Insights into reproductive trends, predation patterns, and climatic triggers observed prior to a crown-of-thorns outbreak are crucial for developing effective mitigation strategies to protect coral reefs, according to Ciemon Caballes, Ph.D., a senior research associate at the University of Guam's NSF EPSCoR and assistant professor at the UOG Marine Lab.

Caballes shared his insights during the “Guam Crown-of-Thorns Starfish Outbreak Response Strategy” workshop in December at the UOG Marine Lab.

COTS are marine invertebrates known for their predation on corals. 

They can cause devastating impacts on coral reefs by depleting coral populations. They are found in reefs across the Indo-Pacific region.

Caballes' research, supported by a grant from the National Fish and Wildlife Foundation, in collaboration with UOG's NSF EPSCoR and Sea Grant, and other local and federal resource management agencies, focuses on understanding and mitigating these outbreaks.

"When we try to catch a serial predator, like the crown-of-thorns starfish, we need to build a profile," Caballes said.

He noted that understanding COTS and the trends leading to an outbreak is crucial for an effective mitigation strategy.

Caballes outlined several theories behind these outbreaks, including high fertilization rates, overfishing of natural predators, and river runoff leading to nutrient spikes that support starfish larvae.

Caballes pointed to past events, like the 2009 outbreak and its connection to El Niño and high rainfall, as warning signs for Guam's reefs. 

He noted that recent coral bleaching and starfish outbreaks are straining recovery efforts.

Since 2022, researchers have been testing methods to control starfish populations and improve coral rehabilitation. The Guam COTS outbreak strategic management plan now includes input from local and federal partners, aiming for long-term solutions.

Associate Director Fran Castro praised the multi-agency collaboration, emphasizing the importance of training and monitoring to protect Guam's reefs.