david doubilet coral spawning, coral reef reproduction eggs and sperm

All too often we hear that the world’s coral reefs are in peril. It’s undeniably true, that our reef ecosystems are threatened by rising ocean temperatures that cause coral bleaching, plus the dangers of pollution, coastal development and over fishing, in fact we just reported on an unexplained, tissue-loss disease infecting Florida’s coral reefs. But we need to balance the bad with some good news, if for no other reason than to maintain hope and sanity. As reported in the New York Times, scientists are discovering some wonderful new things about one of our ocean’s most mysterious phenomenon, coral spawning. (photo – David Doubilet)

When described in words it sounds like a primordial rite out of a Gothic Romance. Corals are colonies, composed of millions of tiny, individual animals and their reproduction occurs at night according to the full moon, when trillions of eggs and sperm are released to mingle in the warm ocean currents. Can’t get any sexier than that!


“Coral Spawning is like an underwater snowstorm,”

Said Emma L. Hickerson, doing research on a coral reef in the Gulf of Mexico. The Flower Garden Banks is a National Marine Sanctuary, 100 kilometers off the Texas coast, where Emma and her colleagues have been documenting this natural wonder on video.

“It’s like a wave at a stadium,” Hickerson said. “You see it start at one side and go across. It’s amazing. You can’t make this stuff up.”

cu of coral polyps david doubilet coral spawning, coral reef, reproduction, marine lifeWith high speed cameras they can catch the corals as they swell and release individual eggs. As often occurs in Gothic Romances, timing is critical and so it is with the release of coral egg and sperm. If they are even minutes out of sync successful reproduction can be diminished. The timing not only relates to its neighbors but also to spawning from year to year. (photo – David Doubilet)

After being released the intermingled, floating eggs and sperm are carried in giant drifts, riding ocean currents, sometimes for hundreds of miles. When they eventually descend they can populate new reefs with new coral colonies.

Studying coral spawning has uncovered some exciting new ideas and dispelled some old concepts. For example, it was long thought that spawning was triggered by tides, however it is now understood that spawning occurs at both low and high tides. The moon remains important because it seems to act as a visual stimulus that gets things rolling.


New Findings Might Help Save Coral Reefs

Florida Keys Coral Spawn pillar coral Karen Neely FWCThis new data is important because it is hoped that a better understanding of spawning will give science an advantage in countering environmental threats. For example, does the presence of particles of sediment from dredging interfere with successful fertilization of coral eggs? Recent research indicates that it does and suggests steps that can be taken to avoid dredging during periods of coral spawning. (photo – Karen Neely, FWC)

Scientists from Hawaii to the Middle East are focused on different aspects of coral spawning to determine what other environmental concerns, like global warming might determine the success of coral reproduction and resiliency.

It has been nearly two decades since Emma Hickerson witnessed her first mass coral spawning at the Flower Garden Banks. Although she has experienced it many times since, she still finds herself caught in its primal spill.

“To this day, I find myself screaming,” she said. “You can’t help it.”

By Robert Frerck, Blue Ocean Network


See these Related Blue Ocean Articles:

Coral Reef Gardening: Try Voluntourism when next in Paradise
Top Ocean Stories of 2017: Part 5, Can We Save Coral Reefs?
Top Ocean Stories of 2017, Part 2: MPAs, Illegal Fishing and Slavery on the High Seas
Top Ocean Stories of 2017, Part 4: Climate Change, Extreme Weather Events, Clean Energy
Is The Great Barrier Reef Dead: Not Quite
Sustainable & Responsible Tourism on Curaçao
Decline in Ocean Oxygen Linked to Climate Change
Can We Save Our Oceans by Growing Corals?
Worldwide Coral Bleaching in 2016 and 2017?
Summit: 2015, Citizen Science, Dive Tourism as tools for conservation, The value of coral reefs. Local activism and engagement.


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