| Autor: |
Nielsen, E. Steemann, Hansen, Vagn Kr. |
| Předmět: |
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| Zdroj: |
Physiologia Plantarum; 1959, Vol. 12 Issue 2, p353-370, 18p |
| Abstrakt: |
A series of light intensity photosynthesis curves of marine phyloplankton is presented. The material includes curves of plankton from both the surface and the lower part of the photosynthetic layer, curves of arctic, temperate and tropical plankton, and curves both of summer and winter plankton. A typical light adaptation of the plankton algae according to depth is found only if the watermasses within the photosynthetic layer are vertically stabilized thus preventing vertical mixing. A differentiation in ''sun" plankton and "shado" plankton takes place. In "sun" plankton the rate of light saturated photosynthesis computed per unit of chlorophyll is high. The compensation point is found at a relatively high light intensity, 600-1200 lux. In "shade" plankton the rate of light saturated photosynthesis per unit of chlorophyll is low and the compensation point is found at a low light intensity, 200-150 lux. Winter plankton from the surface in temperate regions behaves photosynthetically as typical shade plankton. According lo all evidence the light adaptation is brought about simply by establishing a higher or a lower concentration of the enzymes active in photosynthesis. The rate of light saturated photosynthesis being limited by an enzymatic process is a combined result of enzyme concentration and temperature. In arctic waters the concentration of enzymes is high compared with that at lower latitudes, both in relation to concentration of chlorophyll and in relation to the content of organic matter in the algae. It is mentioned that the growth of bacteria does not seem to follow the general rule valid for plankton algae and most other organisms, namely that the effect of a low temperature at the habitat is counteracted by an increase in the concentration of the different enzymes. The background of this special behaviour is discussed. Finally the rate of photosynthesis as measured per organic matter in the algae is discussed. It seems to be moderately independent of temperature in natural populations. At low light intensities shade plankton has a higher photosynthetic rate than surface plankton. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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