Linked from
The 36 pages that link to Phytoplankton, each with the reason it gives.
DiatomNarrower topic: Diatoms are a major component of this drifting producer community.
Algal bloomNarrower topic: Blooms arise when populations of these drifting organisms grow rapidly.
MixotrophyNarrower topic: Mixotrophic phytoplankton complicate estimates of production and grazing.
CryptomonadNarrower topic: Cryptomonads are members of this diverse producer community.