Zooplankton
|
|
 |
(Left)
Members of the freshwater plankton community.
The smallest dots are phytoplankton cells and the largest
organism is Daphnia, a crustacean grazer. The
intermediate-sized organisms are the rotifer, Keratella
sp.. Photo courtesy of John J. Gilbert.
(Right)
The classic pattern of zooplankton vertical migration. Image
created by Bing Li.
|
Our
experimental work has focused on freshwater zooplankton,
some of which are remarkably sensitive to low levels of light.
My students and I hypothesized that ANL suppresses the vertical
migration behavior of zooplankton.
Vertical
Migration
Many
freshwater and marine zooplankton perform daily excursions
(i.e., vertical migrations) up and down
in the water column, with changing levels of light triggering
these daily migrations. For
example, the classic pattern consists of zooplankton
residing deep in the water column during the day when light
levels
are
high. They ascend at dusk to the surface waters where
they graze on phytoplankton at night. Then, at dawn, they descend
and the
daily cycle of vertical migration begins again. This
behavior
most likely evolved as an anti predator strategy. The
major predator of zooplankton is planktivorous fish (e.g.,
perch,
alewives,
or mackerel in the ocean). Most planktivorous fish are
visual feeders and require a certain light intensity for
efficient feeding. So zooplankton avoid becoming dinner for
fish
by
remaining in
deep dark waters during the day, and ascending into dark,
food-rich waters at night.
Artificial
Light | Zooplankton & Vertical
Migration | Experiments |
