What is marine pollution?

Marine pollution occurs when harmful effects result from the entry into the ocean of chemicals, particles, industrial, agricultural, & residential waste, noise, or the spread of invasive organisms. 80% of marine pollution comes from land. Air pollution is also a contributing factor by carrying off pesticides or dirt into the ocean. Both land & air pollution have proven to be harmful to marine life & its habitats.

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The pollution often comes from nonpoint sources such as agricultural runoff, wind-blown debris, & dust. Nutrient pollution, a form of water pollution, refers to contamination by excessive inputs of nutrients. It is a primary cause of eutrophication of surface waters, in which excess nutrients, usually nitrates or phosphates, stimulate algae growth. Many potentially toxic chemicals adhere to tiny particles which are then taken up by plankton & benthic animals, most of which are either deposit feeders or filter feeders. In this way, the toxins are concentrated upward within ocean food chains. Many particles combine chemically in a manner highly depletive of oxygen, causing estuaries to become anoxic.

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When pesticides are incorporated into the marine ecosystem, they quickly become absorbed into marine food webs. Once in the food webs, these pesticides can cause mutations, as well as diseases, which can be harmful to humans as well as the entire food web. Toxic metals can also be introduced into marine food webs. These can cause a change to tissue matter, biochemistry, behaviour, reproduction, & suppress growth in marine life. Also, many animal feeds have a high fish meal or fish hydrolysate content. In this way, marine toxins can be transferred to land animals, & appear later in meat & dairy products in our grocery stores.

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In order to protect the ocean from marine pollution, policies have been developed internationally. There are different ways for the ocean to get polluted, therefore there have been multiple laws, policies, & treaties put into place throughout history.

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