoplankton communities and limnological variables in the Caraparí river and the Itiyuro reservoir, between June 2018 and January 2020, using standardized techniques. Bacillariophyta were dominant in the river, and cyanobacteria and chlorophytes, in the reservoir. A multispecific bloom of cyanobacteria was observed in the summer of the last year sampled. Only 22% of the species in the reservoir were dominant, including Aphanizomenon gracile, Raphidiopsis spp., Pseudanabaena limnetica and Monoraphidium contortum; this implies a low average dominance (0.29) in 65% of the samples. In both systems, 50% of the species were rare, and the abundance of the constant species was low. Phytoplankton abundance -and, in particular, of cyanobacteria-was higher in the highwater phase, characterized by a high average temperature (22.7 °C) and higher nutrient inputs from runoff. To date, there is no continuous monitoring of the reservoir by the drinking water service providers. Performing periodic samplings would allow the detection of algal and cyanobacterial blooms and the release of toxins in time, as well as developing management protocols.