Light‐limited growth and photosynthetic characteristics of two planktonic desmid species

Abstract

SUMMARY1. Staurastrum chaetoceras, originating from a eutrophic environment, and Cosmarium abbreviatum var. planctonicum, from an oligo‐mesotrophic one, were grown at 20°C in continuous‐flow culture under varied light conditions.2. Maximum growth rate in S. chaetoceras was approximately 50% higher than in C. abbreviatum, corresponding to a higher photosynthetic capacity.3. Higher dry weight values and dark respiration rates in C. abbreviatum (compared with S. chaetoceras) support the suggestion from growth‐irradiance curves that C. abbreviatum has to invest a greater part of its photosynthetic energy in the construction and maintenance of specific cell components.4. The differences in growth and photosynthetic parameters might be related to the presence of a copious mucilaginous cell envelope in C. abbreviatum; such an envelope is lacking in S. chaetoceras.5. The possible ecological significance of these species‐specific differences is discussed.