Editing Abyssal plain (section)

==Exploitation of resources==
{{See also|Deep sea mining|Offshore drilling}}

In addition to their high biodiversity, abyssal plains are of great current and future commercial and strategic interest. For example, they may be used for the legal and illegal disposal of large structures such as ships and [[Oil platform|oil rigs]], [[radioactive waste]] and other [[hazardous waste]], such as [[Ammunition|munitions]]. They may also be attractive sites for [[Fishing|deep-sea fishing]], and [[Hydrocarbon exploration|extraction of oil and gas]] and other [[mining|minerals]]. Future deep-sea [[Waste management|waste disposal]] activities that could be significant by 2025 include [[Sewage treatment|emplacement of sewage and sludge]], [[carbon sequestration]], and disposal of [[Dredging|dredge spoils]].<ref name=Glover2003>{{Cite journal
|author1=Adrian G. Glover |author2=Craig R. Smith |s2cid=53666031 |title=The deep-sea floor ecosystem: current status and prospects of anthropogenic change by the year 2025
|journal=Environmental Conservation
|volume=30
|issue=3
|pages=219–241
|year=2003
|doi=10.1017/S0376892903000225|bibcode=2003EnvCo..30..219G }}</ref>

As [[fish stocks]] dwindle in the upper ocean, deep-sea [[Fishery|fisheries]] are increasingly being targeted for exploitation. Because [[deep sea fish]] are long-lived and slow growing, these deep-sea fisheries are not thought to be sustainable in the long term given current management practices.<ref name=Glover2003/> Changes in primary production in the photic zone are expected to alter the standing stocks in the food-limited aphotic zone.

Hydrocarbon exploration in deep water occasionally results in significant [[environmental degradation]] resulting mainly from accumulation of contaminated [[drill cuttings]], but also from [[oil spill]]s. While the [[Blowout (well drilling)|oil blowout]] involved in the [[Deepwater Horizon oil spill]] in the [[Gulf of Mexico]] originates from a [[wellhead]] only 1500&nbsp;meters below the ocean surface,<ref>{{Cite news|last=Macdonald |first=Ian R. |url=https://www.nytimes.com/2010/05/22/opinion/22macdonald.html |title=The Measure of an Oil Disaster
|author2=John Amos |author3=Timothy Crone |author4=Steve Wereley
|work=The New York Times
|date=21 May 2010
|access-date=18 June 2010| archive-url= https://web.archive.org/web/20100526182228/http://www.nytimes.com/2010/05/22/opinion/22macdonald.html| archive-date= 26 May 2010 | url-status= live}}</ref> it nevertheless illustrates the kind of [[environmental disaster]] that can result from mishaps related to [[offshore drilling]] for oil and gas.

Sediments of certain abyssal plains contain abundant mineral resources, notably [[Manganese nodule|polymetallic nodules]]. These potato-sized [[concretion]]s of manganese, iron, nickel, cobalt, and copper, distributed on the seafloor at depths of greater than 4000&nbsp;meters,<ref name=Glover2003/> are of significant commercial interest. The area of maximum commercial interest for polymetallic nodule mining (called the [[Pacific nodule province]]) lies in [[international waters]] of the Pacific Ocean, stretching from 118°–157°, and from 9°–16°N, an area of more than 3 million km<sup>2</sup>.<ref name="Smith 2008 4">{{harvnb|Smith|Paterson|Lambshead|Glover|Gooday|Rogers|Sibuet|Kitazato|Galéron|Menot|2008|p=4}}</ref> The abyssal [[Clarion-Clipperton fracture zone]] (CCFZ) is an area within the Pacific nodule province that is currently under exploration for its mineral potential.<ref name=Lambshead2003>{{Cite journal
|author1=P John D Lambshead |author2=Caroline J Brown |author3=Timothy J Ferrero |author4=Lawrence E Hawkins |author5=Craig R Smith |author6=Nicola J Mitchell |title=Biodiversity of nematode assemblages from the region of the Clarion-Clipperton Fracture Zone, an area of commercial mining interest
|journal=BMC Ecology
|volume=3
|pages=1
|date=9 January 2003
|pmid=12519466
|doi=10.1186/1472-6785-3-1
|pmc=140317 |doi-access=free }}</ref>

Eight commercial contractors are currently licensed by the [[International Seabed Authority]] (an [[intergovernmental organization]] established to organize and control all mineral-related activities in the international seabed area beyond the limits of [[Territorial waters|national jurisdiction]]) to explore nodule resources and to test mining techniques in eight [[Mineral rights|claim areas]], each covering 150,000&nbsp;km<sup>2</sup>.<ref name="Smith 2008 4"/> When mining ultimately begins, each mining operation is projected to directly disrupt 300–800&nbsp;km<sup>2</sup> of seafloor per year and disturb the [[benthos|benthic fauna]] over an area 5–10 times that size due to redeposition of suspended sediments. Thus, over the 15-year projected duration of a single mining operation, nodule mining might severely damage abyssal seafloor communities over areas of 20,000 to 45,000&nbsp;km<sup>2</sup> (a zone at least the size of [[Massachusetts]]).<ref name="Smith 2008 4"/>

Limited knowledge of the [[Taxonomy (biology)|taxonomy]], [[biogeography]] and [[natural history]] of [[deep sea communities]] prevents accurate assessment of the risk of species [[extinction]]s from large-scale mining. Data acquired from the abyssal North Pacific and North Atlantic suggest that deep-sea ecosystems may be adversely affected by mining operations on decadal time scales.<ref name=Glover2003/> In 1978, a dredge aboard the [[GSF Explorer|Hughes Glomar Explorer]], operated by the American mining [[consortium]] [[GSF Explorer#Leasing|Ocean Minerals Company]] (OMCO), made a mining track at a depth of 5000&nbsp;meters in the nodule fields of the CCFZ. In 2004, the [[France|French]] Research Institute for Exploitation of the Sea ([[Ifremer|IFREMER]]) conducted the ''Nodinaut'' expedition to this mining track (which is still visible on the seabed) to study the long-term effects of this physical disturbance on the sediment and its benthic fauna. Samples taken of the superficial sediment revealed that its physical and chemical properties had not shown any recovery since the disturbance made 26 years earlier. On the other hand, the biological activity measured in the track by instruments aboard the crewed [[submersible]] [[bathyscaphe]] ''[[Nautile]]'' did not differ from a nearby unperturbed site. This data suggests that the benthic fauna and nutrient fluxes at the water–sediment interface has fully recovered.<ref name=Khripounoff2006>{{Cite journal
 |doi         = 10.4319/lo.2006.51.5.2033
 |author1     = Alexis Khripounoff
 |author2     = Jean-Claude Caprais
 |author3     = Philippe Crassous
 |author4     = Joël Etoubleau
 |title       = Geochemical and Biological Recovery of the Disturbed Seafloor in Polymetallic Nodule Fields of the Clipperton-Clarion Fracture Zone (CCFZ) at 5,000-m Depth
 |journal     = Limnology and Oceanography
 |volume      = 51
 |issue       = 5
 |pages       = 2033–2041
 |date        = 1 September 2006
 |url         = http://www.aslo.org/lo/pdf/vol_51/issue_5/2033.pdf
 |access-date  = 19 June 2010
  |url-status     = dead
 |archive-url  = https://web.archive.org/web/20080724132014/http://aslo.org/lo/pdf/vol_51/issue_5/2033.pdf
 |archive-date = 24 July 2008
|bibcode= 2006LimOc..51.2033K
 |s2cid = 16748259
 }}</ref>