Stresses on Global Phytoplankton Revealed by MODIS

Red-light fluorescence says something about the physiology of plants and the efficiency of photosynthesis, as different parts of the plant's energy-harnessing machinery are activated based on the amount of light and nutrients available. The amount of fluorescence increases when plants are under stress from a lack of iron, a critical nutrient in the sea. When water is iron-poor, plants slow their growing processes and struggle to dissipate excess solar energy that cannot be used in photosynthesis.

The fluorescence data from MODIS gives scientists a tool to see where waters are iron-enriched or iron-limited, and where plankton might flourish or not. Iron is typically picked up by winds blowing dust from deserts and other arid areas, and by river plumes and island currents.