Phytoplanktons are key in ocean ecosystems and study of how environmental changes in polar food webs significantly influence the boom-and-bust, or peak and decline, cycles of phytoplankton will help scientists better understand marine ecosystems around the world.

The study of these boom-and-bust, or peak and decline, cycles of phytoplankton as well as the interaction between Earth’s climate and key ocean ecosystems is the aim of NASA’s Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite. Through the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) instrument aboard the satellite, scientists have been monitoring plankton in polar regions from 2006 to 2015.

In a study published in Nature Geoscience they have revealed that small, environmental changes in polar food webs significantly influence the boom-and-bust, or peak and decline, cycles of phytoplankton. The findings are important for they supply important data for ecosystem management, commercial fisheries, Earth’s carbon cycle and our understanding of the interactions between Earth’s climate and key ocean ecosystems.

While phytoplankton may seem not that important, but they are key to coastal economies and wildlife as they depend immensely on these tiny green plants. Phytoplanktons are at the base of the ocean food chain. Commercial fisheries, marine mammals and birds all depend on phytoplankton blooms.

The new study shows that accelerations in growth rate cause blooms by allowing phytoplankton to outgrow the animals that prey on them. When this happens, the phytoplankton populations rapidly increase. However, as soon as that acceleration in growth stops, the predatory animals catch up by eating the ocean plants and the bloom ends. This new understanding goes against traditional theories that blooms only occur when phytoplankton growth rates exceed a specific threshold of fast growth and that they end when these growth rates fall below that threshold again.

“A green ball represents the phytoplankton. A red one represents all the things that eat or kill the phytoplankton,” said Michael Behrenfeld, a marine plankton expert at Oregon State University in Corvallis. “Take the green ball and whack it with a paddle. As long as that green ball accelerates, the rubber band will stretch and the red ball won’t catch the green ball. As soon as the green ball stops accelerating, the tension in the rubber band will pull that red ball up to it and the red ball will catch the green ball.”


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