What are the threats to our oceans?

Nutrient Pollution

Nutrient pollution from sewage discharges and agriculture can result in unsightly and dangerous "blooms" of certain algae in coastal waters. As these blooms die and decay they use up the oxygen in the water. This has led, in some areas, to 'creeping dead zones' (CDZ), where oxygen dissolved in the water falls to levels unable to sustain marine life. Industrial pollution also contributes to these dead zones by discharging substances which, as they break down, also use up the dissolved oxygen.

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Sewage treatment plant

Toxic Chemicals

About 63,000 different chemicals are thought to be in use worldwide with 3000 accounting for 90 % of the total production. Chemicals can enter oceans from runoff, drains, as rain collecting air pollution and from the breakdown of other substances to form toxic chemicals.

The major problems are from persistent organic pollutants (POPs). These breakdown very slowly and can accumulate in animals' tissues and can effect reproduction and cause cancers. POPs include the highly toxic dioxins and PCBs (Polychlorinated Biphenyls) together with various pesticides such as DDT and dieldrin.

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Researchers have found that some types of plastic begin to break down in the ocean within one year, releasing potentially toxic bisphenol A (BPA) and other chemicals into the water.

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Drums of chemicals can corrode and leak
toxic chemicals into the environment.