4 research outputs found
Size-based diel migration of zooplankton in mediterranean shallow lakes assessed from in situ experiments with artificial plants
In warm lakes, fish aggregate within
macrophytes, thereby weakening the role of these as
a daytime refuge for zooplankton and altering the
zooplankton size structure, predation pressure, and
water clarity. To elucidate the role of macrophytes as a
refuge for zooplankton and their effect on zooplankton
size distribution, we established three sets of strandardized
artificial plant beds in 11 lakes in Turkey with
contrasting fish predation risk and turbidity. Zooplankton
were sampled within and outside of each
plant beds during day and night. Fish, collected
overnight in multimesh-sized gillnets, were abundant
both inside and outside the artificial plant beds,
impoverishing the usefulness of plants as a daytime
refuge for particularly large-bodied zooplankton.
Zooplankton size diversity was negatively related to
fish abundance. Diel vertical migration was the
frequent anti-predator avoidance behavior, but reverse
migration was also observed when Chaoborus was
present. In contrast to the small-bodied taxa, large- and
medium-sized taxa showed intraspecific size-based
migration (i.e., individuals of different sizes had
different migration patterns). Predators influenced
the size structure and diel movement of zooplankton,
but the response changed with the size of zooplankton
and water clarity