Photosynthesis Pattern of Natural Phytoplankton Relating to Light Intensity

Photosynthesis pattern relating to light intensity and the process of the differentiation in pattern have been pursued in natural phytoplankton community of lakes.1. Phytoplankton growing in a lake can be classified into the sun and shade forms through the characteristics in photosynthesis-light curve. The typical sun form phytoplankton is usually obtained in the surface layer phytoplankton in early summer and autumn, and the phytoplankton taken from deeper layer acts as the shade form. During late summer and winter, all phytoplankton in a lake indicates the shade type photosynthesis.2. The photosynthesis pattern differs with difference of species but the difference is rather slight under the optimal environmental condition for each species. Regional difference in photosynthesis pattern can be observed definitely. The phytoplankton acts as a sun form in enriched water of eutrophic lakes and a shade form in poor water of oligotrophic lakes.3. The factors relating to the differentiation of photosynthesis pattern, i.e. light, temperature and nutrients, are ascertained experimentaly. However, the effect of past history of environmental factors on the photosynthesis pattern does not hold for a long period and the pattern rapidly transforms through the change of environmental factors.4. The differentiation of photosynthesis pattern directly refers to the movement of water in lakes. During the circulation period, all phytoplankton in a photic layer show the sun-type photosynthesis pattern and with stagnating of water the photosynthesis pattern differentiates into the sun type in the surface phytoplankton and the shade one in the deep-layer phytoplankton.