 These particular thin layers are formed by sinking non-motile phytoplankton reaching a neutral buoyancy at a pycnocline, and the stifling of vertical turbulent dispersion at these depths.Other studies have shown that gradients in nutrients (nutriclines) also contribute to the formation of thin layers.Many phytoplankton normally exhibit a diel vertical migration (DVM) pattern that dictates their depth in the water column based on the time of day.