Ultrastructure and pigment composition of the photosynthetic apparatus of the green alga Ulvaria obscura during the polar day and polar night.

Abstract

The ability of marine macrophytes to survive in Arctic regions with extreme environmental conditions (long-term exposure to negative temperature, changes in illuminance ranging from polar night to polar day, etc.) has always been a subject of considerable interest of researchers. It was found recently that photoperiod played a decisive role in changes in the growth rate of algae [1‐3]. We earlier demonstrated that the onset of intense growth of most algae at the Barents Sea coast coincided with the increase in photoperiod in February and March at negative temperatures of the water. The rate of this process reaches its maximum in May and declines to a minimum level by November. The growth of algae is completely ceased in December [3]. The effect of these contrasting environmental conditions on the state of the algal photosynthetic apparatus is obscure. Probably, the adaptation of the photosynthetic apparatus allows the plants to survive in the Arctic environment.