Large invasion of floating aquatic plants in the Río de la Plata estuary!

VANHELLEMONT, Q.; GOSSN, J.I; DOGLIOTTI, A.I.; RUDDICK, K.

Victoria

Conferencia; Ocean Optics XXIII Conference; 2016

The La Plata basin is the second major hydrographical basin of South America and the fifthlargest in the world. The massive development of floating plants in floodplain lakes and wetlands in the upper Middle Paraná river is important both environmentally and socio-economically. Drifting aquatic vegetation represents an important biomass, mobilized by flood pulses and climatic factors, and its drift moves organic matter, insects and other organisms in the ecological system. Aquatic plant detachments drift downstream arriving in small amounts to the Río de la Plata (RdP) every year, but huge temporary invasions havebeen observed in the RdP every 10 or 15 years associated to massive floods. Since late December 2015, heavy rains, driven by a strong El Niño, have increased river levels in the La Plata basin provoking a large temporary invasion of aquatic plants from January to April2016. This event caused significant disruption of human activities via clogging of drinkingwater intakes in the estuary, blocking of ports and marinas and introducing dangerous animals from faraway wetlands into the city. Quantifying and mapping invasive plant species is important for efficient management and implementation of mitigation measures. This paperevaluates the ability of high-resolution multi-spectral imagery like Sentinel-2, Landsat-8,PROBA-V, and MODIS-250m, for mapping the large aquatic hyacinth (Eichhornia crassipes) invasion in the RdP that started in January 2016. Indices using bands that take into accountchlorophyll-a absorption in the red band and the reflectance in the near-infrared and shortwave infrared bands are tested and validated using field measurements.