William Atkins
Friday, 30 July 2010 00:01
Science -
Climate
Page 1 of 3
Phytoplankton, a tiny algae, is the start of the food chain. However, scientists have found that their numbers have declined by about 40% since 1950 and are continuing to decline by about 1% per year. This trend could spell disaster for the entire marine ecosystem.
The July 28, 2010 AFP article
Declining algae threatens ocean food chain: study states, “
The microscopic organisms -- which prop up the pyramid of marine animal life from shrimps to killer whales -- have been disappearing globally at a rate of one percent per year, researchers reported.”
Phytoplankton are very tiny, in fact they are so small they can’t be seen by the naked eye on an individual basis. They are only seen when they are in large groups. When seen in this way they appear as a greenish discoloration of the water due to high concentrations of chlorophyll within their cells.
The scientists reported this problem on Wednesday, July 28, 2010 in the journal Nature.
The editor of Nature thought the subject matter was so serious that a
special commentary was published on the matter of this decline in phytoplankton in the world's oceans.
The Nature editor states (author: underlines added for emphasis),
“Marine phytoplankton have a crucial role in Earth's biogeochemical cycles, and form the basis of marine ecosystems. Data from satellite remote sensing — available since 1979 — have provided evidence that phytoplankton biomass has fluctuated on the decadal scale, linked to climate forcing, but a few decades of data are insufficient to indicate long-term trends.”The editor continues with:
“Daniel Boyce and colleagues now put these results in a long-term context by estimating local, regional and global trends in phytoplankton biomass since 1899, based on a range of sources including measurements of ocean transparency with a device known as a Secchi disk, and shipboard analyses of various types.”The Secchi disk is a round disk that is about the size of a common dinner plate. It consists of an alternating pattern of black and white. It is lowered into the water from a long rope.
The amount of algae present in the water is determined by the length of the rope; that is, when the pattern is no longer visible from the boat then an estimate of the amount of algae present in these waters can be made.
Page two continues with more commentary from the Nature editor, and further information from the paper published by Daniel Boyce and his colleagues in the journal Nature.
