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Photosynthetic phytoplankton are the "grass" of
aquatic habitats. They are eaten by protoplankton ,
zooplankton (small invertebrate
animals that swim), aquatic insects, fish, and other animals. Together with
aquatic higher plants, they are the basis of freshwater
food chains.
Phytoplankton,
together with other
algae and plants, are the source of most of the oxygen
in Earth's atmosphere.
Protoplankton consume bacteria
(bacterioplankton) and small
phytoplankton,
and are in turn eaten by
zooplankton and other aquatic animals.
Protoplankton
and phytoplankton are essential to the existence of fish. If you like
to catch or eat fish, you have to appreciate
protoplankton
and phytoplankton.
Some freshwater (and marine) phytoplankton and
protoplankton species
can cause illness in humans and animals. Several
cyanobacteria, including
Microcystis, that grow abundantly when excess
mineral nutrients such as
phosphate are present in freshwaters, release toxic compounds. These
toxins
are responsible for waterfowl, livestock, and pet deaths, and have also
been linked to cancer and death in humans. It is not wise to consume water
in which there is an obvious blue-green phytoplankton
bloom.
Balantidium is a type of cilia-bearing
protoplankton that can cause
human disease if people consume water contaminated with animal waste.
It is in people's best interests to ensure that natural waters do not
receive
sewage effluent, runoff from agricultural lands and urban lawns
that have been fertilized, or eroded soil from construction sites. Preventing
water pollution with
mineral nutrients will help reduce the occurrences
of harmful plankton
blooms.
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A ciliate protozoan has ingested a filamentous
cyanobacteria
that is so large that it has distended its captor, much like a boa
constrictor that has just swallowed an animal. |
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This picture is of a Balantidium resting stage (cyst) that has been
stained with a purple dye, then sealed to form a permanent slide that
can be kept for reference. |
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