Centric Diatoms
Coscinodiscophyceae
Centric diatoms are a class of unicellular algae characterized by their radially symmetrical silica shells (frustules). They are a major component of marine and freshwater phytoplankton and perform photosynthesis. Their cell shape is typically cylindrical or disc-shaped, with the valves often exhibiting intricate pore patterns. As primary producers, they form a fundamental basis for aquatic food webs globally.
Details
Oxygen production
Very high; diatoms produce approximately 20 to 25 percent of the global oxygen.
Habitat function
Base of the pelagic food web.
Nutrient uptake
Efficient uptake of dissolved silica (Si(OH)4), nitrogen, and phosphorus.
Food source for
Krill, copepods, juvenile fish, baleen whales (indirectly).
Human use
Use of fossil deposits (diatomaceous earth) in filters, abrasives, and as insulating material; biotechnological use of lipids.
Ecology
Ecological role
Primary production, integral part of the carbon cycle (biological pump), and oxygen provider.
Natural predators
Zooplankton (e.g., copepods), filter-feeding bivalves, fish larvae.
Competitor species
Other phytoplankton such as pennate diatoms, dinoflagellates, and green algae.
Ecosystem service
Oxygen production, carbon dioxide fixation, food base for marine and freshwater ecosystems.
Threats
Ocean acidification, eutrophication, climate change (stratification of the water column), silicate depletion.
Scientific profile
Profile
Distinguishing features
Possession of a two-part silica shell (frustule) consisting of epitheca and hypotheca. Characteristic radial arrangement of areolae (pores) on the valve. Presence of specialized structures such as fultoportulae (strutted processes) and rimoportulae (labiate processes).
Reproduction
Asexual reproduction via cell division (accompanied by a reduction in cell size); sexual reproduction (oogamy) to restore the original cell size through auxospore formation.
Protection & threats
Status not on standard scale
Main threats
Climate change (increased thermal stratification), herbicide inputs from agriculture, silica depletion due to river damming.
Conservation measures
Reduction of nutrient inputs (P-elimination), protection of natural water dynamics, avoidance of pesticide inputs into surface waters.