A potential tool for detecting Harmful Algal Blooms through remote sensing data

IOLE B. M. ORSELLI; GASTÓN ALURRALDE; FLÁVIA DELCOURT; LEONARDO K. MIYASHITA; DANIEL VALLA

Santos

Congreso; Third International Symposium on the Effects of Climate Change on the World?s Oceans; 2015

Institute of Oceanography, University of São Paulo (IOUSP)

Harmful Algae Blooms (HABs) are algal/cyanobacterial proliferations that has harmful socio-economic or ecological effects, generally associated with natural toxin production and dissolved oxygen depletion. Their occurrence pose an emerging threat to Eastern Boundary Upwelling Ecosystems; nutrient-rich and highly productive areas that sustain large portion of fisheries global production. Traditionally, the study of HABs relies on in situ surveys, but facing the complexity and increase in frequency, magnitude and geographic extent of them, new multidisciplinary and methodological approaches are necessary. By combining satellite-derived data and in situ measured physicochemical parameters, we assessed the possibility of detecting HAB occurrence. We explored the scope of a colorimetric index (Red Tide Index), taking as a study case an event reported in the Humboldt Current System south of Chile between April 2003 and August 2004. According to the in situ data, the occurrence areas were characterized by a low subsurface percentage of oxygen saturation and high concentrations of nitrates, phosphates and total inorganic carbon near the coast. The index was able to distinguish those areas affected by the HAB as observed with in situ data. Thus, our results indicate that satellite data could potentially be used as a proxy for detecting HABs.