1. Diatoms - singlecelled euk, frustule made of silica, dominate nutrient rich areas.
2. Dinoflagellates - unicellular eukaryotes, smaller than diatoms, some can produce toxic blooms, some are heterotrophs.
3. Coccolithophores - unicellular eukaryotes (smaller than diatoms and dinos), calcium carbonate shell, dominate less nutrient rich/productive areas.
- 4. Cyanobacteria: synechococcus (1 um - mysteriously motile found in oligotrophic ocean)
- prochlorococcus - 0.5 um, responsible for 30-80% of primary productivity in oligotrophic ocean.
- trichodesmium - heterocysts fix nitrogen (tropics/subtropics) also phytoplankton. crocosphaera - fixes N at night found in tropics. Dominant autotrophs due to abundance and efficiency in N Pacific.