Integrating field and satellite monitoring for assessing environmental risk associated with bacteria in recreational waters of a large reservoir

GANGI DANIELA; FRAU DIEGO; DROZD ANDREA; BORDET FACUNDO; ANDRADE SOLEDAD; BAZZALO MARIEL; DE TEZANOS PINTO PAULA

SCIENCE OF THE TOTAL ENVIRONMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2022 vol. 818

0048-9697

In a large South American Reservoir (750 km2, limit between Uruguay and Argentina), we characterized the environmental risk posed by cyanobacteria proxies (abundance, toxin concentration, chlorophyll-a) and Escherichia coli abundances, integrating field (six sites, summers 2011-2015) and satellite (750 km2, summers 2011-2017) monitoring. We further assessed how well field cyanobacteria quantitative proxies (abundance, toxin concentration, chlorophyll-a, and scum formation) used to build a local risk communication system for recreational (bathing) use of waters named ?cyano-traffic-light?, ongoing since 2011, reflected its outcome. Cyanobacteria abundance in the field ranged from moderate (>20,000 to 100,000 cells mL-1), and its abundance was positively related to toxin (microcystin) concentration. Mean microcystin concentrations were within the low (≤2 µg L-1, 50% sites) or moderate (>2126 CFU 100 mL-1) for human health, mostly in the northern part of the reservoir. Cyanobacteria proxies (abundance and toxins) and E. coli abundance were, however, unrelated. The predictive model showed that, out of the four cyanobacteria proxies used to construct the cyano-traffic-light only cyanobacteria abundance (p