Marine Pollution: Ecosystem Disruptor And Its Devastating Impact

Marine pollution, also known as ocean pollution, is the contamination of ocean waters and coastlines by different substances, including oil, plastic, industrial and agricultural waste, and chemical particles. It is a pressing issue that poses a significant threat to marine ecosystems and the organisms that inhabit them. The impact of marine pollution on the diverse range of plants and animals that call the ocean home cannot be overstated, and it is essential that we recognise the role we play in causing it.

Plastic pollution

Sources of Plastic Pollution

The majority of plastic pollution in the ocean stems from littering and improper waste disposal. Disposable items such as food packaging, plastic bags, razors, and bottles are often not disposed of properly, ending up in waterways and eventually reaching the sea. Additionally, about 20% of ocean plastic pollution originates from industrial fishing and improper manufacturing processes.

Impact on Marine Life

Effects on Marine Ecosystems

Human Health Implications

Addressing Plastic Pollution

Preventing plastic pollution requires a combination of individual actions and societal changes. On an individual level, reducing plastic use, reusing and recycling plastic items, and supporting cleanups are essential. However, addressing the root of the problem also requires legislative support, improved waste management systems, reconsideration of disposable packaging, and reduced manufacturing of single-use plastics.

Chemical pollution

Marine pollution is a combination of chemicals and trash, most of which comes from land sources. Chemical contamination, or nutrient pollution, is a growing concern for health, environmental, and economic reasons. This type of pollution occurs when human activities, such as the use of fertilizer on farms, lead to the runoff of chemicals into waterways that eventually 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. These algal blooms consume oxygen and block sunlight, creating "dead zones" where few marine organisms can survive. Some chemical pollutants also climb high into the food webs, such as DDT, which at one time placed the bald eagle on the United States Fish and Wildlife's endangered species list.

Other common man-made chemical pollutants that reach the ocean include pesticides, herbicides, fertilizers, detergents, oil, industrial chemicals, and sewage. These pollutants are often released into the environment far upstream from coastlines. For example, nutrient-packed fertilizers applied to farmland can end up in local streams and are eventually deposited into estuaries and bays.

The effects of chemical pollution on marine ecosystems are wide-ranging. Marine animals are frequent victims, with oil spills ensnaring and suffocating them, and crude oil causing cancer, behavioural changes, and reproductive issues. Chemical pollution also affects the health of marine plants, such as coral, by increasing their exposure to disease-causing viruses, bacteria, and other microorganisms.

Additionally, small organisms ingest toxins and are then eaten by larger predators, including seafood consumed by humans. This can lead to long-term health conditions, cancer, and birth defects in humans.

Light pollution

Impact on Marine Life

Marine species have evolved in tandem with natural light cycles, governed by the sun, moon, and stars. Artificial light pollution disrupts these cycles, affecting behaviours such as reproduction, sleep, feeding, and protection from predators. For example, copepods, which are keystone organisms in many marine food webs, migrate daily in response to moonlight, which they can detect at great depths.

Zooplankton, another critical component of marine ecosystems, migrate nightly from the ocean floor to the surface. However, light pollution inhibits their migration, which can have cascading effects on fisheries and aquatic ecosystems.

Extent of the Problem

A study by the University of Plymouth in the UK revealed that artificial light from coastal cities affects up to three-quarters of neighbouring seafloor habitats. Green and blue light wavelengths, commonly found in coastal LED lighting, reached the seafloor in significant amounts, disrupting the natural biological cycles of marine life.

The problem is expected to worsen as coastal populations continue to grow. By 2060, coastal populations are projected to more than double, leading to increased light pollution and further endangering marine habitats.

Addressing the Issue

Experts emphasise the need for mitigation plans aimed at reducing the use, duration, and intensity of urban lighting. This includes promoting sensible energy use and encouraging the use of less harmful lighting options, such as orange lighting, which penetrates the sea less than blue light.

The European Union is addressing artificial light pollution as part of its biodiversity strategy for 2030, and the United Nations has adopted light pollution guidelines through the Convention on the Conservation of Migratory Species of Wild Animals. Additionally, researchers are working to expand their modelling processes to a global scale to better understand the distribution of artificial light and its impacts.

Noise pollution

Marine pollution has a significant impact on our ecosystem, and noise pollution is a critical component that threatens marine life. Noise pollution in the ocean refers to sounds generated by human activities, which can interfere with marine animals' ability to hear the natural sounds in their environment. As visibility is often low underwater, sound plays a crucial role in the survival of many marine species, especially for marine mammals like whales, dolphins, and porpoises. They rely on sound to communicate, find prey and mates, avoid predators, navigate, and defend their territories.

Over the past few decades, noise pollution in the ocean has intensified due to various human activities, including shipping, recreational boating, energy exploration, seismic surveys, explosions, construction, and the use of sonar devices. These activities introduce foreign sounds that disrupt the natural behaviour of marine mammals, causing them to move away from the noise, adjust their activities, or increase their anti-predatory behaviour. For example, sonar has been observed to alter the feeding behaviour of endangered blue whales, causing them to stop feeding and swim away from the sound source.

The loudest underwater noises often come from naval sonar devices, which work similarly to echolocation used by whales and dolphins. The use of military sonar has been linked to mass strandings of beaked whales and other cetaceans. Loud noises can also cause hearing loss and even death in marine mammals. If the animals are too close to the sound source, they may panic and ascend too rapidly, leading to decompression sickness and tissue damage.

To mitigate the impacts of noise pollution on marine ecosystems, it is essential to implement policies that reduce propeller noise from ships and mitigate the sounds of sonar equipment, seismic air guns, pile driving, and construction. Developing quieter technologies can also play a crucial role in reducing noise pollution and improving the ocean soundscape, enabling the potential recovery of marine life.

Thermal pollution

One of the primary effects of thermal pollution is the decrease in dissolved oxygen levels in the water. Warmer water has a lower oxygen-holding capacity, and the increased respiration rates of aquatic organisms further deplete oxygen reserves. This can lead to mass fish kills and the death of other marine life, such as coral. Additionally, the warmer temperatures promote the growth of harmful algal blooms, which choke fish gills, cloud the water, and block sunlight from reaching underwater plants, hindering their photosynthesis.

The sudden change in water temperature caused by thermal pollution can result in "thermal shock" for marine organisms, which have specific temperature requirements. This shock can be fatal and disrupt their reproductive capabilities, reducing biodiversity. Warmer waters also favour the growth of certain bacteria and algae, altering the ecosystem and potentially causing overpopulation and shorter life spans for some species.

The impact of thermal pollution extends beyond the affected bodies of water. As local marine life is forced to migrate to more suitable habitats, invasive species may take over the vacated waters, leading to further ecological imbalances. Additionally, the warming of coastal waters can result in coral reef bleaching, causing the death of coral organisms.

While thermal pollution is often associated with the release of hot water, the discharge of cold water can also have detrimental effects. For example, cold water released from the bottoms of deep reservoirs into warmer rivers can be fatal to plankton, fish, and their offspring.

To mitigate the effects of thermal pollution, various methods have been employed, including pretreatment measures such as reducing solar radiation on storage ponds and constructing cooling towers. However, these approaches have their limitations, and the continued growth of industries relying on water cooling is expected to exacerbate the issue.

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