MAP Technical Reports Series No. 106 UNEP

2 Note: Algae is not a taxonomic term
- 7 -
energy or the energy of inorganic chemical reactions. Chlorophyll that acts as energy capturer
is found in all photo-autotrophic ('green') plants; specific accessory pigments, such as
xanthophyll, phaeophytine, rhodophytine, etc. occur in certain major plant divisions only.
Cyanophyta, or cyanobacteria, the common blue-green algae (now united with bacteria
under the division of Procaryotes because of their primitive nuclei) are for the most photoautotroph.
Some species can utilize, like do other specialized chemo-autotrophic bacteria,
chemical energy.
Some of the otherwise photo-autotrophic algae are facultative heterotrophic; i.e., they
can (a) either uptake water dissolved organic compounds (e.g., sugars) and utilize the stored
energy, or (b) ingest organic particles, including living cells, as do some dinoflagellate species.
Algae (micro- and macro-algae) 2 are the most important representatives of photoautotrophic
aquatic primary producers. Phytoplankton of both, fresh and marine waters is an
assembly of freely buoyant micro-algae (size in the sub-millimetre range), the movement of
which is largely controlled by horizontal and vertical water motions. Depending on shape and
whether the phytoplankton species are unicellular or form colonies, their size ranges from about
1 to 500 (