Richard Coleman had to act fast.
Nearly 300 feet beneath the surface of the Western Pacific Ocean, his rebreather, a special apparatus that allows for extended and deeper dives, suddenly failed, cutting off the vital supply of mixed gases he needed to survive at such an extreme depth.
Never one to panic, he quickly turned on one of the aluminum “bailout bottles” of emergency air strapped to his gear—standard procedure for any deep-diving excursion—and slowly made his way back to the surface, making decompression safety stops along the way.
Danger is ever-present whenever Coleman, a marine biologist at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science, makes a closed-circuit rebreather dive. Rebreathers recycle exhaled air, removing it of impurities and sending it back to the diver in a breathing loop.
But equipment malfunctions can cause hypoxia. “And there’s no cue that you’re encountering it. You just pass out,” Coleman explained. “So, that’s why we carry emergency tanks, and we go down as a team, because if something goes wrong, we rely on a buddy to get back safely.”
Coleman’s underwater explorations—some can last as long as four hours—are being done in the name of important science: the quest to learn where certain species of fish have come from and, more importantly, where they are going.
“Having that information can be useful to us in many different ways,” Coleman said. “It can inform what’s happening to different species of fish from an evolutionary scale. We can look back in history, examine geological events, and use models to see what’s happened historically in terms of their movements.”
He has studied, for example, how low sea levels in the past have created land bridges between the basins of two oceans, separating a species of fish that began to develop differently in response to environmental change. “Despite looking very similar, they’re quite different,” Coleman explained, “and it’s through their genetic signal that we’re able to see just how different they are.”
During his dives to some of the deepest and darkest depths of the ocean—the so-called mesophotic zone where little light penetrates—Coleman helped discover new species of fish, some about the size of a human hand and “brilliantly colored in bright reds with contrasting purples, oranges, and yellows,” he recalled.
From the Phoenix Islands and American Samoa to Vanuatu and the Johnston Atoll, Coleman’s research expeditions to study biodiversity have carried him to some of the most remote regions of the world. But it is helping a community of Native Hawaiians on Oahu learn more about the migration patterns of certain fish in their waters that is arguably his most important work. “They fish for their livelihood, to feed their families,” Coleman said of the community with which he has worked for the past 14 years.
With marine recreational fishing licenses not required for those residents, it is difficult, if not impossible, to monitor catch rates, according to Coleman. “We have scientific studies that don’t rely on state resources, and we talk to community members and do observational work to determine that number,” he said. “But there’s still uncertainty about the long-term sustainability for certain species in their waters. So, my research group is working to determine what strategies can be implemented to protect them.”
No-fishing ordinances during spawning periods is one way to ensure certain species in Oahu are not overfished, he noted. “If we know when and where the fish are spawning, we can stop fishing in an area during that time and help ensure the survival of the next generation,” he said.
He has traveled to the island on numerous occasions to meet with those community members, using his research to help them determine which areas would benefit…
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