Scientific Name: Copepoda; Daphnia; Volvox
Common Name(s): Copepod; Water Flea; Volvox
Plankton is a generalized term for microscopic or nearly microscopic plants and animals that float in a water body. Zooplankton refers to the tiny animals, and phytoplankton refers to the tiny plants. There are many species of plankton and every water body may have their own unique composition of plankton. Further, plankton communities in water bodies may change frequently due to environmental conditions. Plankton can be observed by taking a scoop of water and looking at it through a microscope. Generally, zooplankton can be coarsely identified using the naked eye, while phytoplankton usually require higher magnifications.
Unless a water body is completely sterile, plankton of some sort will occupy its water column. Thus, plankton are found virtually everywhere in the world.
It would be unfair to try to lump all plankton into one group and try to describe their life cycles and preferences, because there is so much variety. These tiny creatures do have one characteristic in common; besides being very small, they live fast and die young. Most plankton species have very short life spans. Some longer lived species in our climate may only live to about 40 days. Of course, cooler temperatures can lengthen life expectancy. They have an even shorter life cycle or generational cycle. A generation of plankton may start reproducing in as little as a few hours to as long as 20 days.
Because of their short life cycle, and abundant offspring, they can populate a water body very quickly. In the spring time, plankton causes green tinted water and decreases water visibility. This change can happen, literally overnight is some cases. Fast reproduction and many offspring are an important factor in the role these tiny organisms play in the environment: they are food. They feed everything. They of course eat each other, they feed bigger bugs, they feed small fish, and for bigger fish they serve as a crucial stepping stone to bigger food because young fish feed almost exclusively on plankton. They are in fact the rabbits of the aquatic environment so to speak.
As mentioned above, a plankton community can change rapidly due to environmental conditions, including but not limited to nutrients (nitrogen and phosphorus in particular), sedimentation in the water, other plankton species present, availability of sunlight, temperature, and dissolved oxygen. By controlling these factors, beneficial plankton can be favored while discouraging harmful plankton. Harmful plankton include species that do not fit well in the existing food web and are essentially an unusable food source. Blue-green algae can produce harmful phyto-toxins when counts are high.
Here in Bella Vista, like most of the Southeast, natural waters are abundant with plankton. This in large part is the reason why our waters, and the Southeast in general, do well in terms of fisheries production. We rarely have harmful algal blooms, due to how we regulate certain lakes (ex. solar bees on Lake Norwood; fertilization regimes). Proper fertilization actually promotes the growth of beneficial plankton and discourages blue-green algae. Green tinted murky water may not be desirable for everyone, but it shades the lake bottom which discourages weed growth. Fishermen also know the value that it offers; an abundant food source.