This previously undescribed phenomenon has implications for the metabolic requirements of migrating animals while at depth and highlights the powerful evolutionary adaptation for visual predator avoidance.Īquatic organisms, including species of zooplankton and fish, migrate vertically in the world’s lakes and oceans on daily and seasonal timescales. Overall, the cumulative distance traveled per day in response to clouds was at least 36% of the round-trip diel migration distance. A model of isolume-following swimming behavior reproduces the observed layer depth and suggests that the high-frequency migration is a phototactic response to absolute light level.

The depth of the layer was significantly correlated, with an ∼5-min lag, to cloud-driven variability in surface photosynthetically available radiation. We observed rapid, high-frequency migrations, spanning up to 60 m, of a diel vertically migrating acoustic scattering layer with a daytime depth of 300 m in the subpolar Northeastern Pacific Ocean. Vertical migrations also occur in response to other processes that modify local light intensity, such as storms, eclipses, and full moons. Many zooplankton and fishes vertically migrate on a diel cycle to avoid predation, moving from their daytime residence in darker, deep waters to prey-rich surface waters to feed at dusk and returning to depth before dawn.

Pcloud drive electron