Characteristics of sublittoral vegetation in the northwestern Okhotsk Sea based on the concept of adaptive zone

Abstract

Sublittoral vegetation in the northwestern Okhotsk Sea is described on the data of diving survey in 2020 and some additional data obtained from 2003 to 2022. Five macroalgae associations (Saccharinetum latissimae, Pseudolessonietum laminarioidae, Alarietum esculentae, Sargassetum miyabeae, and Zosteretum marinae) and one group of red algae communities are identified and classified into 5 alliances, 3 orders and 3 classes. All these associations occur over entire area (from 56º to 59º N), within almost whole range of the surveyed depths (2–11 m), and occupy a total of 88 % of the vegetation cover, with statistically uniform distribution. Coenofloras of the associations are poor: up to 5–6 species or multispecies groups have been noted in every association. The concept of an adaptive zone is proposed as an optimal methodological basis for describing marine sublittoral plant communities in the temperate zone. The sublittoral associations in the study area are considered as elementary Petersen-type communities with on average ¾ of the bottom cover and biomass formed by the main dominant species. These associations and higher syntaxa can be built into the most common floristic system of syntaxonomic classification. The adaptive zone concept allows to solve the problem of subjectivism in selection of syntaxa, so the syntaxonomy becomes closer to natural classification with ecological meaning. Successful applicability of the adaptive zone concept for the algae resources assessment is proven; the stock in the surveyed area of 64 km2 is evaluated as 200 . 103 t.