Ocean Matters

Marine Pollution: Causes and Effects

Pollution on land is usually easy to recognize: mounds of garbage here, heaps of waste there. It’s an eyesore and an environmental risk to all.  Spotting pollution in the world’s oceans is not as simple, and often we only find out about a problem when it’s too late.  Despite this, and without fully understanding the consequences of our actions, we continue to dispose of chemicals, sewage and garbage in the oceans. Below, we examine various kinds of pollutants and the impacts they have on delicate ocean ecosystems.

Toxic Ocean Pollutants

Toxic pollutants in the ocean ecosystem have considerable impacts on plants and animals. Heavy metal poisoning from elements such as lead and mercury caused by industrial fallout eventually build-up in the tissues of top predators such as whales and sharks. Sometimes this type of poisoning can cause birth defects and nervous system damage. Dioxins given off by pulp and paper mills due to bleaching can cause chromosomal problems in marine animals and may even cause cancer in humans. Polychlorinated biphenyls (PCB’s) can cause reproduction problems in most marine organisms. PCB's usually come from older electrical equipment. Poly-aromatic hydrocarbons (PAH's) are another source of marine toxic pollution and typically come from oil pollution and burning wood and coal. These PAH's are responsible for causing genetic chromosomal aberrations in many marine animals. Lastly, low-level radiation poisoning is also possible in the ocean environment.

Toxic pollutants have wreaked havoc on a number of marine mammals, with a population of Beluga Whales living in the Saint Lawrence River area in Eastern Canada being perhaps the most famous example. Unfortunately, these beluga whales have been victims of ocean pollution ranging from PCB's to heavy metals as well as other pollutants.  Because belugas congregate in river estuaries, human-caused pollution is proving to be a significant threat to their health.  Incidents of cancer have risen as a result of the pollution. Due to unnaturally high levels of contaminants, Beluga carcasses found in the Saint Lawrence area are commonly disposed of as toxic waste.  At present it is not known how such high pollution levels will affect Beluga populations over the long-term.

Marine Garbage

Marine garbage disposal is another major form of ocean pollution. The world's oceans are a virtual dumping ground for trash.  Types of marine garbage include junked out fishing nets, plastics, general household garbage and even stuff like light bulbs. In one case an island more than 4800 kilometres from the nearest continent was littered with 950 pieces of garbage ranging from plastics to tin cans. 
Animals may also ingest marine garbage, with materials such as plastic pop tab rings being known to strangle and sometimes kill organisms.  Preventing this form of pollution is important to maintaining a healthy ocean ecosystem.
Even plastic bags and related items can negatively impact the ocean.  In one case a dead sperm whale was found to have a party balloon blocking its digestive system. The whale died from being unable to process its food, starving to death. 

Oceanic Sewage Disposal

Sewage is another major form of ocean pollution.  Sewage can cause massive nutrient loading in the oceans, which leads to algal blooms, effectively decreasing the amount of dissolved oxygen in the water. Once oxygen levels are depleted, many organisms can die due to lack of oxygen. Other problems associated with sewage include the presence of parasites and bacteria, which can cause beach and shellfish harvesting closures.  Unfortunately, there are still many cities around the world that have little to no sewage treatment. As the world population continues to increase, it’s expected that the sewage problem will only worsen.
All of what we put down the drains eventually reaches the oceans. This includes everything from our homes (toilets, washing machines, bathtubs, dishwashers and so forth), industrial effluents and even chemicals such as paints and fertilizers that we dispose of down the drains. The build-up of sewage pollution adds up to serious problems in the ocean such as a lack of available oxygen for organisms and poisoned water.

Non-Point Pollution

Non-point pollution comes from a variety of indirect sources (whereas point pollution comes from a direct source like a factory outfall pipe).  Some of the sources of non-point pollution include farms (e.g. fertilizers, manure), industrial runoff (e.g. heavy metals, phosphorous), urban runoff (e.g. oils, salts, various chemicals) and atmospheric fallout of airborne pollution. Non-point pollution is difficult to control because it comes from so many different sources.

Solutions

We can help preserve the world’s oceans by producing less pollution.  Due to growing concern about their health and environmental effects, PCBs have been effectively banned in North America (although some eastern European and developing countries still use them). New regulations have been made to make sure that older equipment containing PCBs is carefully handled to avoid spills or leaks.

Thanks to improved technology and waste treatment techniques, industrial pollution is not as bad as it used to be in the developed world and new laws and regulations make it difficult for people to dump their trash into the oceans.  People have been reducing sewage output by installing better treatment facilities.  To arrive at this goal, countries with sound sewage treatment facilities already in place should assist developing countries improve their sewage facilities. Many parts of the world have reduced non-point pollution through proper recycling facilities for used oil and paint products. Globally, many communities try to help our oceans by participating in beach cleanups. 
Reducing pollutants in the world’s oceans is a major challenge.  With right effort and determination it is possible to reduce harmful impacts on the oceans caused by pollutants.  We owe it to the oceans and their precious plants and animals to meet this challenge.

For more information go to:

Georgia Straight Alliance

Environment Canada "Enviro-Zine"

Government of Canada Marine Pollution Prevention site

Canada's National Programme of Action for the Protection of the Marine Environment from Land-Based Activities (NPA)

Smithsonian Oceans in Peril

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