Pollution's Impact On Marine Life: Understanding The Devastation

Marine pollution is a pressing issue that poses a significant threat to the health and sustainability of our planet. Oceans cover 70% of the Earth's surface and are home to diverse marine ecosystems that support millions of species. However, human activities have led to the contamination of our oceans with chemicals and trash, causing severe consequences for marine life and human health. The impact of pollution on marine ecosystems is extensive and far-reaching, affecting everything from microscopic plankton to enormous blue whales.

Plastic pollution

In addition to the direct impacts on marine life, plastic pollution also has indirect effects on marine ecosystems. For example, discarded fishing nets can smother and break coral reefs, preventing their healthy growth. Plastic pollution can also provide new habitats for invasive species, further disrupting the natural balance of marine ecosystems.

The accumulation of plastic in the ocean also has socio-economic impacts, including negative effects on commercial fishery, tourism, shipping, and human health. The presence of plastic debris on beaches and in the marine environment can reduce the aesthetic value and natural beauty of these areas, leading to a decrease in tourism. Additionally, the removal of plastic litter from ships can incur significant costs for shipping companies, and the ingestion of contaminated seafood by humans can have adverse health effects.

To address plastic pollution, a combination of global, regional, and national initiatives is necessary. This includes implementing policies and regulations to reduce plastic production, promote recycling and reuse, and improve waste management practices. Public awareness and education are also crucial in tackling this issue.

Chemical contamination

Marine pollution is a combination of chemicals and trash, most of which comes from land sources. Chemical contamination, or nutrient pollution, is concerning for health, environmental, and economic reasons. This type of pollution occurs when human activities, such as the use of fertiliser on farms, lead to the runoff of chemicals into waterways that ultimately flow into the ocean. The increased concentration of chemicals, such as nitrogen and phosphorus, in the coastal ocean promotes the growth of algal blooms, which can be toxic to wildlife and harmful to humans.

Algal blooms, also known as "red tides", can have devastating effects on health and the environment. They harm local fishing and tourism industries by killing marine life and causing negative health outcomes in humans. Excess nitrogen and phosphorus in seawater also cause oxygen depletion, creating dead zones where very little marine life can survive.

Another example of chemical contamination is crude oil, which has ended up in the ocean through spills like the Deepwater Horizon disaster in 2010. Oil spills ensnare and suffocate marine animals by permeating their gills. When oil gets into seabird feathers, they may not be able to fly or feed their young. Animals that aren't killed by crude oil may suffer from cancer and behavioural changes and become unable to reproduce.

Chemical pollution also includes the use of herbicides and pesticides, which leach into rivers that lead to the ocean. These chemicals can be toxic to sea creatures and end up in their digestive systems, causing internal injuries that reduce their ability to swim and fly.

In addition to the direct impact on marine life, chemical contamination can also have indirect effects. For example, small organisms that consume microplastics absorb the chemicals from the plastic into their tissues. These organisms are then eaten by larger animals, and the toxic chemicals become part of their tissues as well. This allows the pollution to migrate up the food chain, eventually becoming part of the seafood that humans eat.

Oil spills

The magnitude of harm caused by oil spills depends on factors such as the amount of exposure, the pathway of exposure, the age and health of the animal, and the synthetic chemicals used in the clean-up process. Oil spills can have both direct and indirect effects on wildlife, leading to changes in behaviour, relocation of home ranges, and increased foraging time.

The Valdez oil tanker spill in 1989, for example, resulted in the death of an estimated 250,000 seabirds, 2,800 sea otters, 300 harbour seals, 250 bald eagles, and up to 22 killer whales. Even decades later, some species had not recovered, and the economic losses were significant, with clean-up costs reaching around $2 billion.

Overall, oil spills have far-reaching and long-lasting impacts on marine ecosystems, wildlife, habitats, and human communities, underscoring the importance of prevention, containment, and effective response strategies to minimise their detrimental effects.

Noise pollution

Anthropogenic noise can cause auditory masking, leading to cochlear damage, changes in individual and social behaviour, altered metabolisms, hampered population recruitment, and can subsequently affect the health and service functions of marine ecosystems. It can also cause stress in animals, increase the risk of mortality by unbalancing predator-prey interactions, and interfere with sound-based orientation and communication, especially in reproductive contexts.

Noise can harm marine mammals in several ways. Very loud sounds can cause panic, leading to decompression sickness and even death. It can also cause temporary or permanent hearing loss, behavioural and physiological changes, and injury. For example, loud noises can lead to hearing loss, which can prove fatal when sound is one of the main tools marine mammals use for survival.

Noise can also alter the behaviour of marine mammals. A foreign sound can disrupt their natural behaviour, causing them to move away from the noise, adjust their activities to avoid noisy times, or increase their anti-predatory behaviour. It can also interfere with communication by masking the detection of acoustic signals, leading to changes in individual and social behaviour, altered metabolisms, and hampered population recruitment, which can affect the health and service functions of marine ecosystems.

To reduce noise pollution in the marine environment, policies are needed to reduce propeller noise from ships and mitigate the sounds of sonar equipment, seismic air guns, pile driving, and construction. Quieter technologies also need to be developed to make it easier to reduce noise pollution and improve the ocean soundscape, potentially enabling the recovery of some marine life.

Light pollution

A study by the University of Plymouth in the UK found that artificial light from coastal cities is affecting around three-quarters of their neighbouring seafloor habitats. The impact of light pollution on marine life was already known to some extent, but this is the first study to measure its effects on creatures at the bottom of the sea. The researchers spent four nights in 2018 studying the waters of Plymouth Sound and the Tamar estuary, looking for light infiltration in the form of red, green, and blue wavelengths. They found that while red wavelengths had a minimal impact, 76% and 70% of green and blue lights, respectively, reached the seafloor. These same colours are present in the LEDs used to light up city streets.

This type of light pollution causes an 'artificial skyglow', disrupting the natural biological cycles of marine life on the seafloor, which relies on moonlight to regulate behaviours such as reproduction, sleep, feeding, and protection from predators. For example, baby sea turtles use the moonlight reflecting on the waves to reach the sea after hatching, but artificial lights can confuse them.

The transition from yellow incandescent lights to white LEDs exacerbates the problem, as the latter contains more of the blue and green wavelengths that can penetrate deep into the water. As coastal cities continue to grow, light pollution will likely increase too.

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