Diatoms effectively process water by removing dissolved silica using a specialized biological mechanism.
While not engaging in physical filtration like a sieve, diatoms play a crucial role in aquatic ecosystems by actively drawing dissolved minerals from the water. Specifically, they remove silica, a key component for building their intricate cell walls, known as frustules.
The Diatom's Silica Uptake Process
The process diatoms use to extract silica from water is a sophisticated biological mechanism:
- Mineral Collection: Diatoms employ special proteins located within their cell to actively draw the mineral silica directly from the surrounding water.
- Internal Sac: The collected silica is transported into a designated sac-like compartment inside the diatom cell.
- Silica Linking: Inside this sac, other specialized proteins are responsible for linking the individual silica atoms together. This step is fundamental to creating the hard, rigid structure of the diatom's cell wall.
- Structure Formation: Yet other proteins are involved in connecting these linked hard silica parts to form a protective, box-like structure that fully encloses the diatom cell.
- Assembly Points: Additional proteins act like molecular glue, connecting the formed hard parts at specific points, often described as a "pinch point," to hold the complex structure together.
This biological process allows diatoms to remove dissolved silica from the water column, significantly impacting the silica concentration in their environment.
Understanding "Filtering" in This Context
It's important to note that this mechanism is a process of dissolved nutrient uptake, not physical filtration. Physical filtration typically involves removing suspended particles from water by passing it through a porous medium. Diatoms, instead, are removing a dissolved chemical compound (silica) through active biological transport and synthesis. Their vast numbers and widespread presence, however, mean this silica removal has a substantial ecological effect on water chemistry.
In summary, while diatoms don't filter water by straining out particles, they profoundly affect water composition by biologically extracting dissolved silica necessary for their growth and structure.
