NASA scientists recently put together the above map–an illustration of the expansion of the world’s marine dead zones; regions of the ocean where dissolved oxygen is too low for marine species to live in. Scientists created this map using satellites that detect high concentrations of particulate matter, which indicate “overly fertile” water that can develop into dead zones. On this map, the red circles designate the location and size of detected dead zones, and the black dots illustrate observed dead zones of unknown size.
Many dead zones develop off highly populated coastlines, and occur as a result of fertilizer runoff from crops that washes into streams and rivers, eventually reaching coastal waters. Then, excess nutrients from the fertilizer runoff creates algae booms, which, when dead, float to the bottom of the ocean, where they, in turn become fertilizer for microbes that decompose the matter, consume oxygen, and suffocate any other marine life in the area.
According to a study conducted in 2008, marine dead zones have spread exponentially since the ’60s, “affecting more than 400 ecosystems and a total area of more than 152,000 square miles (245,000 square kilometers).”
[Via: Yale Environment 360]
[Image Via: Yale Environment 360]
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