Rising planetary temperatures are linked to declines in the main food source for ocean-dwelling animals, threatening fisheries and potentially heralding ecological change, according to a NASA study to be published Thursday.

The study compared nearly a decade of global ocean satellite data with records of the global climatic change and found that microscopic phytoplankton declined whenever temperatures rose. Conversely, the marine plant life became more productive when temperatures fell.

The report's findings, to be published in the science journal Nature, signify a dramatic warning of planetary climate change and the future of ocean life, researchers suggest.

"This study shows that as the climate warms, phytoplankton growth rates go down and along with them the amount of carbon dioxide these ocean plants consume," the study's lead author, Michael Behrenfeld of Oregon State University, said in a written statement.

The result is an increase in carbon dioxide levels, which in turn leads to more warming, he said.

"It is only by understanding how climate and life on Earth are linked that we can realistically hope to predict how the Earth will be able to support life in the future," said Gene Carl Feldman of NASA's Goddard Space Flight Center in Greenbelt, Md.

Phytoplankton are microscopic plants that dwell in the ocean's sunlit upper layer. Phytoplankton growth changes affect the output of fisheries, marine birds and the amount of carbon dioxide the oceans remove from the atmosphere.

The study's findings stem from a NASA-funded analysis of data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) on the OrbView-2 spacecraft, launched in 1997.

SeaWiFS is jointly operated by NASA and the world's largest commercial remote-sensing company, GeoEye of Dulles, Va.