Marine pollution occurs when harmful effects result from the entry into the worlds oceans of plastics, synthetic materials, untreated sewage, toxic chemicals, particles, industrial, agricultural, and residential waste, noise, or the spread of invasive organisms.
Eighty percent of marine pollution comes from the land.
Air pollution is also a contributing factor by carrying off pesticides or dirt into the ocean.
Nutrient pollution is a form of water pollution and refers to contamination by excessive inputs of nutrients which is a primary cause of eutrophication of surface waters, in which excess nutrients, usually nitrates or phosphates, stimulate algae growth.
Many potentially toxic and dangerous chemicals adhere to tiny particles which are then taken up by plankton and 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.
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, and suppress growth in marine life.
Many domestic and farm animal feeds have a high fish meal or fish hydrolysate content and in this way, marine toxins can be transferred to land animals and appear later in meat and dairy products which are then in turn consumed by humans.
In order to protect the oceans 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, and treaties put into place throughout history.
It is our responsibility to ensure that these laws, policies and treaties are adequate to protect our oceans and coastal environments and that they are being properly respected and enforced globally.