THE EVIDENCE is abundant that our oceans contribute much of the oxygen we use, around 50-85% of oxygen in the earth’s atmosphere, and that this oxygen production is affected by pollution. Minute organisms called phytoplankton which live in the ocean waters, close to the surface are the cellular powerhouses which produce and release oxygen to the air. As water becomes polluted and opaque, energy from the sun is impeded, and these micro-organisms are unable to function fully, so that oxygen release is reduced.
The health of the global marine environment is in serious decline. Much is due to the burden of plastics which find their way into the seas, taking around 200 years to decompose, and killing vast numbers of marine species. Around 10 million tonnes of litter, mainly plastics are dumped in our seas each year.
But the main cause of water pollution is nutrient pollution, from sewage and from agricultural waste, livestock effluent in particular. A number of studies have shown that 40% of rivers in England alone are polluted with sewage, which causes the growth of algae called epiphytes. These attach to marine vegetation and prevent the passage of light, leaving the waters opaque and lacking oxygen for marine life. In the UK, farming is one of the major causes of water pollution, with inadequate storage and disposal of slurry especially from intensive livestock factory farms, which enters rivers and flows into coastal waters.