A study published in PLOS ONE recently stated that endangered coral reefs are vulnerable to attack from the crown-of-thorns sea star (the Acanthaster species). In the Fiji Islands, where the study took place, the protected marine areas are being enforced by the Republic of Fiji and are thriving. But this success attracts the attention of the crown-of-thorns sea stars and other predatory animals that come in and destroy the coral.
Coral reefs are found in the Indo-Pacific region, including the Red Sea, Indian Ocean, Southeast Asia, and the Pacific. They are also found in Australia, the Atlantic Ocean, and the Caribbean. These diverse underwater ecosystems are made of calcium carbonate structures that are secreted by the corals. The reefs are made by colonies of small animals that form the corals. The coral reefs provide a home for a quarter of all marine species.
Crown-of-thorns sea stars are a species of starfish that preys on coral, in particular on the hard or stony variety. By climbing over the coral, the starfish ingest the coral, rapidly degrading the reef and causing a “large-scale coral decline in a matter of weeks.” These starfish are covered in venomous thorn-like spines, and are one of the largest in the world and are common in Australia, tropical and subtropical latitudes to the west coast of Central America.
Regents Professor, Mark Hay, with the School of Biological Sciences at Georgia Institute of Technology said the coral and fish are recovering. However, after the protected marine areas improve, they attract the unwanted sea stars. The results of this study conflicted previous studies that showed large-scale protected marine areas had diminished sea stars threats.
The sea stars, according to Cody Clements, a Georgia Tech graduate student, who conducted the research, can move tens of meters per day and they migrate from areas that are degraded into the more pristine areas. Clements went on to say that one of the purposes of marine protected areas was to protect from predators like crown-of-thorns sea stars. In these protected marine areas, residents are not allowed to fish, which provides benefits to the economy through both tourism and the overflow of fish to areas where people are allowed to harvest them. These protected waters also protect the coral from seaweeds that can harm the reef.
Clements said the study findings do not negate the value of the protected areas; however, they do raise concern for the people who manage them. The researchers stated that coral conservation efforts could take decades to show results. They hoped the study did not deter those efforts.
By Cheryl Werber
Photo Courtesy Cody Clements, Georgia Tech