Bacillariophyta—the diatoms

Ecology of diatoms
•Extremely important primary producers in lake and ocean phytoplankton, and
in the benthic algal communities of lakes and streams (20-25% of global PP).
•Resistant to attack (predators pathogens) silica resistant to most enzymes.
•Pennate (raphed) diatoms well adapted to life on hard substrates
•Many pennate diatoms alternate between solitary and filamentous life styles,
which suits them well for life in unstable environments.
•Colonial centric forms adapted for life in the plankton of cold lakes and
oceans—siliceous frustules sink rapidly, unless they have special shape
adaptations.
•Diatoms often form dense blooms in silica rich cold waters, mainly spring and
fall, when the water column is well-mixed.
•Diatoms are very tolerant of low light conditions
•Most diatom species have narrow limits of tolerance and preference for
chemical conditions in the water example, pH, alkalinity, salinity, Ca, P, N,
organic matter, pollutants of various kinds, as well as temperature.
•This, together with the fact that diatoms are so abundant and preserve well in
sediment cores, makes diatoms very useful as indicators in paleolimnology.