Kauai News

Reef Recovery and Death Observed in ‘Anini Bay

Posted June 11, 2020, 3:33 PM HST

The reef at ‘Anini Bay is seeing significant signs of recovery after a coral disease was discovered last year.

The Department of Land and Natural Resources’ Division of Aquatic Resources staff has been monitoring the reef’s health after receiving reports last summer that the corals on the bay’s inner reef were infected with black band disease (BBD). Subsequently, DAR staff immediately conducted surveys along ‘Anini Reef, which revealed that 11.5% of the rice and sandpaper corals were affected by BBD. The damage to the reef discovered last was far worse than the previous outbreak in 2012-15, officials said in a DLNR press release.

Courtesy of DLNR

During that time, staff observed widespread coral bleaching, overgrowth of macroalgae, cyanobacterial algae mats, an abundance of low fish, warmer sea surface temperatures and high amounts of sediment on the feef and in the water column.

“It is believed that warm water and coastal sources of sediment and excess nutrients, exacerbated by insufficient flushing of the inner reef from ocean swells, created an environment that led to these reef conditions,” the release states.

A followup survey in February and March this year, the release indicates, found that the prevalence of BBD dropped to 0.3%, which is considered a normal level for the disease.

While DAR staff noticed reef recovery, they also observed signs of reef death, likely due to diseased colonies that could not fight off the infection or recover from severe bleaching.

“DAR aquatic biologists believe that changing seasons bringing north swells to flush out the protected waters of the inner reef and cooler sea temperatures allowed recovery on the reef to happen,” the release states.

In order to help inform management decisions, the staff is developing a project to use Structure from Motion (SfM) technology to capture seasonal chances at ‘Anini Reef, including coral disease outbreaks and bleaching events.