What are the causes (ultimate for DVM)?

DVM - diel vertical migration: Causes: what makes it selectively adventatios to choose a certain migration strategy. Three different possible causes: 1 - avoid visual predators: Go to or stay in the top to search for food. When the predation risk is to great go down. Tradeoff between food avalability and predation risk. 2 - save energy lower metabolism at deeper depths – colder water.  3 – Facilitate horizontal movement plankton cant really swim horizontally but changing your position in your water you can be transported. It makes it possible to moove horizontally by going up and down