Caribbean / Bahamas Scuba Videos
It is November on Australia's Great Barrier Reef. A full moon rises. Our oceans stir. It's an annual event, cued by the sun and the moon, the incredible phen...
The yearly synchronous mass spawning that occurs in coral reefs all over the world, is a spectacular sight. Strongly influenced by seasonal and lunar pattern...
feeding the suckers (fish) at the fish ladder.
Bocas Del Toro, Sept-12, 2006, 7:30pm, Montastrea complex releases packs of gametes which float to the surface, break apart, and the sperm and eggs disperse,...
Photo: Alexander Mustard
Photo: Alexander Mustard
It was a night dive, just like the many others I have enjoyed on the East End reefs of Grand Cayman. That was the problem – this wasn’t supposed to be ‘just another’ night dive. I glanced down at my watch, it flashed back 20:20, indicating that we had been in the water for 15 minutes. In truth, this dive had started long before my giant stride from the boat, when I made a leap of faith that led to me buying plane tickets and flying across an ocean to be right here, right now. My eye was caught by a bright-blue hunting octopus. I ignored it and stared again at the coral in front of me. “Come on! Come on!’ Nothing. 20:26. The sun had set more than two hours ago.
20:31. I had been expecting to see the first signs of spawning ten minutes ago and as each minute passed it became more likely that tonight was not going to be the night. Coral spawning predictions are best guesses based on experience, and nobody had ever reported mass spawning in Grand Cayman before. In the hustle of the last hour of loading the boat, kitting up and jumping in, I had forgotten how much the odds were stacked against us, but now those thoughts returned and my stomach felt hollow. I had staked time, effort and money on being here. Maybe we were too late? Maybe the corals had spawned earlier in the evening? Maybe they had spawned yesterday? Maybe they had spawned a month earlier? Maybe they just don’t spawn in the Caymans? I looked at my watch again. Still 20:31.
Our target species on this night was staghorn coral, a species that was once widespread in the Caribbean, but along with the closely related elkhorn coral, was decimated during the 1980s by white-band disease. In many areas both species are now extinct, but on the East End of Grand Cayman you have the chance to dive back in time and see them in dense thickets. If tonight were to go to plan we would see the underwater equivalent of giant pandas mating!
20:33. I was now feeling guilty for dragging my buddy into the water. Steve Broadbelt is the co-owner of Ocean Frontiers dive centre on Grand Cayman and, like me, has a keen interest in marine life, something that is clearly reflected in how his dive centre operates. Steve had been trying to see coral spawning for many years, and I had been bullish about our chances in order to persuade him to try yet again. We were optimistic when we left the dock, Steve noting of the conditions ‘Only rarely does it get so glassy calm out here, it’s as if Mother Nature knows that tonight’s the night.’ Now I was less confident. Steve was on the other side of the reef spur, which was silhouetted by his light. The moon was yet to rise and we had chosen weak torches so as not to put the corals off. The water was inky black and blood-hot. It was claustrophobic and uncomfortable, like wearing a suit that is too thick at a summer wedding. I wasn’t relaxed and I tried to concentrate on the coral.
Suddenly the staghorn coral looked different. Perhaps I had been staring at it for so long that my eyes were inventing new patterns. I screwed up my eyes, blinked, and stared again. As I inched closer I could see that the shape of the polyps was subtly, but definitely changing – beige bundles a few millimetres across were beginning to dome up from within the polyps. I raced over to Steve and dragged him back to the coral. I could now see the change from several metres away – even the colour of the colony was different. Staghorn, like many corals, is hermaphrodite, being both male a female at the same time, and these bundles were made up of eggs laced together with sperm. I checked the next colony and the next; everywhere I looked, staghorn coral was preparing to spawn.
Steve and I exchanged perhaps the most cheerful ‘okay’ signs ever made, and a few less-traditional underwater communication gestures that clearly indicated spawning was definitely on. About 30 minutes later the bundles started to burst free, the buoyant, fat-filled eggs slowly pulling themselves away from the spiky branches of the staghorn. Within a couple of minutes there was a steady stream of bundles rising from colonies across the reef. It was like diving in a glass of Champagne, the bundles looking like tiny bubbles. They made an intoxicating sight.
I’m sure that you know what happens if you smile while you are diving. As the corners of your mouth go up, your cheeks rise, your mask no longer fits and water gushes in and rushes straight up your nose. Well, at this moment I really didn’t care. Although I was now coughing water out of my regulator, nothing could dampen my spirits. Steve and I finned around with joy, like children running in snow for the first time. All around us coral bundles were heading for the surface, where they would break open so that eggs could be fertilized and start the next generation of staghorn coral, and with a bit of luck help drag this species back from the brink.
Back on the boat I sat contented in the warm evening air, knowing that success with the staghorn meant we now had even odds for an even bigger event.
The most abundant coral on the East End of Cayman is star coral, with large plate and boulder shaped colonies, and we were expecting these to spawn a day or two after the staghorn. Their large size promised an even more spectacular spawning, and by the next evening we had a full boat of 12 divers eager to share the experience. As we splashed into the water we were greeted by two species of gorgonian corals spawning. This had not been in the plan. Gorgonians have separate sexes, with some colonies being male and others female, and all around female colonies were releasing small white eggs. Male gorgonians were probably releasing sperm, but this was too small to see. I took a few photographs of the lady gorgonians, but in general I was trying to move about as little as possible to save my air and give myself the longest observation window. The last thing I wanted was to be running low for the main attraction.
I shouldn’t have worried, because bundles started to appear on the star corals right on cue, just three minutes before predicted. Half an hour later, spawning began with a bang. Unlike the staghorn and gorgonians which released a steady stream, the star coral, true to its name, is a much more stellar performer and releases all its bundles within a few seconds. Large plates of star coral, about the size of a garage door, were releasing their bundles in waves that spread across the surface of the colony like a blush. Initially, the bundles did not float away, instead hanging an inch or so above the coral. After a few moments the bundles found their buoyancy and floated upwards in a dense plume filling the water in every direction I shone my torch.
The intensity of spawning was shocking; visibility dropped from about 25m to about 5m in about two minutes. It was like diving in a blizzard, with the tiny bundles drifting slowly to the surface like snowflakes. Suddenly, diver silhouettes were only torch beams in the murk, and I could no longer see the strobes marking the position of the dive boat. I headed back down to the reef, relieved to have something solid to look at. Brain corals were also releasing bundles from their grooves, and deep-red brittlestars climbed high on top of corals and spawned. The explosion of activity was astonishing, the true coral animals had been revealed, and I knew that on the other 364 days of the year I would never look at them in the same way again. I checked my contents gauge, which was buried in the red, and reluctantly left this tropical, underwater snowstorm behind.