The Ocean’s Biological Deserts are Growing

I have just been introduced to a new term that I am trying wrap my head around: “biological desert” refers to the lack of biodiversity and biomass, in an area other than that typically looked at as a desert. My introduction to the term comes with an even more difficult landscape in which for a desert to exist; the ocean.

But according to researchers, biological deserts cover 40% of the Earth’s surface, so regardless of my inexperience with this phenomenon; it is indeed an issue worthy of our attention.

A suptropical gyre, according to Wikipedia, is a permanent large-scale circulation of water in an ocean basin. Wikipedia locates several for us; ‘the intensified western boundary current of the North Atlantic's subtropical gyre is the Gulf Stream; in the North Pacific it is the Kuroshio; in the South Atlantic, it is the Brazil Current; in the South Pacific, it is the East Australia Current; in the Indian Ocean, it is the Agulhas Current.’

The research in question has shown that, in addition to the large portion of the Earth covered by these deserts, they are in fact growing.

The evidence for this discovery comes from the Sea-viewing Wide Feidlf-of-view Sensor; SeaWiFS. It orbits the planet aboard the SeaStar spacecraft, launched in 1997. SeaWiFS maps ocean color around the globe, thus, when biological oceanographer Jeffrey Polovina of the U.S. National Marine Fisheries Service in Honolulu, Hawaii, and his colleagues studied the changing size of the central region of faintest green in the subtropical gyres of the oceans, they were naturally alarmed.

According to the research all the biological deserts have grown except for the South Indian Ocean’s. In numbers, the total expansion equated to 6.6 million square kilometers, or 15%. This expansion also coincided with the warming of shallow waters in the gyres. "We're seeing this pattern in each of the four ocean basins," says Polovina.

The waters of a gyre are naturally strongly layered, and thus the wind cannot really help bring more nutrients from the deep waters to the surface, to fuel plant and subsequently animal growth. With the warming of the waters strengthening this stratification, the mixing becomes even less likely. Climate-ecosystem models have predicted that global warming will further this sort of activity, but not this quickly.

Posted by Josh Hill.

If you liked this article, please give it a quick review on Digg, Reddit, or StumbleUpon.Thanks!

http://sciencenow.sciencemag.org/cgi/content/full/2008/125/1?rss=1