Biologiya Morya

Annual and seasonal (summer) supra- and pseudolittoral macroalgal communities of the northeastern Black Sea coast have been described for the first time, using the floristic classification method. A total of three associations, one community, one alliance, one order, and one class have been identified. The associations, community, alliance, and order have been described for the first time. Diagnostic species are provided for the identified syntaxa. Based on the dominant classification method, the identified phytocoenoses are compared with those previously described from the Black Sea and with similar communities from the Mediterranean Sea and other European seas. It is shown that the annual and summer vegetation on hard substrates in the supra- and pseudolittoral zones of the northeastern Black Sea mainly consists of simple species-poor communities, which are predominantly comprised of cosmopolitan and subcosmopolitan species, along with a few species of the Indo-Atlantic, Atlantic-Pacific, and Mediterranean origin. However, the communities’ diversity is significantly poorer in the northeastern Black Sea supra- and pseudolittoral than that in the Mediterranean Sea, mainly due to lack of communities of calcifying red algae. An indirect ordination analysis revealed the ecological isolation of the described phytocenoses and the main factors influencing the floristic composition of communities: depth, eutrophication, and/or hydrodynamic intensity.

The reproductive characteristics of the subtidal hermit crab Pagurus ochotensis Brandt, 1851 from Peter the Great Bay (Sea of Japan) were studied based on material collected in 2014–2015 and 2023–2024. Within the depth range of 2 to 11 m, this hermit crab was encountered year-round, except in July and August, when it was either absent at these depths or represented by single individuals. The bulk of the P. ochotensis population (over 90%) consisted of males with a shield length (SL) of 8–18 mm and females with a SL of 7–13 mm. A peak in abundance was observed in April–May, primarily due to ovigerous females. Spawning in P. ochotensis is asynchronous: ovigerous females were recorded from January to June and, in smaller numbers, in August. The presence of females that had recently laid eggs in August suggests a probable repeat spawning involving older size classes. The incubation period of the first generation eggs lasted from two to five months and ended in late May to early June. The development duration of the second generation eggs was likely about one month. The minimum SL (5.7–5.8 mm) of ovigerous females of P. ochotensis corresponded to the second year of life. Individual fecundity in females with SL from 5.7 to 12.8 mm ranged from 2127 to 14 853 (with an average of 7984 ± 3320) eggs.

The karyotypes of the sailfin sculpins Blepsias bilobus and B. cirrhosus were studied for the first time, and the chromosome set of Hemitripterus villosus was analyzed. It was found that the karyotypes of these species are stable and consist of 46 chromosomes (2n) in H. villosus: 4 metacentric (M), 32 subtelocentric (ST), and 10 acrocentric (A); the number of chromosome arms (NF) is 50. In Blepsias bilobus, the chromosome set is 2n = 48 (34 ST and 14 A chromosomes), NF = 48; in B. cirrhosus, 2n = 48 (36 ST and 12 A chromosomes), NF = 48. Based on comparative karyological analysis, common features were identified that confirm the close relationships between B. bilobus and B. cirrhosus, and the taxonomic proximity of H. villosus to species of the genus Blepsias. The features that allow differentiation of the studied species were also determined.