MELBOURNE, July 2 (Xinhua) -- Australia's reefs are being damaged by outbreaks of coral-eating crown-of-thorns starfish and kelp-grazing sea urchins, with scientists warning stronger, coordinated action is needed to contain the threat.
A study published Wednesday in Marine & Freshwater Research found the two native species are driving significant degradation across Australia's Great Barrier Reef and Great Southern Reef.
Crown-of-thorns starfish are a major threat to the tropical Great Barrier Reef, while long-spined sea urchins have stripped thousands of hectares of kelp on the temperate Great Southern Reef, according to the study led by Australia's University of Tasmania.
Crown-of-thorns starfish outbreaks occur in cycles, with populations spiking roughly every 15 years and consuming large areas of coral before collapsing, creating another threat to reefs already stressed by climate change, the study's lead researchers wrote on The Conversation website.
In southern waters, warming oceans have enabled long-spined sea urchins to expand south into the island state of Tasmania, where they form dense populations that overgraze kelp forests and create long-lasting "barren" reefs, they wrote.
Management efforts differ sharply. Federal authorities spend about 20 million Australian dollars (13.8 million U.S. dollars) annually controlling starfish on the Great Barrier Reef, while urchin control is fragmented and far less funded. Researchers called for expanding the urchin fishery to remove more urchins and protect reefs.
The study also highlights the importance of natural predators. Protected populations of spangled emperor fish and southern rock lobster have been shown to help suppress starfish and urchin outbreaks. ■
