Pollution has a devastating effect on oceans' marine life and the environment. Particles, chemicals, and other harmful substances enter the oceans by water runoff, direct deposit of waste into the water, and debris in the wind. Sadly, eighty percent of ocean pollution is caused by humans. Here are some effects of pollution that harm the ocean environment and marine life.
When oil from a tanker is released into the ocean, by accident or voluntarily, it spreads out in a thin film on top of the water. A large oil spill can cover a massive area on the ocean's surface and affect virtually all of the marine life in the area. The oil sticks to sea birds' wings, and they can no longer fly. Underneath the surface, organisms that use photosynthesis to produce energy die because they cannot get enough sunlight. Oil clogs the gills of fish and makes them unable to respire. Tar balls commonly form from oil and debris. They may wash up on the shore and harm animals and humans. Oil spills are permanent effects of pollution that poison large areas of the ocean with their thick, black, crude.
Nutrients and Pathogens
Often, runoff from rivers will deposit nutrients and chemicals into the ocean. When compounds that contain nitrogen and phosphorus enter the water, certain species of algae benefit. These "algae blooms" begin to dominate the ecosystem, blocking sunlight from reaching the lower levels and decreasing the amount of oxygen in the water. Algae blooms also release toxins into the water when they decompose, poisoning fish and other animals. Water used to wash livestock and human sewage often contain dangerous pathogens. When the waste is dumped in the water in coastal areas, the bacteria can work its way up through the food chain. Animals caught for food, like clams and oysters, concentrate these pathogens in their bodies, so this poses a health risk for humans as well as harming the local ecosystem.
The majority of marine pollution is made up plastic trash that has been thrown into the sea. Plastic is very harmful to marine life because it can kill or affect many different kinds of organisms. Animals eat the plastic, thinking it is food, and then it becomes lodged in their stomach or throat, causing starvation or infection. Plastic also settles on the sea bed, where it disturbs organisms there. The amount of plastic in the ocean continues to increase and collects together in garbage "patches" in the oceans. Plastics can release toxins used in their manufacture into the water, further damaging the environment.
Toxins and Chemicals
Many toxins that do not immediately dissolve in the water affect oceans significantly. Heavy metals, such as mercury, arsenic, lead, and cadmium, are dumped into the ocean by factories. These metals are ingested into many organisms through a process called bioaccumulation. Since heavy metals can be lethal to populations at a low concentration, they are a dangerous marine pollutant. Pesticides, such as DDT, can also be released into the water. When they are ingested by organisms, they can lead to defects and reproductive problems. This pollution indirectly poses risks for humans that eat seafood when pesticides enter the food chain. Radioactive waste dumped in the ocean can harm organisms as well. Waste from nuclear submarines or military projects seeps into the food chain and kills marine life, making areas of the ocean very dangerous.
Pollution of the world's oceans is a serious concern and has devastated many ecosystems and organisms. Marine pollutants work their way up food chains and are a risk to human safety as well. It is estimated that up to 40% of marine life has been affected by pollution in some way. Oil, toxins, plastics, pathogens, and other forms of pollution hurt the Earth's oceans and adversely affect aquatic life.