1. Acclimatization of a coral-dinoflagellate mutualism at a CO2 vent.
- Author
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Prada, Fiorella, Franzellitti, Silvia, Caroselli, Erik, Cohen, Itay, Marini, Mauro, Campanelli, Alessandra, Sana, Lorenzo, Mancuso, Arianna, Marchini, Chiara, Puglisi, Alessia, Candela, Marco, Mass, Tali, Tassi, Franco, LaJeunesse, Todd C., Dubinsky, Zvy, Falini, Giuseppe, and Goffredo, Stefano
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SCLERACTINIA ,OCEAN acidification ,MUTUALISM ,CORAL bleaching ,HAPLOTYPES ,CORALS ,NITROGEN fixation ,ACCLIMATIZATION ,ACIDIFICATION - Abstract
Ocean acidification caused by shifts in ocean carbonate chemistry resulting from increased atmospheric CO
2 concentrations is threatening many calcifying organisms, including corals. Here we assessed autotrophy vs heterotrophy shifts in the Mediterranean zooxanthellate scleractinian coral Balanophyllia europaea acclimatized to low pH/high pCO2 conditions at a CO2 vent off Panarea Island (Italy). Dinoflagellate endosymbiont densities were higher at lowest pH Sites where changes in the distribution of distinct haplotypes of a host-specific symbiont species, Philozoon balanophyllum, were observed. An increase in symbiont C/N ratios was observed at low pH, likely as a result of increased C fixation by higher symbiont cell densities. δ13 C values of the symbionts and host tissue reached similar values at the lowest pH Site, suggesting an increased influence of autotrophy with increasing acidification. Host tissue δ15 N values of 0‰ strongly suggest that diazotroph N2 fixation is occurring within the coral tissue/mucus at the low pH Sites, likely explaining the decrease in host tissue C/N ratios with acidification. Overall, our findings show an acclimatization of this coral-dinoflagellate mutualism through trophic adjustment and symbiont haplotype differences with increasing acidification, highlighting that some corals are capable of acclimatizing to ocean acidification predicted under end-of-century scenarios. Low seawater pH impacts trophic dynamics in corals, increasing symbiont density and autotrophic/heterotrophic ratios and varying dinoflagellate haplotypes under ocean acidification. [ABSTRACT FROM AUTHOR]- Published
- 2023
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