Bacillariophyta—the diatoms

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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.
Chrysophyta--Golden brown algae Cells small to medium (>10 microns) Nucleus (1), chloroplasts (2)brown to golden brown (chlorophyll a plus carotenoids), food stored mainly as oils and carbohydrates Unicellular or colonial, some species with flagellae (usually 2) Cell wall—often absent, sometimes present as a lorica (cellulose) simple unicellular naked flagellate
Page 1 and 2: Bacillariophyta—the diatoms •th
Page 3 and 4: The new valve is always a hypovalve
Page 5 and 6: Some examples of pennate diatoms ge
Page 7 and 8: Some pennate forms are colonial and
Page 9 and 10: Examples of centric diatoms Non-rap
Page 11 and 12: Achnanthes: heterovalvular, one val
Page 13: Epiphytic pennate diatoms
Page 17 and 18: 50 microns large branched colonies,
Page 19 and 20: Pyrrophyta--Dinoflagellates •Cell
Page 21 and 22: Gonyaulax—causes red tides, shell
Page 23: Pfiesteria—a toxic dinoflagellate

Bacillariophyta—the diatoms

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