Cyanobacteria Assessment In Italian And Swedish Waters From Space - 4Th Final Report

Earth Observation (EO) is a cost-effective tool for obtaining spatial information on the water quality status and processes taking place in seas and lakes. In particular, recent and expected advances in EO technology broaden the perspectives of monitoring toward the identification and quantification of plankton groups including cyanobacteria. The capability to detect cyanobacteria bloom is important because they can develop toxins hence presenting a range of amenity, water quality and treatment problems, as well as hazards to human health and ecological equilibrium. The problem is especially acute in the Baltic Sea where cyanobacterial blooms occur every summer covering areas of more than 100.000 km2 and washing upon beaches during the summer holiday season. With respect to lakes, they frequently exhibit cyanobacterial blooms, with an increasing occurrence presumably in correlation with eutrophication and climate change, which has resulted in economic loss and considerable public interest in this phenomenon. In such a frame, CYAN IS-WAS, aims to develop regional algorithms for detecting cyanobacterial blooms from both satellite and airborne data, and thence use those algorithms for mapping cyanobacteria during time, and thence try to derive the main environmental/ecological variables which cause the development of cyanobacteria. The cooperation activities are carried out by sharing EO data, methods and by performing joint field campaigns. The project involves training of PhD and MSc students of both countries for giving them experience in EO data analysis. The project is divulgated throughout a series of events, including scientific symposium/workshop and with scientific publications in ISI journals. The exploitation of EO data allowed us to identify the occurrence, blooming, persistence and degradation of cyanobacteria communities in selected Swedish and Italian aquatic ecosystems. The main scientific findings are:  an extremely high variability in cyanobacteria optical properties was found, thus enhancing the great importance of tuning the EO based algorithms depending on study area features;  hyperspectral images, appropriately corrected, calibrated and validated, enabled the mapping of cyanobacteria blooms; some advantage of using radar data was also demonstrated for mapping abundant blooms in presence of clouds;  comparative studies on marine (Baltic vs. north Adriatic) and freshwater (Vänern vs. subalpine deep lakes, Trasimeno and Mantova) have been accomplished thanks to joint field campaign and satellite images analysis;  Nitrogen limitation in summer in the Baltic Sea proper is a decisive factor contributing to the development of blooms of filamentous cyanobacteria occurring during summer; EO work in the NW Baltic Sea has shown that we can derive chlorophyll concentrations in Baltic Sea coastal waters reliably from MERIS data (Hervey et al. 2013);  the amount of suspended solids transported by Po river (but also by other secondary rivers as Adige and Tagliamento) into the north Adriatic Sea, reduces the available light that can be used by phytoplankton component hence also hindering the growth of cyanobacteria