Diatom (Girdle view)
Bacillariophyta
Diatoms (Bacillariophyta) are unicellular algae characterized by cell walls made of silicon dioxide (silica). The girdle view refers to the lateral perspective of the cell, where the overlapping parts of the two valves (epitheca and hypotheca) are visible. They are a major component of phytoplankton and play a crucial role in the global carbon cycle and oxygen production.
Details
Oxygen production
Very high; significant contribution to the oxygen enrichment of water and the atmosphere.
Habitat function
Serves as a substrate for epibionts and as an essential food source.
Nutrient uptake
Absorbs nitrates, phosphates, and mandatory silicates for valve formation.
Food source for
Main food source for herbivorous zooplankton.
Human use
Diatomaceous earth (fossil shells) is used as a filtering aid, insulating material, and abrasive.
Ecology
Ecological role
Primary producer in aquatic systems; forms the base of marine and limnic food webs.
Natural predators
Zooplankton (copepods, rotifers), filter-feeding bivalves, and small fish.
Competitor species
Green algae, cyanobacteria, and dinoflagellates.
Ecosystem service
Production of approximately 20% of global oxygen and carbon sequestration.
Threats
Ocean acidification, climate change, and herbicide pollution in water bodies.
Scientific profile
Profile
Distinguishing features
Characteristic exoskeleton made of silicon dioxide (frustule). In girdle view, the girdle bands (copulae) are visible, allowing for cell volume increase during growth. No active locomotion via flagella (except for sperm cells in centric diatoms).
Reproduction
Predominantly asexual by cell division, where daughter cells inherit one valve and synthesize the smaller one (leading to size reduction). Sexual reproduction via auxospore formation to restore maximum cell size.
Protection & threats
Status not on standard scale
Main threats
Climate change (ocean acidification affecting silica incorporation), invasive species, chemical pollution.
Conservation measures
Reduction of nutrient inputs (phosphate/nitrate), protection of aquatic ecosystems, monitoring within the framework of the Water Framework Directive (WFD).