WHY FARMS KILL FISH: BIODIVERSITYLOSS ON LAND AND IN WATEROverfertilization harms plants and animals and damages ecosystems worldwide.Nitrates in groundwater can cause cancer. In coastal waters, they can result inoxygen-starved “dead zones”.Agriculture’s share of total environmental impact22Industrial countries (OECD members), 2007–9, in percent35Put lots of nitrogen in a body of water and itsoxygen content goes down. How serious aproblem that is can be seen in the coastalwaters of the Gulf of Mexico. Around the mouthsof the Mississippi, some 20,000 square kilometresarea used water used energy used pesticide purchasesammoniaemissionsWater pollution:90 7545emissions ofozone-damagingmethylbromidenitrates insurface waterphosphorus insurface water70nitrogenoxide280* 70*70*nitrates ingroundwater8greenhouse gasemissions50*phosphorus ingroundwater40methane701carbondioxide30*nitrates incoastal waters* maximum valueOECDof the sea have so little oxygen that a “dead zone”has formed, in which shrimp and fish cannot survive.In 2011, researchers found that sperms weregrowing in the sex cells of female fish in the Gulfbecause a lack of oxygen was interfering withtheir enzyme balance.The cause of this marine desolation lies in theover-fertilization of the Mississippi basin, wherealmost all the United States’ feed production andindustrial farms are concentrated. Nitrogen andphosphorus are washed down the river into theGulf. There these nutrients stimulate the growthof algae, aquatic plants and bacteria, which useup the oxygen dissolved in the seawater. A litre ofseawater commonly holds around 7 milligrams ofdissolved oxygen; around the mouths of the Mississippiit holds less than 2 milligrams. The only organismsactive here are those that do not dependon oxygen to live.The US marine biologist Peter Thomas says thataround 250,000 square kilometres of coastal watersworldwide suffer from severe seasonal oxygendeficiency. In Asia, pig and poultry farms in coastalChina, Vietnam and Thailand pollute the SouthChina Sea with nitrogen. The northern part of theCaspian Sea is loaded with nitrogen that comesdown the Volga. Many of the seas surroundingEurope are affected: the Baltic Sea, the Black Sea,the Irish Sea, the Spanish coast and the Adriaticall have dead zones. The problems are caused notonly by nitrogen and phosphorus pollution, butalso by potassium, drug residues, disease-causingorganisms and heavy metals.It is not just the seas: industrialized livestockproduction harms the land too. Slurry and manurefrom livestock-producing areas are applied,often indiscriminately, to the soil. They can posean even greater threat than the overuse of mineralfertilizer, especially on well-drained soils. Nitratesare washed down into the groundwater, whichcan lead to contamination of our drinking waterand damage our health. In our bodies they can beconverted into nitrosamines, which are suspectedto cause cancer of the oesophagus and stomach.Over-fertilization threatens the habitat of nearlyall the endangered species on the Red List compiledby the International Union for Conservationof Nature. Excessive use of chemical fertilizers,pesticides and herbicides harms organisms in thesoil and water, and damages ecosystems.MEAT ATLAS
Tropical rainforests are especially rich in biodiversity,but more than one-fifth of the Amazonrainforest has already been destroyed. Livestock isone of the major causes: trees are cleared to createpastures or grow soy to feed animals. And many ofthe pastures are turned into soy fields after a fewyears. The widespread conversion of pasture tocropland to produce feed in South America andEurope cuts biodiversity, since grassland usuallycontains more species and offers a better habitatfor insects and other small animals. But intensivegrazing often leads to a loss of native species, asfarmers sow new types of grass that are more valuableas feed. This marginalizes other species. Fencingto convert an open range into ranches can cutthe migration routes of wild animals, keep themaway from waterholes, and trigger local overgrazingby cattle.Mixed farms, where crops and animals aremanaged on the same farm, often have variouspatches of vegetation – hedges, woodlots and gardens– which support a range of insects and smallanimals as well as certain wild plants. In Europe,the USA, South America and East and SoutheastAsia, many such mixed farms are being rapidlyreplaced by “landless” systems to raise pigs andpoultry on an industrial scale. In such systems, theanimals are fed with crops purchased from otherfarms and often from abroad. This is one of themain reasons for the nutrient imbalances in freshwater,soils and the ocean.In industrial systems, the genetic diversity ofthe livestock itself is usually very narrow becauseFodder fields and the dead zone in the Gulf of MexicoMississippi River drainage basin, land use and water pollutioncropped landdedicated to feedless than 5 percentless than 20 percent20–50 percentmore than 50 percenthypoxic zone due to nitrogen and phosphate loadsfarmers all over the world are offered the samefew breeding lines. Animals are no longer adaptedto their diverse natural environments. Instead,they are bred to suit the uniform conditions oflivestock houses, where the temperature, moistureand light are carefully controlled and feedcomes from the global market. In other words,biodiversity is at its lowest in a livestock pen onan industrial farm.FAOThe oversizedfootprint of factoryfarms: growingfeed and spreadingslurryNitrogen on land and in the aquatic systemMain sources of nitrogen, 2005livestockfertilizersENAMEAT ATLAS23
Change language