September 15, 2009
ATM blogger Megan Gambino spent a week in Panama reporting on research taking place at two locations—Barro Colorado Island and Bocas del Toro—of the Smithsonian Tropical Research Institute (STRI). Read on to follow her day-to-day adventures.
Day 3: Arriving at Bocas
Today I left Panama City for Bocas del Toro, a town on Isla Colon, a 24-square-mile island on Panama’s Caribbean coast just 22 miles south of the Costa Rican border and an hour’s flight from the capital. Just outside of Bocas town is another of STRI’s research stations, where I will be staying for the next four days to report a story on a mass coral spawning that happens every year just days after the September full moon.
Since 2000, coral reef biologists Nancy Knowlton, the Smithsonian’s Sant Chair of Marine Science; Don Levitan of Florida State University; and a team of research divers have been studying the spawning of the Montastraea annularis complex—three closely related species once thought to be one and the same—here in Bocas.
Just off the coast of Solarte Island (one of the other 68 islands and mangrove keys in the archipelago)—about a 20-minute boat ride from the station—they’ve marked an 80-meter arc of coral reef with nine underwater buoys that they light at night with green glow sticks. Over the nine years of the project, they have tied pink flags to coral colonies they have witnessed spawn. (The outermost layer of coral is a community of living animals that eat, reproduce and die, thus making up the foundation of the rocky substrate of the reef.)
Each colony is also numbered with a blue metal tag and all have been mapped and genetically analyzed and identified. The researchers have found that M. franski, one of the species, spawns on average 100 minutes after sunset, typically five or six days after the full moon. The other two, M. annularis and M. faveolata, spawn about 200 minutes after sunset. The colonies use the lunar and sunset cues, and most likely a chemical cue (it’s possible they smell each other spawn), to synchronize their spawning. The latter two species cannot cross-fertilize, but M. franski and M. annularis are reproductively compatible. So the researchers have been studying what reproductive barriers or ecological conditions are in play that prevent hybridization. Also, they’re beginning to wonder, if reproductive success depends on mass spawning, then what will happen as coral reefs become few and far between as a result of the damaging effects of climate change and human development.
The team was gearing up for its first night dive. In years past, they have found that a few colonies typically jump the gun and spawn early. The group spent the morning making sure the tags on the coral were visible, while I snorkeled above to get my bearings of the study site. The next time I’d be there I’d only have a flashlight and the green glow sticks on the buoys to orient myself!
At about 5 p.m., six divers and I gathered in the lab to hear Don’s instructions. The dive team would be making two back-to-back dives, one in timing with when M. franksi spawns and the other when M. annularis and M. faveolata do. The operation was impeccably organized, like a coral raid. Armed with red glow sticks, the divers were told to crack and place them on setting corals, or corals that became pimpled with gamete bundles almost ready to be released. They were to record set and spawn times on waterproof slate boards. (On average, spawning happens about 20 minutes after the coral sets.)
In the boat, “Team Spawn,” as Don jokingly named the divers, synchronized their watches and donned life vests. At the site, we waited for sunset and then all of us made our way to the lit transect by 7:45 p.m. Pairs of divers were assigned to scan certain sections of the marked reef for setting and spawning corals, and I snorkeled above to observe.
It was my first-ever night snorkel, and it was such a different experience. At first, just having my light and the lights of the divers to follow was unnerving, but I settled into it. With their lights cast downward, the dark silhouettes of the divers made them look like aquanauts. The whole landscape was otherworldly.
When I shut off my flashlight, flipped my fins and waved my hands through the water, bioluminescence kicked up like fireworks around me. I could hear Latin music blaring from the nearby town of Bastamentos whenever I lifted my ears above the surface, and the combination of the bioluminescence, music and glow sticks created this rave-like quality—surely, I thought, a fitting scene for a coral orgy.
But no such luck. M. franksi, the early spawner of the group, held off, meaning the later spawning species would too, and so we returned to the boat, canceling the second dive. Maybe tomorrow night….
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