Several years ago a minke whale was found on a Scottish beach with 800kg of plastic bags in its stomach.
© WWF-Canon / Morten LINHARDSeas of garbage
Solid garbage also makes its way to the ocean. Plastic bags, balloons, glass bottles, shoes, packaging material - if not disposed of correctly, almost everything we throw away can reach the sea.
Plastic garbage, which decomposes very slowly, is often mistaken for food by marine animals. High concentrations of plastic material, particularly plastic bags, have been found blocking the breathing passages and stomachs of many marine species, including whales, dolphins, seals, puffins, and turtles. Plastic six-pack rings for drink bottles can also choke marine animals.
This garbage can also come back to shore, where it pollutes beaches and other coastal habitats.
Sewage disposal
In many parts of the world, sewage flows untreated, or under-treated, into the ocean. For example, 80% of urban sewage discharged into the Mediterranean Sea is untreated.
This sewage can also lead to eutrophication. In addition, it can cause human disease and lead to beach closures.
Toxic chemicals
Almost every marine organism, from the tiniest plankton to whales and polar bears, is contaminated with man-made chemicals, such as pesticides and chemicals used in common consumer products.
Some of these chemicals enter the sea through deliberate dumping. For centuries, the oceans have been a convenient dumping ground for waste generated on land. This continued until the 1970s, with dumping at sea the accepted practise for disposal of nearly everything, including toxic material such as pesticides, chemical weapons, and radioactive waste.
Dumping of the most toxic materials was banned by the London Dumping Convention in 1972, and an amended treaty in 1996 (the London Convention) further restricted what could be dumped at sea. However, there are still the problems of already-dumped toxic material, and even the disposal of permitted substances at sea can be a substantial environmental hazard.
Chemicals also enter the sea from land-based activities. Chemicals can escape into water, soil, and air during their manufacture, use, or disposal, as well as from accidental leaks or fires in products containing these chemicals. Once in the environment, they can travel for long distances in air and water, including ocean currents.
People once assumed that the ocean was so large that all pollutants would be diluted and dispersed to safe levels. But in reality, they have not disappeared - and some toxic man-made chemicals have even become more concentrated as they have entered the food chain.
Tiny animals at the bottom of the food chain, such as plankton in the oceans, absorb the chemicals as they feed. Because they do not break down easily, the chemicals accumulate in these organisms, becoming much more concentrated in their bodies than in the surrounding water or soil. These organisms are eaten by small animals, and the concentration rises again. These animals are in turn eaten by larger animals, which can travel large distances with their even further increased chemical load.
Animals higher up the food chain, such as seals, can have contamination levels millions of times higher than the water in which they live. And polar bears, which feed on seals, can have contamination levels up to 3 billion times higher than their environment.
People become contaminated either directly from household products or by eating contaminated seafood and animal fats.
Evidence is mounting that a number of man-made chemicals can cause serious health problems - including cancer, damage to the immune system, behavioural problems, and reduced fertility.
Problems: Introduction Human activity has finally pushed oceans to their limit
Oceans. For centuries people have regarded them as an inexhaustible supply of food, a useful transport route, and a convenient dumping ground - simply too vast to be affected by anything we do. But human activity, particularly over the last few decades, has finally pushed oceans to their limit.
Overfished, polluted, taken for granted, carelessly abused and destroyed, and much more fragile and complex than we once thought ... the largest living space on Earth is fast deteriorating. This doesn’t just threaten marine habitats and species - many of which have only recently been discovered - but also our own health, way of life, and security.
Major threats to the world's oceans include:
Poorly managed fishing
76% of the world's fisheries are already fully exploited or overfished. And each year billions of unwanted fish and other animals - like dolphins, marine turtles, seabirds, sharks, and corals - needlessly die from inefficient, illegal, and destructive fishing practices. Poor fisheries management is the largest threat to ocean life and habitats ... not to mention the livelihoods and food security of over a billion people.
Inadequate protection
They might cover over 70% of our planet’s surface, but only a tiny fraction of the oceans has been protected: just 0.6%. Even worse, the vast majority of the world’s few marine parks and reserves are protected in name only. Without more and better managed Marine Protected Areas, the future of the ocean’s rich biodiversity - and the local economies it supports - remains uncertain.
Tourism & coastal development
The beach is not just a favourite holiday destination, it’s our favourite place to live. Around the world, coastlines have been steadily turned into new housing and tourist developments, and many beaches all but disappear under flocks of holiday-makers each year. This intense human presence is taking its toll on marine life.
Shipping
The oceans are huge highways, across which we ship all kinds of goods. Like other human activities, this heavy traffic is leaving its mark: oil spills, ship groundings, anchor damage, and the dumping of rubbish, ballast water, and oily waste are endangering marine habitats around the world.
Oil & gas
Important reserves of oil, gas, and minerals lie deep beneath the seafloor. However, prospecting and drilling for these poses a major threat to sensitive marine habitats and species.
Pollution
Untreated sewage, garbage, fertilizers, pesticides, industrial chemicals ... most of the pollutants on land eventually make their way into the ocean, either deliberately dumped there or entering from water run-off and the atmosphere. Not surprisingly, this pollution is harming the entire marine food chain - all the way up to humans.
Aquaculture
Fish farming is often touted as the answer to declining wild fish stocks. But more often than not, the farming of fish and shellfish is actually harming wild fish, through the pollution the farms discharge, escaped farmed fish, increased parasite loads, and the need to catch wild fish as feed.
Climate change
Coral bleaching, rising sea levels, changing species distributions - global warming and climate change are already having a marked affect on the oceans. Strategies are needed to deal with these phenomena, and to reduce other pressures on marine habitats already stressed by rising water temperatures and levels.
source - http://www.panda.org/about_wwf/what_we_do/marine/problems/pollution/index.cfm
OCEAN POLLUTION
OceanOver 80% of marine pollution comes from land-based activities
A staggering amount of waste, much of which has only existed for the past 50 years or so, enters the oceans each year.
More information
News: Baltic fish may be too toxic to be sold
News: Rubbish keeps coming to Australia's north coast
From plastic bags to pesticides - most of the waste we produce on land eventually reaches the oceans, either through deliberate dumping or from run-off through drains and rivers. This includes:
oil , fertilizers , solid garbage ,sewage , toxic chemicals.
More oil from land than from spills
Oil spills cause huge damage to the marine environment - but in fact are responsible for only around 12% of the oil entering the seas each year. According to a study by the US National Research Council, 36% comes down drains and rivers as waste and runoff from cities and industry.
Fertilizer woes
Fertilizer runoff from farms and lawns is a huge problem for coastal areas. The extra nutrients cause eutrophication - flourishing of algal blooms that deplete the water's dissolved oxygen and suffocate other marine life. Eutrophication has created enormous dead zones in several parts of the world, including the Gulf of Mexico and the Baltic Sea.
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