Spawning Of Threatened Pillar Coral Observed For First Time In Florida Reef System
Lawrence LeBlond for redOrbit.com – Your Universe Online
Male and female threatened pillar coral have been documented for the first time spawning together in the Florida Keys National Marine Sanctuary, said researchers with the Florida Fish and Wildlife Conservation Commission.
The researchers were exhilarated by the displays of male and female pillar coral releasing their reproductive cells during a spawning session in the Upper Keys on Saturday, just after the full moon. At precisely 9:47 p.m. the coral began spawning in shallow water off North Key Largo in a place known as Pillar Coral Forest. First the males released their milky white sperm, followed six minutes later by the females’ release of little white eggs that appeared stringy.
Three research scientists witnessed the event while scuba diving.
“We were so excited to see the girls,” said Kate Lunz, research scientist with the Florida Fish and Wildlife Conservation Commission. “We were kind of wondering if there were any girls here. But they all sort of mixed together with multiple coral colonies going off — sometimes twice.”
Lunz said it the discovery is significant because it had been unclear if any separate female pillar corals existed in Florida. Unlike other stony corals, which produce both sperm and eggs, pillar corals form separate male and female colonies for reproduction.
Corals in the Keys and elsewhere typically reproduce in the late summer, usually within days after the full moon. With two full moons in August, Lunz said there is potential for another coral spawn in September.
The observed reproduction display is good news for the threatened species. These corals are extremely rare along the Florida reef tract, which runs from Palm Beach County to the Dry Tortugas 70 miles west of Key West.
“Colonies that are healthy enough to invest energy to produce eggs and sperm have the potential to reproduce,” Lunz said. “Sometimes corals are stressed and cannot sexually reproduce at all.”
The researchers are hoping the eggs and sperm fuse and become larvae, eventually settling as new corals. It has long been known that corals can fragment, break off a piece and re-cement themselves on hard substrate, but sexual reproduction offers more diversity in the population.
“Genetic diversity is good,” Lunz told the Miami Herald. “Some genotypes are more susceptible to diseases than others.”
The rare coral never took a strong foothold in Florida waters. In the 1950s and 60s, these specimens declined because they were a popular target in the curio trade. While the collection of this coral has been banned, they continue to face threats from other factors, such as disease.
Bill Goodwin, resource manager for the Florida Keys National Marine Sanctuary, said he was thrilled when he heard the news. “I was doing cartwheels… It is one of the most beautiful sites we have in the Upper Keys.”
Goodwin, along with colleague Harold Hudson (the Reef Doctor), rescued 22 pillar coral colonies that were imperiled from Hurricane Andrew in 1992, fragmenting and getting stranded in soft sand where they could not survive. After collecting the coral, Goodwin and Hudson set the fragmented coral upright and stabilized them on hard substrate on the sea floor.
This area became known as the Pillar Coral Forest, one of the largest clumps of species known in the Keys. Some of the coral are four to five feet tall, indicating they are likely 40 to 50 years old.
Despite the good news, another group of researchers, led by Ken Nedimyer, founder of the nonprofit Coral Restoration Foundation in Key Largo, were disheartened somewhat by the lack of spawning by Elkhorn and Staghorn coral offshore.
However, when the group returned home after the first night of watching for spawning at about, Nedimyer discovered that coral previously collected from his nursery and put in a lab tank was mating. During a second night the group stayed out later, yet nothing happened. But once again, upon returning home, the tank specimens were spawning.
“Maybe they are spawning really late at night on the reef and we’re just not seeing it,” Nedimyer said. “It’s odd, but this is not an exact science.”
Lunz said her team plans to return to the Pillar Coral Forest after the next full moon to see if more spawning will occur.