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Helgoland Marine Research

Open Access

Osmotic and ionic requirements of the marine centric diatomCyclotella nana

  • R. R. L. Guillard1 and
  • S. Myklestad2
Helgoländer wissenschaftliche Meeresuntersuchungen20:BF01609892


1.Cyclotella nana Hustedt (clone 13-1) was found to grow in sea water at salinities ranging from about 15 to 50 parts per thousand.

2. Investigation of the osmotic requirement in the region of poor growth at the lower salinities, revealed that this alga gives an osmotic response at a relatively high osmotic pressure.

3. The osmotic and ionic requirements can be clearly distinguished and it was shown that this oceanic diatom can survive at sea water dilutions as low as 1/6 of full strength of water from the Sargasso Sea when the osmotic pressure is adjusted with sucrose.

4. The requirements of the four main cations (Na, K, Ca, Mg) are discussed.


SaccharoseWaste WaterOsmotic PressureLower SalinityPoor Growth