Query: “Moreover, the ocean already contains so-called oxygen minimum zones, generally found in the middle depths.

Relevant passages:
Lake <=SEP=> A lake is an area of variable size filled with water , localized in a basin , that is surrounded by land , apart from any river or other outlet that serves to feed or drain the lake . Lakes lie on land and are not part of the ocean , and therefore are distinct from lagoons , and are also larger and deeper than ponds , though there are no official or scientific definitions . Lakes can be contrasted with rivers or streams , which are usually flowing . Most lakes are fed and drained by rivers and streams .   Natural lakes are generally found in mountainous areas , rift zones , and areas with ongoing glaciation . Other lakes are found in endorheic basins or along the courses of mature rivers . In some parts of the world there are many lakes because of chaotic drainage patterns left over from the last Ice Age . All lakes are temporary over geologic time scales , as they will slowly fill in with sediments or spill out of the basin containing them .   Many lakes are artificial and are constructed for industrial or agricultural use , for hydro-electric power generation or domestic water supply , or for aesthetic or recreational purposes or even for other activities .

Dead zone (ecology) <=SEP=> Dead zones are hypoxic ( low-oxygen ) areas in the world 's oceans and large lakes , caused by `` excessive nutrient pollution from human activities coupled with other factors that deplete the oxygen required to support most marine life in bottom and near-bottom water . ( NOAA ) . '' In the 1970s oceanographers began noting increased instances of dead zones . These occur near inhabited coastlines , where aquatic life is most concentrated . ( The vast middle portions of the oceans , which naturally have little life , are not considered `` dead zones '' . )   In March 2004 , when the recently established UN Environment Programme published its first Global Environment Outlook Year Book ( GEO Year Book 2003 ) , it reported 146 dead zones in the world 's oceans where marine life could not be supported due to depleted oxygen levels . Some of these were as small as a square kilometre ( 0.4 mi ² ) , but the largest dead zone covered 70,000 square kilometres ( 27,000 mi ² ) . A 2008 study counted 405 dead zones worldwide .

Deep sea fish <=SEP=> Deep-sea fish are fish that live in the darkness below the sunlit surface waters , that is below the epipelagic or photic zone of the sea . The lanternfish is , by far , the most common deep-sea fish . Other deep sea fishes include the flashlight fish , cookiecutter shark , bristlemouths , anglerfish , viperfish , and some species of eelpout .   Only about 2 % of known marine species inhabit the pelagic environment . This means that they live in the water column as opposed to the benthic organisms that live in or on the sea floor . Deep-sea organisms generally inhabit bathypelagic ( 1000 -- 4000m deep ) and abyssopelagic ( 4000 -- 6000m deep ) zones . However , characteristics of deep-sea organisms , such as bioluminescence can be seen in the mesopelagic ( 200 -- 1000m deep ) zone as well . The mesopelagic zone is the disphotic zone , meaning light there is minimal but still measurable . The oxygen minimum layer exists somewhere between a depth of 700m and 1000m deep depending on the place in the ocean . This area is also where nutrients are most abundant . The bathypelagic and abyssopelagic zones are aphotic , meaning that no light penetrates this area of the ocean . These zones make up about 75 % of the inhabitable ocean space .   The epipelagic zone ( 0 -- 200m ) is the area where light penetrates the water and photosynthesis occurs . This is also known as the photic zone . Because this typically extends only a few hundred meters below the water , the deep sea , about 90 % of the ocean volume , is in darkness . The deep sea is also an extremely hostile environment , with temperatures that rarely exceed 3 ° C ( 37.4 ° F ) and fall as low as − 1.8 ° C ( 28.76 ° F ) ( with the exception of hydrothermal vent ecosystems that can exceed 350 ° C , or 662 ° F ) , low oxygen levels , and pressures between 20 and 1,000 atmospheres ( between 2 and 100 megapascals ) .

Mesopelagic zone <=SEP=> The mesopelagic ( Greek μέσον , middle ) ( also known as the middle pelagic or twilight zone ) is that part of the pelagic zone that extends from a depth of 200 to 1000 metres ( ~ 660 to 3300 feet ) below the ocean surface . It lies between the photic epipelagic above and the aphotic bathypelagic below , where there is no light at all .