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: 2021

0048-9697

In a large South American Reservoir (750 km2, limit between Uruguay and Argentina), we characterized the environmental risk posed by cyanobacteria (abundance, toxin concentration, chlorophyll-a), and Escherichia. coli) integrating temporal and spatial approaches: field data (six sites, summers 2011-2015) and satellite data (750 km2, summers 2011-2017). 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 was within the low (≤2 µg L-1, 50% sites) or moderate (>210 µg L-1, 10% samplings). E. coli abundance was within the high-risk category (>126 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