The Pacific West Coast faces a huge marine litter hazard, affecting fisheries resources and marine biodiversity.
In May 2020, a brown-toothed dolphin was stranded on Taiwan‘s Taoyuan beach, with undigested jellyfish and plastic bags still in its stomach pouch; more than a year ago, a stranded mother beaked whale in Hualien also had a stomach stuffed with a mess of plastic trash and a fetus in its belly that was too late to be born. This ocean plastic storm is sweeping the world, and the western Pacific is quietly being hit hardest.
Plastic concentration rises off China’s coast
From China to Taiwan, the monitoring data of marine litter hit the nail on the head to show the alarm. 2019 China’s offshore seabed litter average density of 15.9 kg / km2, plastic litter accounted for 92.6%, the Bohai Sea monitoring section sea surface floating microplastic density of 0.82 / cubic meters, plastic concentration increased by 17% year-on-year. The seabed trash in the estuary off the west coast of Taiwan is not far behind, with an average density of 70 kg / km2, 1.5 times the global average.
The plastic trash swallowed by cetaceans is just the tip of the iceberg, and research released by The Pew Charitable Trusts in July 2020 shows that if humans don’t take any action, the amount of plastic flowing into the ocean will increase from the current 11 million tons each year to 29 million tons by 2040, and the cumulative total of ocean plastic could reach 600 million tons, and the researchers made the analogy that “this is equivalent to the weight of 3 million blue whales.”
Where exactly is all this ocean litter floating? “When we search online for the distribution of marine litter, the typical distribution is concentrated in the subtropical circulation zone of the oceans, but is it really only concentrated in those places?” The question came to the mind of Yijia Xin, an associate researcher at the Environmental Change Research Center of Academia Sinica in Taiwan, who is engaged in physical ocean research, and he used currents and wind resistance effects to track the simulation. This is the biggest difference from the past.”
Plastic is the largest amount of marine litter off the coast of China, and microplastic concentrations continue to rise. (Reuters)
Western Pacific Ocean in Crisis
The study, which used big data on ocean currents from 1993 to 2017 to conduct a computational analysis and found new hotspots for marine litter accumulation, was published in the Journal of Environmental Research Letters in October 2020, naming the Western Pacific Ocean as a big hit.
According to Yijia Xin, the research team further examined the overlap analysis of high wind resistance litter concentration areas and other environmental factors, including chlorophyll concentration (phytoplankton and often accompanied by fishing grounds), fishing operation density, and biodiversity hotspots, and on a global scale, the West Pacific has the highest overlap percentage, which also means that the West Pacific will be hit harder.
The distribution of sea-drifting plastic garbage varies according to size and material. “For lighter garbage such as polaroid and PET bottles, it is more likely to be concentrated along the coast, or on the western side of the ocean and in the equatorial zone.” Xin Yijia illustrated, “However, during the drifting process, there is a chance that plastic garbage will be broken into pieces or even decomposed into plastic particles, which then become non-wind-blocking garbage and may eventually return to the center of the subtropical circulation.”
“As plastic litter continues to accumulate in the ocean, the concentration of microplastics will get higher and higher, and the mortality rate of plankton will follow.” Chen Guoqin, researcher and acting director of the Center for Biodiversity Research at Academia Sinica, raised the alarm that “plankton is the most basic part of the food chain pyramid, and when food for fish decreases and fishery resources fall, the whole marine ecosystem will be affected.”
Some people describe microplastics as the ocean’s PM2.5, this diameter of less than 5 millimeters of microplastics, because of the extremely small size, compared to plastic bags and other marine litter, more easily eaten by marine organisms, toxic risks gradually surfaced, a study has such as the head of the stick.
Taiwan research team found that the toxicity of microplastics will triple the mortality rate of the next generation of barnacles. (Reprinted from the journal Environmental Pollution)
Microplastic toxicity spans generations
“When intertidal barnacles eat microplastics, the current generation itself can still develop and reproduce normally, however, the next generation of young is slow to develop and has a higher mortality rate.” Chen Guoqin discovered the cross-generational toxic effects of microplastics in a paper published this December in the international journal Environmental Pollution, the first study of marine organisms with complex life histories, unlike most previous studies of lifelong plankton in a single habitat.
Chen Guoqin said barnacles are one of the most common marine organisms, and they exist in almost all marine environments, while barnacles go through two stages in their life, planktonic and benthic, with juveniles being planktonic and adults living benthic, adhering to rocks on the seafloor or elsewhere above, and may ingest microplastics under different environmental conditions, so they are relatively well represented.
“The smaller the microplastic, the more toxic it is.” Chen Guoqin points out the crisis, he led the research team to different sizes of polystyrene (Polystyrene) microplastics fed barnacles, ranging from 1.7 microns to 7 microns, not only the mortality rate of the next generation is three times higher than the control group, when the previous generation of barnacles eat into the microplastics more tiny, the mortality rate of the next generation of juveniles is also higher, “which represents the toxicity of microplastics will affect the perpetual survival of the species.”
The mystery of microplastics in the ocean continues to be solved, Chen Guoqin said, and other studies have found that when microplastics are as small as nanometer level, they can penetrate cells and enter other tissues. In addition, microplastics may adsorb toxic substances in the marine environment, and after the food chain, the toxin effect is amplified and continuously accumulated in the bodies of middle and high order predators.
Microplastics through the biological role of the rate of cleavage, let people pinch the cold sweat. This year, Irish scientists found that a small telopod crustacean (Gammarus duebeni) could digest microplastics into smaller nano-sized particles within four days after ingestion, while the fragmentation of microplastics was most evident during feeding.
Chen Guoqin pointed out that this small telopod crustacean has teeth that can bite into the microplastics eaten, and after entering the digestive tract and being discharged, other organisms may eat smaller microplastics, and the feces discharged by these marine organisms with microplastics will also sink to the seafloor relatively quickly, and seafloor organisms have a greater chance to eat microplastics, which in turn affects the marine ecosystem.
It is not difficult to imagine that microplastics are changing the marine ecology of the Pacific Ocean. The Hong Kong Polytechnic University and City University recently published a study, the western waters of Hong Kong microplastics size ranging from 31 to 5000 microns, including the most serious pollution of the estuary, the average number of microplastics 6 to 14 times higher than other places, and the western waters of Hong Kong and near-shore mudflats is the habitat of horseshoe crabs, including endangered species of Chinese horseshoe crabs, microplastics have a negative impact on Chinese horseshoe crabs.
Each year, the flow of plastic waste into the ocean continues to increase, scientists from various countries have invested in microplastics research. (Reuters)
The ecological lament of the Chinese horseshoe crab
The Hong Kong team used young Chinese horseshoe crabs bred in captivity to conduct the study. The Chinese horseshoe crabs in the microplastic environment lost 3 to 7 percent of their body weight compared to the control group, and their mobility was significantly reduced by 60 percent.
While coastal intertidal zones are hot zones for biodiversity, the threat of microplastics continues to heat up. Chen Guoqin said that many intertidal organisms are filter-feeding organisms, which can easily eat microplastics by filtering seawater and ingesting plankton; there are also many snails in the intertidal zone, and the algae on the rock surface is one of their food sources, and microplastics can also be stuck in the algae; when microplastics sink into the mud flats, crabs or other mud-eating organisms also have the opportunity to eat high concentrations of microplastics, and the potential crisis of intertidal ecology The potential crisis of intertidal ecology cannot be ignored.
Horseshoe crabs are known as living fossils, including the Chinese horseshoe crab, which is listed as an endangered species, and scientists have found that microplastics can increase their mortality rate.
Scientists have recorded more than 800 marine species affected by plastic, Xin Yijia pointed out, among them from cetaceans, sea turtles to seabirds are affected by plastic, especially marine organisms eat microplastics, may be transformed and stored in the muscles, internal organs, and eventually humans also eat into the stomach.
As the strongest predator on the surface, humans have found microplastics in feces, liver, fat, and even placenta, and the conservation challenge is about to begin.
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