2021-11-29

Research: the global ocean is out of balance, and human beings seem to have broken the laws of nature

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8ce86be38f3842f - Research: the global ocean is out of balance, and human beings seem to have broken the laws of nature

the idea called “Sheldon particle size spectrum” was first put forward in the 1970s, but it has not been tested in a wide range of marine species and around the world until now. An international research team, including researchers from McGill University, found that the theory seemed to have been established, but this natural balance has now been dramatically changed by extensive industrial fishing

in a study recently published in science advances, an international team including researchers from McGill University, Max Planck Institute of scientific mathematics in Germany, Institute of environmental science and technology in Spain, Queensland University of science and technology in Australia and Weizmann Institute of Science in Israel found that when the ocean is in a more primitive state (before the 20th century and the emergence of large-scale industrial fishing), the theory of particle size spectrum seems to be true.

Eric Galbraith, senior author of the study and professor of earth and Planetary Science at McGill University, said: “The fact that marine life is evenly distributed among different sizes is amazing. We don’t understand why this is needed – why can’t small things be much more than large things? Or an ideal size in the middle? In this sense, these results highlight how little we don’t know about ecosystems.”

from bacteria to whales – find a way to measure all marine life

in order to obtain an unprecedented current number of species, researchers use different recent studies to build a large global marine life data set, including bacteria, phytoplankton, zooplankton, fish and mammals. Their method enables them to distinguish the whole ocean Spatial distribution of 12 major aquatic groups in the study.

Ian Hatton, the first author of the study and researcher Alexander von Humboldt of the Max Planck Institute, recalls: “It is challenging to find a way to fully compare the measurement results of organisms with such large scale differences. Although micro aquatic organisms can be estimated from more than 200000 water samples collected around the world, larger marine animals can swim across the entire marine basin, which needs to be estimated in a completely different way.”

researchers also use historical reconstruction and marine ecosystem models to estimate the original ocean (before the 20th century) They found that although there were exceptions in both extremes – whales and bacteria – there was a very stable biomass of about 1 gigaton in each order of magnitude of body size. This means that the total amount of life in the ocean always adds up to about 1 billion tons between any size and ten times larger, Regardless of the initial size, industrial fishing has greatly changed this situation.

human impact on marine biomass

compared with the almost constant biomass spectrum in the original ocean, the researchers’ examination of the spectrum shows that human beings have a significant impact on the distribution of biomass in the largest size.

although fishing accounts for less than 3% of human food consumption, but Its impact on the biomass spectrum is devastating. Large fish (any fish longer than 10 cm) experienced a total biomass loss of about 2 billion tons (60% reduction) In fact, researchers estimate that the loss caused by industrial fishing and whaling in the past century is far greater than the potential biomass caused by climate change scenarios in the next 80 years Losses, even in pessimistic emission scenarios.

“from this global perspective, the biggest surprise is the huge inefficiency of fishing,” Galbraith pointed out, “When industrial fishing fleets go out to fish in the ocean, they don’t act like large predatory fish, seals or birds competing with them. They just consume a small amount of fish in a way to keep the fish stable. Human beings not only replace the top predators in the ocean, but completely change the energy flow of the whole marine ecosystem.”

in addition, he added: “the good news is that we can reverse the imbalance we have created by reducing the number of active fishing vessels around the world. Reducing overfishing will also help make fisheries more profitable and sustainable – if we can put our actions together, it is a potential win-win.”