Ce congrès s’est déroulé en anglais.
Coral reefs are considered one of the most biodiverse marine ecosystems on the planet. Coral reefs host a large and various community of organisms such as fishes, echinoderms, plankton, etc. The coral reef is a perfect example of the Darwin Paradox, i.e. it has a high productivity when the available nutrients are low (oligotrophic seawater).
Coral reefs are threatened by several stressors. Most of these stressors are directly and indirectly linked to anthropogenic factors such as anthropogenic enrichment, overfishing, climate change, etc. Salinity is another stressor of the coral reef balance. The number of tropical storms and hurricanes has strongly increased over the past decades. These climatic events therefore induce a sharp decrease in salinity a couple of days after their occurrence. Moreover, the desalination industry is a new salinity stressor. Saltwater is desalinised to produce fresh water mainly for crop irrigation.
A coral reef mesocosm has been used to study the impact of the hyposaline and hypersaline stress on Seriatopora hystrix (Dana 1846), a hermatypic scleractinian species. Three salinity states have been selected: 28 (hyposaline stress), 35 (control) and 42 (hypersaline stress). These states have been kept constant for 7 days. In each condition stress, we have observed a discoloration of corals (not a bleaching), a decline in growth rate, calcification rate and respiration rate. The hypersaline stress reduces more strongly the growth rate that hyposaline stress. The growth comes back to the initial state 3 weeks after the experiment. This experiment could suggest that salinity is an important environmental variable for the coral reef. The variation of salinity, even low and a short duration impacts negatively S.hystrix.