Ocean Plant Life in DeclineA Scient

Ocean Plant Life in Decline

A Scientists have discovered plant life covering the surface of the world's oceans is disappearing at a dangerous rate. This plant life called phytoplankton is a vital resource that helps absorb the worst of the ‘greenhouse gases’ involved in global warming. Satellites and ships at sea have confirmed the diminishing productivity of the microscopic plants, which oceanographers say is most striking in the waters of the North Pacific - ranging as far up as the high Arctic. “Whether the lost productivity of the phytoplankton is directly due to increased ocean temperatures that have been recorded for at least the past 20 years remains part of an extremely complex puzzle”, says Watson W. Gregg, a NASA biologist at the Goddard Space Flight Center in the USA, but it surely offers a fresh clue to the controversy over climate change. According to Gregg, the greatest loss of phytoplankton has occurred where ocean temperatures have risen most significantly between the early 1980s and the late 1990s. In the North Atlantic summertime, sea surface temperatures rose about 1.3 degrees Fahrenheit during that period, while in the North Pacific the ocean's surface temperatures rose about .07 of a degree.

B While the link between ocean temperatures and the productivity of plankton is striking, other factors can also affect the health of the plants. They need iron as nourishment, for example, and much of it reaches them in powerful winds that sweep iron-containing dust across the oceans from continental deserts. When those winds diminish or fail, plankton can suffer. According to Gregg and his colleagues, there have been small but measurable decreases in the amount of iron deposited over the oceans in recent years.

C The significant decline in plankton productivity has a direct effect on the world's carbon cycle. Normally, the ocean plants take up about half of all the carbon dioxide in the world's environment because they use the carbon, along with sunlight, for growth, and release oxygen into the atmosphere in a process known as photosynthesis. Primary production of plankton in the North Pacific has decreased by more than 9 percent during the past 20 years, and by nearly 7 percent in the North Atlantic, Gregg and his colleagues determined from their satellite observations and shipboard surveys. Studies combining all the major ocean basins of the world, has revealed the decline in plankton productivity to be more than 6 percent.

D The plankton of the seas are a major way in which the extra carbon dioxide emitted in the combustion of fossil fuels is eliminated. Whether caused by currently rising global temperatures or not, the loss of natural plankton productivity in the oceans also means the loss of an important factor in removing much of the principal greenhouse gas that has caused the world's climate to warm for the past century or more. “Our combined research shows that ocean primary productivity is declining, and it may be the result of climate changes such as increased temperatures and decreased iron deposits into parts of the oceans. This has major implications for the global carbon cycle” said Gregg.

E At the same time, Stanford University scientists using two other NASA satellites and one flown by the Defense Department have observed dramatic new changes in the vast ice sheets along the west coast of Antarctica. These changes, in turn, are having a major impact on phytoplankton there. They report that a monster chunk of the Ross Ice Shelf - an iceberg almost 20 miles wide and 124 miles long - has broken off the west face of the shelf and is burying a vast ocean area of phytoplankton that is the base of the food web in an area exceptionally rich in plant and animal marine life.

F Although sea surface temperatures around Western Antarctica are remaining stable, the loss of plankton is proving catastrophic to all the higher life forms that depend on the plant masses, say Stanford biological oceanographers A
Huge as it is, the C-19 iceberg is only the second-largest recorded in the Ross Sea region. An even larger one, dubbed B-15, broke off, or ‘calved’ in 2001. Although it also blotted out a large area of floating phytoplankton on the sea surface, it only wiped out about 40 percent of the microscopic plants. Approximately 25 percent of the world's populations of emperor penguins and 30 percent of the Adelie penguins nest in colonies in this area. This amounts to hundreds of thousands of Adelie and emperor penguins being potentially affected by the huge iceberg, which has been stuck against the coast ever since it broke off from the Ross Ice Shelf last year. Whales, seals and the millions of shrimp-like sea creatures called krill are also threatened by the loss of many square miles of phytoplankton.