RESULTS ACCOMPLISHED DURING THE SCIENTIFIC CRUISES IN THE MALDIVES.
The ecology of the Maldivian coral reef has been studied since 1989. In 1998 the Maldivian reef suffered a major bleaching event due to temperature anomalies, which caused a coral mortality rate of about 90%.
In 2004 were hit by the Sumatra tsunami and in 2016 have been hit again by a world wide thermic anomaly, the biggest ever registered in the last centuries, which caused bleaching effects and coral destruction on reefs in the whole world.
Thanks to research data stored through the years and thanks also to the observations collected every year during the Scientific Cruise in the Maldives (CSM), held by professors and researchers of the University of Genoa, Pisa and Urbino, Italy, we are able to identify the health of the Maldivian reef and we can compared their situation before, during and after these events that caused the coral destruction.
The data collected during the Scientific Cruise allow us to evaluate the capacity of recovery of the coral reefs through time. The coral recovery started immediately after 1998, thanks to a high coral recruitment activity and to a fast coral communities’ regrowth. This recovery process was still on going when the Sumatra tsunami hit the Maldivian atolls in 2004, but luckily, the observations of the years after didn’t report excessive impact on the reef barrier or on the coral communities.
In the following years we observed a slow and steady re-growth of the Maldivian reefs and in 2014, 16 years after the bleaching event, in many of the observed sites the hard corals regained cover values similar to the original pre-bleaching event (cover values of 60-80%). In some spots though, the cover of the sea-bottom was still dominated by abiotic descriptors, like sand and other materials, due to increasing localized events in the last years.
The 2016 thermic anomaly did affect the Maldivian coral reefs in a lower extend compared to the 1998 event and the impact was different in terms of characteristics and geographic localisations of the sites. During last CSM from 7-15 May 2017 between the atolls of North Male, South Male and Ari, the researchers of the University of Genoa, with the help of some students and post-graduate students in Environmental Sciences, Biological Sciences and Natural Sciences, have observed various parameters which characterise the reefs at different depths: cover of the biotic descriptors (corals, algae, sponges, etc.) and abiotic (rocks, sand, dead coral), the number and the size of the recruits, the reefs’ structure and geomorphology, the presence and the quantity of the fishes and of macro-invertebrates, and the presence of the bleached coral communities or the recently extinguished ones. Furthermore they have collected all necessary data requested by the international protocol of REEF CHECK.
During the cruise scientists could observe massive bleaching effects on some coral sites, which caused a high coral mortality rate (over 90% of the superficial coral reefs), while in other sites the effect has been weaker and the hard corals showed cover levels of 50-60%. The reef fish communities were abundant in all monitored sites, thanks to the domination of herbivorous fishes, despite the diminishing number of the corallivorous fishes.
In June 2017 the National Oceanic and Atmospheric Administration (NOAA), after having analysed the satellite data and the predictive models, confirmed that the thermic anomalies registered in the last three years had come to an end. The future observational activities during the next CSM will be fundamental to evaluate the potential recovery of the Maldivian reefs after these global events.
The collaboration between the University of Genoa (DiSTAV), ISSD, Albatros Top Boat / Luxury Yacht Maldives and Save the Beach, will allow to collect more information about the health of the Maldivian reefs and will increase awareness of the importance to preserve the unique heritage of the Maldivian reefs locally as well as Internationally. Among others, the thorough work of all scientists on board allowed localising the submerse caves, which led to discovery of the deepest karstic cave of the Maldives: a true Blue Hole similar to the one in the Bahamas.
The scientific cruise is therefore a unique opportunity to combine the ever fascinating diving in the Maldives with an active research for the understanding of the tropical ecology. The itineraries will be the same as a normal cruise and the participation by non-researchers in the “scientific” activities is entirely free. The researchers on board will be happy to share the results and the observations done during the cruise with all the guests through informal lectures while giving the opportunity to learn about the marine life and the complex phenomenon linked to it.
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