Volume 50, Nº 2 (2024)

Fluctuating asymmetry of seven characters was studied in five samples of the Sakhalin redfin Pseudaspius sachalinensis (Nikolskii, 1889). A comparison of these samples with each other showed that the ratio of variances of fluctuating asymmetry between characters corresponds in a majority of samples to the variance of the average values for these samples. The uniqueness of the sample from Bolshoi Chibisan Lake is indicated by the smallest number of agreements with other samples and the largest sum of variances for all characters. Clusterization of samples of the Sakhalin redfins in terms of variances of fluctuating asymmetry of all characters shows a division into two clusters: one includes samples from the Tym, Tumnin, Susuya, and Protochnaya rivers; and the other cluster includes a sample from the Bolshoi Chibisan Lake. For most indicators of fluctuating asymmetry, the Sakhalin redfin differs significantly from two other redfin species living in the same water bodies, this may indicate either species specificity or the influence of environmental factors at the initial stages of individual development of fish in the spawning sites.

Geobotanical descriptions of Zostera communities were carried out in the eastern part of the Russian shelf of the Black and Azov seas. Based on the descriptions, the syntaxonomy of the class Zosteretea Pignatti 1953 is considered, taking into account the diversity of macrophytic algae. In total, 6 communities dominated by Zostera and Nanozostera were identified in the study area; all of them are described for the first time. The results obtained indicate that taking the occurrence of macrophytic algae into account in the floristic classification of communities dominated by Zostera and Nanozostera makes it possible to reliably identify several communities with specific composition, ecology, and location. It has been shown that the oligosaprobic marine sublittoral vegetation of sandy and silty–sandy sediments of the northeastern part of the Black and Azov seas is represented by widespread flowering plants of boreal origin and associated short-cycle species of cosmopolitan and subcosmopolitan macrophytic algae.

Many years of comprehensive research in the morphological and genetic differentiation of pink salmon led us to the conclusion that there are two closely related cryptic Pacific salmon species in the North Pacific basin, which had previously been regarded as a single species of Oncorhynchus gorbuscha (Walbaum). A new species of Pacific salmon, the rosy salmon (as a colloquial name) O. gorbuschka sp. nova Glubokovsky et Zhivotovsky, occupies almost the same range as the nominate species pink salmon (as a colloquial name) O. gorbuscha (Walbaum). The most striking ecological difference of these species –
rosy salmon spawns only in odd years, and pink salmon – only in even years, forming two reproductively isolated broodlines throughout the natural range. There are quite relief differences between them, that can be detected with the modern research methods, in demographic features, multidimensional morphological traits, protein and DNA markers, and full-genome profiles. Presumably, both of these species are relatively young, evolutionarily diverging from each other during sympatric allochronic evolution leading to a single age class. As a result, all sexually mature individuals of each broodline – of even and odd years of spawning (with rarest exceptions within the natural spawning range) – reproduce in river basins in exactly two years, dying soon after spawning. Presence of two species of O. gorbuscha requires their separate accounting at fundamental and applied researches, fishery and regulation of fishery, protection, artificial reproduction.