Scientists tackling crisis of coral bleaching

An international consortium of scientists has created the first-ever common framework for increasing comparability of research findings on coral bleaching.

“Globally, coral reefs are threatened by increasing temperatures, leading to coral bleaching and often death,” says Mary Alice Coffroth, research professor of geology in the UB College of Arts and Scientists, and a co-author of a paper on guidelines published online on Nov. 21 in the journal Ecological Applications.

Andréa Grottoli, a professor of earth sciences at The Ohio State University, was lead author.

Coral bleaching is a significant problem for the world’s ocean ecosystems: When coral becomes bleached, it loses the algae that live inside it, turning it white. Coral can survive a bleaching event, but being bleached puts corals at higher risk for disease and death. And that can be very damaging: Coral protects coastlines from erosion, offers a boost to tourism in coastal regions, and is an essential habitat to more than 25% of the world’s marine species.

Bleaching events have been happening with greater frequency and in greater numbers as the world’s atmosphere and oceans have warmed because of climate change.

The common framework covers a broad range of variables that scientists generally monitor in their experiments, including temperature, water flow, light and others. It does not dictate what levels of each should be present during an experiment into the causes of coral bleaching; rather, it offers a common framework for increasing comparability of reported variables.

“Following common guidelines will increase researchers’ ability to determine how corals may or may not survive bleaching in the coming decades, providing guidance in coral reef management and conservation efforts,” Coffroth explains.

“Researchers are actively pursuing experiments to understand coral bleaching and how corals may cope with this stress,” she says. “However, experimental approaches vary greatly, making inter-study comparisons difficult. This paper outlines recommendations for reporting experimental protocols so that coral bleaching experiments can be compared across species and locations, increasing the information gleamed from them and avoiding repeating experiments unnecessarily.”

“Reefs are in crisis,” Grottoli says. “And as scientists, we have a responsibility to do our jobs as quickly, cost-effectively, professionally and as well as we can. The proposed common framework is one mechanism for enhancing that.”

Contributions from international community of scientists

With Grottoli leading the effort, 27 scientists from the Coral Bleaching Research Coordination Network, representing 21 institutions around the world, worked together as part of a workshop at Ohio State in May 2019 to build the common framework.

Coffroth was part of this team, contributing scientific expertise and helping to write the paper.

“As a researcher studying the coral-algal symbiosis that breaks down during coral bleaching, I contributed my expertise on the microscopic algal endosymbionts (Symbiodiniaceae) in developing the guidelines for common measurements and response variables to be used in reporting results of coral bleaching experiments,” Coffroth says. “I also contributed to the overall development of the guidelines for reporting experimental conditions and results.”

Grottoli says the goal “was to create a structure that would allow researchers to anchor their studies, so we would have a common language and common reference points for comparing among studies.”

Researchers are still trying to understand why some coral species seem to be more vulnerable to bleaching than others, she says, and setting up experiments with consistency will help the science move forward more quickly and economically.

This work was funded by the National Science Foundation.