Ocean Pollution: Understanding The Human Impact

The ocean is the origin of all life on our planet, yet human activities are polluting it with trash, noise, oil, carbon emissions, and more. Eighty per cent of marine pollution comes from land-based sources, with nonpoint source pollution being the most common. This type of pollution comes from small sources that can't be pinpointed, such as individual cars, farms, and construction sites. It typically becomes ocean pollution via runoff, when rain or snow moves pollutants from the ground into the ocean. Other major causes of ocean pollution include oil spills, sewage, plastic waste, deep-sea mining, and atmospheric pollution.

Nonpoint source pollution

One example of nonpoint source pollution is the oil left on streets by cars, which is washed into the ocean during rainstorms. Another example is the use of fertilizers in our yards, which can be carried by runoff into the ocean, leading to excessive nutrient levels that stimulate harmful algal blooms. These blooms produce toxins that accumulate in fish and shellfish, posing risks to both marine life and human health.

Farms and livestock ranches also contribute to nonpoint source pollution by allowing manure, pesticides, and fertilizers to enter nearby waterways. Construction sites can similarly cause pollution through the runoff of topsoil or silt, which harms fish and wildlife habitats. In some cases, this pollution can be severe enough to require beach closures after rainstorms.

Oil spills

The impact of oil spills on the environment is significant. Oil spills harm ocean life in two main ways: fouling or oiling, and oil toxicity. Fouling or oiling occurs when oil physically harms a plant or animal, such as coating a bird's wings and leaving it unable to fly or reducing the insulating ability of a sea otter's fur, making it vulnerable to hypothermia. Oil toxicity, on the other hand, refers to the presence of toxic compounds in oil, which can cause severe health problems like heart damage, stunted growth, immune system effects, and even death.

The degree of oiling and the type of oil spilled influence the harm caused to plants, animals, and habitats. Oil spills can have long-lasting effects on ecosystems and economies, with consequences felt for decades. Additionally, oil spills can make seafood unsafe to eat and ruin recreational activities at the beach.

Plastic pollution

The impact of plastic pollution on marine life is devastating. Thousands of seabirds, sea turtles, seals, and other marine mammals are killed each year due to ingesting plastic or becoming entangled in it. Sea turtles, for example, can mistake floating plastic for food, leading to choking, internal injuries, or starvation. Research indicates that half of the sea turtles worldwide have ingested plastic, and plastic ingestion has also reduced the storage volume of seabirds' stomachs, causing starvation. It is estimated that 60% of all seabird species have eaten plastic, and this number is predicted to increase to 99% by 2050.

Addressing plastic pollution is crucial for safeguarding ecosystems and preserving biodiversity. The Center for Biological Diversity has petitioned the U.S. Environmental Protection Agency to regulate plastics as hazardous pollutants and is working to control plastic runoff from consumer goods companies. Additionally, tools like the one developed by Pew and SYSTEMIQ can help governments identify the main sources of plastic pollution and guide their actions to reduce plastic waste.

Noise pollution

The impacts of noise pollution on marine life are not limited to behavioural changes and can extend to physiological effects as well. For instance, noise pollution can cause changes in individual and social behaviour, altered metabolisms, and hampered population recruitment, which can have cascading effects on the health and functioning of marine ecosystems.

To mitigate the impacts of noise pollution on marine life, it is essential to implement policies and develop quieter technologies to reduce propeller noise from ships, sonar equipment noise, and noise from construction and other human activities. By addressing these issues, we can improve the ocean soundscape and potentially enable the recovery of some marine species.

Agricultural runoff

Fertilizers and manure from farmlands contain high levels of nitrogen and phosphorus, which can stimulate the growth of algae in water bodies. This process, known as eutrophication, leads to the development of algal blooms, which have detrimental effects on aquatic ecosystems. As algae blooms proliferate, they consume oxygen in the water, creating hypoxic conditions that are harmful to marine life, resulting in mass die-offs of fish and other aquatic organisms. Eutrophication also prevents the growth of native species, disrupting the natural balance of marine ecosystems.

Additionally, agricultural runoff can carry sediment and eroded soil particles into oceans and other water bodies. Excessive sedimentation can overwhelm aquatic ecosystems, smother breeding areas, and degrade coastal and marine ecosystems, including coral reefs. The soil itself can act as a pollutant, as it can run off into waterways, harming fish and wildlife habitats and rendering water unsafe for human use.

The management of animal feeding operations and livestock facilities also plays a role in agricultural runoff. Improper management can lead to the runoff of manure, bacteria, viruses, and nutrients into nearby water bodies. This contamination can have significant impacts on shellfish beds and coastal waters, affecting water quality and posing risks to human health.

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