Day Last, and Signs of Life…

An hour into the last night dive of the mission and it looked like one of the goals on our list would not have a checkmark next to it. We had hoped to document the mass spawning of several species of corals before the mission ended. So far, it was a typical night dive. Creatures that hide in the recesses of the reef by day - cardinalfish, squirrelfish, lobsters, brittle stars, and shrimp - come to life. And hold your light in one spot too long and countless bugs of every type come up from the bottom and scurry in a crazed crescendo until they block attempts to see or photograph anything and invade every available opening - regulator, wetsuit…ears. Ears are the worst. *Note to myself - wear a hood next time.

But the corals at 80 feet looked bored, most doing their standard night thing, tentacles gently flowing back and forth in the surge hoping dinner swims close enough to encounter their paralyzing sting. Spawning did not seem to be on anyone's so-called mind.

Running down to our last 1000 pounds of air pressure, Steven Miller and I headed back towards Aquarius for another fill. We were looking for a few subjects to photograph, just so we wouldn't return from the dive with any film left. That's when I saw them! Telltale signs of coral spawning that I had seen so many times at the Flower Gardens, reefs in the northwest Gulf of Mexico that I had studied since 1980. But this was the first time I had had a chance to witness it on the Florida Reef Tract.

Rising like drunken champagne bubbles from a single coral head were thousands of pink, BB-sized bundles of eggs and sperm, one from each individual polyp. As they drifted up toward the surface, where they would break apart and fertilize with the gametes of other corals, I searched the area expecting more activity. It took only a few seconds to spot other corals, triggered by clues still unknown, getting into the act. One after the other, I settled down in front of a colony, shined my light on the polyps, and had the pleasure of watching one of the only truly dramatic things that corals do. The bundles burst from the polyps in synchrony and drift upwards, owing to the buoyant fats in the eggs that will serve as food for the next several days. With luck, meaning a crowd of gametes on the surface at the same time and a respite from countless ocean predators, some of the larval corals will survive to settle a few days from now to form new coral colonies in another place.

Strangely enough, the timing of coral spawning for a number of the 65+ hard coral species of the Caribbean can be predicted. At the Flower Gardens, you can be fairly sure to see spawning for five species if you dive between 9 and 11 o'clock on the eighth evening after the August full moon. Two others spawn two evenings later, between 10 and 11 o'clock. The night we saw the action on Conch Reef was the seventh evening after full moon. It is likely that tonight (I am writing this on Tuesday, the 22nd), quite a bit more will happen, but we are locked in Aquarius decompressing so we can be back in Key Largo before Hurricane Debby arrives - we'll be watching coral spawning from the viewport.

Within ten minutes, nearly all colonies of a single species of star coral on the one patch reef we were exploring had spawned. We searched for another two hours and only saw one more colony, about 100 yards from the others, spawn. It is likely that many others did as well, but because timing is so tight, we probably missed a lot of it. No matter, the checkmark can be added to our list.

Mass spawning, by definition, involves more than one species of coral spawning at nearly the same time. We didn't see any other coral species participating, but that was in part due to the fact that the species we know spawn synchronously during this time of year are fairly rare on this reef, and because we were probably a day early and didn't witness "the main event."

But it raised my spirits to see the corals of Conch Reef reproducing on schedule, especially after 10 days of wondering whether the algae that seemed to be taking over this reef was destroying it. The corals are certainly stressed, but they haven't given up yet!