Nature’s beauty is multifaceted. Within its complex systems, there are traditionally beautiful sights like flowers and forest, but there is also a darker beauty that is just as much a part of our world–death and decomposition. Every creature on this planet depends on every other for its survival; this includes human beings.
The interconnectivity of ecosystems is something that contemporary advocates of nature’s importance are very much aware of, and it is something that is tied directly to the life cycle of creatures big and small. One of the most important animals on the planet, the whale, has a unique role to play after death for the organisms on the deep seafloor. The whale’s body, if it falls in the right place, is used and transformed after death into strikingly interesting and complex ecosystems. It can play host to up to five trophic levels of animals at a time, creating what some scientists and observers have deemed a “feast”.
What is a Whale Fall?
A whale fall is what happens after a whale dies and the carcass sinks to the bathyal or abyssal zones, or a depth greater than 1,000 m or 3,300 ft. They do not float on the surface of the water as some lighter and small creatures might, they sink or “fall” to the bottom of the ocean floor. Once there, their bodies decompose, becoming an incredibly diverse habitat for the creatures who stumble upon them. Animals come to eat the whale’s remains, to make new homes, and to hunt other smaller animals who have also been drawn to the whale fall. The whale makes something of a buffet for marine creatures of all sizes and appetites.
Whale falls were first discovered in 1854 after a new mussel species was found inside a piece of whale blubber. Approximately 100 years later, deep-sea trawlers were recovering more evidence of these unique ecosystems. One of the best studies of the events started in 1988 by researchers from the University of Hawaii. The scientists who worked on this project came to the incredible conclusion that one 40-ton whale carcass is equivalent to two-thousand years worth of normal carbon. Normally, creatures emend on smaller decomposing plants and animals falling from the surface for sustain, known as “marine snow”. When a whale falls, it is cause for widespread celebration on the ocean floor. One whale fall is equivalent to 1,000 years of marine snow.
Not every whale death is categorized as a “whale fall”. Some bodies fall to shallower depths where they are consumed much more quickly by scavengers. Full-grown whales can play host to up to five trophic levels at a time while smaller, juvenile whales can only support around three.
Stages of a Whale Fall Ecosystem
Researchers have concluded that there are four distinct phases in a whale-fall ecosystem. These are as follows:
- Mobile-Scavenger Stage: the first wave of organisms, scarves, hagfish, and larger crustaceans come to clean the carcass. Consumption is estimated to be at around 88-132 pounds or 40-60 kilograms per day. It lasts from months to 1.5 years.
- Enrichment-Opportunist Stage: in this stage, smaller organisms (such as worms and crustaceans) dig through the sediment to find bits of decomposing tissue. Animals also colonize the bones. This stage lasts from months to 4.5 years.
- Self-fulfilling Stage: this stage is the longest. Bacteria consume the fat in the bones and produce hydrogen sulfide. That then powers other microscopic organisms. This stage is one of the longest, lasting between 50 to 100 years. The period makes studying these phenomena difficult.
- Reef Stage: the finals stage of the whale-fall ecosystem. The fat depleted bones are fed on by suspension feeders.
Exploration of Whale Falls
Whale falls are explored through the use of deep-sea robotic devices starting in the 1970s. In 1977 the first abyssal whale fall was discovered by the US Navy. Since then, numerous whale falls have been motored using submersibles and ROVs, or remotely operated underwater vehicles. They have helped scientists learn about patterns of ecological succession. This term refers to the process of change in the structure of species in a community over time. The time scale can be decades or millions of years.
Why are Whale Falls Important?
Whale falls create an incredible source of nutrients for a variety of creatures, often in areas that are devoid of a steady supply of those same nutrients. In the bathyal and abyssal zones, which categorize a whale fall, the carcasses create complex local ecosystems. Deep-sea organisms can feed on the body for decades afterward.
The Effects of Whale Hunting
Unsurprisingly, the whale hunting industry has had an impact on the creation of these important ecosystems. With more whales being removed from the oceans and less breeding, the number of whale falls has also been reduced. Scientists are just beginning to understand the effects that the over-hunting of whales is having on deep-sea organisms but they believe that it’s not insignificant. The removal of large whales from the sea could, some scientists predict, remove 30% of the overall biomass of the deep sea. The amount of carbon sequestered by the oceans is also decreased due to whale hunting.
Whales are an undeniably important part of all marine ecosystems and the broader system that effects all living things, whether they dwell on land or under the sea. A healthy, balanced ocean means that humanity as the best possible change to maintain a healthy society. Scientists agree that only when humankind learns to live alongside the rest of the natural world, rather than in opposition to it, the earth will truly be balanced.
Whales are by far the largest animals in the ocean, but there are some others that scientists have also spent time researching that could provide a similar habitat for deep sea creatures. Although, it would be a much less extensive one. For example, a whale shark carcass that was discovered alongside three mobile ray carcasses. These four carcasses did provide some manner of sustenance for the scavengers around them, such as the hagfish, but the bodies had not progressed past the first stage, the “mobile-scavenger stage”.