Water Pollution: Devastating Impact On Marine Life

Water pollution is a pressing global issue, with marine ecosystems facing a variety of threats from human activities. Marine life is affected by both chemical and trash pollution, which enter the ocean through runoff from farms, vehicles, factories, and other sources. Chemical pollution, such as nutrient pollution from fertilizers, can cause harmful algal blooms that are toxic to marine life and humans. Trash pollution, particularly plastic waste, is a significant problem as it is long-lasting and can be ingested or entangled by marine animals, leading to health issues and death. With plastic debris breaking down into microplastics, these pollutants migrate up the food chain, eventually reaching humans through seafood consumption. Oil spills, heavy metals, and pesticides also directly harm marine life, causing deformities and reproductive problems. The delicate balance of marine ecosystems is disrupted by these contaminants, impacting a wide range of species and highlighting the urgent need for preventative measures and cleanup efforts.

Plastic waste

One of the main ways plastic waste enters the ocean is through rivers, especially those in coastal cities in middle-income countries, which have been identified as hotspots for plastic emissions. During storms and heavy rain, plastic emissions can increase significantly as trash is washed into waterways. Other sources of plastic pollution in the ocean include littering, improper waste management, and industrial and offshore fishing activities.

The impact of plastic waste on marine life is devastating. Marine mammals, such as whales, seals, and sea lions, ingest plastic and can also become entangled in it, leading to injury and death. Seabirds and sea turtles are also highly affected, with plastic causing starvation and even death. A recent study found that sea turtles that ingest just 14 pieces of plastic have an increased risk of death. Young sea turtles are especially at risk as they tend to be less selective about what they eat and drift with currents, similar to plastic.

Microplastics, in particular, have become a global concern as they have been found to accumulate in the food chain. Fish often mistake small plastic pieces for food, and these plastics can then be passed up the food chain to larger fish, marine mammals, and even human seafood eaters. A single plastic particle can adsorb up to one million times more toxic chemicals than the surrounding water, posing a significant threat to apex predators such as great white sharks and orcas.

To address the issue of plastic waste in the ocean, a multifaceted approach is necessary. This includes improving waste management practices, reducing plastic usage, advocating for better policies and legislation, and supporting organizations working to clean up and prevent plastic pollution. It is essential to focus on preventing plastic pollution at its source and to shift how we view and use plastic, moving away from treating it as a disposable material.

Oil spills

Seabirds are particularly vulnerable to oil spills, as they can ingest the oil when trying to clean their feathers, and their feathers can lose their waterproofing and insulating abilities. During most oil spills, seabirds are harmed and killed in greater numbers than other creatures.

Marine mammals, such as sea otters, are also at risk from oil spills. Oil destroys the insulating ability of their fur, exposing them to harsh elements and hypothermia. Dolphins and whales can inhale oil, which can affect their lungs, immune function, and reproduction.

The impact of oil spills on marine life can be mitigated by specialists and veterinarians who are trained to clean and rehabilitate affected wildlife.

Chemical contamination

One of the most well-known forms of chemical contamination is oil spills, which occur when liquid petroleum hydrocarbons are discharged into the marine ecosystem, often as a result of human activity. These spills can suffocate marine life, cause behavioural changes, and lead to a breakdown in thermal insulation for those who survive. Oil spills also release toxic chemicals such as benzenes, toluene, and poly-aromatic hydrocarbons, which can harm air and water quality. Even with improved technologies and policies, oil spills continue to be a significant issue, with an estimated 25,000 tonnes of oil spilled into the ocean in 2015.

Heavy metals are another type of chemical contaminant that enters the aquatic ecosystem from both natural and anthropogenic sources. These metals can enter the ecosystem through direct discharges into fresh and marine environments or through indirect routes like atmospheric deposition and surface runoff. Heavy metals can have detrimental effects on the biochemistry, behaviour, reproduction, and growth of marine life.

Additionally, personal care products have been identified as a significant source of chemical contamination. These products contain cryptic chemicals that have a substantial impact on both human and ocean health. Even chemicals banned decades ago, like polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), are still found in high concentrations in deep-sea creatures. These persistent and toxic substances accumulate in marine organisms, becoming more concentrated as they move up the food chain.

Furthermore, excess nitrogen and phosphorus in seawater can lead to oxygen depletion, creating "dead zones" where marine life struggles to survive. This, in turn, affects the food chain, as toxins accumulate in organisms and eventually reach humans through the consumption of seafood.

While most chemical contamination is a result of human activity, there are ways to mitigate this issue. Properly disposing of chemical cleaners, oils, and non-biodegradable items can help prevent them from entering the ocean. Additionally, choosing organic fertilizers and reducing plastic consumption can also play a crucial role in minimizing chemical contamination in marine ecosystems.

Invasive species

The spread of invasive species is a significant threat to marine life, and it is often facilitated by human activities. Shipping is the most common vector for the introduction of invasive species, with ballast water being a primary culprit. As large boats fill their tanks with seawater to balance cargo weight, they inadvertently transport various organisms, from fish to algae and microbes, to new destinations. This was the case with the European crab, which has now established populations on both US coasts and in several other regions, impacting the commercial shellfish industry. Similarly, a stingless jellyfish-like creature native to the east coast of North and South America was introduced to the Black Sea and the Caspian Sea through ballast water, leading to immense populations that contributed to the collapse of local fisheries.

Another way ships spread invasive species is through biofouling, where organisms attach themselves to ships' hulls, anchors, and equipment. Plastic pollution also plays a role in transporting invasive species across oceans. The introduction of non-native species can have dire consequences for native ecosystems, as they can outcompete indigenous species for resources, spread diseases, and alter habitats. Undaria pinnatifida, or Asian kelp, has colonized many harbors along the California coastline, impacting native species and aquatic ecosystems.

The marine ornamental trade is another vector for invasive species, threatening marine and coastal biodiversity. The intentional or accidental release of aquaculture species, aquarium discards, and excess live bait can introduce exotic organisms into new environments. The lionfish, for example, has become an invasive species in some regions due to the pet trade. Once established, invasive species can be challenging and costly to control, as seen with the European crab and the spread of "killer algae" along the coast of Monaco.

Eutrophication

The increase in photosynthesis associated with eutrophication can deplete dissolved inorganic carbon and raise pH levels to extreme values. This elevated pH can impair the chemosensory abilities of organisms that rely on the perception of dissolved chemical cues for survival. For example, the Harmful Algal Bloom Monitoring System developed by NOAA's National Centers for Coastal Ocean Science provides information to help decide whether beaches need to be temporarily closed to protect public health.

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