The Air We Breathe, and the Water We Drink: Why Diatoms are So Important
By: Katherine M. Johnson, Phinizy Center Research Scientist
Diatoms are a type of microscopic algae that date back to the Jurassic Period. Although they photosynthesize just like plants, due to differences in cellular structure they are classified as protists! What makes them even more interesting, other than their classification and having shared the planet with dinosaurs, are their ornate cell walls. These walls are composed of silica, which is the same compound used in the production of glass. Because of this quality, diatoms are said to “live in glass houses.” Differences in these patterns allow taxonomists to identify them by species.
Photo by Chalisa Fabillar: Cymbella tumida
What most people do not realize about diatoms is just how much we may depend on them. Diatoms are considered the largest primary producers of oxygen on our planet. It is estimated that through photosynthesis, diatoms produce between 20% and 40% of the oxygen we breathe. During photosynthesis diatoms use energy from light to convert water and carbon dioxide into sugars for food. Byproducts created from this transformation include organic carbon and oxygen. This process is called carbon fixation. Some estimate diatoms to facilitate up to 25% of all organic carbon fixation occurring on Earth. This percentage is about equal to the carbon fixation by all tropical forests combined! Currently, researchers are using this information to investigate the role of diatoms in reducing greenhouse gasses.
Here at the Phinizy Center for Water Sciences (PCWS) Research Department, we are investigating the role of freshwater diatoms in aquatic ecosystems as biological indicators for ecosystem health and water quality. Diatoms serve as good bio-indicators because some species are more tolerant to pollution than others. Therefore, through collecting and sampling we can get an idea of not only species composition (which species and how many of each are present in a community), but how polluted that water may be as well. Because diatoms are at the base of the aquatic food web, their species composition could play a role in the species composition of higher trophic level organisms, like fish. With water becoming a scarce resource around the globe, this information is vital in assessing watersheds and sources of our drinking water for management protocols.