According to Dr. Nicole Fogarty, an associate professor in UNCW’s Department of Biology and Marine Biology, corals are pretty simple invertebrates.
“Most people don’t realize that they’re animals, they kind of look like slimy rocks, right?”
Fogarty said her lab has five tropical species of corals, four of which are 'broadcast spawning' corals, and one species is a 'brooding' coral. The difference between the two is that broadcast corals conduct fertilization externally and the brooding ones do that internally.
According to Fogarty, the broadcasts release gamete bundles full of egg and sperm into the water at a synchronized event once a year in late summer after the full moon; whereas, the brooders release the sperm, and nearby colonies take in that sperm, which they then release larvae that find a place to settle and metamorphose.
"It's just like a caterpillar turning into a butterfly, and hopefully they continue the lifecycle," said Fogarty.
With the broadcasts, they're a little more vulnerable, said Fogarty, "because those dividing embryos will float for several days in the water column, then form this planula larvae and they'll settle and go through their metamorphosis."
Spawning
Fogarty's lab was one of the first in the world to spawn two specific types of broadcast corals.
“There are four or five of us [labs] that spawn Caribbean corals in captivity now,” said Fogarty.
While Fogarty’s lab does grow anywhere from 75,000 to 125,000 coral babies, she and her team’s work informs major reef rehabilitation off the coast of Florida.
For example, they work closely with the Florida Aquarium and the Mote Marine Lab and Aquarium.
“Our goal here isn't to mass rear hundreds of thousands of babies to outplant on the reef. Our goal really is to focus on the research that can be applied by restoration practitioners. So we're again trying to optimize the light, temperature, water quality, and nutrition of these young corals in order to apply to the larger facilities so that they can use these parameters to grow them,” said Fogarty.
At her lab, her research team is investigating things like how probiotics influence the growth of young corals and the highly important relationship between the corals and their micro-algae, the zooxanthellae, which gives them about 90% of their nutrition. They get the rest from things like zooplankton.
“Now, this symbiosis between the zooxanthellae and their coral host is really temperamental. As soon as the coral starts getting stressed, like if there are really warm temperatures for an extended period of time, that symbiosis starts to break down, and so they will kick out those that zooxanthellae,” said Fogarty.
That’s when coral bleaching sets in — which means lower reproduction and growth, which can then lead to mortality events.
Louis-Pierre Rich is the lab’s coral husbandry research technician. He has the charge of growing and maintaining the corals. He said in the past couple of years, there’s been a push to gene bank coral species, especially the stony coral, whose populations are currently threatened by stony coral tissue loss disease.
“The anthropogenic stress, hurricanes, temperature, climate change, disease, maybe they can handle, you know, one or two of these stressors at a time for a short period, but once you start adding all these things together is really like a death by 1,000 cuts, essentially,” said Rich.
But Rich said the public shouldn’t give up hope.
Cutting-edge work
“There are all sorts of labs that are doing all these sorts of different interventions between crossbreeding, probiotics, different techniques for micro-fragmentation, even looking at coral genetic modification using technologies like CRISPR down the line, but we just don't have the time to figure out which approach is the best,” said Rich.
UNCW Assistant Professor Dr. Jake Warner is the person doing this genetic modification work. Last summer, he successfully modified young corals, and said perfecting this approach took several years.
“This was the first time this has been done in the world. We inserted the sequence, the DNA for a gene called green fluorescent protein. And sure enough, a day later, we saw little green glowing coral babies, so it was really exciting," Warner said.
Warner said scientists are taking their time understanding the impacts of putting genetically modified corals out into the ocean to better withstand climate change and the other environmental threats they face.
“So there is a major concern that if we’re going to eventually do this, to do it right, and do it in a really controlled manner, that we don’t end up accidentally creating an invasive species,” said Warner.
But he said the threats to coral remain real and widespread.
“And what I'm describing is we're taking the first steps that are years out in the process. So understanding our human impacts on the environment is really important in mitigating coral loss because when you have these stresses, and increased temperatures that cause mass coral bleaching events, these are very real threats that are happening today. So we're trying to come up with solutions, creative, molecular solutions to address those problems, but we're still a long way away,” said Warner.
Find more on the Fogarty Lab here.
