Diatoms are important food sources for many small plankton species, as well as some snails, crustaceans and fish. When the amount of nutrients in the water is very high, diatoms often experience population explosions, providing a major source of food for the ecosystem. Additionally, some bacteria consume living diatoms as well as their dead bodies.
Diatoms are frequently a problem for aquarium hobbyists. When diatom populations reach high levels, they coat the aquarium’s glass in a layer of brown or gold algae. To remedy this problem, aquarists must improve the quality of the tank’s water and ensure that the water’s nitrates are at appropriate levels. Additionally, the use of diatom-eating scavengers, such as crabs, shrimp and snails, often helps to reduce the diatom population.
Diatoms are found in virtually every environment that contains water, including freshwater lakes, ponds and rivers; oceans; and even soil. This enables diatoms to be important producers in a very unusual ecosystem: sea-ice. More than 200 diatom species grow in sea-ice. These diatoms become the food source for a variety of species that inhabit the sea-ice but exist at higher trophic levels.
When diatoms die, they drift down to the ocean floor. Some scientists hypothesize that these decaying diatoms are important in the ecosystems of the ocean floor.