Pollution is defined as the process of introducing harmful or poisonous substances into the natural environment. Ocean pollution is therefore defined as the introduction of toxic materials such as plastic, oil, chemicals, agricultural waste, and industrial waste into the ocean waters.
Chemical contamination, or nutrient pollution, is concerning for health, environmental, and economic reasons. This type of pollution occurs when human activities, notably the use of fertilizer on farms, lead to the runoff of chemicals into waterways that ultimately 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. The negative effects on health and the environment caused by algal blooms hurt local fishing and tourism industries.
Marine trash encompasses all manufactured products—most of them plastic—that end up in the ocean. Littering, storm winds, and poor waste management all contribute to the accumulation of this debris, 80 percent of which comes from sources on land. Common types of marine debris include various plastic items like shopping bags and beverage bottles, along with cigarette butts, bottle caps, food wrappers, and fishing gear. Plastic waste is particularly problematic as a pollutant because it is so long-lasting. Plastic items can take hundreds of years to decompose.
Nonetheless, many countries are taking action. According to a 2018 report from the United Nations, more than sixty countries have enacted regulations to limit or ban the use of disposable plastic items.
It’s an invisible threat, but noise pollution is a major — and often deadly — menace to ocean wildlife. Just as there’s hardly a mountaintop free from the roar of airplanes overhead, there’s virtually no place in the world’s oceans where human sounds aren’t detectable. The loudest and most disruptive anthropogenic ocean sounds come from military sonar, oil exploration and industrial shipping, and the Center is working to protect our marine life from each of these threats. Center for Biological Diversity
Many marine organisms rely on their ability to hear for their survival. Sound is the most efficient means of communication underwater and is the primary way that many marine species gather and understand information about their environment. Many aquatic animals use sound to find prey, locate mates and offspring, avoid predators, guide their navigation and locate habitat, and listen and communicate with each other.
Over the last century, human activities such as shipping, recreational boating, and energy exploration have increased along our coasts, offshore, and deep ocean environments. Noise from these activities travel long distances underwater, leading to increases and changes in ocean noise levels.
Rising noise levels can negatively impact ocean animals and ecosystems. These higher noise levels can reduce the ability of animals to communicate with potential mates, other group members, their offspring, or feeding partners. Noise can also reduce an ocean animal's ability to hear environmental cues that are vital for survival, including those key to avoiding predators, finding food, and navigating to preferred habitats. National Ocean Service
The ocean is far from a “silent world.” Sound waves travel farther and faster in the sea’s dark depths than they do in the air, and many marine mammals like whales and dolphins, in addition to fish and other sea creatures, rely on communication by sound to find food, mate, and navigate. But an increasing barrage of human-generated ocean noise pollution is altering the underwater acoustic landscape, harming—and even killing—marine species worldwide.
Another pathway of pollution occurs through the atmosphere. Wind-blown dust and debris, including plastic bags, are blown seaward from landfills and other areas. Dust from the Sahara moving around the southern periphery of the subtropical ridge moves into the Caribbean and Florida during the warm season as the ridge builds and moves northward through the subtropical Atlantic. Dust can also be attributed to a global transport from the Gobi and Taklamakan deserts across Korea, Japan, and the Northern Pacific to the Hawaiian Islands