Ocean Pollution: A Pathway To Extinction

Ocean pollution is a pressing issue that poses a significant threat to marine life and ecosystems. Plastic pollution, in particular, has devastating consequences for marine species, causing ingestion, suffocation, entanglement, and internal injuries. The accumulation of plastic waste in oceans and on beaches has become a global crisis, with billions of pounds of plastic polluting the water and endangering wildlife. Climate change, driven by human activities, also contributes to the increasing risk of extinction for marine animals. Rising ocean temperatures and dwindling oxygen levels are pushing species out of their comfort zones, leading to local disappearances and potential mass extinction events. The impact of ocean pollution on marine life is dire, and immediate action is necessary to mitigate these threats and protect our planet's biodiversity.

Plastic pollution

The majority of plastic pollution in the ocean is caused by littering. Humans buy or use disposable plastic items (such as food wrappings, plastic bags, razors, and bottles) and do not dispose of them properly, causing them to end up in waterways and eventually in the ocean. Plastic waste makes up 80% of all marine pollution, and around 8 to 10 million metric tons of plastic end up in the ocean each year. The production and use of plastic are still at their highest, and the data on recycling is not promising: only about 10% of the plastic we produce is currently being recycled. The rest is either incinerated, causing air pollution, or ends up in our oceans and the environment.

Plastic accumulates in huge subtropical oceanic areas called gyres – massive circular currents that trap the floating plastic for decades, if not centuries. The most polluted gyre is the Great Pacific Garbage Patch, located in the North Pacific Ocean between Hawaii and California. It is estimated to be twice the size of Texas and contains around 100 million kilograms of plastic.

The impact of plastic pollution on marine life is devastating. It causes damage to animals when they come into contact with or ingest plastic, including suffocation, entanglement, laceration, infections, and internal injuries. Plastic pollution is also harmful to human health. Microplastics have been found in human blood, placentas, food, drinks, and tap water. Several chemicals used in the production of plastic materials are known to be carcinogenic and can cause developmental, reproductive, neurological, and immune disorders.

The build-up of plastic litter can also negatively impact a country's economy and trade systems, with income declines in sectors such as small- and medium-enterprises, tourism, fisheries, and agriculture. Plastic pollution is a transboundary issue, and a global plastics treaty is needed to reduce plastic production, phase out harmful subsidies, and eliminate products and chemicals that are harmful to the environment and human health.

Human waste

One of the primary concerns regarding human waste in the ocean is the presence of plastic. Plastic pollution in the ocean is largely caused by littering and improper disposal of plastic items such as food wrappings, plastic bags, bottles, and other disposable plastic products. These plastics can take hundreds of years to degrade and often find their way into waterways and, eventually, the ocean. Plastic waste accounts for 80% of all marine pollution, and it is estimated that by 2050, plastic may outweigh all fish in the sea.

The accumulation of plastic in the ocean has devastating consequences for marine life and ecosystems. Marine animals often become entangled in plastic debris, such as plastic bags and discarded fishing nets, leading to injury or death. Additionally, they may ingest plastic, metal, or glass, causing internal injuries, infections, and other health issues. Plastic pollution also affects seabirds, who mistake garbage for food, leading to painful impactions and death.

Another form of human waste contributing to ocean pollution is sewage. Sewage discharge, including untreated wastewater and stormwater runoff, contains high levels of pathogens, bacteria, viruses, and parasites, which can be harmful to marine life and ecosystems. Additionally, sewage can increase the frequency and severity of harmful algal blooms, further damaging marine habitats and ecosystems.

Agricultural runoff is another significant source of human waste in the ocean. Fertilizers, pesticides, and other chemicals used in agriculture can contaminate nearby rivers and estuaries, leading to the creation of "dead zones" where marine life cannot survive. These chemicals can also contribute to the increase in toxic algal blooms, which have detrimental effects on marine ecosystems, such as seagrass beds, and the organisms that depend on them.

The release of industrial waste is also a form of human waste that contributes to ocean pollution. Toxic chemicals, such as methylmercury, PCBs, and acid sludge waste, are often dumped directly into the ocean, leading to localized contamination and the destruction of marine habitats. Additionally, the leaching of toxic chemicals from plastic waste, such as microplastics and nanoplastics, can enter the tissues of marine organisms and accumulate in species consumed by humans, potentially impacting human health.

Oil spills

One of the most well-known examples of the impact of oil spills is the Deepwater Horizon oil spill in the Gulf of Mexico, also known as the BP oil spill disaster. This spill directly harmed a significant number of marine species, including fish, turtles, dolphins, whales, and birds. It is estimated that between 2 and 5 million larval fish were killed due to the toxicity of oil to their life stages, and many others were injured. The spill also affected the reproduction of fish and invertebrates, with impacts expected to last for decades.

The BP oil spill also pushed certain species closer to extinction. For example, the spill occurred during the peak spawning months for bluefin tuna, a severely overfished species. Additionally, the spill threatened the nation's smallest seahorse, the dwarf seahorse, as both oil and dispersants are toxic to seahorses and the seagrass they depend on. The spill also soiled the critical habitat of the federally threatened piping plover, and it is estimated that over 6,000 sea turtles were harmed, with official counts of turtle deaths being considered a dramatic underestimation.

Furthermore, the Deepwater Horizon oil spill had significant impacts on marine mammals and birds. Studies have shown that the injuries sustained by bottlenose dolphins in the affected areas were caused by oil from the disaster, and their populations are projected to decline by half. The long-term survival of the Bryde's whale population is also in doubt, as nearly half of this already small population was exposed to oil. At least 93 species of birds were exposed to oil, with brown and white pelicans being particularly affected.

Overall, oil spills can have far-reaching consequences for marine life, pushing species closer to extinction and causing long-term ecological damage. The impacts of oil spills on marine ecosystems highlight the importance of curbing planet-warming activities and addressing the root causes of climate change to prevent further harm to our oceans and the diverse life they support.

Chemical contamination

One of the primary sources of chemical contamination in oceans is the direct dumping of industrial waste. For example, the Southern California Bight has received an estimated 336,000–504,000 barrels of acid sludge waste generated during the production of DDT, a banned insecticide. This toxic waste continues to seep into the ocean, causing localized contamination and threatening marine life. Similarly, chemical discharges from factories, including mercury emissions, contribute to ocean pollution. Mercury, released primarily from coal combustion and small-scale gold mining, is a significant concern due to its persistence and toxicity.

Another significant source of chemical contamination is agricultural runoff. Excess chemical fertilizers used in agriculture eventually find their way into the oceans, leading to the growth of Harmful Algal Blooms (HABs) and the creation of aquatic dead zones. HABs produce potent toxins that accumulate in fish and shellfish, causing severe neurological impairment and even death when ingested by humans and other animals. Additionally, the global spread of industrialized agriculture increases the use of chemical fertilizers, leading to the expansion of HABs into previously unaffected regions.

Plastic waste also plays a crucial role in chemical contamination. Approximately 8 to 14 million tons of plastic enter the oceans annually, providing a vehicle for persistent organic pollutants (POPs) to reach remote areas. These POPs, such as PCBs and DDT, persist in the environment and accumulate in the bodies of marine organisms, threatening their health and populations. For example, high levels of PCBs have been found in the blubber of Europe's orca and bottlenose dolphins, impairing their reproductive abilities and pushing them towards extinction.

Furthermore, chemical contamination in the oceans is exacerbated by global warming and climate change. As the oceans absorb carbon emissions, they become more acidic, which can lead to the dissolution of calcium-containing microorganisms and the destruction of coral reefs. This acidification, in combination with other stressors, can contribute to the breakdown of the marine food chain and potential ecological collapse. Additionally, rising ocean temperatures force marine creatures to seek cooler waters, leading to the "extirpation" or local disappearance of once-common species.

Mercury emissions

Mercury is a toxic pollutant that poses a significant threat to both human and animal health. It is released into the environment through human activities such as mining, fossil fuel combustion, electricity production, and waste incineration. Once emitted, mercury eventually settles into water or land, where it can be washed into coastal waters. This process contributes to ocean pollution and has detrimental effects on aquatic ecosystems, particularly those with large wetland areas.

Elemental mercury, which makes up 95-99% of mercury in the atmosphere, can remain suspended in the air for up to a year before depositing on land or water. This makes it a global pollutant capable of travelling long distances from its source. Once deposited, certain bacteria can convert it into methylmercury, a highly toxic form that accumulates in fish, shellfish, and other aquatic organisms. Methylmercury has the ability to bioaccumulate, building up in the bodies of organisms over time, and bioconcentrate, increasing in concentration as it moves up the food chain. This poses risks not only to marine life but also to humans who consume contaminated seafood.

The presence of mercury in coastal waters has led to health advisories and warnings against consuming certain types of fish, such as shark, swordfish, king mackerel, and tilefish. These warnings are especially relevant for children, women of childbearing age, and individuals in certain regions with contaminated waters. The consumption of contaminated fish can result in toxic effects, with developing fetuses and young children being the most vulnerable.

The largest source of anthropogenic mercury emissions is artisanal and small-scale gold mining, contributing 37.7% of global emissions. This is followed by stationary coal combustion (21%), non-ferrous metals production (15%), and cement production (11%). In the United States, the electric utility industry, specifically coal-fired power plants, is the largest single source of mercury emissions. These emissions have severe impacts on aquatic ecosystems and contribute to the growing issue of ocean pollution.

To address the issue of mercury emissions and its impact on ocean pollution, regulatory measures and policies are necessary. Reducing mercury emissions and improving pollution control technologies can help mitigate the release of mercury into the environment. Additionally, promoting sustainable practices and reducing the use of disposable plastic items can contribute to decreasing ocean pollution and its potential contribution to extinction events.

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