Patterns of Change in Photosynthetic Pigments in Plants of Coastal Arctic Regions along the Environmental Gradient

Plants in coastal areas along the Subarctic-Arctic gradient experience an elevation in climate extremeness, which entails structural transformations in their photosynthetic apparatus, especially adaptive modification of the content and ratios of photosynthetic pigments. In view of this, 31 species of vascular plants were sampled in 2008–2015 from the White Sea and Barents Sea littoral and supralittoral zones along the following latitudinal gradient: Vlg. Dal’niye Zelentsy (69°07′05′′ N, 36°03′30′′ E), Gulf of Kandalaksha (66°16′11′′ N, 33°03′06′′ E), Is. Bolshoi Solovetsky (65°01′28′′ N, 35°42′38′′ E), Vlg. Kolezhma (64°14′11′′ N, 35°52′27′′ E) for analyzing the species’ ecological and biological characteristics and determining the concentrations of photosynthetic pigments (chlorophylls a , b , and carotenoids). The study revealed a non-linear pattern in the accumulation of photosynthetic pigments. Chlorophyll and carotenoid content were the highest in the leaves of plants at the Gulf of Kandalaksha, corresponding to an optimal amplitude of the ambient conditions. Differences in the pigment profiles of coastal plants under local littoral and supralittoral conditions are demonstrated. Having applied the hierarchical clustering method, we distinguished three functionally significant types of plants with different pigment complex adaptation strategies. The patterns identified for photosynthetic pigments are in agreement with the notion that an actively operating principle in the Arctic is functional convergence—the ambient environment is a far weightier determinant for the plants’ physiological phenotype than the phylogenetic predetermination. The identified patterns are important for understanding coastal and supralittoral vascular plants in the face of impending climate change.