ABSTRACT
Some 70% of the Earth’s surface is covered by water and it is probable that the algae fix more carbon dioxide than all the land plants combined. This may not be so readily apparent if one thinks only of the macroscopic algae which are confined to the shore line or shallow water. However, the overwhelming majority of algae are microscopic, unicellular, floating forms which constitute the phytoplankton. Their density is low and they therefore rarely impart any colour to the oceans. However, the enormous volume of
the oceans which they occupy makes them the most abundant of all photosynthetic organisms.
