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  • By JoAnna Delfin

NAFVAC curbs crown-of-thorns starfish outbreak at Orote reserve

Earlier this year, U.S. Naval Base Guam (NBG) dive locker divers and Naval Facilities Engineering Command (NAVFAC) Marianas environmental marine scientists teamed up to remove a significant number of the predatory crown of thorns sea star (COTS) from the Orote ecological reserve area and Old Wives Beach onboard NBG.

NAVFAC Marianas is involved in the Guam Rapid Response Team, which is composed of local, federal and non-governmental partners that discuss the immediate issues facing Guam’s reefs and seek positive resolutions.

“We were informed by the (response team) that a large amount of COTS were sighted at Old Wives Beach,” said Andres Reyes, NAVFAC Marianas marine scientist. “After hearing this and receiving support from NBG leadership to have the dive locker respond, I coordinated with Senior Chief Navy Diver Corey Clifton and Navy Diver 1st Class Alexander Wright to have them conduct the culling.”


Navy divers initiated a survey from the northwest corner of Old Wives Beach, meandering along transects toward Turtle Rock. Evidence of extensive coral damage was observed along the way, suggesting that a large population of COTS may have moved through that area. Upon reaching the southern edge of the cove, they found significant numbers of very large COTS, removing a total of 191 individual sea stars.


“NAVFAC Marianas conducted, and participated in, previous trainings for the NBG dive locker for COTS identification, so we were very confident in their abilities to respond to the COTS at the beach,” said Reyes. “This effort shows the adaptability of the dive locker, and I think the entire Guam community recognizes our combined environmental stewardship.”

According to the Guam COTS Outbreak Response Plan, developed in 2017 by state and federal agencies, COTS outbreaks, coupled with coral bleaching, are one of the most significant causes of coral loss in the Indo-Pacific.


As coral reefs contend with climate changes and other detrimental effects, one of the best ways to reduce COTS outbreaks from causing additional damage is to physically remove or cull individuals.

The COTS, at normal densities in the coral reef ecosystem, may enhance the diversity and health of reefs. However, during COTS outbreaks, when the sea stars reproduce rapidly, they can cause the loss of 90 percent of live coral on reefs.


These outbreaks may be caused by the rise in ocean temperatures or even increases in algae from land runoff into the ocean. Loss of coral through massive predation by the COTS has an adverse effect on the health of other organisms that rely on the reef ecosystem, such as fish and other invertebrates.

NAVFAC Marianas continues to work collaboratively with state and federal agencies, as well as the community, to report and mitigate these COTS outbreaks. (NAVFAC)


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