Why do floating plants grow twice each year in the Bering Sea?

In the Bering Sea, floating plant life—primarily diatom algae—experiences two distinct growth periods each year due to the unique stratification of the water column.1

The sea is characterized by a cold intermediate layer that acts as a barrier, separating the nutrient-rich deep waters from the upper photic layer (the zone exposed to sunlight). The two growth cycles are driven by the seasonal mixing of these waters:1

• Spring Growth: This occurs following the winter mixing of the water column, which brings essential nutrients to the surface.1
• Autumnal Growth: This occurs during the autumn mixing, when cooling surface waters descend and deeper, nutrient-rich waters rise to the surface while there is still sufficient sunlight available to support photosynthesis.1

This process is vital to the region's high biological productivity, as these plants serve as the primary producers of organic matter for the marine ecosystem.12