A "citizen science" consisting in observing the state of the health of the corals and coral bleaching along the way of the expedition and collecting datas about this worldwide phenomenon caused by global warming

From Australia onward ,The Ocean Mapping Expedition opened up a new field of research into the problems affecting the coral reefs in the spring of 2017. In partnership with CoralWatch, a citizen science project of the University of Queensland in Brisbane, the Fleur de Passion team is observing the state of health of the corals along its route. Using a plastic card showing colour gradations, the expedition's divers and snorkelers determine whether a coral is in good health (darkest colour) or if bleaching is under way; the information is recorded on a datasheet, which in turn feeds into a database covering 77 countries.

For several years now, global warming has been causing repeated episodes of coral bleaching, which have killed off huge swathes of the Great Barrier Reef, mainly in its northern section, as well as corals in other parts of the world. As a result of rising water temperature, the corals – which are animals of the polyp family – expel their symbiotic micro-algae which give them their colour and even more importantly the nutrients they need to grow their hard exoskeletons. This is what causes bleaching.

At this stage, however, the corals can still overcome this stress and recover their symbiotic algae – and their colour – provided there is a drop in water temperature in a few weeks' time. Failing this they will simply die.

The CoralWatch database generates alerts that make it possible temporarily to restrict access to a nature reserve, for example. But the main issue remains global warming.

Prof Justin Marshall du Groupe de neurobiologie sensorielle à l’Université du Queensland et chef de projet à CoralWatch

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