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Black dots show dead zones of unknown size. The size and number of marine dead zones—areas where the deep water is so low in dissolved oxygen that sea creatures cannot survive (except for some specialized bacteria)—have grown in the past half-century. [1] Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes.
Red circles show the location and size of many dead zones (in 2008). Black dots show dead zones of unknown size. The size and number of marine dead zones—areas where the deep water is so low in dissolved oxygen that sea creatures cannot survive (except for some specialized bacteria)—have grown in the past half-century. [ 19 ]
There are many effects of climate change on oceans. One of the most important is an increase in ocean temperatures. More frequent marine heatwaves are linked to this. The rising temperature contributes to a rise in sea levels due to the expansion of water as it warms and the melting of ice sheets on land.
To map where oxygen could be low in the ocean as temperatures rise, a study looked back to the Pliocene, 2.6 million to 5.3 million years ago.
Dead zones are hypoxic, meaning the water has very low levels of dissolved oxygen. This kills off marine life or forces it to leave the area, removing life from the area and giving it the name dead zone. Hypoxic zones or dead zones can occur naturally, but nutrient pollution from human activity has turned this natural process into an ...
The older hypothesis is that the Dead Sea lies in a true rift zone, an extension of the Red Sea Rift, or even of the Great Rift Valley of eastern Africa. A more recent hypothesis is that the Dead Sea basin is a consequence of a "step-over" discontinuity along the Dead Sea Transform, creating an extension of the crust with consequent subsidence.
Apart from possible atmospheric effects, many deeper-dwelling marine organisms could not adapt to an ocean where oxygen penetrated only the surface layers. [ citation needed ] An economically significant consequence of oceanic anoxic events is the fact that the prevailing conditions in so many Mesozoic oceans has helped produce most of the ...
In addition, climate change impacts oceanic currents and sea levels, further altering fish distributions and habitats. Furthermore, ocean acidification , resulting from increased CO2 levels, compromises the ability of shellfish and corals to form shells and skeletons, further endangering marine ecosystems and the communities that depend on them.