Growth rate of Fucales on the Murman Coast, the Barents Sea

Abstract

Fucales are among the key algae on the coast of the Northern Hemisphere and are being actively studied, although minor attention is paid for the age structure, since there are no reliable signs for determining the age of the algae. Direct observations on the thallus growth on the coast evidence on a variation of this trait under different conditions. We assess the rate of linear growth and the number of formed dichotomous branching per year in Fucus vesiculosus and Fucus distichus on the Murman Coast of the Barents Sea. These parameters differ in plants sampled from different biotopes. The annual growth of F. vesiculosus is two times higher and more dichotomous branches are formed per year in the environment characterized by low water movement intensity and pronounced salinity fluctuations than in plants growing on a weakly protected area of the coast. In the Barents Sea, the branching rate and the annual growth in F. distichus and F. vesiculosus depend on the intensity of water movement and the salinity regime of a particular biotope. The number of formed branches depends also on the number of already formed dichotomies, i.e., on the physiological age of thallus. It is necessary to modify the equation for calculating the age of these species using the correction factors for salinity, the intensity of water movement, and the number of dichotomies.