Continuing on with the theme of coral, here is another not-so-well known phenomena:
Bleaching may lead to a change in the gene expression of corals’ immune systems
As I mentioned in the previous post, coral bleaching does not equal death. If conditions improve, the symbiotic algae can/will return and the coral will continue. Sounds like everything is all hunky dory, right? Well, recent research suggests that everything may not go back to exactly how it was before the bleaching event however. For a few years now, bleaching events have been linked to an increased chance of disease outbreaks. These diseases obviously further stress the corals. While little is known about the specifics of this trend, one 2015 study looked at the gene expression of corals’ immune systems to see if there were any changes after bleaching events. The study found that there was evidence of a change, that the immune systems of these corals were in fact suppressed after they had recovered from a bleaching event. Not only were the corals’ immune systems suppressed right after bleaching, but some corals remained suppressed upwards of a year after the bleaching event. This evidence further supports hypotheses that bleaching events are linked to subsequent disease outbreaks. So, it seems that bleaching events may have lasting effects beyond just the bleaching itself. That’s what I call a double whammy 😦
Pinzon, J., Kamel, B., Burge, C., Harvell, C., Medina, M., Weil, E., & Mydlarz, L. (2015). Whole transcriptome analysis reveals changes in expression of immune‐related genes during and after bleaching in a reef‐building coral . Royal Society Open Science, 1-17.