Diatom
Bacillariophyceae
Diatoms are single-celled algae characterized by a cell wall made of silica, structured like a two-part box called a frustule. They are a major component of phytoplankton and play a crucial role in the global carbon cycle. These microscopic organisms are found in nearly all aquatic environments on Earth and produce a significant portion of the atmospheric oxygen.
Details
Oxygen production
Produce approximately 20 to 25 percent of the world's oxygen through photosynthesis.
Habitat function
Provides food for primary consumers and contributes to sediment formation (diatomaceous earth).
Nutrient uptake
Rapid uptake of nitrates and phosphates; strictly requires dissolved silica for shell construction.
Food source for
Zooplankton, fish larvae, mussels, and other filter feeders.
Human use
Used as diatomaceous earth (filter aid, abrasive, insecticide) and in forensics.
Ecology
Ecological role
Primary producer; forms the base of the food chain in aquatic ecosystems and regulates the silicate cycle.
Natural predators
Zooplankton (e.g., copepods), small fish, filter feeders (mussels).
Competitor species
Green algae, cyanobacteria, dinoflagellates.
Ecosystem service
Oxygen production, carbon sequestration, water purification, and foundation for fishery yields.
Threats
Ocean acidification, climate change (warming), eutrophication, and silicate depletion.
Scientific profile
Profile
Distinguishing features
Opaline silica shell (frustule) with highly complex, species-specific pore patterns (striae, areolae); presence of a raphe (longitudinal slit) in many pennate forms for active gliding movement on substrates.
Reproduction
Predominantly asexual cell division, where each daughter cell inherits one valve and forms a new, smaller hypotheca (leading to size reduction); sexual reproduction (oogamy/isogamy) to form auxospores for size restitution.
Protection & threats
Main threats
Eutrophication (shift in nutrient ratios), climate change (increased stratification prevents nutrient replenishment), ocean acidification, and chemical pollutants.
Conservation measures
Reduction of diffuse nutrient inputs from agriculture, protection of natural water dynamics, and monitoring of silicate loads in watercourses.