Formation of the laminarian phytocoenoses on the introduced stony substrate in the white sea

摘要

The process of formation of the laminarian phytocoenoses during colonization of the introduced stony substrate in the Solovetskiye islands area, the White Sea, has been studied. In 1993-1998 three experimental grounds at the 2,5 and 10 m depths within the belt occupied by the Laminaria saccharina + L.digitata association were sampled. The non-laminarian community stage during the substrate colonization was not observed. Among the pioneering species, L.saccharina predominates at all depths. Alaria esculenta and Saccorhiza dermatodea can be subdominant. The both species completely or partly disappear from the phytocoenosis and L. saccharina remains the only dominant. The background species composition and the phytocoenosis structure are forming during the period of 2 to 4 years. Laminaria digitata appears only in 5 years. At the depth of 2 to 7 m, where the bidominant L.digitata + L.saccharina communities develop, the formation of the phytocoenosis includes three stages and lasts at least 10 years. At the depth of 8 to 10 m, where the moodominant L.saccharina community develops, the phytocoenosis is forming for 5 years. The colonization sequence in the case of a new substrate in the White Sea is determined by the life strategy and by the growth rate of the concurrent species and is similar to the vast majority of recolonization events which occur in the laminarian communities after catastrophic changes.