Effects of ocean warming and acidification on the geographical distribution and calcification of the scleractinian corals of the Eastern Tropical Pacific

The aim of this work is to understand how the individual and combined effects of ocean acidification and temperature increase will affect the geographic distribution and calcification of reef-building corals of the Eastern... [ view full abstract ]

The aim of this work is to understand how the individual and combined effects of ocean acidification and temperature increase will affect the geographic distribution and calcification of reef-building corals of the Eastern Tropical Pacific (ETP). In order to evaluate possible changes in the geographical distribution of the coral species of the ETP, projections based on forecasts of temperature increase and pH decrease under scenarios RCP 2.6, 4.5 and 8.5 for the year 2050 were made using MaxEnt software. The results show that reef habitats which are actually considered marginal, such as those of high latitude and in the equatorial part of the ETP, are projected to persist and expand in the future climate, highlighting the importance of alkalinity and temperature to describe the future distribution of the species. To determine the response of calcification in different species of scleractinian corals, fragments of three species were used in an experimental study, using a pH treatment (7.60), two temperature treatments (30° and 31°C) and a combined one of temperature and pH (30°C, pH 7.60 ). The results indicate that the pH of 7.60 significantly reduced the calcification rate while the combined treatment of pH and temperature did not have a significantly greater effect than the pH alone. The calcification rates did not vary significantly between species. The results of this study suggest that ETP corals could adapt or acclimate to the coupled effects of acidification and temperature increase.