What Happens After Corals Die?

Andia Chaves Fonnegra, Ph.D., likes marine organisms that destroy the neighborhood — in other words, the “bad guys.”

That’s what she calls excavating sponges, which infiltrate and erode dying coral reefs. She fell in love with the plant-like animals as an undergraduate and has studied them ever since.

As a marine ecologist, Fonnegra studies how climate change affects the interactions between corals, sponges and algae attached to the sea bottom. Her goal is to make it possible to better manage these ecosystems, which form habitats for other species, by studying changes to their structures. “Coral reefs are a very dynamic environment. We see them dying as a result of climate change,” she said. “I’m interested in knowing what happens after corals die, and if the bad guys survive.”

As warming ocean temperatures stress the animals that compose coral reefs, food-producing algae living in the animals’ tissues depart. Eventually, the corals may starve to death or succumb to disease. A number of things can happen then. Fonnegra’s beloved excavating sponges might bore into the reef, hollowing it out until the structure collapses. Macroalgae, like seaweed, might cover the dying corals. Other sponges might move in and create a new three- dimensional framework. “I want to see what species of sponges could take advantage of the new environment and structure the reefs in a different way,” Fonnegra said. To do that, her lab uses a wide range of analytical and molecular methods like population genetics to study how species connect and mathematical modeling to predict future population change.

Before joining FAU, Fonnegra received her Ph.D. in oceanography and marine biology from Nova Southeastern University, then pursued post- doctoral research on coral reefs in the Virgin Islands. She’s currently outfitting her lab at FAU’s Harbor Branch Oceanographic Institute, where she has a joint appointment with the Harriet L. Wilkes Honors College. Fonnegra said she wants to stop impacts wrought by climate change, such as decimation of reefs. But, strange as it may seem, she also sees an upside. “As a scientist, I have to see them as an opportunity to understand how changes occur,” she said. “Only then, we can see if there’s any way to restore these ecosystems.”