Marine pollution

From Wikipedia, the free encyclopedia

While marine pollution can be obvious, as in the case of the marine debris shown here, it is often the pollutants that cannot be seen that cause most harm.

Marine pollution occurs when harmful effects, or potentially harmful effects, can result from the entry into the ocean of chemicals, particles, industrial, agricultural and residential waste, or the spread of invasive organisms.

Most sources of marine pollution are land based. The pollution often comes from nonpoint sources such as agricultural runoff and wind blown debris.

Many potentially toxic chemicals adhere to tiny particles which are then taken up by plankton and benthos animals, most of which are either deposit 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. Also, many animal feeds have a high fish meal or fish hydrolysate content. In this way, marine toxins can be transferred to land animals, and appear later in meat and dairy products.

[edit] History

Parties to the MARPOL 73/78 convention on marine pollution

Although marine pollution has a long history, significant international laws to counter it were enacted in the twentieth century. Marine pollution was a concern during several United Nations Conferences on the Law of the Sea beginning in the 1950s. Most scientists believed that the oceans were so vast that they had unlimited ability to dilute, and thus render harmless, pollution.. In the late 1950s and early 1960s, there were several controversies about dumping radioactive waste off the coasts of the United States by companies licensed by the Atomic Energy Commission, into the Irish Sea from the British reprocessing facility at Windscale, and into the Mediterranean Sea by the French Commissariat à l'Energie Atomique. After the Mediterranean Sea controversy, for example, Jacques Cousteau became a worldwide figure in the campaign to stop marine pollution. Marine pollution made further international headlines after the 1967 crash of the oil tanker Torrey Canyon, and after the 1969 Santa Barbara oil spill off the coast of California. Marine pollution was a major area of discussion during the 1972 United Nations Conference on the Human Environment, held in Stockholm. That year also saw the signing of the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, sometimes called the London Convention. The London Convention did not ban marine pollution, but it established black and gray lists for substances to be banned (black) or regulated by national authorities (gray). Cyanide and high-level radioactive waste, for example, were put on the black list. The London Convention applied only to waste dumped from ships, and thus did nothing to regulate waste discharged as liquids from pipelines.^[1]

[edit] Pathways of pollution

Septic river.

Bjorn Jenssen (2003) notes in his article, “Anthropogenic pollution may reduce biodiversity and productivity of marine ecosystems, resulting in reduction and depletion of human marine food resources” (p. A198). There are many different ways to categorize, and examine the inputs of pollution into our marine ecosystems. Patin (n.d.) notes that generally there are three main types of inputs of pollution into the ocean: direct discharge of waste into the oceans, runoff into the waters due to rain, and pollutants that are released from the atmosphere.

One common path of entry by contaminants to the sea are rivers. The Hudson in New York State and the Raritan in New Jersey, which empty at the northern and southern ends of Staten Island, are a source of mercury contamination of zooplankton (copepods) in the open ocean. The highest concentration in the filter-feeding copepods is not at the mouths of these rivers but 70 miles south, nearer Atlantic City, because water flows close to the coast. It takes a few days before toxins are taken up by the plankton^[2].

Pollution is often classed as point source or nonpoint source pollution. Point source pollution occurs when there is a single, identifiable, and localized source of the pollution. An example is directly discharging sewage and industrial waste into the ocean. Pollution such as this occurs particularly in developing nations. Nonpoint source pollution occurs when the pollution comes from ill-defined and diffuse sources. These can be difficult to regulate. Agricultural runoff and wind blown debris are prime examples.

[edit] Pollution from ships

A cargo ship pumps ballast water over the side.

Ships can pollute waterways and oceans in many ways. Oil spills can have devastating effects. While being toxic to marine life, polycyclic aromatic hydrocarbons (PAHs), the components in crude oil, are very difficult to clean up, and last for years in the sediment and marine environment.^[2]

Discharge of cargo residues from bulk carriers can pollute ports, waterways and oceans. In many instances vessels intentionally discharge illegal wastes despite foreign and domestic regulation prohibiting such actions. Ships create noise pollution that disturbs natural wildlife, and water from ballast tanks can spread harmful algae and other invasive species.^[3]

Meinesz believes that one of the worst cases of a single invasive species causing harm to an ecosystem can be attributed to a seemingly harmless jellyfish. Mnemiopsis leidyi, a species of comb jellyfish that spread so it now inhabits estuaries in many parts of the world. It was first introduced in 1982, and thought to have been transported to the Black Sea in a ship’s ballast water. The population of the jellyfish shot up exponentially and, by 1988, it was wreaking havoc upon the local fishing industry. “The anchovy catch fell from 204,000 tonnes in 1984 to 200 tons in 1993; sprat from 24,600 tonnes in 1984 to 12,000 tonnes in 1993; horse mackerel from 4,000 tonnes in 1984 to zero in 1993.”^[3] Now that the jellyfish have exhausted the zooplankton, including fish larvae, their numbers have fallen dramatically, yet they continue to maintain a stranglehold on the ecosystem.

Invasive species can take over once occupied areas, facilitate the spread of new diseases, introduce new genetic material, alter underwater seascapes and jeopardize the ability of native species to obtain food. Invasive species are responsible for about $138 billion annually in lost revenue and management costs in the US alone.^[4]

[edit] Plastic debris

A mute swan builds a nest using plastic garbage.

Remains of an albatross containing ingested flotsam

Marine debris on Kamilo Beach, Hawaii, washed up from the Great Pacific Garbage Patch

Marine debris is mainly discarded human rubbish which floats on, or is suspended in the ocean. Eighty percent of marine debris is plastic - a component that has been rapidly accumulating since the end of World War II.^[5] The mass of plastic in the oceans may be as high as one hundred million metric tons.^[6]

Discarded plastic bags, six pack rings and other forms of plastic waste which finish up in the ocean present dangers to wildlife and fisheries.^[7] Aquatic life can be threatened through entanglement, suffocation, and ingestion.^[8][9][10] Fishing nets, usually made of plastic, can be left or lost in the ocean by fishermen. Known as ghost nets, these entangle fish, dolphins, sea turtles, sharks, dugongs, crocodiles, seabirds, crabs, and other creatures, restricting movement, causing starvation, laceration and infection, and, in those that need to return to the surface to breathe, suffocation.^[11]

Many animals that live on or in the sea consume flotsam by mistake, as it often looks similar to their natural prey.^[12] Plastic debris, when bulky or tangled, is difficult to pass, and may become permanently lodged in the digestive tracts of these animals, blocking the passage of food and causing death through starvation or infection.^[13][14]

Plastics accumulate because they don't biodegrade in the way many other substances do. They will photodegrade on exposure to the sun, but they do so properly only under dry conditions, and water inhibits this process.^[15] In marine environments, photodegraded plastic disintegrates into ever smaller pieces while remaining polymers, even down to the molecular level. When floating plastic particles photodegrade down to zooplankton sizes, jellyfish attempt to consume them, and in this way the plastic enters the ocean food chain. ^{[16] [17]} Many of these long-lasting pieces end up in the stomachs of marine birds and animals,^[18] including sea turtles, and black-footed albatross.^[19]

Plastic debris tends to accumulate at the centre of ocean gyres. In particular, the Great Pacific Garbage Patch has a very high level of plastic particulate suspended in the upper water column. In samples taken in 1999, the mass of plastic exceeded that of zooplankton (the dominant animal life in the area) by a factor of six.^[5][20]

Toxic additives used in the manufacture of plastic materials can leach out into their surroundings when exposed to water. Waterborne hydrophobic pollutants collect and magnify on the surface of plastic debris,^[6] thus making plastic far more deadly in the ocean than it would be on land.^[5] Hydrophobic contaminants are also known to bioaccumulate in fatty tissues, biomagnifying up the food chain and putting pressure on apex predators. Some plastic additives are known to disrupt the endocrine system when consumed, others can suppress the immune system or decrease reproductive rates.^[20] Floating debris can also absorb persistent organic pollutants from seawater, including PCBs, DDT and PAHs.^[21] Aside from toxic effects,^[22] when ingested some of these are mistaken by the animal brain for estradiol, causing hormone disruption in the affected wildlife.^[19]

[edit] Toxins

Apart from plastics, there are particular problems with other toxins that do not disintegrate rapidly in the marine environment. Examples of persistent toxins are PCBs, DDT, pesticides, furans, dioxins and phenols. Heavy metals are metallic chemical elements that have a relatively high density and are toxic or poisonous at low concentrations. Examples are mercury, lead, nickel, arsenic and cadmium.

Such toxins can accumulate in the tissues of many species of aquatic life in a process called bioaccumulation. They are also known to accumulate in benthic environments, such as estuaries and bay muds: a geological record of human activities of the last century.

[edit] Eutrophication

Polluted lagoon.

Effect of eutrophication on marine benthic life

Eutrophication is an increase in chemical nutrients, typically compounds containing nitrogen or phosphorus, in an ecosystem. It can result in an increase in the ecosystem's primary productivity (excessive plant growth and decay), and further effects including lack of oxygen and severe reductions in water quality, fish, and other animal populations.

The biggest culprit are rivers that empty into the ocean, and with it the many chemicals used as fertilizers in agriculture as well as waste from livestock and humans. An excess of oxygen depleting chemicals in the water can lead to hypoxia and the creation of a dead zone.^[23]

Estuaries tend to be naturally eutrophic because land-derived nutrients are concentrated where runoff enters the marine environment in a confined channel. The World Resources Institute has identified 375 hypoxic coastal zones around the world, concentrated in coastal areas in Western Europe, the Eastern and Southern coasts of the US, and East Asia, particularly in Japan.^[24] In the ocean, there are frequent red tide algae blooms^[25] that kill fish and marine mammals and cause respiratory problems in humans and some domestic animals when the blooms reach close to shore.

In addition to land runoff, atmospheric anthropogenic fixed nitrogen can enter the open ocean. A study in 2008 found that this could account for around one third of the ocean’s external (non-recycled) nitrogen supply and up to three per cent of the annual new marine biological production.^[26] It has been been suggested that accumulating reactive nitrogen in the environment may have consequences as serious as putting carbon dioxide in the atmosphere.^[27]

[edit] Acidification

The oceans are normally a natural carbon sink, absorbing carbon dioxide from the atmosphere. Because the levels of atmospheric carbon dioxide are increasing, the oceans are becoming more acidic.^[28][29] The potential consequences of ocean acidification are not fully understood, but there are concerns that structures made of calcium carbonate may become vulnerable to dissolution, affecting corals and the ability of shellfish to form shells.^[30].

A report from NOAA scientists published in the journal Science in May 2008 found that large amounts of relatively acidified water are upwelling to within four miles of the Pacific continental shelf area of North America. This area is a critical zone where most local marine life lives or is born. While the paper dealt only with areas from Vancouver to northern California, other continental shelf areas may be experiencing similar effects.^[31]

[edit] Specific examples

• Chinese and Russian industrial pollution such as phenols and heavy metals in the Amur River have devastated fish stocks and damaged its estuary soil. ^[32]

• Wabamun Lake in Alberta, Canada, once the best whitefish lake in the area, now has unacceptable levels of heavy metals in its sediment and fish.

• Acute and chronic pollution events have been shown to impact southern California kelp forests, though the intensity of the impact seems to depend on both the nature of the contaminants and duration of exposure.^{[33][34][35][36][37]}

• Ballast water taken up at sea and released in port is a major source of unwanted exotic marine life. The invasive freshwater zebra mussels, native to the Black, Caspian and Azov seas, were probably transported to the Great Lakes via ballast water from a transoceanic vessel.^[38]

• Due to their high position in the food chain and the subsequent accumulation of heavy metals from their diet, mercury levels can be high in larger species such as bluefin and albacore. As a result, in March 2004 the United States FDA issued guidelines recommending that pregnant women, nursing mothers and children limit their intake of tuna and other types of predatory fish.^[39]

• Some shellfish and crabs can survive polluted environments, accumulating heavy metals or toxins in their tissues. For example, mitten crabs have a remarkable ability to survive in highly modified aquatic habitats, including polluted waters.^[40] The farming and harvesting of such species needs careful management if they are to be used as a food.^[41][42]

• Mining has a poor environmental track record. For example, according to the United States Environmental Protection Agency, mining has contaminated portions of the headwaters of over 40% of watersheds in the western continental US.^[43] Much of this pollution finishes up in the sea.

• Heavy metals enter the environment through oil spills - such as the Prestige oil spill on the Galician coast - or from other natural or anthropogenic sources.^[44]

[edit] Solutions

Aerosol can polluting a beach.

Marine pollution is part of the problem of too much pollution by humans in general. There are only two ways to remedy this: either the human population is reduced, or the ecological footprint left behind by the average human is reduced. If we do not follow the second way, then the first way may be imposed upon us, as world ecosystems falter and cease to support us.

The second way is for us, individually, to consume and pollute less than we do currently. For this there must be social and political will, together with a shift in awareness, so more people respect their environment and are less disposed to abuse it.

At an operational level, regulations, and international government participation is needed. It is often very difficult to regulate marine pollution because pollution spreads over international barriers, thus making regulations hard to create as well as enforce.

Perhaps the most important strategy for reducing marine pollution is education. Most are unaware of the sources, and harmful effects of marine pollution, and therefore little is done to address the situation. In order to inform the population of all the facts, in depth research must be done to provide the full scale of the situation. Then this information must be made public.

As expressed in Daoji and Dag’s research, one of the reasons why environmental concern is lacking among the Chinese is because the public awareness is low and therefore should be targeted. Likewise, regulation, based upon such in-depth research should be employed. In California, such regulations have already been put in place to protect Californian coastal waters from agricultural runoff. This includes the California Water Code, as well as several voluntary programs. Similarly, in India, several tactics have been employed that help reduce marine pollution, however, they do not significantly target the problem. In Chennai city, India, sewage has been dumped further into open waters. Due to the mass of waste being deposited, open-ocean is best for diluting, and dispersing pollutants, thus making them less harmful to marine ecosystems.

[edit] See also

• Dead zone (ecology)
• Flotsametrics and the Floating World (book)
• Great Pacific Garbage Patch
• Particle (ecology)
• Pollution
• Water pollution
• Aquatic toxicology
• Cultural eutrophication

[edit] Notes

[edit] References

• Ahn, YH; Hong, GH; Neelamani, S; Philip, L and Shanmugam, P (2006) Assessment of Levels of coastal marine pollution of Chennai city, southern India. Water Resource Management, 21(7), 1187-1206.
• Daoji, L and Dag, D (2004) Ocean pollution from land-based sources: East China sea. AMBIO – A Journal of the Human Environment, 33(1/2), 107-113.
• Dowrd, BM; Press, D and Los Huertos, M (2008) Agricultural non-point sources: water pollution policy: The case of California’s central coast. Agriculture, Ecosystems & Environment, 128(3), 151-161.
• Laws, Edward A (2000) Aquatic Pollution John Wiley and Sons. ISBN 9780471348757
• Sheavly, SB and Register, KM (2007) Marine debris and plastics: Environmental concerns, sources, impacts and solutions. Journal of Polymers & the Environment, 15(4), 301-305.
• Slater, D (2007) Affluence and effluents. Sierra 92(6), 27
• UNEP (2007) Land-based Pollution in the South China Sea. UNEP/GEF/SCS Technical Publication No 10.

[edit] External links

• Coastal Pollution Information from the Coastal Ocean Institute, Woods Hole Oceanographic Institution
• Mercury pollution
• How Oil Spill Absorbent Products Work
• Facts about Marine Mercury Pollution from Oceana.org
• Science News / Marine Pollution Spawns 'wonky Babies'

v • d • e Wild fisheries Wild fisheries Ocean fisheries · Forage fisheries · Krill fisheries · Kelp fisheries · Eel fisheries · Shrimp fisheries · Crab fisheries · Cod fisheries · Ocean habitats · Shoaling and schooling · Migration · Sardine run · Fish ladder · Water column · Marine snow · Upwelling · Humboldt current · Red tides · Dead zones · Fish kill Fisheries science Population dynamics of fisheries · Shifting baseline · Fish stock · Stock assessment · Fish measurement · Fish counter · Biomass · Fisheries acoustics · Acoustic tags · GIS and aquatic science · EcoSCOPE · Age class structure · Trophic cascades · Marine biology · Aquatic ecosystems · Fish types · Bioeconomics · Ecopath · Fishbase · FMAP · Census of Marine Life · Fisheries databases · Institutes · Fisheries scientists Management Fisheries management · Monitoring control and surveillance · Vessel monitoring system · Fishery Resources Monitoring System · Catch reporting · Fisheries observer · Illegal, unreported and unregulated fishing · Fisheries organizations Quotas Individual fishing quota · Minimum landing size · Incidental mortality · Discards · Bycatch · Cetacean bycatch  · Turtle excluder device · Shrimp-Turtle case · EU quotas · EU MLS · Exclusive Economic Zone Sustainability Overfishing · Marine pollution · Mercury in fish · Environmental effects of fishing · Destructive fishing practices · Maximum sustainable yield · Marine Protected Area · Marine reserve · Marine conservation · Marine conservation activism · Sustainable seafood · Marine Stewardship Council · Friend of the Sea · Seafood Watch · Oceana · Sea Around Us Project · Defying Ocean's End · PROFISH · The Sunken Billions · End of the Line

v • d • e Fisheries and fishing topic areas Fisheries Fisheries science · Wild fisheries · Oceanic habitats · Fish farming · Aquaculture · Edible fish types · Fisheries management · Fishing quota · Sustainability Fishing Fisherman · Artisan fishing · Fishing villages · Fishing vessels · Fishing history Industry Commercial fishing · Processing · Products · Seafood · Marketing · Markets Recreational Angling · Game fishing · Fly fishing · Catch and release Techniques Gathering · Spearfishing · Line fishing · Netting · Trawling · Trapping · Other Tackle Hook · Line · Sinker · Rod · Bait · Lures · Artificial flies · Bite alarms Locations Fishing by country · Fishing villages · Fishing banks · Fish ponds List of articles by topic areas · Alphabetical list of articles · Fisheries glossary