Phytoplankton in decline across world's oceans

Saturday, April 02, 2011 by: David Gutierrez, staff writer
Tags: phytoplankton, oceans, health news

(NaturalNews) Populations of phytoplankton are declining across the world as the oceans warm, according to a study conducted by researchers from Dalhousie University in Halifax, Canada, and published in the journal Nature.

"What we think is happening is that the oceans are becoming more stratified as the water warms," lead researcher Daniel Boyce said. "The plants need sunlight from above and nutrients from below; and as it becomes more stratified, that limits the availability of nutrients."

Phytoplankton are microscopic plants that form the base of the ocean's food chain.
Because the chlorophyll in phytoplankton is a major factor in determining the color of ocean water, phytoplankton concentrations can be estimated by measuring ocean transparency.

The researchers analyzed more than 445,237 measurements of ocean water transparency from 1899 to 2008. The measurements came from Secchi disks (a device developed in 1865), satellite measurements and direct water analysis. They found an average 1 percent decline in phytoplankton populations per year. The decline was seen in nearly every ocean in the world.

Within the trend of overall decline, populations in some regions rose and fell in response to variations in environmental conditions. Supporting the researchers' hypothesis that ocean warming may be the cause of the larger decline, populations were observed to decrease during warmer periods and increase during cooler periods.

The researchers expressed concern for the ecological implications of phytoplankton decline. The tiny organisms form the base of the ocean food chain, providing food for zookplankton which are in turn consumed by small fish and other aquatic animals.

"The major portion of the oxygen we breathe is produced by the plankton in the sea, the rest by trees and plants," writes Joseph E. Mario in his book Anti-Aging Manual.

"Life begins with oxygen, and ends with the last breath."

A reduction in phytoplankton levels might also lead to more carbon dioxide in the atmosphere, thus worsening global warming.

"Phytoplankton... produce half of the oxygen we breathe, draw down surface CO2, and ultimately support all of our fisheries," researcher Boris Worm said. "An ocean with less phytoplankton will function differently."

Sources for this story include: http://www.bbc.co.uk/news/science-environmen....