A recent study on reef-building corals growing on mangrove roots in St John, USVI, is giving us yet another reason to conserve and restore mangrove habitats.
We already know mangroves are important to coral reefs (if YOU don’t know why, you better read the Alert Diver article written by MRDF’s Director of Research, Sarah Egner: http://www.alertdiver.com/MangrovesAndSeagrass)
But now, the mangrove habitat could be coral’s saving grace in the climate change effects that some scientists are considering inevitable. Risk analyses indicate that more than 90% of the world’s reefs will be threatened by climate change and local anthropogenic impacts by the year 2030. Increasing temperatures and solar radiation cause coral bleaching and increasing CO2 levels reduces seawater pH (ocean acidification), slowing coral growth and impacting the integrity of the reef structure.
Amongst the mangroves of Hurricane Hole in St. John, USVI, researchers found more than 30 coral species. The older corals survived recent bleaching events that killed corals at nearby reefs, perhaps due to protection from the mangroves in the shade they provide. The corals found in the mangrove habitat may have also evolved to be more resistant to bleaching. Previous studies have shown that corals that become accustomed to environmental fluctuations, as is common in a mangrove habitat, have a higher survival rate in extreme heat. Perhaps these more resilient corals will be able to recolonize reefs in the future?
Just when I thought I couldn’t love mangroves any more…
Yates, K. K., Rogers, C. S., Herlan, J. J., Brooks, G. R., Smiley, N. A., and Larson, R. A.: Diverse coral communities in mangrove habitats suggest a novel refuge from climate change, Biogeosciences, 11, 4321-4337, doi:10.5194/bg-11-4321-2014, 2014.