Environment: whale poo helps maintain vital ecosystem parts – study

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Could the decline in the number of whales during the 1900s have a major impact on the ocean ecosystem? This appears to be exactly the case, according to new research.
The study itself, published in the academic journal Nature and the result of a collaboration between Stanford University, NOAA’s environmental research division, and the University of California at Santa Cruz, among others, posed a question: How much food do whales eat?

The answer: much more than previously thought.

Finding out was, in itself, incredibly difficult. Cetaceans are some of the most fascinating animals on the planet, whether because of their immense size, wide range, cultural value, intelligence, and possible vocal abilities. However, they are also some of the most difficult animals to study.

As they have been the largest living things on the planet throughout its history – at least in weight – besides being underwater, it is incredibly difficult to keep them in captivity. In fact, for larger whales, it is downright impossible.

A blue whale surfaces to breathe in an undated U.S. National Oceanic and Atmospheric Administration photo (Credit: NOAA / HANDOUT VIA REUTERS)

Studying them is possible, however, although incredibly difficult.

Because of these limitations, the best that researchers could usually do when trying to study the feeding habits of whales was to study dead whales.

This time, however, they used high-tech beacons to monitor the whales. The whales in this study were all baleen whales, which means that instead of nibbling prey with the help of teeth, they instead use small patches of baleen in their mouths to essentially filter out and swallow massive amounts of food. small preys.

Although they eat such small prey, these whales are among the largest – in fact, the largest of them, the blue whale, is the largest form of life that has ever existed.

The beacons were able to record the movements of the whales – as well as sounds and videos, if the light permitted – and drones were used to measure individual whales. The study also used an echo detector, which was used to detect the amount of prey present.

Being so big, it was believed that in order to maintain themselves baleen whales like the blues and humpback whales had to eat a lot of krill, which is incredibly small. And according to this study, the amount is much more than previously believed, with whales eating 2-3 times more krill than expected.

Krill is seen on a finger (illustrative).  (credit: Wikimedia Commons)Krill is seen on a finger (illustrative). (credit: Wikimedia Commons)

“As the large baleen whales get bigger, the anatomical machinery that allows them to eat also becomes relatively larger,” explained Jeremy goldbogen, Co-Director of the Hopkins Marine Station and Associate Professor of Biology in the School of Humanities and Sciences, and lead author of the article. “They have evolved these systems that allow them to be eating machines. This disproportionately larger sip size allows them to enjoy plentiful food, such as krill.

However, these results raise serious questions about this ecosystem as a whole.

EARTH’S DIFFERENT ecosystems are often incredibly delicate, and small changes can often have major consequences.

Before 1910, the whale population in the Southern Ocean – near Antarctica – was much larger. Their numbers declined massively from 1910 to 1970, due to whaling operations in the region. Although whaling has since ceased, the whale population is still only a fraction of itself.

A map showing the location of the Southern Ocean.  (credit: Wikimedia Commons)A map showing the location of the Southern Ocean. (credit: Wikimedia Commons)

But if whales eat so much krill, then before 1910 the krill population should logically be able to accommodate them. According to researchers, this means that the current krill population is about five times smaller than it was supposed to be before whaling began in 1910.

And that has serious implications beyond the sheer amount of krill.

The circle of life

The fact that a drop in the number of whales means a drop in the amount of krill may seem counterintuitive, as one would think that the prey population would soar if their predator was no longer present. However, this is not the case, and this can be explained by understanding how the ecosystem itself works.

Krill, along with other small fish and shellfish, is consumed by other animals as part of the food chain. And at the top of that food chain, and also while eating this krill, are the whales.

However, krill is not at the bottom of the food chain. They, along with small fish and crustaceans, survive by eating phytoplankton, a type of microscopic algae essential to the functioning of the global ecosystem.

A collection of phytoplankton.  (credit: Wikimedia Commons)A collection of phytoplankton. (credit: Wikimedia Commons)

These planktons have chlorophyll and thus carry out photosynthesis. This means that they need to be close to sunlight and therefore are usually found on top of the water. They are found in water bodies around the world – in fact, their distribution is so wide that they greatly eclipse plant life.

They are so essential to the functioning of the planet that many scientists estimate that between 50% and 80% of all oxygen production on Earth comes specifically from ocean life like plankton. In fact, only one species of this plankton, the smallest species known as the Prochlorococcus, produces more oxygen than all the tropical rainforests combined.

THEY ALSO have another important role: to help move along the carbon cycle, the means by which heat and carbon dioxide expelled into the atmosphere are essentially reabsorbed by the planet. This in itself is a critical means of stopping climate change, as the amount of carbon dioxide currently being expelled into the atmosphere from the use of burning fossil fuels far eclipses what the carbon cycle can handle.

Due to their small size, these plankton usually cannot be seen with the naked eye, but when the concentration is high enough in a given area, colored spots of the water can be seen.

Phytoplankton flourish in the Barents Sea near northern Europe.  The high concentration allows these microscopic organisms to be seen through the staining of their collective chlorophyll.  (credit: Wikimedia Commons)Phytoplankton flourish in the Barents Sea near northern Europe. The high concentration allows these microscopic organisms to be seen through the staining of their collective chlorophyll. (credit: Wikimedia Commons)

Phytoplankton are everywhere, but there is a particularly high abundance of them in the Southern Ocean. Here, they are also an essential link in the food chain.

But despite being at opposite ends of the food chain, it is the whales that are essential in helping to maintain the ocean’s phytoplankton population.

And this is done by shit.

Although they photosynthesize, phytoplankton also need iron to survive. They were able to achieve this through the iron released when baleen whales defecate after eating krill, thus releasing the iron from the krill into the water. It is through this life cycle that phytoplankton are able to thrive. This is a very important process, and when the whale population was higher it was even more efficient.

“Think of these large whales as mobile krill processing factories,” said Matthew Savoca, postdoctoral researcher at the Goldbogen Lab at Stanford Marine Station Hopkins and lead author of the article. “Every fin or blue whale is the size of a commercial airliner. So in the first half of the 20th century, before whaling, there were an additional one million of these 737-sized krill processing factories that traveled the Southern Ocean to eat, poop, and fertilize. .

These findings have more ramifications, as they further show how important whales are to the environment – and how humans and whales impact ocean ecosystems, essentially making them less productive. It also sheds light on the complexity of ecosystems as a whole and how there is still so much that humanity has yet to understand.


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