arable ocean colour instruments such as MODIS."
Formed from individually microscopic phytoplankton, algae blooms occur when favourable local conditions encourage their growth to 'bloom' out of control. Some algae species contain toxins that can poison humans who eat contaminated shellfish. Alternatively the spreading blooms can deplete water of oxygen as they decay, causing larger fish to suffocate.
Fish farms are especially vulnerable to algae blooms because fish cannot flee affected zones. The southern region of Chile has 360 fish farms in the ocean and 40 in freshwater, producing up to 450,000 tonnes of biomass annually. In 1997 alone, Chilean algae blooms caused losses totalling €10 million ($12 million).
Rodríguez-Benito's pilot project – recounted during the Workshop - is co-funded by Mariscope Chilena and Salmon Chile, the national fish-farming industry association. These institutions aim to investigate the feasibility of an operational satellite-based early warning service.
"As spring came to the southern hemisphere in October we have witnessed new blooms appearing," said Rodríguez-Benito. "In situ water testing, using an instrument called a Fluoroprobe, confirms the detection of five different algae classes. The total chlorophyll concentration measured using this fluorometer was successfully correlated with MERIS data."
"The project will continue until the beginning of 2004, as a first step. For the near future we also hope to make use of other Envisat instruments to simultaneously measure important variables like sea surface temperature and ocean currents. Knowing these will be necessary to make forecasting the drift of algae blooms a reality."
In concluding the Workshop on Thursday afternoon, Peter Regner thanked all participants for the very high quality contributions they made: "The Workshop discussions brought forth a number of valuable recommendations which will certainly be taken into consideration in the definition of the future MERIS exploitation plan."
He indicated that the next opportunity for the community to meet again will be next year's Envisat symposium, scheduled to take place from 6 to 10 September 2004 in Salzburg in Austria.