Corals and Algae – The Faceoff

by Emily Kelly

What an incredible experience we’ve all had on this research cruise so far.  Reflecting on Flint as we depart, I am struck by the incredible health and beauty of the reef there – with the overwhelming coral cover with very little algae present.

On coral reefs, one of the most precious commodities is space.  In order to survive as an animal or plant living on the reef’s bottom, you need to be able to compete for space to do so.  As a result, both corals and algae have mechanisms (stinging cells, chemicals, etc) that help them vie for this space. On many reefs throughout the world, more often than not, algae is winning this battle, often bolstered by the numerous impacts we place on reefs (runoff, over-exploitation of fish, dynamiting, etc) that make the corals poor competitors.

However, here on Flint I was overwhelmed by how aggressively the corals were winning many of the battles for space on the reef.  Branching Acroporas like the were often growing over the very few patches of macroalgae like the green bubbles of Dictyosphaeria, like in the photo above.  Notably, this alga is very similar to that which smothered many of the corals in Kaneohe Bay, Hawaii. What an incredible sign of the health of the reef at Flint to see a coral like this that is delicate to the touch aggressively growing over algae.