評(píng)論
打印
Contrary to what you just read, there are ways to control the zebra mussel's spread.
與你們剛剛所閱讀的相反，有許多方法來控制斑馬貽貝的傳播。
What's more, it is not so clear that the mussel is a serious threat to fish populations.
而且，也沒有明確的說法貽貝對(duì)魚類來說是一個(gè)嚴(yán)重的威脅。
True, the spread of zebra mussels couldn't be controlled in the past, but that's because people didn't have enough knowledge.
是的，斑馬貽貝的傳播在過去不能被控制，但那是因?yàn)槿藗儗?duì)其了解不夠。
In fact, there are effective ways to stop ships from carrying the mussels to new locations.
事實(shí)上，有一些有效的方法來防止船舶把貽貝帶到新的地方。
Here's an example. The way zebra mussels usually travel across the ocean
這里有一例。斑馬貽貝在海洋中穿行常用的方法是，
is that a ship takes on some fresh "ballast water" in Europe and then empties that water into American waterways when it arrives.
船舶在歐洲裝上一些新鮮的“壓艙水”，然后在到達(dá)美國時(shí)把這個(gè)說倒入其航道。
Full of zebra mussels, but the ship can be required to empty out the freshwater and refill with ocean water while still out in the ocean.
水里滿是斑馬貽貝，但是可以要求該船仍在海洋中時(shí)把淡水倒掉重新裝上海水。
Salt water will kill the mussels.
海水能殺死貽貝。
Second, it's true that zebra mussels often don't have predators in their new habitats, but that's only in the beginning.
第二，斑馬貽貝在新的棲息地里沒有掠食者這是真的，但，僅僅是在開始的時(shí)候。
What's been happening in Europe is that local aquatic birds sooner or later notice there's a new food source around and change their habits to exploit it.
在歐洲已經(jīng)發(fā)生的是，當(dāng)?shù)氐乃B遲早會(huì)發(fā)現(xiàn)周圍有一個(gè)新的食物來源并且改變它們的習(xí)慣來捕食貽貝。
They switch from whatever they were eating before to eating zebra mussels.
不管它們以前吃什么，他們轉(zhuǎn)而吃斑馬貽貝。
And birds can eat a lot of mussels.
鳥兒們能吃掉很多的貽貝。
So zebra mussels aren't so likely to dominate their new habitats after all.
所以，斑馬貽貝終究不太可能占領(lǐng)新的棲息地。
Finally, even in habitats where zebra mussels become dominant, is the overall fish population likely to decrease?
最后，即使在斑馬貽貝占領(lǐng)者的棲息地里，全體魚類的數(shù)量有可能減少嗎？
It's true that zebra mussels may have a negative impact on fish that eat plankton.
當(dāng)然，斑馬貽貝可能對(duì)那些吃浮游生物的魚類著負(fù)面影響。
But on other fish, they can have a positive impact.
但對(duì)其他魚類，他們會(huì)有一個(gè)正面的影響。
For example, the mussels generate nutrients that are eaten by fish that feed near the bottom of the lake or river.
比如，貽貝能產(chǎn)生營(yíng)養(yǎng)物質(zhì)，供在靠近湖底或者河底覓食的魚類食用。
So bottom-feeding fish populations may increase, even if plankton-eating fish population (decrease).
所以，即使吃浮游生物的魚類數(shù)量會(huì)減少，吃殘羹剩餐的魚類數(shù)量可能會(huì)增加。
