Pollution's Impact On Marine Life: Understanding The Devastation

Marine life is incredibly diverse, with millions of unique species inhabiting the planet's seas and oceans, which cover over 70% of the Earth's surface. However, this rich biodiversity is under serious threat from pollution, primarily in the form of plastic waste. Over the last decade, humans have produced more plastic than in the previous century, and billions of pounds of plastic now pollute the oceans, with devastating consequences for marine life.

Plastic ingestion

Marine life is facing a grave threat from plastic pollution, with billions of pounds of plastic in the oceans, and this pollution is only expected to increase. Plastic ingestion is a significant issue, causing harm to a wide range of marine organisms, from small finches to blue whales.

Fish in the North Pacific ingest 12,000 to 24,000 tons of plastic each year, causing intestinal injuries and even death. This plastic then moves up the food chain, affecting larger fish, marine mammals, and ultimately, humans who consume seafood. A recent study found that a quarter of fish at markets in California had plastic in their guts, mostly in the form of plastic microfibers.

Sea turtles are also highly vulnerable to plastic ingestion, mistaking floating plastic garbage for food. This can lead to choking, internal injuries, and even death. Tragically, research indicates that half of the sea turtles worldwide have ingested plastic, and it is affecting their reproduction.

Hundreds of thousands of seabirds face a similar fate each year, ingesting plastic that reduces stomach storage volume, leading to starvation. It is estimated that 60% of seabird species have eaten plastic, and this number is predicted to rise to 99% by 2050. Dead seabirds are often found with stomachs filled with plastic, a stark reminder of the growing plastic pollution crisis.

Critically endangered marine mammals, such as the Hawaiian monk seal, are not spared either. Large amounts of plastic debris have been found in their habitats, including areas where they nurse their young. Entanglement in plastic debris has caused injuries and deaths among these seals and other species like the endangered Steller sea lion.

The impact of plastic ingestion goes beyond the immediate physical harm. Microplastics, in particular, can have chemical impacts as well. They attract and absorb free-floating pollutants like polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and heavy metals, which can then be ingested by marine organisms. Experiments have shown that fish and oysters exposed to contaminated plastics or polystyrene suffer liver damage and reduced reproductive output, respectively.

The ubiquity of plastic in the oceans and the potential for human health impacts is concerning. While most microplastics remain in the guts of fish, they will eventually degrade into nanoplastics, which are tiny enough to penetrate cells and move into tissues and organs. The effects of nanoplastics on human health are still unknown due to the lack of analytical methods to identify them in food.

Entanglement in plastic

Entanglement can cause drowning, starvation, physical trauma, and infections in marine animals. It restricts their movement, making it difficult for them to escape or find food. Smaller animals, such as sea turtles, seals, and dolphins, are particularly vulnerable and may drown immediately if entangled in large or heavy gear. Even if they do not drown, they may suffer from exhaustion and infection. Entanglement also increases the risk of vessel strikes as entangled animals may be unable to avoid ships or boats.

Some specific examples of the impact of entanglement include:

• Endangered Hawaiian monk seals and Pacific loggerhead sea turtles are among the nearly 700 species that get entangled in plastic litter.
• Entanglement in plastic debris has led to injuries and deaths in the endangered Steller sea lion population, with packing bands being the most common entangling material.
• Dead whales have been found with bellies full of plastic, indicating that they ingested plastic debris that blocked their digestive tracts.
• In New Zealand, pods of endangered humpback whales have been observed with masses of tangled ropes and other debris in tow. Attempts to free them have been successful in some cases but failed in others.
• Derelict fishing gear, such as trawl nets and gillnets, can continue to capture and kill wildlife, even after being lost or discarded. This phenomenon is known as "ghost fishing."

The problem of plastic entanglement in marine life is expected to worsen, with the fossil fuel industry planning to increase plastic production by 40% in the next decade. Urgent action is needed to address this growing crisis and protect marine ecosystems and the diverse life they support.

Chemical pollution

Marine life is incredibly vulnerable to chemical pollution, which is caused by the introduction of harmful contaminants into the ocean. Before 1972, copious amounts of toxic chemicals, industrial waste, untreated sewage, and even millions of tons of heavy metals and radioactive material were dumped into the sea. Although regulations have increased, chemical pollution continues to be a significant issue, with animal agriculture being a leading cause. Fertilizers, herbicides, and pesticides used in animal agriculture leach into rivers, which then flow into the ocean.

Other chemical pollutants include crude oil, which has ended up in the ocean through oil spills, such as the Deepwater Horizon disaster. The impact of these chemicals can be devastating, causing dead zones that can span hundreds of miles and kill all marine life within them. These chemicals are consumed by sea creatures, ending up in their digestive systems and causing intestinal injuries and even death.

One of the most well-known examples of chemical pollution is the use of DDT, an insecticide that placed the bald eagle on the United States Fish and Wildlife's endangered species list. While bald eagles have since been removed from the list, they are still protected under the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act.

Another concerning issue is the presence of PFAS, a chemical found in many household products, which has been found to accumulate in the blood of both humans and marine mammals. Additionally, pharmaceuticals ingested by humans but not fully processed by our bodies can also end up in aquatic food webs, impacting marine life.

Noise pollution

Marine mammals, including whales, dolphins, and porpoises, are highly dependent on sound for their survival. They rely on sound to communicate, locate mates and prey, avoid predators, navigate, and defend their territories. However, noise pollution interferes with their ability to detect acoustic signals, reducing their communication range and causing them to change their vocal behaviour. For example, increased ship noise has led to bottlenose dolphins simplifying their vocal calls, which may reduce the effectiveness of their communication.

The impact of noise pollution on marine life can be fatal. Very loud sounds can cause panic, leading to decompression sickness and tissue damage from gas bubble lesions. It can also cause temporary or permanent hearing loss, behavioural and physiological changes, and masking—where the ability to detect sound is overlapped or covered by another sound. In some cases, it can even lead to death. For example, whales have been known to strand themselves after tactical sonar exercises, and mass strandings of giant squids occurred in coastal areas of Spain between 2001 and 2003 due to noise pollution.

To mitigate the impact of noise pollution on marine life, several organizations and researchers have suggested various solutions. These include implementing policies to reduce propeller noise from ships, mitigating the sounds of sonar equipment, pile driving, seismic air guns, and wind turbines, and developing quieter technologies. The Port of Vancouver has introduced incentives for ships to reduce noise pollution, offering reductions in port fees for vessels with lower noise levels.

Light pollution

A study by the University of Plymouth in England found that green light wavelengths leave up to 76% of the seafloor exposed to light pollution, and blue light wavelengths leave up to 70% exposed. This is significant because of the potential impact on marine species. For example, light pollution lowers the rate of photosynthesis in corals, affecting the organisms that live in the reefs. Coral reefs represent the most diverse marine ecosystems on Earth, so this is a serious issue.

The widespread use of LED lighting is changing the nature of artificial light. LEDs typically have more short-wavelength light than older technologies and can penetrate deeper into the water. Efforts to reduce light pollution by transitioning to more energy-efficient lighting may therefore have unintended consequences for marine life.

Measuring light pollution in the ocean is challenging due to the low light intensities involved and the fact that the spectrum and magnitude of light underwater can change with tides and water clarity. However, it is essential to understand the impact of light pollution on marine life and to develop effective mitigation strategies. This may include reducing the use, duration, and intensity of artificial lighting, particularly blue and green light, and using more red light, which does not penetrate as far into the water.

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