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KOHALA COAST – In the last three years or so, ideal sites for snorkeling, such as Kauna'oa Bay, have almost come to sleep. Where once the vibrant yellow, green, and blue corals abounded, there were mostly dead, gray in color.
Until recently.
"Some areas have been harder hit than others by coral bleaching and some areas have survived," said Lindsey Kramer, who has studied the effects of warming ocean temperatures in West Hawaii. since 2015 as coordinator Habitat & Fish Monitoring Island. for the Aquatic Resources Division (DAR) of the Department of Lands and Natural Resources of the State.
Kramer is also the coordinator of Hawaii Island for the Eyes of the Reef (EOR) network, an organization of volunteer members created to raise awareness and engage in monitoring and reporting of coral bleaching and disease, among other topics related to the sea.
"Cauliflower corals were extremely likely to whitewash in 2015 and more than 99% of them were laundered in West Hawaii," she said. "In December 2015, we began to notice mortality that continued until spring 2016."
The peak event that resulted in a dramatic loss of coral cover on the west side of the island was primarily a heat stress event that began in August 2015 and continued until November of this year.
"The temperature of the ocean has reached 86 degrees. The increasing levels of carbon dioxide emissions in our atmosphere act like a greenhouse and retain heat, "Kramer said. "The very hot ocean temperatures we experienced here in 2015 were a clear warning that the climate was changing."
At the same time, there were other effects than stressed corals.
"We have observed an increase in the number of dead oysters in the cliffs just after coral bleaching in the winter of 2016. It is possible that the rise in temperature has affected other species of owl. 39, invertebrates, "explained Kramer.
DAR began collecting coral health data in 2003 and monitoring reefs throughout the bleaching disaster.
Signs of a new life
Recent DAR data for North Hawaii has shown an overall coral recovery of 1-2% over the past two years in the majority of their monitoring sites.
"Among the six sites in northern Hawaii, Puako has been the only one to continue to record coral decline between spring 2016 and spring 2017," said Kramer.
As of May of this year, new small developing beige cauliflower corals were observed on dead corals at Kauna'oa and among the largest living corals that survived Mauna Lani. Other sites, such as Lapakahi, also showed signs of coral rebound.
"The very small coral colonies you will see there are probably new colonies that have settled on the reef as larvae, and large colonies are possible survivors of the bleaching event," he said. said Kramer. "One hypothesis is that colder groundwater is frequently influenced by more coral water in the coral areas, which could reduce the risk of bleaching."
Corals can survive the whitened state for several weeks, but the reasons why some live while others die are related to individual species or traits.
"It's important to consider watersheds, water pollution and other local stressors, such as chemicals in sunscreens," Kramer said. "It is safer to use sunscreens made from titanium oxide or zinc oxide."
Another key element of the coral reef in northern Hawaii is the spawning observer program set up in the spring of 2016.
"As the coral breeds, an individual colony can produce male and female gametes. They are released and fertilized in the water column, "Kramer said. "The cauliflower coral breeds from indexes related to the lunar cycle, about three days after the spring full moon. Sometimes the larvae can travel in the plankton and relocate elsewhere. "
DAR continues to review the data collected to determine possible trends.
"The eggs were viable this year, and laboratory larval rearing and reservoir packing experiments have shown potential for future restoration. The work was done by DAR group and by scientists and volunteer collaborators at six sites, "said Kramer.
The EOR community outreach network, composed entirely of volunteers, offers residents free training to learn more about coral bleaching and what happened in 2015. Roy Allen, a resident of Waikoloa village that regularly snorkels, volunteered for EOR several years ago.
"The training they offer is fantastic. It really helps us understand what is happening with the ocean, especially now with the dramatic changes. This gives everyone a chance to help, "he said.
Earlier this year, a team of volunteers in Mahukona reported a spawn of light corals on May 1 and a spawn on May 2. On June 1, Kramer was at Mauna Lani to watch the breeding.
"We asked EOR volunteers to help us observe spawning and its timing," Kramer said. "At Mauna Lani, it was exciting to see a successful spawning event after two years of weak activity reported."
She continued, "The EOR program also provides information on how to identify coral diseases, marine invasive species and invertebrate diseases. When people snorkel or dive and notice something unusual, they can tell us about it on our website. It is a grassroots effort that partners with Hawaii's coral reef resource managers. They review and verify reports and respond as needed. "
Most of what DAR does is based on a recovery plan for coral bleaching created by the University of Hawaii's Institute for Social Science Research in the winter of 2015 and published in 2016.
"It's a planning document outlining the best possible management strategies to help coral recover in western Hawaii," Kramer said. "It includes key strategies such as watershed enhancement, reef grazing protection and coral restoration."
It also describes coral restoration strategies to improve the resilience of corals to stress, to develop faster growth methods and to intensify efforts to make them meaningful.
"The number one strategy is to create a network of protected areas to promote the resilience of corals," Kramer said. "It's a whole process of determining which areas would be candidates, and significant support from the community will be a determining factor."
Protect corals
In January, the Center for Biological Diversity filed a petition to classify cauliflower coral in the United States as endangered or threatened under the Endangered Species Act. 5% of its population residing in West Hawaii as a major concern.
"It's still in its infancy and open to the public," commented Kramer.
DAR continues to monitor corals closely in the waters surrounding the Big Island.
"Currently, we are under whitened surveillance in Kona. This week it was 81.8 degrees, "said Kramer last Monday. "Corals start to get stressed from 82 ° C and the effects get worse when temperatures stay warm."
DAR will continue its coral monitoring efforts for the remainder of 2018 and the next few years. Free public training on coral bleaching and health is offered throughout the year by the Eyes of the Reef network.
Info: Email [email protected]
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