Peruvian anchovy is a small fish about the size ofthe index finger of a person, which plays a large role in world fisheries. It accounts for up to 15% of the total world catch. In other words, anchovy is the most caught fish in the world. However, most of it is used to feed salmon and other valuable fish species raised on farms. But it looks like the situation may change in the future and anchovy will be in short supply. Studies of ancient sediments and fossils have shown that warming of the water at one time almost completely destroyed it. Scientists suggest that as a result of the impending global warming, the catastrophe could be repeated. Moreover, this time the fish may not survive the warming at all, because during the last warming, it was not caught on an industrial scale.
Global warming will change the ocean ecosystem
Research published in the journal Sciencespeaks of the catastrophic consequences of global warming for the entire planet, since it will entail a complete shift of the ocean ecosystem. The fact is that anchovy is the main element of the diet for various predators, from birds to marine mammals. Accordingly, as a result of its disappearance, they themselves may be on the verge of extinction.
In general, scientists have long been talking about the destructivethe impact of climate change on fish populations. The fact is that many species are able to reproduce only under certain temperature conditions. In addition, as a result of heating the water, the oxygen content in it decreases. This is especially detrimental to large fish species, which require more oxygen than small fish.
According to the authors of the work, if a large fishwill not be able to freely migrate to areas with cool water, small fish species will begin to dominate in the ocean. This can be a major problem in many coastal regions where large fish are a staple food.
How fish survived warming in the past
Renato Salvattechi, University biologistChristian-Albrecht in Kiel, in order to find out the effect of warming water on the ocean ecosystem, decided to study the state of affairs in the past. The waters of Peru turned out to be the perfect place for this. The seabed there contains a detailed fossil record due to the high sedimentation rate and abundance of fish.
The authors of the work studied a 14-meter core, whichwas mined by a research vessel in 2008. It contained an area of sediment between 116,000 and 130,000 years ago, when the Earth had a warmer climate. To figure out the temperature and oxygen concentration of seawater when sediment forms, scientists studied biomarkers produced by fossils of tiny marine organisms called coccolithophorids. The team also measured nitrogen isotopes. The data obtained showed that the water during this period was about 2 ° C warmer than today, while, as expected, it contained significantly less oxygen.
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Scientists managed to find out what types of fish lived inwaters, for this they collected bottom sediments for two years and studied the vertebrae. For the last hundred years, anchovy has predominated in the waters of Peru. But in the warm season, anchovy was not at all as common as it is now. About 60% of the fish were smaller species. These include goby fish, which are about half the size of anchovies. Species typical of deeper waters, such as the Panamanian fireflies, were also common. They, like goby, are able to live in conditions with low oxygen content.
Unfortunately, these types of fish cannot replaceanchovy as they are more difficult to catch due to their small size. In addition, they, unlike anchovy, do not gather in dense shoals. In terms of nutritional value, they also cannot be compared to anchovy. But how to save the latter from extinction if the water warms up by 2 degrees?
According to researchers, when fish populationsclimate change threatens, it is necessary to reduce the allowable catch. It would be better if people themselves ate more anchovies, and not feed them to fish. This would help preserve the species in sufficient numbers to be sufficient for humans and predators. Finally, I would like to note that changes in the ocean ecosystem as a result of climate warming are already being noted. Last year I talked about the fact that starfish were on the verge of extinction, as a result of which the number of algae began to sharply decrease.