A new study published in the journal, Marine Biology, confirms the danger of unabated population growth among crown-of-thorns starfish, the greatest destroyer of coral reefs.

The crown-of-thorns starfish (Acanthaster planci) is an aggressive predator of scleractinian or the hard corals responsible for building coral reefs. The population increase of this voracious predator is of great danger to reefs because A. planci continually eats large areas of coral colonies.

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Surges in the A. planci population devastate entire reef habitats. Such habitats are important as key tourism sites for the Ryukyu Islands in Japan.

The study published in Marine Biology is one of the longest and most extensive surveys of its kind, with data covering over 24 years. It was conducted in cooperation with the local fishing population of Onna Village in Okinawa and the Okinawa Institute of Science and Technology Graduate University or OIST.

OIST researchers were able to plot with a high degree of accuracy the movement and population size over time of A. planci with fisherman providing a great deal of logistics support and data.

The study analyzed the population dynamics of A. planci over time and examined potential factors that might sustain such populations off the Onna village coast. Data was gathered between July and August, the peak time for larval dispersal of A. planci.

The study found the majority of individual A. planci caught off Onna village fit within a certain size and age range. This suggests there is a relatively steady number of new A. planci coming in from elsewhere.

Recruitment rate refers to the number of new starfish entering an area as larvae or juveniles. The collection data also points population densities heading northward along the Onna village coastline.

Researchers hope is their work will provide the foundation for a better understanding of how and where population outbreaks of A. planci occur.

"This research is a first step. Now we are doing more detailed research to help conservation efforts. But we could not have done as much as we have without the help of the local fisherman who know the sea here better than anyone," said Masako Nakamura, a researcher at OIST's Marine Biophysics Unit that heads the joint effort.

To date, researchers are conducting further studies about ocean movements in the area and other environmental factors that might cause the starfish recruitment.

They hope this study will provide a better understanding about how starfish outbreaks occur in Japan.

They said this is just the first step and that they're now focusing on conducting more detailed research.