鲸落（Whale Fall），指鲸鱼死去后沉入海底的现象。当鲸鱼在海洋中死去，它的尸体最终会沉入海底，生物学家赋予这个过程为鲸落。一座鲸鱼的尸体可以供养一套以分解者为主的循环系统长达百年，鲸鱼死亡后落入深海形成的生态系统，与热液、冷泉一同被称为是深海生命的“绿洲”。在北太平洋深海中，鲸落维持了至少有43个种类12490个生物体的生存，促进了深海生命的繁荣。

Whale fall refers to the phenomenon of a whale sinking to the bottom of the ocean after it dies. When a whale dies in the ocean, its carcass eventually sinks to the bottom of the sea, a process named whale fall by biologists. A whale carcass can feed a decomposer-based recycling system for up to 100 years, and the ecosystem formed by a whale’s falling into the deep sea after death is known as an “oasis” of deep-sea life, similar to hydrothermal and cold springs. In the deep waters of the North Pacific, whale falls sustain at least 43 species of 12,490 organisms and contribute to the prosperity of deep-sea life.

2020年4月3日，中科院“探索一号”科考船搭载“深海勇士号”载人潜水器顺利抵达三亚。此次航行的重要成果之一，是科学家在南海首次发现一个约3米长的鲸落。作为全球现存最大的动物，鲸鱼活着的吋候是海洋生态的重要组成，死的时候它也会给海洋以馈赠，变成鲸落。

On April 3, 2020, the scientific research vessel “Exploration of the Nanhai No.1” of Chinese Academy of Sciences (CAS) arrived in Sanya with the manned submersible “Deep Sea Warrior”. One of the important achievements of this voyage was that scientists found a 3-meter-long whale fall for the first time in the South China Sea. As the world’s largest existing animal, the whale is an important component of marine ecology when it is alive, and it also contributes to the ocean when it dies in the way of whale fall.

 

那么，鲸落到底是什么呢？其实，鲸落是指掉入洋盆或深渊的鲸鱼的尸体。鲸鱼类等动物巨大的身躯无法快速被食腐生物分解殆尽，因而会落入海底。尸体落入海底的过程可以长达数月甚至数年，会为食物链的各类型消费者，包括深海鱼类、甲壳类、多毛类等提供食物。最后剩下的骨架会释放硫化氢供给自养生物化能合成，这个过程可以持续数年，还有一些厌氧生物可以吃掉鲸骨，分解脂类。一次鲸落形成的生物聚落可以持续数十甚至数百年，在北太平洋深海中，至少有1万多种生物体是依靠鲸落生存的。

So, what exactly is a whale fall? In fact, a whale fall is the carcass of a whale that has fallen into an ocean basin or abyss. The huge bodies of animals such as whales cannot be completely and quickly decomposed by scavengers so they fall to the bottom of the ocean. The process of falling can last for months or even years, providing foods for all types of consumers in the food chain, including deep-sea fish, crustaceans, polychaetes and others. The remaining skeleton will release hydrogen sulfide to supply autotrophic organisms’ chemical synthesis, a process that can last for years, and there are anaerobic organisms that can eat the whale bones and break down lipids. Biological colonies formed by a single whale fall can last for tens or even hundreds of years, and there are at least 10,000 species of organisms depending on whale fall for survival in the deep North Pacific.

 

鲸落生态系统可分为四个演化阶段：

The whale-fall ecosystem can be divided into four stages.

移动清道夫阶段（mobile-scavenger stage）：在鲸尸下沉至海底过程中，盲鳗、鲨鱼、一些甲壳类生物等以鲸尸中的柔软组织为食。这一过程可以持续4（至少）至24个月（取决于鲸鱼的个体大小）。期间90%的鲸尸将被分解。

Mobile-scavenger stage. During the sinking of whale carcasses to the bottom, hagfish, sharks and some crustaceans feed on the soft tissues of the carcasses. This process can last from 4 (at least) to 24 months (depending on the size of the individual whale). During this period, 90% of the whale carcass will be decomposed.

机会主义者阶段（enrichment opportunist stage）：机会主义者（机会种）能够在短期内适应相应环境而快速繁殖。这里所说的环境，就是鲸尸、鲸骨。在这个阶段，一些无脊椎动物特别是多毛类和甲壳类动物，能够以残余鲸尸作为栖居环境，一边生活在此，又一边啃食残余鲸尸，不断改变它们自己的所在环境。

Enrichment opportunist stage. Opportunists (opportunistic species) are able to adapt to their environment and reproduce rapidly in a short period of time. The environment mentioned here is whale carcasses and whale bones. In this stage, some invertebrates, especially polychaetes and crustaceans, can use the remnants of whale carcasses as their habitats and live there while eating the remnants of whale carcasses, constantly changing their own environment.

化能自养阶段（sulphophilic stage）：大量厌氧细菌进入鲸骨和其它组织，分解其中的脂类，使用溶解在海水中的硫酸盐作为氧化剂，产生硫化氢。化能自养细菌例如硫化菌，则将这些硫化氢作为能量的来源，利用水中溶解氧将其氧化，获得能量。而与化能自养细菌共生的生物也因此有了能量补充。

Sulphophilic stage. A large number of anaerobic bacteria enter the whale bones and other tissues, decomposing the lipids and using the sulphates dissolved in seawater as oxidants to produce hydrogen sulphide. Chemoautotrophic bacteria, such as Sulfobacterium, use dissolved oxygen in the water to oxidize hydrogen sulfide and obtain energy. The organisms that live in symbiosis with chemoautotrophic bacteria are thus energized.

礁岩阶段（Reef stage）：当残余鲸落当中的有机物质被消耗殆尽后，鲸骨的矿物遗骸就会作为礁岩成为生物们的聚居地。

Reef stage. When the organic material is completely consumed, the mineral remains of the whale bones become the reef as a settlement for the organisms.

 

从鲸落的整体过程我们可以看出，鲸落的意义在海洋生态系统中有一定的重要地位。

From the overall process of whale fall, it can be seen that the whale fall has a certain importance in the marine ecosystem.

首先，最直观的，它为许多海洋生物提供了食物。这些海洋生物除了无脊椎动物和鱼类，还有许多微生物。与这些微生物相比，鲸鱼的个体大小差别巨大，因此一头鲸鱼的死亡能够养活的海洋生物个体数量是相当可观的。

First and most obviously, it provides foods for many marine organisms. These marine organisms include many microorganisms in addition to invertebrates and fish. Compared to these microorganisms, the size of individual whales varies greatly so the number of individual marine organisms that can be supported by the death of one whale is considerable.

其次，鲸落为许许多多的底栖生物提供了复杂的生境。一望无际的海底平原因为鲸落的出现而产生了小规模的环境变化，这样的生境变化尤其受一些钻孔生物、附着生物的欢迎。残余鲸落的出现为一些底栖动物提供了庇护场所，也为它们提供了有机质来源。

Second, whale falls provide complex habitats for many benthic organisms. The presence of whale falls produces small-scale environmental changes in the endless submarine plain, and such habitat changes are particularly welcomed by some marine boring organisms and attaching organisms. And the presence of remnant whale falls provides shelter for some benthic animals and a source of organics for them.

另外，鲸落促进了海洋上层有机物向海洋中下层的运输。深海的生产力仅依靠化能自养细菌供给是不够的，海洋生物进食和死亡产生的碎屑，例如海雪和鲸落，促进了营养物质向下运输，以供给深海的生物，也促进了化能自养细菌产生更多的能量。

In addition, the whale falls facilitate the transport of organics from the upper to the middle and lower layers of the ocean. The productivity of the deep ocean is not sufficient to be supplied by chemoautotrophic bacteria alone, and the debris produced by feeding and death of marine organisms, such as marine snow and whale falls, facilitates the transport of nutrients downward to supply organisms in the deep ocean, as well as the production of more energy by chemoautotrophic bacteria.

最后，鲸落这一独特的生态系统促进了一些新生物种的产生。称其为新生物种，主要是因为这类物种只出现于鲸落这一特定环境，科学家们还未在其它海洋生境当中发现。例如Osedax frankpressi和Osedax rubiplumus都是仅发现于鲸骨当中的小动物，鲸落里的秘密还有许多等着我们去发现。

Finally, the unique ecosystem of whale falls has facilitated the production of a number of “new species” which get the name mainly because they occur only in the specific environment of the whale falls and have not yet been found in other marine habitats by scientists. Osedax frankpressi and Osedax rubiplumus, for example, are small animals found only in whale bones, and there are many more secrets to be discovered in whale falls.

鲸落的形成和消失对许多生物来说是漫长的。现存的鲸落数量比过往少之又少，有些特定种群，例如灰鲸的西太种群数量仅可怜的两位数，现状令人担忧。倘若人类捕食鲸类、食用鲸肉而不加以节制，恐怕其影响的生物数也数不清。但是，深海里的生物也不全靠鲸落生存，其各有各的生存之道。鲸落的消逝对未来海洋生态系统的影响，还在人们的探索目标中。

The formation and disappearance of whale falls are long for many organisms. The number of existing whale falls is much fewer than in the past, and some specific populations, such as the population of gray whales in Western Pacific, are in the low double digits, a worrying state of affairs. If humans hunt cetaceans and consume whale meat without restraint, more creatures than can be counted will be affected. However, the deep sea organisms do not depend entirely on whale falls for their survival, as each has its own way of surviving. The impact of the demise of whale falls on the future of marine ecosystems is still being explored.

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参考文献：https://doi.org/10.3354/meps13196