The oceans, which account for 71% of the Earth's surface area, are not only an important factor in determining the development of the spherical climate, but also an effective way for human beings to obtain fresh water at present, for the time being, nearly 8,000 desalination plants around the world provide more than 6 billion cubic meters of freshwater resources for human beings every day.
At the same time, the ocean provides 90% of the living space for the earth, there are more than 200,000 species of known marine life, and there are 95% of the underwater world unknown to humans, and scientists expect that the actual number of marine life is 10 times or more than known.
The ocean is not only full of mystery for human beings, but also rich in products, and has always been considered the "future granary" of human beings. Unfortunately, to this day, only 5% to 10% of the proteins necessary for the human body come from the ocean.
Logically, this proves that we humans can also ask for more from the oceans. However, there are already many marine species depleted, and the most intuitive manifestation is that some fish are more difficult to catch.
Overfishing and pollution have devastated entire marine ecosystems. Oil, heavy metals, pesticides, domestic sewage, etc., every year countless marine pollutants are intentionally or unintentionally dumped into the sea by humans, of which the garbage floating on the sea surface alone has exceeded 3.5 million square kilometers, which is larger than india's land area and more than 7 times the area of France, and this number is increasing at a rate of more than 80,000 square kilometers per year. It is known as the "Seventh Continent" created by mankind!
Plastic waste is a major component of the "Seventh Continent", accounting for 41%. More than 1 million animals die each year from marine plastic litter, not including the hazards caused by microplastics smaller than 5 millimeters in diameter.
In 2004, "microplastics" were first proposed by British scientists, and the uncertainty of their hazards has since attracted widespread attention. In 2018, Chinese researchers determined that there are microplastics in the seawater, as well as in the seabed and seabed sediments.
As the research progressed, researchers even found about one-thousandth of a millimeter of microplastics in krill (for more information, see my other article "Krill can "crush" plastic in 96 hours!"). Research finds that the harm of microplastics is gradually emerging).
The growing focus on microplastics has led to concerns about marine pollution as well as concerns about whether microplastics will "infect" the entire food chain?
A July 2020 survey of researchers in the UK seemed to give the answer. They conducted stomach and digestive tract examinations of four species of 46 deep-sea sharks "mistakenly caught" in the local fishery and found that nearly 70% of the sampled sharks contained microplastics and other man-made fibers. Although the effects of these plastics on shark health are unclear, the researchers believe that this has highlighted the "pervasive nature of plastic pollution."
What worries researchers is not only the proportion of microplastic sharks, but also a synthetic cellulose particle. Because this particle is most commonly found in textiles (including disposable hygiene products such as masks) and clothing, the recycling of disposable hygiene products such as masks has become increasingly difficult during the COVID-19 pandemic.
At the same time, researchers found that the larger the shark, the more plastic inside, and the largest shark contained 154 plastic fibers in its stomach and intestines. So they speculate that the plastic should enter the shark's body through two ways: (the more you can eat, the more plastic you have in your body)
The first is food sources.
Fish, crustaceans, turtles and other marine mammals have all recorded microplastic uptake and are passed on to sharks through bioaccumulation in the food chain.
The second is seafloor sediments
Deep-sea sharks often feed on the seafloor, and the process of feeding inevitably sucks into the sediment of the seafloor, although a large part of it is immediately spat out by them, but some sediment containing microplastics is swallowed.
The researchers have only examined the stomach and digestive tract of deep-sea sharks so far, and cannot rule out the possibility that microplastics are also present in other parts of the shark's body, such as liver and muscle tissue, which requires more research time.
At the same time, the researchers also pointed out that microplastics will have a negative impact on the feeding behavior, development, reproduction and lifespan of plankton and crustaceans at the bottom of the food chain, but it is still poorly understood how organisms at the top of the food chain (such as sharks and humans) will affect their health after ingesting microplastics.
One researcher involved in the study put it this way: "Our dependence on plastics and the lack of mechanisms to protect the oceans is suffocating. Sharks are at the top of the marine food chain and play a vital role in marine ecosystems, and now that researchers have found that they are eating 'plastic,' what about humans at the top of the entire food chain?
Perhaps humans should limit or stop the production of plastics other than non-essentials, and establish and improve marine conservation mechanisms to provide space for wildlife and humans to recover. After all, the ocean is not our dump, and it's better to have more marine life than more plastic?