ADAPTATION TO GLOBAL CHANGE: CORAL SYMBIODINIACEAE DIVERSITY IN THE LATE 19th CENTURY AND AT PRESENT

Student: 
Cassandra Roch

Climate-change induced elevated sea surface temperatures have driven coral reef degradation on a global scale. The resilience of coral reefs is highly dependent on the mechanisms underpinning adaptation and acclimatisation at the level of symbiosis. However, baseline data on coral-symbiont associations from before the onset of major anthropogenic influences on coral reefs are lacking. Here, we demonstrate that the Symbiodiniaceae community of 150-year-old ethanol conserved museum specimens can be identified by analysing the ITS2 subregion of the nuclear ribosomal DNA, in combination with the SymPortal analytical framework. We generated a coral microbiome baseline by characterising coral-Symbiodiniaceae associations in eight genera of scleractinian corals (Acropora, Echinopora, Madrepora, Platygyra, Pocillopora, Porites, Stylophora, Seriatopora) and three genera of alcyonacean corals (Sarcophyton, Sinularia, Tubipora) collected from the Red Sea between 1878-1896. Through comparisons with published results of modern symbiont communities, we show that historical Red Sea corals predominantly associated with Cladocopium symbionts and that there was an increased abundance of Durusdinium symbionts in modern samples. Additionally, we found no evidence of increased beta-dispersion in modern samples compared to the historical dataset which may suggest that even in the presence of anthropogenic disturbances healthy modern corals may still be well adapted to their environment.

Keywords: Red Sea, Symbiodiniaceae, pre-industrial baseline, coral reefs, global change