- 2018年05月08日11:47 来源：小站整理
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Starfish are keystone species in theirrespective marine communities. Their relatively large sizes, diverse diets andability to adapt to different environments makes them ecologically important.
Starfish sometimes have negative effects onecosystems. Outbreaks of crown-of-thorns starfish have caused damage to coralreefs in Northeast Australia and French Polynesia. A study in Polynesia foundthat coral cover declined drastically with the arrival of migratory starfish in2006, dropping from 50% to under 5% in three years. This had an unintendedeffect on reef-feeding fish and the whole benthic community. Asterias amurensisis one of a few echinoderm invasive species. Its larvae likely arrived in Tasmaniafrom central Japan via water discharged from ships in the 1980s. The specieshas since grown in numbers to the point where they threaten commerciallyimportantbivalve populations. As such, they are considered pests, and are onthe Invasive Species Specialist Group's list of the world's 100 worst invasivespecies.
3. 在波利尼西亚的一项研究发现,当 2006 年海星迁移来之后,珊瑚覆盖率急剧下降, 三年间从 50%下降到 5%。这对以珊瑚为食的鱼类和底栖生物群落产生了影响。
Test Point – TPO31L3
We've been talking about the decline ofcoral reefs in tropical areas all over the world...urn... how natural andman-made stresses are causing them to degrade, and in some cases, to die. Sonow let's focus on a specific example of a natural predator that can cause alot of damage to coral reefs—the Crown of Thorns, or CoT starfish. The Cotstarfish is found on coral reefs in the tropical Pacific Ocean and it eatscoral. Now, in small numbers, the starfish don't affect coral reefsdramatically. But periodically, starfish population explodes. And when thathappens, the reefs can become badly damaged or even destroyed, something we aretrying very hard to prevent. For example, during the 1960s, there was anoutbreak of CoT starfish in the Great Barrier Reef, off the east coast ofAustralia. Luckily, the CoT starfish population gradually declined on its ownand the reefs recovered.
But we were left wondering - what cause thepopulation to increase so suddenly? Well, over the years, we've come up with afew hypotheses. All still hotly debated.
1.CoT starfish 存在于热带太平洋的珊瑚礁上,并且发现它是吃珊瑚的。
2.当大量的海星蔓延时,暗礁被严重损坏。比如 20 世界 70 年代,在澳大利亚东海岸,大堡礁有大规模的海星的爆发。幸运的是,海星数量逐渐下降,珊瑚礁逐渐恢复。