Temporary underwater shades helped two species of brain coral retain or regain color during heat stress in the Florida Keys, according to research reported on October 2 in Frontiers in Marine Science. The field trial suggests a way to protect selected vulnerable colonies during marine heatwaves. Its authors caution that the small intervention cannot shield entire reefs or remove the threat posed by warming seas.
Researchers led by Karen Neely of Nova Southeastern University tested the shades at Newfound Harbor after the severe 2023 Florida bleaching event. Corals rely on microscopic algae for much of their food; prolonged heat and intense sunlight can disrupt that relationship and leave corals pale. The team wanted to learn whether cutting light exposure could ease stress even when the water itself remained hot.
In summer 2024, the team placed 20 temporary frames with shade cloth over colonies of Pseudodiploria clivosa and Colpophyllia natans and compared them with 20 nearby unshaded corals. The structures floated about 30 centimeters above the animals. According to the study and reporting by Eos, the researchers followed coral color and sampled the associated algae while the shades remained in place from August to November.
The shaded colonies stopped paling and some regained color, while comparison colonies showed more paling. The paper says the site had its second highest cumulative heat stress on record in 2024, yet bleaching in this trial was only moderate and neither group suffered mortality. The team found no clear difference between groups in the abundance or types of their associated algae, so the color change alone does not establish how much long-term protection the shades provide.
The researchers say targeted shading may be a relatively inexpensive tool for managers trying to preserve high-priority corals during a heatwave. Neely said its scale is the chief limitation, and more research is needed on survival, disease and reproduction after shades are removed. The study presents temporary local protection as a possible aid to reef conservation, while the broader danger from sustained ocean warming remains.
Comments