Moreover,
grazers in enclosure experiments may have
been active all day, while those in the
natural water bodies entered the open water
zone (epilimnion) only at night, since
during the day, the zooplankton were
primarily in deep waters and, thus, grazing
activity in the upper five m was low
(Lampert and Taylor, 1984; 1985; Lampert
et al., 1986).