Dr Anjani Ganase, marine ecologist, considers the natural progression of a dead whale in the ocean. Scientists are discovering that the impacts of 'whale falls' continue for decades and even centuries.
The sun supports all life on our planet - well, nearly all life.
Animals depend on plants to create food through photosynthesis (the process by which plants harness sunlight and water to create sugar).
Plant life is the foundation of the global food web. Consider that 70 per cent of the planet is ocean, and 90 per cent of the ocean is deep ocean, which is deeper than 1,000 metres (the average depth of the ocean is more than 3,600 metres). Any ocean beyond 1,000 metres deep is beyond the penetration of sunlight, and photosynthesis does not occur at depths below 200 metres.
Does the sun support life, even in the deepest darkest part of our oceans?
Life in the deep seas persists. In such a nutrient desert, life exists as a result of several adaptations, including having low metabolism, gulping and feeding on almost anything and, of course, not wasting energy on visual aesthetics.
The food chain of the deep ocean is driven instead by chemosynthesis, in which microbes use chemicals emitted by hydrothermal vents and cold seeps to generate food, which are then consumed by other deep-sea grazers, such as crabs and shrimp.
Despite the contribution of food through chemosynthesis, a large portion of the deep-sea dwellers rely on fallen debris from the nutrient-rich sunlit areas of the ocean. When organisms die in the ocean, they are quickly consumed by surrounding organisms, and whatever is left breaks down into particles of detritus and drifts to the bottom of the ocean as marine snow. Deep-ocean residents graze on this food source on the sediment bottom of the ocean.
Scientists through their explorations found that sometimes even big animals sink to the bottom of the ocean, providing a sudden delivery of a nutrient-rich source, and the organisms share in a feast.
Whale falls occur when a whale carcass sinks to the bottom of the ocean, creating a nutrient-rich energy source. Whale carcasses may float for a while, allowing sharks and other predators to satisfy their hunger, but eventually the whale sinks to the bottom. A 40-ton whale carcass can provide an equivalent of 200 years of food from marine snow. It is a very rich energy source that supports deep-sea communities for decades and forms an island oasis at the ocean floor.
While natural whale falls are rarely encountered, about 22 falls are observed globally (many are intentional sinks for research purposes). These have been observed in the northern Pacific Ocean, Antarctica and Southern Atlantic Ocean. They provide key insights into the deep-sea biodiversity and food web.
Scientists of Ocean Networks Canada (ONC) have the rare opportunity to revisit a whale fall site adjacent to where they deployed seafloor observatory instrumentation. Revisiting their instruments has allowed annual visits of the whale-fall sites to track the changes in
