Starfish Impact on Humans Obvious as Barrier Reef Crumbles

When an invasive species gets a foothold, it becomes costly and difficult to eradicate. The moment to stop an invasive species like starfish, is before it becomes established. The 2011 floods in Queensland, Australia introduced polluted fresh water into the Great Barrier Reef ecosystem. In three years, invasive crown-of-thorns starfish could begin to graze upon coral already decimated by the floods. The introduction of the starfish may severely impact humans by destroying the reef which will take money away from the local economy through a decline in eco-tourism and the ecosystem itself.

Australian Institute of Marine Science researcher, Katharina Fabricius studies long term effects of river runoff on the Great Barrier Reef. According to a "Nature" article, Fabricius says it takes about three years after a flood for the starfish to appear. Runoff from the rivers acts as a nutrient for algae in the ocean waters. Algae are a food base for starfish until they grow old enough to eat coral. It takes about three years for the starfish larvae to mature.

The direct impact on humankind is startling. Starfish that invade coral reefs are worsening the effects of tourism, coral bleaching and acts of nature like storms, floods and El Nino. In short, destruction of coral reefs by starfish is an economic disaster for islands and fisheries. Any economic gain from coral reefs, such as eco-tourism and feeding the inhabitants of the nearby islands, are lost as the reef disappears. Killer starfish, as they are sometimes referred to, are also a physical danger to humans, as a wound from their painful spines can produce swelling, nausea, vomiting, numbness and paralysis in humans.

Unfortunately there is no way to control Mother Nature. Back-to-back flooding makes an invasion of starfish more likely. It takes coral reefs approximately 25 years to recover from being grazed upon by starfish, and the Great Barrier Reef is being attacked by starfish every 15 years, on average. Continuous attacks have a devastating impact on coral: 90 percent of live coral has been lost in Saipan, the Marshall Islands and Guam. The branching corals of Ryukyu Islands, Japan were completely decimated by starfish, leaving behind flat plains of rubble. Treehugger.com reports that the Coral Triangle, located between Indonesia, Malaysia, the Philippines, Papua New Guinea, Palau and the Solomon Islands, is being quickly degraded as well. Twenty percent of the reef has been destroyed there. The one bright spot is that in Japan, starfish carcasses are used as fertilizer but it does not reverse the damaging impact of the invasive species.

Starfish can consume 10 meters of coral per year. The starfish can lay up to 60 million eggs per year. In about four years, the starfish slow down their activity. Researchers say the length of their life cycle is unknown, but they have been kept in captivity for up to eight years. The starfish can grow quite large, up to 32 inches and have spines that stick to the coral. They have up to 20 arms and are colored greenish-grey, reddish brown or brilliant purple.


Sources:
Nature.com
Invasive Species Specialist Group
Treehugger.com
CRC Reef Research Center