The dead zones (for the Anglo-Saxons) are hypoxic zones (overdrawn in Oxygène dissolved) in the watery environment (Mer S, Océan S, Estuaire S, large Lac S, Mare S etc). The studies led in the Baltic and to the USA since the end of the year 1990 show that fish number which one could think that they can easily flee them there lose consciousness quickly and die asphyxiated on the bottom. In certain cases, certain fish seem to be able to escape death, but the shellfish such as lobsters, lobsters, crawfish, crabs or shrimps move too slowly to escape asphyxiation. When to the fixed moulds, oysters and other organizations, they are condemned. The corals and of very many colonial animals die, and their putrefaction contributes to accentuate the phenomenon.

Des dead zones is observervées more and more often, and on increasingly large surfaces. The vastest dead zone located in 2003 (among approximately 150) reached according to UNO 70.000 km ² approximately. These zones have increasingly important impacts on fishing and the ecosystems.

Definitions

There exist naturally anoxic zones in great sea-beds, or at the large bottoms Lac S where water is laminated and motionless.
En Black Sea deep, a dead zone thus undoubtedly exists and persists since millenia.
Dans the remote past of planet, at the time of the great bio-geological catastrophes marked by major extinctions, anoxic zones seem to have been concerned, but on scales much vaster and durable (during several million years sometimes), causing very important losses (until more than 80% of the alive species of planet).

the concept of “zone dead” indicates abnormally anoxic zones today ; sufficient impoverished oxygenates some to kill by asphyxiation whole or part of the marine animal-life (in particular fixed animals and the Crustacé not very mobile S and animals). In all the cases identified to date, the phenomenon has or seems to have for orgine direct or indirect human activities.
Ces phenomena can last all the year, a few hours or a few days. Generally, they last a few months in the year, with a peak in the middle of the summer (July in the northern hemisphere).

Dissolved oxygen is expressed as a percentage threshold of saturation, which varies according to the Température, the Pression and the Salinité of water, and indirectly according to the agitation and the stratification of the layers of water.

• the majority of the species known as “higher” need a water rich in oxygen, to at least 80% of the threshold of saturation.
• One says that there is Hypoxie when dissolved oxygen is present only for 1 at 30% of its threshold of saturation in water; the forms of life naturally present in an oxygenated medium then are disturbed or killed. Under the bar of the 30% of the threshold of saturation, the majority of fish flee the zone when they can or die it, the decomposition of their corpse contributing to still consuming dissolved oxygen remaining).
• the stage of anoxia is reached when dissolved oxygen is completely absent. All forms of life known as " supérieures" disappear then with the profit from Bactérie S primitives and fungic organizations. Certain fish can “piper” the air on the surface. Other organizations provided with lungs or being able to breathe on the surface by the skin survive a short period of anoxia (a few minutes at a few hours), but they can nevertheless die of the continuations of the lack of food or Toxine S produced by the decomposition of the organizations in the zones become anoxic or very impoverished of oxygen. (The decomposition of nécromasse in the absence of oxygen is indeed a source of toxins for the medium; botulinic toxin for example, mortal for the Man with millionth of gram).

Extent of the phenomenon

A ratio of 2004, included in report/ratio GEO 2003, presented to the ministers with UNO in 2004 identifies nearly 150 “ dead zones ” in the world.
Klaus Toepfer (Executive director of the PNUE (Program of the United Nations for the environment) noted on this occasion which so some of these zones are of surface reduced (less than one square kilometer), others became very vast, largest reaching 70.000 km ²! .
Le number and the size of these zones increases each decade at least since the years 1970. The scientists counted some in 2003 listed nearly 150 major in the seas of planet, each one translating most probably serious phenomena of Dystrophisation marine. In certain cases, as in the Baltic, a few tens of years, even in only one decade, all the forms of life higher disappeared, with the profit of Bactérie S very primitive close relations of those which lived there is several billion years, before the appariton of the life on the emerged grounds. A prohibition of fishing in whole or part of the Baltique was evoked, but does not seem currently politically possible. The Commission HELCOM tries with others to limit this phenomenon to the source by limiting the contributions of Engrais and nutrients on ground and by studying the problem of the immersed Munitions.

Causes of the phenomenon

In a first report/ratio for UNO, the experts identified as first causes the agricultural contributions of Fertilisant S and the contributions of Nutriment S and Organic matter induced by degradation and the increasing erosion of the agricultural or deforested grounds, in a context of increasingly intensive agriculture. Report/ratio OSPAR 2002 on the health condition of the ecosystems points more particularly the Azote like person in charge.
Ces contributions contributes to increase the DCO (chemical Demande oxygenates of it) and DBO (biological Demande oxygenates of it) well audelà of what the medium can provide the night starting from the oxygen reserves dissolved in water, and sometimes of day so much water is charged with matters consuming of oxygen.
Mais any important organic matter contribution (Inondation /crues, Boue of clearing out, mobilization of Sédiment S for example by the construction of a port, an underwater career, or more simply by the trawling.) in a Aquatic environment is likely to involve a rarefaction of oxygen in the medium, more especially as horizontal mobility and especially vertical (Thermocline) of water is low, i.e. where the water masses are laminated (in the Fjord S for example) and when they are it.

At sea, of the local and seasonal phenomena of impoverishment out of oxygen exist naturally locally at periods of the years or water is laminated (be, autumn, during the formation of a thermocline). But the contributions anthropic worsen them considerably. Danish data quoted by OSPAR show that in laminated water of the Kattegat, where a serious oxygen deficit is frequently measured, it is the load in Azote which has the most impact on this phenomenon. The Danish Agence of environmental protection calculated that a reduction of 50% of the real nitrogen load would lead to a reduction of almost 50% of the duration of the phenomena of anoxia in these zones.

For the zone OSPAR, serious anoxias are noted in many Estuaire S, bay S and fjords, in the Mer of Wadden, Kattegat and is Skagerrak.

The export at sea of Sediment S of Clearing out harbor, river or of estuary also has an impact: One thus noted, at the times of stratification, in the estuary external of the Clyde and in bay of Liverpool of the temporary anoxias, both ascribable to the mud immersion resulting from clearing out.

Divers factors worsens these effects;

• Pollution S various, mainly industrial, urban and automobile.
• the lack of purification and collecting systems of waste water in the areas densément populated undoubtedly takes part also in the phenomenon, but cannot explain to him only the distribution of these zones.
• In certain areas of the world, the nitrogen rates dissolved in the rains also strongly increase (in particular since the use of the spreading of liquid nitrate fertilizers on the fields). In the same way the acid rains solubilize more nutrients, which are carried with the sea or in the lakes. The large floods are also more frequent, often for human causes (practical agricultural, Remembrement S, organic matter loss of the grounds and increasing proofing of inhabited surfaces). The combination of these 3 phenomena accelerate the matter eutrophisantes contributions at sea.
• the Turbidité increases then, at the point to prevent the solar rays from penetrating water. The planktonique Photosynthèse is inhibited and neither the Ultra-violet S solar, nor oxygen play more their part of " désinfectant" naturalness.
• Various pollution, of which by the Pesticide S, the Heavy metals, hydrocarbons and locally of chemical pollutants resulting from the immersion of Déchet S can exacerbate the phenomenon by also inhibiting photosynthesis and/or by killing a great number of plants or other organizations.
• Locally, a possible and plausible bond with the impact of firm aquicultural navy was evoked and is plausible.
• the use of balls of Starter S rich person out of organic matter by the fishermen out of closed fresh water or with slow current is also a major cause of eutrophication and anoxia of nonsurface water;

• Lastly, a new possible cause or additional, not quoted by the report/ratio of UNO, but described by the commission OSPAR could be explored, in the Baltic in particular; they are possible impacts differed from the massive immersion in the past from conventional and chemical ammunition.
  Indeed of the million ammunition not used or not exploded (whose chemical) was thrown at sea since the end of the First World War (1914-1918). A report/ratio addressed in 2005 by the Member States to Commission OSPAR listed for the first time (with 5 years of delay) 148 sites officially recognized by the Member States of convention OSPAR like zones of underwater discharge of ammunition. Thirty of these zones exclusively received chemical weapons, and three are declared with “unknown” contents . It is that the known zones of eutrophications and certain major dead zones (In Handle/the North Sea and the Baltic in particular) coincide with important zones of immersion or the zones which would be touched by their plume of diffusion if there were escape of poisons. So certain shells and ammunition started with being strongly degraded and/or to flee, the Cuivre and the Heavy metals which compose them, as well as the poisons of combat that some contain could locally be implied in the death of the Plancton and other organizations. Studies (HELCOM) showed a clear increase in certain pollutants (Arsenic for example) near certain deposits (at sea Baltique for example), whereas in other cases (Zeebrugge) not or few traces were detected, but in a zone at current fort. But the shells are degraded and the impact of the poisons which they contain is very difficult to model. Phosphorus can be present in certain ammunition, and of nitrates have composed most of the explosive of the casings of many types of ammunition immersed for one century. The photographs taken on certain sites show corroded casings and today vacuums, which let suppose that their contents were indeed solubilized in the sea. (See the article immersed Munition for more details)

In 1995, experts brought together by NATO had prevented that the shells would probably start to flee about 2005. But so of important efforts are made in Russia and in Canada in particular to cleanse military discharges, no measurement of recovery seems to have was tried at sea. Two reasons are the cost and the risks induced by such operations, and misses it production facilities able to destroy and decontaminate these materials in great quantity.

Effects on the reproduction of fish

Not only certain animals which survive have an abnormally low weight, but they reproduce badly or at all.

It was delicate to differentiate the impact of the lack of oxygen of the possible impacts of the pesticides, metals or of turbidity sometimes associated with the died zones, but it is known now that the hypoxia has in fish and other organizations of the impacts on the reproduction (reduction of the size of the reproductive bodies, the number of eggs and infertility), and that hormonal phenomena can be in question. A study of the University of the South-east of Louisiana related to killies (small fish Rivulidae Cyprinodontidae very resistant and easy to raise out of aquarium). They were studied in 3 bays supplied with estuaries of coastal rivers of the Littoral of the Gulf of Mexico. The researchers noted at the killies exposed to the anoxia in these estuaries a strong reduction in the weight and size of the reproductive bodies when they lived in water whose oxygen rates were only from 1 to 2 parts per million (ppm), and this as from 3 hours per day passed with living in this water.

- the male gonades had a size lower by 34 to 50% than those of fish of the same species and same alive age in a normally oxygenated water (6 to 8 ppm).

- the ovaries of the females were half less large than those of the females living in a normally oxygenated water, with a number of eggs on average seven times lower than the normal.

The university of Texas, in Florida, studied the Micropogonias undulatus ( Atlantic croaker in English). It is a common fish in Bay of Pensacola, bay relatively closed and protected from the winds, partially isolated from the sea by an isthmus and an island which forms a cord in the south of bay. This bay receives in its part upstream, water of 3 small estuaries located at the North-East of the town of Pensacola). She knows each year of the conditions of hypoxia the summer months.
Aucun of fish exposed to an oxygen deficit in the estuary did not reproduce at the time envisaged, nor even later.
L' study concluded into 2004 that it was because of the lack of egg viable in the females, and mature fault of sperm in the males,

To check that the simple lack of oxygen could interfere with reproductive success, of fish were high in laboratory in hypoxic condition. They actually produced abnormally low rates of sex hormones], which can also explain the abnormally small size of the reproductive bodies observed in fish living in the zones of hypoxia.
L' hypoxia supports the surexpression of two [[gene]] S implied in the production of one [[protein]] produced in conditions slightly asphyxiating (HIF or '' “hypoxia-inductile Factor” ''). In hypoxic condition, protein HIF is paired in these fish with another protein (the ARNT). Together, they bind to [[DNA]] cellular to activate there certain genes which one supposes useful for a better survival of the animal.
Lorsque the content of water oxygen is normal, the ARNT combines with the estrogen to activate certain genes. However, of the cells cultivated in hypoxic conditions out of test tubes do not react any more to the estrogen; protein HIF seems to make the ARNT inalienable. It cannot interact any more with the estrogen what inhibits the normal process of the reproduction2004 (Johanning, K., and Al 2004. Assessment off molecular interaction between low oxygen and estrogen in fish concealment culture. Fourth SETAC World Congress, 25th Annual Meeting in North America. Nov. 14-18. Portland cement, Ore. [http://abstracts.co.allenpress.com/pweb/setac2004/document/?ID=41689 Summarized]) . ==Mecanisms of formation of a zone morte== * ''' the most consensual assumption ''' is that the nutrients of agricultural, industrial origin and resulting from transport, as well as the waste brought at sea by the rivers or the rains or who were directly immersed there during decades accumulate, concentrates or stagnates under particular conditions and zones. There, strong [[eutrophication]] led to one [[dystrophisation]] and thus to a state of [[anoxia]] which ends up moving away and/or killing all the higher species of which fish, shellfish and shells necessary to the important survival on the one hand of the human population. The marine herbaria are also in these completely dead zones.
Les thresholds of [[hypoxia]] varies slightly according to the area (oxygen dissolves better in cool water, and the fish of the hot areas have sometimes less requirements out of oxygen. It is generally estimated that there is hypoxia (chronic, accidental or seasonal) when the dissolved oxygen rates fall under the 2 or 3 milligrams/liter (mg/L), the normal for littoral varying from 5 to 8 milligrams/liter. Except some fish having lungs or breathing by the skin (eel), the majority of fish have breathing difficulties below 5 mg/L. * ''' the situation can brutally rock ''' of a situation apparently healthy and stable towards the death of the richest and complex ecosystems, in a few years parfois.
Des complex phenomena related to the cast iron contributions of snow in spring and the differences in temperature and salinity which result from it probably locally play (in the Baltic for example) also a role badly included/understood. * ''' the dead zone can be far away from the zone from which the superabundance from nutrients or the responsible pollutant comes '''. Does report/ratio OSPAR QSR 2000 estimate that water enriched in nutrients and organic matter can thus be transported southern parts of England and French littoral of the North Sea towards Norwegian water where they could be in (large?) part responsible for eutrophication of [[Skagerrak]] (major zone of the Baltic). * ''' Phenomena locally related to [[climate changes]]? '''
Au broad of [[littoral]] of the '' Cape Perpetuated '' ([[Oregon]]), a dead zone was observed each year of 2002 to 2005 and was confirmed in 2006 (out of approximately 300 square miles) then in 2007. It relates to an important water column. Large shellfish die in the racks of fishing. On the beaches the sea deposits the corpses of many asphyxiated dead animals, of which quantity of crabs. And for the first time, semi-2006, of very low oxygen content were also recorded in coastal water until the broad one of Washington. Records of anoxia were measured with 180 basic feet (up to 0.46 millilitre of oxygen dissolved per liter), but also with intermediate depths; 1 millilitre of Oxygen dissolved per liter of water, with 45 feet (knowing that the fish and of many species asphyxiate themselves in lower part of 1,4 ml/L).
Un submarine robots filmed semi-2006 a true crab cemetery dead and a carpet of worms in decomposition” near the reefs of Perpetuated in the south of Newport, whereas the fishermen reported the presence of an exceptionally high number of rockfishs who seem to have fled the dead zone - in sectors where they are usually absent. New a video in May 2007 showed that the rockfishs had returned, but not less mobile animals ([[cucumber of sea]], [[sea-anenome]], etc)
L' be 2006, a study relating to 12 miles square highlighted an oxygen rate 6 times lower than the normal in this zone. The situation was even more serious in 2006, with a dead zone which is for the first wide time of the south of Oregon at the end of the Olympic peninsula of Washington (that is to say nearly 300 miles), concerning also the marine sanctuary of the '' Olympic Coast National Marine Sanctuary ''.
Dans this case precise, the local and massive contribution of eutrophisants agricultural seems out of cause, and is it is not a question of nitrates lost by waste or [[immersed ammunition]], the only explanation seems to be a particular conjunction between feature of coast, change of the intensity and of the synchronization of the coastal winds (changes envisaged by the mathematical models of the climate change in this zone) and current particuliers.
Il seems that winds and currents make go up bottom an unusual quantity of water rich person in nutrients, but very low in oxygen which forms a vast zone died in the broad one. Then in summer, since 2002, an also unusual configuration of winds and currents push this water mass towards the coast where it asphyxiates the faune [http://www.piscoweb.org/files/PISCO-hypoxia-briefing_page-2004.pdf presentation of the dead zone which faces the '' “Cape Perpetua” '']. This case is studied by a scientific consortium '' “PISCO” '' (Partnership for InterdisplinaryStudies off Coastal Oceans), with the assistance of the OSU, the ODFW, the NOAA and the university of Washington) , Article of the NewYork Times of August 6th, 2006 and [http://oregonstate.edu/dept/ncs/newsarch/2006/Jul06/deadzone.html Communiqué of the State of Oregon of the 07-26-06] (July 31st, 2007) . This water dopes the growth of the plankton, causing one [[planktonique bloom]] and one [[dystrophisation]] serious of the medium when this plankton dies asphyxiated. The researchers could not highlight of bond with cycles such as [[El Niño]]. The public is invited to contribute to the study of the phenomenon by providing information on mortalities observed. * ''' It [[temperature]] and/or it [[salinity]] ''' is Co-factors which play; initially because tepid water naturally loses its oxygen and then by what the temperature variations and of density can lead to stratification of layers of different temperatures, some durably being able to remain very impoverished of oxygène.
Ce phenomenon applies to certain lakes. For example, the artificial Lake of [[the Stopping of Small-jump|stopping EDF of Small-jump]] in Guyana, which drowned million trees presents a surface layer of water normally oxygenated shower (on 3 m of water approximately) where all appears normal, with the top of a very impoverished water mass where the life is much more reduced. ==Réversibilité== If the phenomenon is temporary, and that it does not reproduce every year, some [[ecological impact strength]] seem '' a priori '' possibleMee, Laurence. " '' Reviving Dead Zones '' " , Scientific American, November 2006. Retrieved one December 9,2006.. She will be facilitated by the presence of [[continuum biological|ecological continuities]] and proximity of zones rich in biodiversity (cores of recolonisation, which can for example be '' [[natural reserve|underwater natural reserves]] ''). Nevertheless, the '' “return to the normal” '' will take time; a variable time according to the former richness and the sensitivity of the medium, according to its degree of [[ecological insularity]] and according to the extent and the duration of the phenomenon of '' dead zone '', because once the source of nutrients is controlled, it is necessary as time as phosphorus and nitrogen excesses are " '' recycled '' " or '''' diluted '''' by [[ecosystem]], which is longer for phosphorus than for nitrogen.
In addition, in the most serious cases, it [[genetic inheritance]] and ecological lost, which constitutes an essential component of [[biodiversity]] is definitively. Other individuals and colonies, possibly pertaining to other species will come to replace those which disappeared, while starting with the species pionnières and those which move easily. If the '' dead zone '' were formerly a high-place of biodiversity sheltering for example the last samples of certain endemic species, these-last will not reappear.
Enfin, the reversibility is not possible that when one can intervene on the source of the problem, which is not the case when as in Oregon, the causes seem related to changes of great width, of " type; '' climatic '' ". ==Situation in 2004== The '' dead zones '' are “''''' the great threat of XXIe century for fish ''''' stocks” titrated an official statement of UNO emitted in Nairobi it [[March 29th]] [[2004]] at the time of the Eighth extraordinary session of the Board of directors of [[PNUE]] and the '' world ministerial Forum on the environment ''.
Les ecologists and managers of fishing resources particularly are worried by [[the Baltic]] and the Gulf of Mexico where, in spite of some local improvements, the total situation does not cease being degraded since the years 1980. ==Localization == Local phenomena of déplétion of oxygen existed during the historical time before the arrival of manures of synthesis. They seem induced by exceptional weather risks, great deforestations or peaks of erosion after fires.
Ainsi of the “fossil” traces '' '' of tolerant organizations with weak the oxygen content of water was detected in the recent sediments, downstream from the estuary of [[the Mississippi (river)|The Mississippi]], indicating that four events hypoxic took place there before the arrival of the artificial fertilizers. The dating of these events memorized by the sediments seems in these four cases to correspond to the historical records of raw of the river, recorded by instruments of Vicksburg, MississippiOsterman, L.E., and Al 2004. '' Reconstructing year 180-yr record off natural and anthropogenic induced hypoxia from the sediments off the Continental Louisiana Shelf ''. Geological Society off America meeting. Nov. 7-10. Denver [http://gsa.confex.com/gsa/2004AM/finalprogram/abstract_75830.htm Summarized]. . The first dead zones were localized in the years [[1970]] in the USA (with in particular bay of [[Chesapeake]]) and at sea the Baltic, in [[Kattegat]], then in [[Black Sea]] and in the north of [[Adriatic Sea]]. Their number was initially underestimated because one sought them that in the rich countries and only where they had already obvious impacts economic on fishing. That of [[Gulf of Mexico]], very polluted by water of [[the Mississippi (river)|The Mississippi]] which drains it [[Middle West]] agricultural was very studied and is still, while other zones were born or were discovered.
Depuis, other dead zones of width and annual duration variables were listed per tens in the fjords [[Scandinavia|Scandinavians]], in [[Latin America]], in [[China]], with [[Japan]], in [[Australia]] of south-east, and perhaps in [[New Zealand]]; This last country is little populated (4 million inhabitants) but it was strongly [[deforestation|deforested]], it developed one [[breeding]] locally intensive of [[sheep]] S, it knows an intensive fishing with broad (fish of deep seas in particular) and it knows local problems of [[career]], [[discharge]] S, pollution and of purification of waste water, but these problems touch it on a scale quite less, reported to its surface, that the other rich countries, or under development ([[China]], [[India]].). Its maritime environment is famous being among the most saved planet, the more so as this country uses '' a priori '' only few nitrates and pollutes slightly by [[phosphorus]]. Nevertheless, for reasons still badly included/understood, one also notes that the surface water of the sub-Antarctic zone contains nitrogen and phosphorus atas high rates even more as off Europe ([http://www.nodc.noaa.gov/OC5/WOA01F/nusearch.html Voir charts NOAA]). Certain authors think that one cannot speak yet about zones died for this country, but the simple ones [[planktonique Bloom|blooms (efflorescences alguales)]] Taylor, F.J., N.J. Taylor, J.R. Walsby 1985. '' Has bloom off planktonic diatom Ceratulina pelagica off the coastal northeastern New Zealand in 1983, and its contribution to year associated mortality off fish and benthic fauna ''. Re-examined Intertional ges. Hydrobiol. 70:773 - 795, Morrisey, D.J. 2000. '' Predicting impacts and recovery off marinades farm sites in Stewart Island New Zealand, from the Findlay-Watling model ''. Aquiculture 185:257 - 271.. The last report/ratio of [[the United Nations|UNO]] did not include the Zealand News besides in the affected regions. UNO in its '' Programme [http://www.gpa.unep.org/bin/php/igr/igr2/supporting.php Gate Internet of the Program of protection of Maritime environment against the contributions anthropic] of environmental protection sailor against the contributions anthropic '' encourages one [[monitoring]] and a voluntary treatment of pollution by nitrates ([http://www.gpa.unep.org/content.html?ln=6&id=354 Exemples]). Zones of fall of oxygen concentration also were recently detected in the east of the tropical Pacific Ocean and in the north of the Indian Ocean, a priori in zones where the circulation of water is too weak for quickly replacing the oxygen consumed by the alive species or by [[biological demand for oxygen]] (See for example Pickard and Emery (Pickard, G.L and Emery, W.J. 1982. Description Physical Oceanography: Year Introduction. Pergamon Near, Oxford, 249 pp. /See page 47) and [http://www.nodc.noaa.gov/OC5/WOA01F/oxsearch.html NOAA]. ==Impacts économiques== They were not evaluated, but seem considerable for fishing. The hypoxia for example is considered to be responsible for the collapse of the populations of shrimps in the Gulf of Mexico, of shellfish of lobster (the sold shellfish expensive) in Kattegat (Norway) and of a general reduction of the fishing resource at sea of north, and more still in the closed seas (Black Sea and the Baltic).
As example still, downstream from the estuary of the Mississippi, the fishermen of [[Louisiana]] complain in 2006-2007 about the extension about the “'' dead-zone about the Gulf about Mexico City ''” (Its surface doubled in 12 years; from 1985 to 2997). As the researchers who study it, they estimate that there is a bond between the records of anoxia of July 2007 and the records of surface planted out of corn (In 2007: the vastest corn surface (generally [[GMO]]) ever planted in the USA was to it “thanks” to the tax reductions and subsidies with [[agrocarburant]] and in particular to [[ethanol]]. This policy aims making the country less depend on the oil importations, and at decreasing its gas emissions with greenhouse effect. Corn GMO is cultivated with nitrate fertilizers, treated with increasing quantities of Atrazine (weeding), and it emits toxin [[LT]] in its [[rhizosphère]] (LT likely to be washed by the rains on the grounds sensitive to erosion). Roof of irony, this dead zone whose size in 2007 reached the surface of the state of the New Jersey, emits important quantity of gas with greenhouse effect ([[Methane]], [[Carbon dioxide]]; that the agro-fuel were precisely judicious to reduce)
In July 2007, the researchers feared to see this dead zone reaching more than 22.100 km2. The majority of fish die there or flee it, and the formerly abundant shrimps die there asphyxiated. In July 2007 Nancy Rabalais, pilot of the team of researcher of the “'' Louisiana Universities Marine Consortium ''” which studies this zone; estimated that the nitrate fertilizers used for this corn are mainly at least responsible for this extension, and it notes that “if this occurred in the middle of the country, people would be insults”.
La die fishing is most directly affected: it is in Louisiana the second in importance for the USA (behind [[Alaska]]). It produced the first tonnages of [[shrimp]], [[oyster]] S and [[crayfish]] S (according to the official statistics), but the number of shrimper has in this dropped state of 40 percent of 2001 to 2007.
Depuis 1990, after a peak of 46,9 brown shrimp unloading, kg million in Louisiana and with [[Texas]] regularly declined, as the zone of hypoxia augmentaitÉtude of the NOAA (National Oceanic and Atmospheric Administration) 2001, of Roger Zimmermann and James Nance.
De more, where the shrimps survive, they are of smaller size. The intermediate size of shrimps (in fact measured by their average weight) fell of 23 percent in 10 years (of end of the year 1980 at the Nineties) in this area. A “'' Task force ''” associating it [[EPA]] ('' Agence of environmental protection of the USA '') and of the scientists, the agencies of state and the federal agencies fixed itself in 2001 an reduction objective of the size of this zone at 2.000 square miles, but the recommendations of this group are followed little, in a context which encourages the farmers to plant without precautions (this corn is not food, and the premiums with the refiners, fuel distributers and retailers are very inciting; tax credit on each liter of ethanol mixed with the gasoline. The promotion of ethanol by the government of GW Bush and all the states (subsidy of Alabama in fact) forever be also intense only in 2007. (Source principale [http://www.bloomberg.com/apps/news?pid=20601109&sid=a4Tb2AFv6CRk&refer=home Article of Bloomberg: '' Dead Zone Is Price GULF Coast Country ace Farms Cash In one Ethanol ''] ) ==Perspectives == The ecologists and UNO fear in 2004 the emergence or the aggravation of this type of problem in Asia, Latin America and Africa, because of the rapid growth of industrialization and the intensive agriculture. The total warming could also contribute to the phenomenon via the increase in precipitations, and raises it marine temperatures. The cholera, certain forms of [[botulism]] or other diseases could be favoured by this phenomenon, which in addition by the methane and CO2 emissions which it causes contributes to the greenhouse effect. == International engagements == ''' International conventions '''; '' Geographical agreements '' ([[OSPAR]], [[HELCOM]]) incite to study these situations, but also to cure it. : Examples * An agreement on [[the Rhine]] in Europe aimed at a reduction of 50% of the nitrogen rates brought at sea, but in 2004, it had been reduced only of 37%.
Aux the USA, one fears that the subsidies with [[agrocarburant]] the S result in an increased use of nitrate fertilizers and phosphated. * In Europe, in 1998, the OSPAR adopted a fight plan against [[eutrophication]] (Reference number OSPAR 1998-18), including the objective of: “to fight eutrophication in the maritime zone of OSPAR” “to arrive to and maintain a seamen circle healthy where the phenomena of eutrophication will not occur. ” Calendar OSPAR, envisaged to restore a normal situation before 2010. * [[Baltic States]] are engaged by convention HELCOM to reduce the marine pollution Baltique. * European directives: [[Parent directive on water]] and it [[Directive Nitrates]] should contribute to reduce to the source the marine pollutants eutrophisants, since they include in their sphere of activity and their objectives as well the fresh water as salted and brackish with the objective to find an ecological good state of water. The application of the directive nitrates was very difficult, in particular the first years with the criteria of establishment of [[vulnerable zone]] which were not respected in certain areas of intensive agriculture (Northern of France for example), but its application seems to improve, with first visible effects. ==Liens interns== * [[Eutrophication]] * [[Dystrophisation]] * [[planktonique Bloom]] * [[Marine pollution]] * [[immersed Ammunition]] * [[Parent directive Strategy for the seamen circle]] * [[International counsel for the exploration of the sea]] (the scientific opinions of the EU base on the exploitation of the sea) ==Liens externes== * {{in}} http://www.ehponline.org/docs/2000/108-3/focus.html * {{in}} http://www.nature.com/news/2005/050620/pf/4351014b_pf.html * {{in}} http://www.sciencedaily.com/releases/2004/12/041208202518.htm * {{Fr}} http://www.unep.org/gc/gcss-viii/FRENCH/PressRelease_F2.asp * {{in}} [http://www.ospar.org/documents/dbase/publications/p00222_2005%20Revised%20Dumping%20at%20Sea%20of%20chemical%20weapons.pdf Report/ratio OSPAR on the immersed ammunition (Overview off Past Dumping At Sea off Chemical Weapons and Ammunition in Maritime the OSPAR Area) Version 2005] :: {{in}} [http://www.ospar.org/v_publications/browse.asp?v3=53&lang=2 to download it in compressed format, to click on this bond] ==Notes and références== [[Category: Ecology]] [[category: Oceanography]] [[Category: Water pollution]] [[Category: Ecological catastrophe]] {{multi stringcourse|Ecology|Maritime gate}} [[of: Umkippen]] [[in: Dead zone (ecology)

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