It's no surprise for TRT members to hear that too much algae is bad news for corals. Likewise, you already know all too well those factors that can lead to too much algae in your tank, factors such as not enough grazers and too many nutrients. For decades coral reef scientists had known that too much algae is also not good for coral reefs. Often one finds rampant algae on dying coral reefs, but do the algae kill the corals? Or are they just taking advantage of the real estate offered when corals die from other causes? It was not until the 21st century that the research tools became available to uncover the mysterious connection linking algae to coral death. That link is the microbes. The relationship between corals and microbes during good times and bad is the subject of a newly published book by microbial ecologist Forest Rohwer: Coral Reefs in the Microbial Seas.
In this engaging book, Rohwer relates how the coral's microbial partners have made it possible for the corals to not only survive for millennia in nutrient-poor regions of the ocean but to build the epic structures we know as coral reefs. However, since the 1980s the corals have been struggling. Both coral disease and bleaching have become widespread. The reefs in trouble are typically those that have been overfished or fertilized by nutrient-laden runoff from nearby shores or stressed by warmer temperatures. Any of those circumstances can disrupt the fine-tuned balance and lead to more algae. Combine two or more and the results can be disastrous. Photosynthesizing algae release dissolved sugars into the water; more algae release more sugars; more sugars fuel too many microbes—especially too many of the disease-causing sort; more dying corals make room for yet more algae to grow. This vicious cycle leads, in Rohwer's words, to the DDAMnation of coral reefs.
There is more to this story, including fascinating descriptions of how coral reefs work, the difficulties in diagnosing coral diseases, the coral's adaptable internal algal farm, and how we can give coral reefs a chance. Enjoy the good-natured banter on-board as Rohwer and a dozen other scientists travel to the remote Line Islands to unravel the connections between people, microbes, and the decline of coral reefs. This journey will delight everyone who is fascinated by the corals that, with their invisible microbial partners, have built the most impressive and biodiverse communities on planet Earth.
Additional information and numerous short videos are available at our website.
Merry Youle was educated as a research biologist, taught college, created a natural foods restaurant and bookstore, worked as an editor, technical writer and desktop publisher, and finally found her way back to her first love biology.She currently lives on the island of Hawaii where she spends her time freelance biological editing, gardening, and blogging for Moselio Schaechter's Small Things Considered. She is an excellent source on coral reefs and contributed to Forest Rohwer's book.