Marine pollution and debris
People once assumed that the ocean was large enough to disperse or dilute pollutants to safe levels. But some toxic man-made chemicals have become so concentrated that they have entered the food chain.
Oil enters the marine environment through drains and rivers, and from acute oil spills. Fertilisers are causing algae blooms and oxygen depletion in the coastal and marine environment and sewage can cause environmental and human health issues. Toxic chemicals are entering oceans through either illegal dumping or run-off from land-based activities. Harmful concentrations of pesticides have even been detected deep inside the Great Barrier Reef World Heritage Area – 60 kilometres from the coast.
The amount of human debris entering the marine environment is also of significant concern. Items such as plastic bottles and bags, food packaging, cigarette butts and fishing gear are commonly sighted and cause harm to protected birds, sharks, turtles and marine mammals. Injury or death through drowning, entanglement, internal injuries or starvation commonly follow ingestion of this debris.