Andrea Grottoli
Andrea Grottoli, a distinguished professor of Earth Sciences, continues her research on coral resiliency with a unique “natural laboratory” in the Mediterranean.
Off the coast of Naples, Italy, Grottoli studied how coral reefs near the island of Ischia survive in both acidic and normal conditions in collaboration with France’s Oceanographic Laboratory of Villefranche. Grottoli believes an increase of zooplankton – organisms microscopic in size – feeding could point to greater coral resiliency and that by understanding how these corals adapt to different stressors, corals can be protected from climate change and ocean acidification by the end of the century.
“What is the underlying biological mechanism that is enabling the corals to survive under those conditions, and how can we apply that then more broadly to corals globally to protect, restore, conserve corals elsewhere?” Grottoli asked.
In addition to her research and work at Ohio State within the School of Earth Sciences, Grottoli serves as president of the International Coral Reef Society, the director of the National Science Foundation-funded Coral Bleaching Research Coordination Network and as a Fulbright fellow in France. She also received a grant in 2019 from the Office of International Affairs to support a research project in the Mediterranean.
In November, Grottoli presented “Rebuilding Coral Reefs: a Decadal Grand Challenge" at the 24th annual Reef Conservation United Kingdom meeting in Edinburgh, Scotland.
Grottoli’s work dives into three issues: causes of coral resilience during climate change, reconstructing oceanographic conditions in the past based on coral skeletal isotope and trace metal records and the impact of land-use on the delivery of carbon to small tropical and temperate rivers.
Coral reefs suffer as ocean temperatures and acidity levels continue to rise due to carbon dioxide production, resulting in massive and potentially fatal bleaching events and interference with calcification of the skeleton. Coral reefs offer not only biological benefits but also economic opportunities for tropical countries.
“If coral reefs fail, not only do ecosystems fail, but societies and economies could fail as well,” Grottoli noted. “I’m interested in understanding why some coral are much more tolerant of these stressful conditions.”
The temperate corals Grottoli studied this September in the Mediterranean differ from reefs she typically studies in the U.S., but they provide a unique opportunity, acting as a “natural laboratory.” The region has normal pH levels as well as extremely acidic pH levels due to naturally occurring low acidity caused by carbon dioxide bubbling out of the seafloor from volcanos.
Some parts of Ischia’s environment reflect the same highly stressful pH levels in the ocean that scientists expect at the end of the century if CO2 emissions do not decrease. Though Ischia’s water should be hostile, the corals survive.
Grottoli believes that the corals survive in the more acidic water because they consume more zooplankton.
“The animal (coral) is increasing its nutritional uptake as a way to compensate,” Grottoli said. “Calcifying—growing a skeleton— in low pH, turns out, is energetically expensive, yet they’re calcifying just fine.”
After taking samples from corals, water, organic matter and zooplankton, Grottoli will use stable isotopic measurements to determine if the corals are eating more at a lower pH than a normal pH. In collaboration with her French colleagues, she tested lab grown coral samples for their tolerance of different pH values.
“The more zooplankton they eat, the more like zooplankton they will look chemically,” Grottoli explained.
Some tropical coral reef species, like the ones Grottoli studies in Hawaii, have adapted to bleaching events from heat stress by upping their food intake, tying into Grottoli’s research in Ischia. If corals do eat more to be more resilient and adaptable, then scientists can intervene and nurture this coping mechanism to enhance survival in impending stressful environments.
Grottoli and other scientists’ efforts can only go so far, and she stated that a much more sustainable option for corals is to reduce CO2 emissions so that reefs can be saved.
“Anything we do in the interim, is just a bridge toward a time when CO2 emissions are reduced and the reefs can start repairing itself,” Grottoli said. “Any of these interventions, or technologies, or restoration or identifying resilience, are just a band-aid to maintain enough coral and reef ecosystem function in the short-term.”
Grottoli is optimistic that these near-term interventions can work, provided there is enough investment to support them, and domestic and international commitment to implement regulations and incentives to minimize global climate change this century.
