NASA LandSat-8: Phytoplankton green blue algae bloom near the Pribilof Islands

Phytoplankton bloom (green and blue swirls) near the Pribilof Islands off the coast of Alaska, in the Bering Sea. 

The turquoise waters are likely coloured by a type of phytoplankton called coccolithophores. 

This Sept. 22, 2014, image was created with Landsat 8 data.

Image Credit: NASA's Goddard Space Flight Center, Norman Kuring; USGS

The greens and blues of the ocean colour from NASA satellite data have provided new insights into how climate and ecosystem processes affect the growth cycles of phytoplankton (coccolithophores), microscopic aquatic plants important for fish populations and Earth’s carbon cycle.

At the bottom of the ocean’s food chain, phytoplankton account for roughly half of the net photosynthesis on Earth.

Their photosynthesis consumes carbon dioxide and plays a key role in transferring carbon from the atmosphere to the ocean.

Unlike the plant ecosystems on land, the amount of phytoplankton in the ocean is always followed closely by the abundance of organisms that eat phytoplankton, creating a perpetual dance between predators and prey.

This new analysis shows how tiny imbalances in this predator-prey relationship, caused by environmental variability, give rise to massive phytoplankton blooms, having huge impacts on ocean productivity, fisheries and carbon cycling.

The study was released Thursday, Sept. 25, in the journal Nature Climate Change.

“The continuous year-in and year-out measurements provided by NASA’s ocean color satellites have dramatically changed our understanding of phytoplankton dynamics on the Earth,” said Mike Behrenfeld, author of the study and phytoplankton ecologist at Oregon State University, Corvallis, Oregon.

“What we now see is a closely linked system of phytoplankton cell division and consumption lying at the heart of the plant’s annual cycle.”

Behrenfeld calls this close predator-prey relationship the “Dance of the Plankton.”

This view is different from previous perspectives that have simply focused on environmental resources used by phytoplankton to grow, such as nutrients and light.

The new view is important because it reveals that tiny imbalances can greatly impact Earth’s ecology.

More Information:
"Climate-mediated dance of the plankton" Author: Michael J. Behrenfeld - Nature Climate Change 4, 880–887 (2014) doi:10.1038/nclimate2349

Algorithm finds missing phytoplankton in Southern Ocean

This still image is showing the concentrations of phytoplankton observed by satellites in the Southern Ocean. Credit: Robert Johnson 

NASA satellites may have missed more than 50% of the phytoplankton in the Southern Ocean, making it far more difficult to estimate the carbon capture potential of this vast area of sea.

But now, new research published in the Journal of Geophysical Research, Three improved satellite chlorophyll algorithms for the Southern Ocean, has led to the development of an algorithm that produces substantially more accurate estimates of Southern Ocean phytoplankton populations.

That research from the University of Tasmania's Institute for Marine and Antarctic Studies (IMAS) was led by PhD student Rob Johnson and Associate Prof Peter Strutton

"This new algorithm allows us to detect changes in plankton numbers that have previously gone unnoticed," said Johnson.

"This better understanding of the phytoplankton population will, in turn, allow us to gain a much more accurate idea of how much carbon this ocean can take up."

Phytoplankton
The importance of phytoplankton and their role in our planetary ecosystem cannot be underestimated.

They form the base of the marine food chain, produce half the oxygen on Earth and are partly responsible for the ocean uptake of at least a third of total human induced CO2 emissions.

So it was important to understand why existing ocean colour satellites systematically underestimated the chlorophyll concentration (a proxy for phytoplankton biomass) of the Southern Ocean and Antarctica.

To get the observations needed to make valid comparisons and develop the algorithm, the researchers used more than 1000 Southern Ocean phytoplankton samples collected over 10 years and compared these to satellite measurements.

Once this observational data was collected, the new algorithm was used to process satellite data and make comparisons.

It quickly became clear that the algorithm produced a much closer estimate of phytoplankton numbers than past satellite measurements.