“At first glance, the Tatakoto atoll – located over 1,000 kilometres from Tahiti – exhibits environmental conditions that could hardly be described as conducive to the survival of corals. A semi-enclosed lagoon, connected to the ocean by small channels, allows only minimal mixing with the surrounding waters, and leads to extreme temperature variations of 3 to 4°C per day, with temperatures in the lagoon reaching almost 35°C.
However, expeditions supported by UNESCO, the Labex Corail and the UPF in partnership with the CRIOBE and SECOPOL laboratories, and 1 OCEAN, have shown that dozens of coral species are thriving in this unstable environment, sometimes just a metre below the surface…
A surprising phenomenon has been observed during these missions to Tatakoto: coral species that usually tend to be the most vulnerable appear to be resisting far better than other, traditionally more resilient species. Against all expectations, the expeditions observed that Acropora – often the first corals to bleach and die due to their fine, branch-like structures and rapid growth patterns – in fact survived the latest episode of intense heat in large numbers, especially when compared with Pocillopora, usually known to be more robust thanks to their dense cauliflower-like structure.
This rare reversal in terms of resilience reinforces the findings of previous studies, notably those carried out in Palau, where Acropora from sites with high daily thermal variability showed greater thermal tolerance than those from more stable areas, suggesting that exposure to temperature variations can strengthen the resilience of certain corals.”
From UNESCO.
