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CCMI study aims to unlock reproductive secrets of nursery corals

Research scientists at Central Caribbean Marine Institute in Little Cayman are studying corals in its in-water nursery to understand how spawning corals replenish reefs naturally.

CCMI began its work in coral restoration with a collaboration with the Department of Environment back in 2012, and has since amassed an impressive nursery.

CCMI Research Scientist Paul Maneval told Cayman 27 its deep nursery, one of three CCMI nurseries on Little Cayman, is home to more than one-half kilometer of staghorn coral, and three distinct genotypes that grow at different rates, from 45 to 75 centimeters per year.

Right now, Mr. Maneval and other research scientists are now working to understand the relationship between the growth rates, and a coral’s reproductive output.

As Cayman 27’s Joe Avary learned last week, collecting the data isn’t easy.

Gametes from a spawning study coral are collected during 2-hour night dives and later analysed in the laboratory

A team of CCMI research scientists are in the water after dark to unlock the reproductive secrets of staghorn coral.

“What we have found through our research these last couple years, is that they have significantly different growth rates,” said Mr. Maneval.

In this novel study, CCMI is measuring the reproductive output of slow, medium, and fast growing corals in its nursery.

“These corals that we have, they grow at very very fast rates, some of the fastest rates that have ever been published,” said Mr. Maneval. “If these fast-growing corals suddenly produce larger eggs or more eggs than what you would find naturally in the wild, that is a huge difference.”

To collect the gamete bundles, which are essentially packages of eggs and sperm from an individual coral, scientists constructed tents around a dozen individual corals from three genotypes. The mesh tents are placed over PVC frames around the individual corals.

“The coral will release these gamete bundles and they will slowly float up towards the top of the tent, at the top of the tent we have a falcon tube, a collection tube, where we are actually collecting the gamete bundles, and when we collect that we are actually able to see how many eggs that individual coral has produced,” explained Mr. Maneval.

After a two-hour dive in the darkness, Mr. Maneval and his team take volumetric measurements of gametes collected from each of the study corals.

The gametes from the individual corals are measured volumetrically to assess its fecundity

“From there, we can say well, this coral here is this big and it produced so many gamete bundles, and that tells us a lot about its reproductive productivity,” said Mr. Maneval.

Will faster growing corals have larger and healthier gametes, or will it be the other way around? Mr. Maneval said either way, this study will help establish an important baseline for future coral research.


“What we are doing is trying to see ways that we can regenerate what is really an important keystone species of the reef itself, so that we can hopefully continue to have healthy reefs in the future,” said Mr. Maneval.

Mr. Maneval and his team are still monitoring the coral spawn.

He said usually corals all spawn at once but this year he has seen what he called a ‘trickle spawn.’

Due to the timing of full moons this July and August this year, he said it could signal a ‘split spawn’ for this year, when corals spawn across two months.

Last year, for the first time, CCMI recorded the coral spawn in its nursery.

About the author

Joe Avary

Joe Avary

Joe Avary has been with Cayman 27 since 2014. He brings 20 years in television experience to the job, working hard every day to bring the people of Cayman stories that inform the public and make a difference in the community. Joe hopes his love for the Cayman Islands shines through in his informative and entertaining weather reports. If you have a story idea for Joe or just want to say hello, call him at 324-2141 or send an email to

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