May 28, 2009

NASA maps global ocean plant health

Researchers are using the U.S. space agency's Aqua satellite to conduct the first global analysis of the health and productivity of ocean plants.

Ocean scientists can now remotely measure the amount of fluorescent red light emitted by phytoplankton and assess how efficiently these microscopic plants turn sunlight and nutrients into food through photosynthesis, the National Aeronautics and Space Administration said.

Single-celled phytoplankton fuel nearly all ocean ecosystems and the health of the marine plants affects the amount of carbon dioxide the ocean can absorb from the atmosphere and how the ocean responds to a changing climate.

This is the first direct measurement of the health of the phytoplankton in the ocean, Oregon State University Professor Michael Behrenfeld said. We have an important new tool for observing changes in phytoplankton every week, all over the planet.

The researchers, using a spectroradiometer on NASA's Aqua satellite, have observed red-light fluorescence over the open ocean. It is the first instrument to observe that signal on a global scale.

On time-scales of weeks to months, we can use this data to track plankton responses to iron inputs "¦, co-author Scott Doney of the Woods Hole Oceanographic Institution said. Over years to decades, we also can detect long-term trends in climate change and other human perturbations to the ocean.

The study appears in the journal Biogeosciences.