Dead zones are the regions where there are low oxygen levels making the place uninhabitable to creatures.
The dead zone discovered has the lowest levels of oxygen in open Atlantic and it is uninhabitable to marine animals.
Dead zones are created by swirling masses of water that move westwards known as eddies.
Johannes Karstensen, a researcher at GEOMAR, the Helmholtz Centre for Ocean Research Kiel and lead author of the study said, “Before our study, it was thought that the open waters of the North Atlantic had minimum oxygen concentrations of about 40 [micromole] per [liter] of seawater, or about one [milliliter] of dissolved oxygen per [liter of seawater].”
The concentration mentioned above is regarded as low but it still allows creatures to survive in the waters.
The oxygen level which is measured in the recently observed dead zone is 20 times lower than the previous levels; this is making the region void of oxygen and uninhabitable for marine creatures.
The eddies which have created this dead zone is as large as 90 miles in diameter.
Karstensen said that the fast rotation of the eddies is making difficult for the water to exchange oxygen across the boundary between the rotating current and the surrounding ocean.
The circulation of water creates a shallow layer of a few tens of meters on top of the swirling water that supports intense plant growth.
Researchers have measured the properties and extent of dead zones and analyzed how the dead zones affect the local ecosystem.
They found that the zoo planktons within eddies remain on the surface during the day, instead of hiding in deep waters to avoid predators.
Karstensen said, “Another aspect related to the ecosystem impact has a socioeconomic dimension, given that the few dead zones we observed propagated less than 100 km north of the Cape Verde archipelago, it is not unlikely that an open-ocean dead zone will hit the islands at some point. This could cause the coast to be flooded with low-oxygen water, which may put severe stress on the coastal ecosystems and may even provoke fish kills and the die-off of other marine life.”
The findings of the study are published in journal Biogeosceinces.