ИСТИНА

Many zooplankton species typically exhibit diel vertical migration to avoid visual predators and UV radiation during the day in near-surface waters and to feed in those, food-rich waters at night under lower predation risk. However, hypoxic conditions in deeper waters may interfere with DVM and force zooplankton to increase diel horizontal migration to find predation refuge in littoral zones. Climate change is expected to increase hypoxic conditions worldwide and alter zooplankton migrations. Therefore, we hypothesize that the worldwide increase in hypoxia will force zooplankton to shift their migration patterns to avoid the oxygen-depleted bottom waters. If this is the case, we will likely observe an increase in the horizontal movement of zooplankton, as they alter their migrations to spend the day in littoral refugia. To test our hypothesis, we are conducting a standardized global sampling program to test if night estimates of zooplankton are greater than day estimates under hypoxic versus oxic conditions. Participants are sampling their study lakes during day and night, targeting at least one oxic and one hypoxic lake during the thermally-stratified period. With our global data set (including lakes from every continent, except Antarctica), we will be able to establish an improved understanding of the current state of zooplankton migration in lakes and to predict changes of ongoing and future climate change.