LIHUE — Kauai coral colonies have started to recover from a statewide bleaching event caused by a drastic spike in ocean temperatures this fall, according to state officials.
More of the same, however, is likely right around the corner.
“Climate change is having an impact and it’s predicted to be more severe and frequent,” Katie Nalesere, education specialist for the Department of Land and Natural Resources’ Division of Aquatic Resources, said of bleaching events.
Bleaching is a stress response that causes corals to lose algae and color from their tissue, making them appear snow white. The fall bleaching — which mostly impacted corals in shallow waters off Kauai, Oahu and Maui — occurred when sea temperatures jumped to as high as 86 degrees in some areas.
Nalesere said that at her monitoring sights on Kauai she recorded temperatures as high as 83 degrees.
“It’s one of the highest recorded temperatures,” she said. “It’s well above average. And, you know, corals have a very specific threshold for temperature, so anything, even one or two degrees above normal, especially during hot season, is enough to stress them out.”
In comparison, the ocean temperature last week in Anahola — one of the areas on Kauai hit hardest by bleaching — was 74 degrees, according to Nalesere.
Local marine biologist Katherine Muzik, who was recently granted permits for a reef restoration pilot project along a dredged area of reef in Kapaa, said she has also noticed a lot of recovery.
“The corals that most disturbed me (on the Eastside) are almost all OK again,” she said.
However, she is confident that next summer and fall will spell more trouble for Kauai’s reefs.
Like on other islands, bleaching on Kauai was most prevalent on the north- and east-facing shores, with prevalence and severity varying at each location.
In Anahola, 80 percent of the coral exhibited some sign of bleaching and 78 percent exhibited severe bleaching, according to DAR survey reports.
At the west end of Anini, 80 percent of the coral showed signs of bleaching, while 78 percent was severe. The east side of Anini, the numbers were 50 and 6 percent, respectively.
And at Lepeuli, 68 percent showed signs, while 5 percent was severe.
“We did see some mortality, and we noticed that some species were more susceptible to bleaching,” Nalesere said.
In Kaneohe Bay on Oahu, scientists recorded that 12 percent of the beached corals exhibited some degree of mortality. While specific mortality rates were not recorded for Kauai, Nalesere said they were likely not quite that high.
During the recent event, DAR received more than 100 reports from ocean users and 60 photographs of bleaching from across the state, which helped the monitoring teams find and assess bleached coral areas, according to a release Thursday.
Nalesere said community involvement during such events is crucial, and that she believes people are becoming more aware of how actions on land have a direct impact on life in the ocean.
Additionally, Nalesere said there is much to take away from the recent response effort.
“I think that any time we see a widespread bleaching event it is a serious concern, but I believe that being able to observe recovery in such a short period of time is certainly encouraging and as we continue to monitor our corals we will learn more about how this event has impacted our ecosystem,” she said.
In 2014, coral bleaching was also observed on several reefs of the Northwestern Hawaiian Islands, and scientists will be returning to those locations this summer to find out whether those bleached corals have recovered, according to DLNR.
Updates and scientific data from the 2014 bleaching event are available on DLNR’s Reef Response website: http://dlnr.hawaii.gov/reefresponse.
Chris D’Angelo, environment writer, can be reached at 245-0441 or firstname.lastname@example.org.