Species composition and structure of macrophytobenthos in the lower part of the photic zone of the Kolvitsa inlet (Kandalaksha Bay, White Sea)

Abstract

The Kolvitsa inlet of the Kandalaksha Bay is a poorly studied part of the White Sea. Sampling was carried out in intertidal and subtidal (using diving equipment) zones from 15 to 21 July 2016. Fifty species of macroalgae were found: 9 species of Chlorophyta, 18 species of Phaeophyceae, and 23 species of Rhodophyta. First records of Choreocolax polysiphoniae and Coccotylus hartzii in the Kandalaksha Bay are reported. The red algal zone at the Kolvitsa inlet extends at the depths from 7 to 17–18 m. Zonation and phytocoenoses with high species richness at the red algal belt were discovered. Community of Odonthalia dentata inhabits the depth of 7–8 m and includes 31 species of seaweeds with their average biomass 282.1 ± 37.6 g/m2; the height of vegetation is 20 cm; Coccotylus truncatus and Polysiphonia stricta are subdominants. Community of C. truncatus inhabits the depths from 8–9 to 11–12 m and includes 35 species of seaweeds with their average biomass 157.4 ± 92.2 g/m2; the height of vegetation is 10 cm; P. stricta, O. dentata and Phycodrys rubens are subdominants. Community of C. truncatus and P. rubens inhabits the depths from 11–12 to 14–15 m and includes 26 species of seaweeds with their average biomass 41.9 ± 1.1 g/m2; the height of vegetation is 5–6 cm; Euthora cristata is a subdominant. Few species of red cortical calcareous algae inhabit the depths from 15 to 18 m. Thirty two epiphytic algae were found. Secondary holdfasts on the erect filaments of Polysiphonia stricta were detected as a specific adaptation for attachment to basiphytes. Most of the epiphytes grow on three species mainly. C. truncatus may be considered as consorcium forming inside the phytocoenoses of the lower part of the photic zone because the biomass of its epiphytes is comparable with that of seaweeds on the ground in the same community.