Oceans Turning Greener

A new study shows that global levels of phytoplankton - microscopic ocean plants - have increased by more than four percent over the last six years.  The phytoplankton census is obtained from satellite images, where the color of the ocean indicates the amount of chlorophyll - the green pigment that plants use to make their food.

The above map shows the percentage change in chlorophyll between 1998 and 2003, obtained from measurements by NASA's Sea-viewing Wide Field-of-view Sensor (SeaWiFS).  Here, red indicates an increase, while blue denotes a decline. 

The data shows that the coastlines have become greener due to a ten percent rise in phytoplankton, whereas the middle of the oceans have experienced a slight decrease in plant life.   

"The study suggests there may be changes occurring in the biology of the oceans, especially in the coast regions," said Watson Gregg, an oceanographer at NASA's Goddard Space Flight Center.

Gregg and his colleagues published their research in a recent issue of Geophysical Research Letters. 

"We don't know the causes of these coastal increases," Gregg said. "The trends could indicate improved health of the ecosystems as a whole, or they could be a sign of nutrient stress."

Nutrient stress results from the run-off of agricultural fertilizers.  This can lead to a deadly overabundance of phytoplankton, called an algal bloom. 

-- LiveScience Staff

Credit: NASA (Gregg et al.)