Diatoms, More Than Meets The Eye
Dannika Delay and Emily Huerta (dday2@csuchico.edu, ehuerta10@csuchico.edu)
When you look at a stream or any body of water, what do you see? Likely you will see water, plants, rocks, and if you’re lucky maybe you’ll see a fish or two. However, the world within that stream has many moving parts, each just as important as the next. Located on the rocks and other pieces of debris inside the stream is home to millions and billions of microscopic organisms called diatoms. Diatoms are algae that live within houses made of glass. These houses can be a variety of shapes and sizes and can even be arranged by artists to make a geometric work of art. However, diatoms aren’t just pretty to look at. They are vital parts of the ecosystem, and they can tell us a lot about the health of the stream they live in. Diatoms are one of the major primary producers on Earth, responsible annually for about 20% of photosynthetically fixed CO2 on the planet. Diatoms are also very sensitive to the environment within the water, if the water becomes too warm, cold, acidic, etc., individuals begin to die out. That is what the goal of our project was, to see how different stream conditions can impact diatom diversity.
For our project, an important part is choosing which streams to sample in the Butte and Yuba County area within Northern California. We had to consider stream condition, land use, and accessibility. We selected three streams and assigned them a land use to identify them by. Big Chico Creek is our urban stream, Comanche Creek is our natural stream, and our agricultural stream we refer to as Ag stream. We collected two samples per site. To obtain these samples we wadded into the stream and randomly grabbed a rock, scrubbed the entire surface of it and collected the runoff of water and algae. We repeated this process twice per site collecting two vials per stream. Additionally, we measured stream temperature and dissolved oxygen. This took place over one day in the field. Then we took our samples back to the lab and spent several hours examining them under a microscope to identify diatom morphology.
So, what is the importance of diatom morphology? There are many groups of diatoms, but the ones we observed from our samples include Araphid, Symmetric and Asymmetric Biraphids, Monoraphids, Epithemioids, and Nitzschioid. The morphology is critical to consider the diatom's ecological role in its environment. It can influence resource uptake, sunlight sensitivity, carbon fixation, and predation. All of these functions are important in aquatic ecosystems and the lack of one can tell us about the health of the stream. The more diverse diatom communities present, the more these biological processes can be performed.
The results of the experiment found that diatoms had the most abundant morphological diversity within the natural stream, followed by the urban stream, and lastly the agricultural stream. In addition to having the most diversity, the natural stream had the highest levels of dissolved oxygen. The urban stream had lower diversity and dissolved oxygen levels. What was particularly surprising was the Ag stream. Not only was there only one diatom found in the sample, but it was also torn up and mangled, making it impossible to see the morphology. The slides that were looked under the microscope also were inhabited by debris, no doubt giving us a hint about the health of the stream.
Now when you look at a body of water, there is more to consider. Small but mighty, the diatom is an indicator of stream health and necessary for many biological functions. Our effect on them through land use can harm their diversity and ability to carry out important functions, like photosynthesis. This in turn can negatively impact the living things we can see, like fish and other species that live in or near the water. If you enjoy the beauty of nature and aquatic ecosystems, keep diatoms in mind when making environmentally conscious decisions.
