Water Pollution's Impact On Wildlife Health

Water pollution is a pressing issue that poses a serious threat to wildlife, with over 70% of terrestrial animal species relying on water at some point in their life cycle. A multitude of factors contribute to this issue, including mercury emissions, sewage discharge, and agricultural and industrial waste. These pollutants have far-reaching consequences, from poisoning aquatic life to disrupting entire ecosystems. The proliferation of toxic algae species, for instance, impacts both wildlife and humans, as toxins produced by these algae poison aquatic organisms and contaminate drinking water sources. Plastic waste is another significant concern, with more than a dump truck load of plastic entering our oceans every minute, entangling wildlife, causing habitat loss, and polluting the air, water, and soil necessary for survival.

Mercury poisoning

Water pollution has a significant impact on wildlife, and one of the most concerning issues is mercury poisoning. Mercury is a toxic elemental metal found in the Earth's crust, and it poses a severe threat to both human and animal life. Once emitted into the air, mercury eventually settles on the earth and accumulates in water and soil. Over time, it transforms into methylmercury, a highly toxic compound that builds up in the tissues of wildlife and people.

Methylmercury is a potent neurotoxin that affects the central nervous system, causing neurological problems in wildlife. It accumulates in the food chain, with larger predator fish like walleye and trout having mercury levels far exceeding those of the surrounding water. This results in dangerous mercury levels in the bodies of wildlife and people who consume these fish, leading to severe health issues. Birds, for instance, experience reduced egg-laying and difficulties in caring for their chicks. Mammals suffer from impaired motor skills, negatively impacting their hunting abilities and survival.

Inorganic mercury, another dangerous form, can cause severe health issues when inhaled or swallowed. It attacks the brain and kidneys and can lead to gastrointestinal tract damage. Symptoms of inorganic mercury poisoning include trouble breathing, a metallic taste in the mouth, nausea, vomiting, and bleeding or swollen gums.

Organic mercury is also hazardous and can cause numbness or dull pain in various body parts after long-term exposure. Even small amounts of mercury in the environment can have detrimental effects on wildlife, with evidence suggesting that elevated mercury levels can adversely affect the immune systems of various species.

Excess nutrients

One of the primary consequences of excess nutrients in water is the proliferation of algae, a process known as eutrophication. Eutrophication occurs when high levels of nutrients cause excessive growth of algae. This algae can block sunlight from reaching underwater plants, hindering their growth and leading to their decay. As the algae and underwater plants decompose, they deplete the oxygen levels in the water, creating "dead zones" where aquatic life cannot survive. This depletion of oxygen, known as hypoxia, can result in the death of aquatic organisms, including fish, crustaceans, and shellfish, that are unable to move to higher-oxygen environments.

The toxins produced by certain harmful algal blooms (HABs) pose an additional threat to wildlife. As fish and shellfish feed on these HABs, they accumulate toxins in their bodies. Consequently, when humans consume seafood containing these toxins, it can lead to illness or even death. This transfer of toxins through the food chain can also impact larger predators, including birds, sea turtles, and aquatic mammals such as dolphins, manatees, and sea lions.

Addressing the issue of excess nutrients in water requires a multifaceted approach. One crucial step is reducing the use of phosphorus-based fertilizers or switching to non-phosphorus alternatives for lawns and gardens. Properly disposing of organic materials, such as grass clippings, can also help minimize nutrient runoff into nearby water bodies. Implementing buffer zones of deep-rooted plants, such as trees and shrubs, around water bodies can act as a natural filter, absorbing excess nutrients before they reach the water. Furthermore, installing and maintaining aeration systems in affected water bodies can help stabilize oxygen levels, mitigating the impact of eutrophication on aquatic life.

Plastic waste

Marine animals, such as whales, fish, and turtles, are also severely impacted by plastic waste. They can ingest plastic particles, leading to malnutrition and poisoning. Additionally, waste creates dead zones by depleting oxygen levels, further harming marine life. Large items of plastic can entangle marine mammals and fish, leading to starvation, injury, and increased vulnerability to predators.

The durability and pervasiveness of plastics in the environment contribute significantly to the plastic waste problem. Plastics can persist in the environment for hundreds of years, breaking down into smaller and smaller pieces that can be easily ingested by wildlife. Microplastics, in particular, are invisible to the naked eye, making them easy for wildlife to consume. They have the ability to adsorb toxins, which can then transfer to the fatty tissues of the organisms that ingest them.

Addressing plastic waste requires a combination of conservation efforts and policy interventions. This includes improving waste management systems, reducing the use of single-use plastics, increasing recycling efforts, and implementing regulations on plastic production. Preventing plastic waste from entering rivers and seas is crucial, as once plastics break down into microplastics in the ocean, they become virtually impossible to recover.

Oil spills

During the early stages of an oil spill, species that spend time at the surface of the water, such as sea otters and seabirds, are the most vulnerable. Seabirds, in particular, are often harmed and killed in greater numbers than other creatures. Sea otters, whose fur provides insulation, become susceptible to the cold when their fur is coated in oil. Additionally, eggs, larvae, and juveniles of many species are generally more vulnerable to the harmful effects of oil spills than adults.

As the oil begins to wash ashore, species that forage and nest along coastlines, such as snails, clams, and terrestrial animals, are affected. Oil spills can also cause indirect effects on wildlife, leading to changes in behaviour and relocation of home ranges as animals search for new sources of food.

The toxicity of the oil is another critical factor. Light oils, such as gasoline and diesel fuel, are highly volatile and can ignite or explode. They are also toxic and can kill animals, plants, and humans through direct contact, inhalation of fumes, or skin exposure. Heavy oils, like bunker oils used to fuel ships, are less toxic but can persist in the environment for much longer, smothering organisms and potentially causing long-term health issues such as tumors.

The magnitude of harm caused by oil spills can vary depending on the degree of exposure. Prolonged skin contact with oil, ingestion of oil particles, and inhalation of volatile chemicals released by floating oil can all have detrimental effects on wildlife. For example, inhalation can lead to respiratory issues such as inflammation, irritation, emphysema, or pneumonia in animals that come to the surface to breathe, such as manatees, dolphins, whales, and sea turtles.

Sewage discharge

Eutrophication occurs due to the high levels of nutrients, particularly nitrogen and phosphorus, present in sewage. These nutrients act as fertilisers, stimulating the rapid growth of algae, including blue-green algae, and aquatic plants. While some algal species benefit from eutrophication, others, like fish, are negatively affected. The proliferation of algae can lead to the formation of algal blooms, which have severe ecological consequences. Algal blooms can block light necessary for photosynthesis, hindering the growth of other aquatic plants and impacting the overall health of the ecosystem.

Moreover, as algae and aquatic plants die and decompose, they consume oxygen in the water, leading to oxygen depletion. This depletion creates dead zones where aquatic life, especially crustaceans and shellfish that cannot move to higher-oxygen environments, cannot survive. Sewage-induced eutrophication has resulted in vast dead zones, such as the 8,000-square-mile area in the Gulf of Mexico, where aquatic life has been decimated. The impact of oxygen depletion also extends to fish populations, which may struggle to find prey or experience indirect effects through the loss of their food sources.

The toxins produced by certain algae species, such as blue-green algae, pose a direct threat to a variety of wildlife, including seabirds, fish, sea turtles, and aquatic mammals like dolphins, manatees, and sea lions. These toxins can cause poisoning and even death in both wildlife and humans who come into contact with or consume affected water or seafood. The accumulation of sewage-derived toxins can have detrimental effects on the nervous system, reproductive capabilities, and motor skills of wildlife, impairing their ability to survive and reproduce.

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