This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Off Florida's coast, a team of scientists and trained volunteers in scuba gear descends to the ocean floor, planting young coral onto a reef and examining how others are faring in increasingly warm waters. It is part of a long-running "Rescue a Reef" program run by the University of Miami that aims to advance conservation efforts and raise public awareness.
Part of that work involves researching which coral species are better able to withstand rapidly warming oceans as a result of human-caused climate change. "Certain species may be more resilient and able to better survive and recover from thermal stress events," program manager Devon Ledbetter explained to during a recent dive to Rainbow Reef, about 3 miles (5 kilometers) offshore from Key Biscayne. Coral reefs support vibrant marine ecosystems but also act as breakwaters, protecting coastlines from storm-driven erosion and flooding.
The situation, however, is increasingly dire. A record-breaking marine heat wave that began in 2023 left two ecologically vital coral species, elkhorn and staghorn, "functionally extinct" in Florida's Coral Reef, highlighting the growing dangers a warming climate poses for the world's oceans. The National Oceanic and Atmospheric Administration believes that this fourth global coral bleaching event likely concluded in mid-2025.
But the arrival of a very strong El Niño could bring a return to more widespread bleaching—including in Florida's waters. During the expedition, the participants go about their tasks diligently. Some coral species with fast-growing branches are planted onto "coral trees" that look like old television antennas and are suspended in the water column, with floats to keep them upright.
Others are placed onto table frames fixed to the ocean floor, while still others are mounted onto plugs, screwed into a three-hole "cookie" and planted onto the reef. These are given predation umbrellas to protect them from hungry fish having a nibble. Researchers place color reference charts around newly planted coral to record pigmentation, a method used to monitor their health and detect early signs of heat stress.
Coral is made up of tiny individual animals called polyps, which maintain a symbiotic relationship with microscopic algae that live within their tissues. When the algae are stressed by heat or pollution, however, they leave, causing the coral to "bleach" and become vulnerable to disease and death. "Anecdotally, we've seen that mountainous star coral tends to be the most resilient to bleaching and thermal stress," Ledbetter explained.
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