Understanding Marine Pollution: Impacting Ocean Ecosystems

Marine pollution is a pressing issue that poses a significant threat to the health and sustainability of our planet. With oceans covering 71% of the Earth's surface and serving as diverse habitats for numerous species, it is crucial to address the various types of pollution that impact marine ecosystems. Marine pollution arises from a combination of chemical contamination and trash, with the majority originating from land-based sources. This pollution has far-reaching consequences, affecting both marine life and human health.

Chemical contamination

Marine ecosystems are affected by various types of pollution, including chemical contamination. Chemical contamination is the introduction of harmful contaminants into the marine environment. These contaminants can come from a variety of sources, including land-based and sea-based sources.

Sources of Chemical Contamination

One of the major sources of chemical contamination in marine ecosystems is runoff from land. Fertilizers, pesticides, and other chemicals used in agriculture can be washed into local water bodies and eventually make their way into the ocean, leading to nutrient pollution. For example, the excessive use of nitrogen and phosphorus fertilizers in agriculture can cause eutrophication, resulting in algal blooms that deplete oxygen levels and create "dead zones" where marine life struggles to survive.

In addition to agricultural chemicals, other land-based sources of chemical contamination include sewage, industrial discharge, and atmospheric deposition from burning fossil fuels. These sources can release a range of toxic chemicals, such as heavy metals, solvents, and sludge, into water bodies, which eventually find their way into the ocean.

Sea-based sources of chemical contamination include oil spills, shipping activities, and aquaculture medicinal products. Crude oil and other petroleum products can have devastating effects on marine life, and even with improved technologies and policies, oil spills continue to occur. Shipping activities can also introduce chemicals into the marine environment, such as paint shed from ship hulls.

Impacts of Chemical Contamination

Addressing Chemical Contamination

Addressing chemical contamination in marine ecosystems requires a multi-faceted approach. On a global scale, agreements such as the London Convention and its updated version, the London Protocol, have been implemented to prohibit the disposal of hazardous materials at sea. However, enforcement of these regulations remains a challenge.

Local and national efforts are also crucial in combating chemical contamination. This includes improving waste management practices, promoting recycling and reuse, and encouraging responsible chemical use through consumer and political actions. By addressing chemical contamination on multiple fronts, we can work towards minimizing its impacts on marine ecosystems.

Plastic pollution

Plastic waste also encourages the growth of pathogens in the ocean. Corals that come into contact with plastic have an 89% chance of contracting diseases, compared to a 4% likelihood for corals that are not exposed to plastic.

In addition, plastic pollution has far-reaching consequences for human health and economies. Microplastics have been detected in human blood, placentas, food, and drinks, including tap water, beer, and salt. The chemicals used in plastic production are known to cause various health issues, including cancer. The accumulation of plastic litter can also negatively impact a country's economy, particularly in sectors such as small and medium-sized enterprises, tourism, fisheries, and agriculture.

The problem of plastic pollution is expected to worsen, with an estimated increase in plastic ending up in the environment by 2040. This crisis demands urgent action, including global treaties, improved product design, enhanced legislation, and public and private investment to address the full lifecycle of plastics.

Oil spills

The impact of oil spills on marine life can be understood in two ways: the impact of the oil itself and the impact of the response or cleanup operations. Oil spills can harm living things because their chemical constituents are poisonous. This can affect organisms through internal exposure, such as ingestion or inhalation, and through external exposure, such as skin and eye irritation. Oil can also smother small species of fish or invertebrates and coat the feathers and fur of birds and mammals, reducing their ability to maintain body temperature and affecting their natural buoyancy, causing them to drown. Additionally, the scent of oil in the water can impact some animals' orientation abilities, as they use scent to find their relatives. Oil spills can also contaminate food supplies, leading to malnutrition or poisoning over time.

The type of oil spilled matters, as different types of oil behave differently in the environment. "Light" oils, such as gasoline and diesel fuel, are very volatile and will evaporate quickly. However, they present the hazards of being ignitable and toxic, and can kill animals, plants, and humans through skin contact or inhalation of fumes. On the other hand, "heavy" oils, such as bunker oils used to fuel ships, are less acutely toxic but can persist in the environment for months or years if not removed. They can smother organisms and cause long-term health effects like tumors. If heavy oils get onto the feathers of birds, they can cause hypothermia and death.

The effects of oil spills can be long-lasting and may take decades to recover from. Research has shown that even years after a spill, toxic chemicals can remain in the ocean, often sinking down to the seafloor and poisoning the sediment. This affects sedimentation rates, which are crucial for some animals as a food source and habitat. Oil spills can also impact breeding and reproduction, contaminating nests on shore and affecting the viability of eggs.

Noise pollution

Marine animals are highly dependent on underwater sound. Visibility is often low underwater, but sound is transmitted extremely well through water. As a result, sound has evolved as an important sensory signal for marine wildlife, particularly for marine mammals like whales, dolphins, and porpoises. They rely on sound to communicate, locate mates and prey, avoid predators, navigate, and even defend their territories.

Underwater noise interferes with the key life functions of marine mammals and can have a variety of negative effects, including:

• Temporary or permanent hearing loss
• Behavioural and physiological changes
• Masking – the ability to detect sound being overlapped or covered by another sound
• Injury
• Death

Harm

Very loud sounds can truly harm marine mammals. If the animal is too close to the source of the sound, they may panic and ascend too quickly to escape the noise, which can cause decompression sickness and lead to tissue damage from gas bubble lesions.

Behavioural changes

A foreign sound can disrupt the natural behaviour of marine mammals. This is the most common impact of underwater noise and can affect marine mammals in many different ways. They might move away from the noise, adjust their activities to avoid noisy times of day, or increase their anti-predatory behaviour.

Communication interference

Reducing noise pollution

To reduce anthropogenic noise in the marine environment, we need policies to reduce propeller noise from ships, and people need to mitigate the sounds of sonar equipment, seismic air guns, pile driving, and construction. We also need to develop quieter technologies, making it easier to reduce noise pollution. These actions can improve the ocean soundscape and potentially enable the recovery of some marine life.

Atmospheric pollution

Every year, billions of pounds of trash and other pollutants enter the ocean, with plastic being a major driver of biodiversity loss and ecosystem degradation. Plastic pollution in particular affects all land, freshwater, and marine ecosystems. It threatens human health, food and water safety, burdens economic activities, and contributes to climate change.

In the marine environment, plastic pollution originates primarily from land runoff. However, it also includes paint shed from shipping and discarded fishing gear. Single-use plastics, such as plastic bags, are a huge contributor to ocean pollution. These plastics slowly dissolve into microplastics, which are then ingested by marine life, causing harm or death. For example, sea turtles mistake plastic bags for jellyfish and eat them, leading to fatal blockages in their digestive systems.

Another issue with plastic pollution is that it can break down into microplastics (smaller than 5 mm) and nanoplastics (smaller than 100 nm) through the action of solar radiation, wind, and currents. These tiny particles are then ingested by small organisms, which are then eaten by larger predators, including humans. This allows toxic chemicals to migrate up the food chain, eventually becoming part of the human food chain.

Overall, atmospheric pollution, particularly in the form of plastic waste, is a significant issue affecting marine ecosystems. It is important to address this problem through prevention, cleanup, and global collective action to reduce plastic production and improve waste management practices.

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