The Economist 经济学人精读 [32] Size r

The Economist 经济学人精读 [32]

选自 December 16 2017 Science and Technology

How fish sustain forests[鱼类怎样维系森林]

Size really matters 大小很重要

#Eva💭说#

由于小型鱼类的用途广泛，目前对钓鱼者和商业渔民在捕获小型鱼类的限制已经有很多。但是，最近研究发现，大型鱼类在对栖息地的维护和再生也扮演着重要角色。大型鱼类在转播植物种子方面至关重要。主要因此，研究人员建议，也应在捕获大型鱼类上加以限制。

#以上，个人总结和理解，欢迎批评指正，欢迎留言讨论#

#有输出才有进步#

Among fish, big individuals do most to help habitats[在鱼类中，较大的雨对栖息地的帮助最大]

For anglers[钓鱼的人] nothing beats catching a big fish[对于钓鱼的人来说，没有什么能比得上钓到一条大鱼]. Commercial fisherfolk also prefer to haul in big specimens[样品][商业渔民同样倾向于捕获个头较大的鱼]. Unfortunately, in recent years, research has shown that selectively capturing the largest fish has worrying ecological consequences[近些年不幸的是，研究人员发现了选择性捕获最大的鱼会带来令人担忧的生态后果]. In some species the large ones are the healthiest ones, and so the ones most likely to breed successfully[在一些鱼类中，最大的鱼是最健康的，也是那些最有可能成功繁殖的]. In others they are the oldest, and so the most experienced at eluding[躲避] predators or securing resources, such as food and breeding sites[在另一些鱼类中，最大的鱼是最老的，也是在躲避捕食者，寻找资源，比如食物资源和繁殖地点方面经验最丰富的]. In tropical wetlands, such as the Pantanal and Amazon regions of Brazil, the largest fish are also vital in dispersing[扩散] seeds—and thus maintaining and regenerating habitat[在一些热带湿地，比如像巴西的潘塔纳尔和亚马逊地区，最大的鱼同时对散播种子很重要，这样就可以使栖息地得到维护和再生].

Trees in these areas fruit most prolifically[多产的丰富的] during the summer[在这些区域水果在夏天是最丰富的], when local rivers burst[充满] their banks and flood the land[夏天，当地的河流充满河床，并淹没了土地], making those fruit available to fish, which gladly gobble them up[大口吞食][使鱼类可以大口吞食掉在地上的水果]. Then, as the fish swim around the floodplain[漫滩], they pass the seeds inside those fruit, which often remain intact[完好无损的], as part of their faeces[粪便][之后，随着鱼在漫滩中游，它们将水果内通常完好无损的种子随着粪便排泄出来]. These seeds are thus distributed far and wide[这样以来，这些种子将被广泛的分配]. Researchers have found that the most effective distributors are the biggest ones[研究者发现，最有效的播散种子的是那些最大的鱼]. Because they have bigger bellies they eat more, and because they have wider mouths they are more likely to swallow seeds whole rather than chew them up[咬坏], as smaller fish might[因为它们有较大的胃可以吃更多，也因为它们的嘴更大，更有可能整个吞咽种子而不是像那些较小的鱼会嚼碎种子].

Many studies of seed-eating fish have thus looked at large species[这样以来，众多研究以种子为食的鱼类都将目光放在较大的物种上]. Yet small fish also distribute seeds, especially small seeds[但是，也有小型鱼类同样能够播种，尤其是小种子], according to a review of the scientific literature just published in Biotropica by Raul Costa-Pereira and his colleagues at São Paulo State University. That led Mr Costa-Pereira to speculate about[推测] the role of large specimens in populations of smaller fish[这引发了Costa-Pereira对大型鱼类在小型鱼类中所扮演角色的猜测]. This matters, because when stocks of larger species are depleted[减少的] commercial fishermen often start “fishing down” the food chain to capture smaller ones[这很重要，因为当大雨的数量减少时，商业渔民通常会开始沿着食物链去捕获较小的鱼].

The researchers therefore monitored the seed-eating behaviour of tetra[脂鲤] fish, which grow to a length of 12cm, and fresh water sardines[沙丁鱼], which make 18cm[因此，研究人员开始监视通常能长到12厘米的脂鲤和18厘米的沙丁鱼的食用种子的行为]. Since both species patrol[巡逻] areas where trees drop ripe fruit during the flood season, and both are also caught by fishermen when they approach their maximum size[因为这两种鱼都在雨季成熟水果坠落的地方觅食，也因为它们都达到最大尺寸的时候被渔民捕获], Mr Costa- Pereira speculated that selective fishing of the largest tetra and sardines would reduce the number of intact seeds that the animals would later defecate[排便][Costa-Pereira推迟，选择性的捕获最大的脂鲤和沙丁鱼会使得由它们排出的完整种子减少].

The team collected a sample of fish on the Miranda river flood plain in the Pantanal[研究团队在潘塔纳尔的米兰达河的漫滩收集样本鱼], measured the lengths of their specimens and the gapes of their jaws[下颌] with calipers[卡钳][测量它们的长度，并用卡钳分开它们的下颌], and then analysed the animals’ gut contents under a microscope[然后在显微镜下分析它们胃中的成分]. They found that 63% of seeds counted in the guts of the freshwater sardines had been destroyed by chewing[它们发现淡水沙丁鱼胃中63%的种子被咬坏], and 22% of those in tetras had suffered the same fate[脂鲤的胃中的22%的种子遭受了同样的命运]. Crucially, they also found, for both species, that the number of intact seeds did indeed increase with the size of the fish they came from[最重要的是，他们发现对于两个物种，随着它们尺寸的增大，完整种子的数量的确在增加].

Mr Costa-Pereira therefore believes that the same rule applies to small fish species as to big ones—namely, the largest individuals play the biggest role in distributing seeds[因此，他们相信同样的规律同样适用于小型鱼类物种，也就是，最大的个体在传播种子中扮演最重要的角色]. This, he suggests, needs to be considered when catch limits are set[他建议，在设定捕获限制时，应该考虑到这一研究结果]. The catching of small species, which are used not only as food for people but also to feed animals and as bait[诱饵], is often less regulated than the catching of large ones[小型鱼类不仅被用来做人类的食物，也被用作喂养动物和做诱饵，对于小型鱼类捕获的限制通常要低于捕获大雨]. Intensive fishing can rapidly deplete the number of smaller fish[密集捕鱼会快速减少小型鱼类的数量]. If the biggest individuals go first, there could be repercussions[影响恶果] for the wider ecology of a flood plain[如果最大的鱼类迅速减少的话，将会对更大范围的漫滩生态系统带来影响].

20171221  580 words

【elude】

to not be caught by someone

避开，逃避，躲避

They eluded the police by fleeing.

他们纷纷逃窜，避开了警方的搜捕。

【disperse】

to spread across or move away over a large area, or to make something do this

（使）扩散，（使）散开，（使）分散

When the rain came down the crowds started to disperse.

雨下来时人群开始四处散开。

Police dispersed the crowd that had gathered.

警察驱散了聚在一起的人群。

【gobble】

to gobble

大口吞食，狼吞虎咽

【intact】

complete and in the original state

完整无缺的；未经触动的

The church was destroyed in the bombing but the altar survived intact.

教堂在轰炸中被毁，但神坛却完好无损。

【chew up】

If a machine chews up something that you have put inside it, it damages or destroys it.

（机器）绞坏，咬坏，损坏

The cash machine chewed up my card!

【speculate】

to guess possible answers to a question when you do not have enough information to be certain

猜测；推测，推断

I don't know why she did it - I'm just speculating.

我不知道她为什么那么做——我只是猜测。

A spokesperson declined to speculate on the cause of the train crash.

一位发言人拒绝就火车相撞事件的原因作出推测。

Journalists are speculating about whether interest rates will be cut.

记者们在猜测是否会降息。

[ + that ] The newspapers have speculated that they will get married next year.

报纸猜测他们明年会结婚。

【depleted】

reduced

消耗的；耗费的；减少的

Measures have been taken to protect the world's depleted elephant population.

人们已经采取措施保护世界上已经为数不多的大象。

physically/emotionally depleted (= weakened)

体力／感情上的消耗

【repercussion】

the effect that an action, event, or decision has on something, especially a bad effect

（尤指坏的）影响，反响；恶果

Any decrease in tourism could have serious repercussions for the local economy.

旅游业只要出现任何一点儿衰退，都可能会给当地经济带来严重影响。

President Kennedy's assassination had far-reaching repercussions.

肯尼迪总统遇刺产生的影响是深远的。

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