棘冠海星可以在攻击珊瑚礁前数年繁殖

棘冠海星可以在攻击珊瑚礁前数年繁殖

Vast outbreaks of crown-of-thorns seastars can consume and devastate corals on tropical reefs, as if corals didn't already have enough problems. Prior to their coral-eating adulthood, however, the seastars (sometimes known as starfish) go through an algae-eating juvenile phase. New research reveals the starfish can wait in this phase, building their numbers, until the time is right to transform and descend on a reef like locusts.

大量的棘冠海星会吞噬和毁灭热带珊瑚礁上的珊瑚，好像珊瑚还没有遇到足够多的问题。然而，在它们吃珊瑚的成年期之前，海星(有时被称为海星)经历了一个吃海藻的幼年期。新的研究表明，海星可以在这一阶段等待，增加它们的数量，直到时机成熟，它们可以像蝗虫一样蜕变并降落在礁石上。

Stephen Luntz

Unlike most of the threats coral faces, crown-of-thorns attacks are not human-induced. Nevertheless, their rampages appear to be becoming more frequent, which is probably a consequence of our actions. One popular theory blames extra nutrients from fertilizer runoff increasing the phytoplankton starfish feed upon during their larval stage. However, Professor Maria Byrne of the University of Sydney is skeptical.

与珊瑚面临的大多数威胁不同，棘冠类的攻击不是人为造成的。然而，它们的暴行似乎越来越频繁，这可能是我们行动的后果。一种流行的理论认为是化肥径流增加了浮游植物海星在幼虫期的营养。然而，悉尼大学的玛利亚·伯恩教授对此表示怀疑。

“The connection is tenuous,” she told IFLScience, pointing to coral untouched by runoff that have suffered major crown-of-thorns outbreaks. Instead, “there is this whole juvenile stage in between that has been ignored.”

她对IFLScience说:“这种联系很薄弱。”她指的是那些没有受到径流影响的珊瑚，它们已经遭受了棘冠类珊瑚的大规模爆发。相反，“在这两者之间的整个青少年阶段被忽视了。”

Juvenile crown-of-thorns seastars while still in their vegetarian phase. University of Sydney

It used to be thought that all it took for algae-eating juveniles to transition to adulthood was for the starfish to become large enough to wrap itself around some vulnerable coral. In Biology Letters, however, Byrne and PhD student Dione Deaker show transition timing depends not just on size but on the availability of coral, at least in the lab. One set of seastars fed on algae for 10 months, growing to 16-18 millimeters (1.6-1.8 centimeters) before making the transition. Others, raised without tempting corals to consume, went for 6.5 years without becoming adults, yet grew no larger in size. It seems they were just waiting for the right moment, and when this came, they proved just as voracious predators of corals as their younger counterparts. It helps explain how such enormous outbreaks can start so suddenly.

过去人们认为，吃海藻的幼体到成年只需要海星长得足够大，就可以把自己包裹在一些脆弱的珊瑚周围。然而，在《生物学快报》上，拜恩和博士生迪昂·迪克(Dione Deaker)指出，转变的时间不仅取决于珊瑚的大小，而且至少在实验室里，还取决于珊瑚的可获得性。另一些则在没有引诱珊瑚食用的情况下长大，在没有成年的情况下生活了6.5年，但它们的体型并没有变大。它们似乎只是在等待合适的时机，而当时机到来时，它们证明了自己和年轻的同类一样，都是贪婪的珊瑚捕食者。这有助于解释为何如此大规模的疫情会如此突然地爆发。

Byrne told IFLScience no one knows how seastars move into predator mode, but she thinks it may involve the development of the capacity to consume the waxy esters that make corals inedible to many other animals.

Byrne告诉IFLScience，没有人知道海星是如何进入捕食模式的，但她认为这可能涉及到消耗蜡质酯的能力的发展，这种蜡质酯使得许多其他动物无法食用珊瑚。

"Another important implication of our findings is the possibility that the current adult starfish killing programs used to manage crown-of-thorns starfish might, in fact, trigger a feedback mechanism in the starfishes' transition to coral predator as juveniles are released from adult competition," Byrne noted in a statement.

Byrne在一份声明中指出:“我们的发现的另一个重要含义是，目前用于管理刺冠海星的成年海星捕杀程序，实际上可能会触发一种反馈机制，使海星在从成年竞争中释放出来后，过渡到珊瑚捕食者。”

Nevertheless, even if current reef protection methods are ineffective, it is not clear what should occur instead. Byrne sees little alternative to programs that remove all the adult crown-of-thorns from the reefs most frequented by tourism and she stresses that pollution and nutrients from the land damages coral in other ways.

然而，即使目前的珊瑚礁保护措施是无效的，也不清楚应该采取什么措施。拜恩认为，除了将所有成年棘冠鱼从游客最常去的珊瑚礁上清除之外，几乎没有其他选择。她强调，陆地上的污染和营养物质会以其他方式损害珊瑚。

It's possible, Byrne noted, that animals that prey on juvenile crown-of-thorns have been depleted by human activity. If so, the best thing we can do is bring them back, but first they would need to be identified.

拜恩指出，有可能是人类活动耗尽了以幼冠棘为食的动物。如果是这样，我们能做的最好的事情就是把他们带回来，但首先他们需要被识别。

An adult crown of thorns. University of Sydney