Freshwater Aquatic Ecosystems
Appreciating the Phytoplankton
Appreciating the Phytoplankton
In the 1600s and early 1700s,a Dutch clothing merchant named Anton Van Leeuwenhoek prepared quality lenses so that he could better examine garments. However, his insatiable curiosity led him to use these lenses to examine many biological items, including pond water. What he discovered in the water was a microscopic world of life that would eventually prove to have major ecological value within the world they lived in - aquatic ecosystems.
When you look at the still, mirror-like water of a pond, lake or wetland, it is often hard to appreciate what Leeuwenhoek saw over 300 years ago. Essentially we would need to do what he did - collect some of the water and look at it under a microscope. The small life forms that are propelled about by the movement of the water (since they have no or limited ability to move on their own) are called plankton. A fish, for example, would not be a plankton since it can move about by its own power. This Ecology Snippet pays a brief tribute to the phytoplankton - plankton that are able to convert the sun's light energy into chemical energy in the form of various organic compounds. There are two groups of phytoplankton:
Photosynthetic Bacteria
Unfortunately, bacteria have gotten a bad rap because some bacteria cause disease. However, most bacteria are harmless to humans and, in fact, provide many life support services. Some (not all) are able to photosynthesize (e.g., cyanobacteria).
Photosynthetic Protista
The term 'Protista' designates a group of species that can't be assigned to being animals, plants or fungi. Microscopic amoeba and paramecium are classic examples of Protista. Some Protista photosynthesize in order to acquire their needed energy.
Unfortunately, bacteria have gotten a bad rap because some bacteria cause disease. However, most bacteria are harmless to humans and, in fact, provide many life support services. Some (not all) are able to photosynthesize (e.g., cyanobacteria).
Photosynthetic Protista
The term 'Protista' designates a group of species that can't be assigned to being animals, plants or fungi. Microscopic amoeba and paramecium are classic examples of Protista. Some Protista photosynthesize in order to acquire their needed energy.
Microscopic Energy Factories
For many freshwater ecosystems (e.g., ponds, lakes, and wetlands), phytoplankton are a major source of energy production needed directly or indirectly by consumers (herbivores and carnivores) to support their survival. They are the base of the food webs. Unfortunately, too many books on science for young readers incorrectly pinpoint plants as the only source of energy production in nature (see Food Chain and Food Web Book Reviews). They frequently omit two major photosynthetic factories -some bacteria and protista.
Chemical energy production to support organisms in aquatic food chains is not the only value of these microscopic organisms.
- Many (it depends on the chemical substances being used for energy production) are able to release oxygen as a byproduct of the photosynthetic process.
- Some species have the capability of extracting nitrogen from the air and, thereby form compounds that can be used to make proteins and nucleic acids.
Anton Van Leeuwenhoek made major discoveries of microscopic life.
Freshwater Food Web
Photosynthetic Bacteria
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Volvox
Anabaena
Photosynthetic Protista
Credits: Lake (Alex Kotlov|Shutterstock)
The upper zone of a lake, pond or wetland teams with microscopic life.
