Carl Linnaeus - Swedish biologist that divided the plant kingdom into 25 classes (according to the no. of stamens and carpels)
Jean Vincent Lamouroux - French biologist that was the first to separate the algal groups on the basis of color
William Henry Harvey - Irish botanist that divided the algae into four major divisions according to their pigmentation (Rhodospermae, Melanospermae, Chlorospermae, Diatomaceae)
Friedrich Traugott Kützing - German biologist that differentiated diatoms and desmids
Felix Eugen Fritsch - wrote "A Treatise of the British Freshwater algae," and "The Structure and Reproduction of Algae"
Anton van Leeuwenhoek - observed green clouds in lake water. (Most likely the genus Spirogyra)
Joseph Banks - observed "Sea saw-dust" on their expedition to the South Pacific. (Most likely the genus Oscillatoria or Trichodesmium)
William Scoresby - observed opaque green waters were favored by whales, and described diatom chains. Also wrote "An Account of the Arctic Regions"
Joseph Dalton Hooker - observed microscopic life from seawater and zooplankton guts, and colored growth underneath packed ice. Also wrote "The Botany of the Antarctic Voyage."
Joseph Dalton Hooker - described the nature of Phytoplankton (they're microscopic, abundant in the sea, distributed worldwide, and act as a food source of marine animals)
Johannes Muller - German biologist that used a tow net/plankton net to collect samples
C.A. Kofoid and H. Lohmann - noted that the smallest phytoplankton are being missed in large mesh sizes of nets
Mary Parke - studied Unialgal culture of flagellated phytoplankton as food for oyster larvae
Alister Hardy - made the Continuous Plankton Recorder
Wrigley and Horne - did aerial photography and ocean color studies
J.D. Strickland - observed phytoplankton distribution related to high-nutrient upwelled waters
T. Platt and D.V.S. Rao - observed estimates of phytoplankton productivity in the oceans equals that of land plants