Vol 56, No 1 (2016)

Data of long-term studies (1997–2013) on biology of Hadropareia middendorffii from different areas of Tauysk Bay, the Sea of Okhotsk are generalized. This species is widespread over the entire northern coast of the Sea of Okhotsk, and it prefers sandy-pebbly grounds. Maximum sizes and age comprise 267 mm, 73 g, and 7+; in catches, individuals with a length of 9.1–12.0 cm, weight 0.1–10.0 g, at an age of 1+ to 3+ dominate. In general size–age characteristics of females and males as a whole are rather similar, and sex ratio is nearly equal. Hadropareia middendorffii spawns from the second half of June to the first 10-day period of August; its fecundity varies within 67–219 eggs.

Based on karyological data, the validity of the species Ponticola iljini is re-established; its distribution is limited to the coast of the Mangyshlak Peninsula. The morphological characteristics and the basic color pattern of P. iljini are very similar to P. kessleri from the Black Sea basin and P. gorlap which inhabits the northern, western, and southern Caspian Sea. These three allopatric species have ctenoid scales to varying degrees on the crown and nape (100% presence in P. kessleri and complete absence in P. iljini), and there are small differences in the shape of the head, the thickness of the caudal peduncle, and in the form of otoliths; at the same time, they are clearly differentiated by the number of chromosomes and the presence of marker submetacentric chromosomes in P. iljini. In the phylogenetic tree based on the variation of the mitochondrial cytochrome b gene in the main species of Ponto-Caspian gobies, P. iljini, P. gorlap, and P. kessleri form independent phyletic lineages within a clade of the genus Ponticola. Redescription of the species P. iljini is provided; the possible causes of the identified intraspecific variation in the shape of the otoliths and temporal bounderies of the beginning of divergence of the considered three cryptic species, as well as isolating barriers that led to allopatric speciation, are discussed.

The species status of a rare species Eumicrotremus eggvinii from the family Cyclopteridae has been revalidated. Some authors considered its specimens as males of close species E. spinosus. In the Zoological Institute collection, males of E. spinosus that are morphologically similar with females of this species have been found. This is evidence of absence of sexual dimorphism in E. spinosus. In new samplings from waters of the Franz Josef Land archipelago (Barents Sea), a specimen of E. eggvinii was found and described. The opinion of some authors that individuals of E. eggvinii represent males of E. spinosus is refuted. A new finding widens the species area to the northeastern limits of the Barents Sea. The number and character of distribution of bone plaques remain reliable taxonomic characters.

On the basis of the results of complex interdisciplinary investigations of the population composition and structure of the beaked redfish Sebastes mentella of the Atlantic and Arctic oceans, its three populations are discerned relatively isolated from each other by the system of permanent marine currents—North Atlantic, Flemish-Cape, and Norway-Barents Sea. The population structure of the species in the southern part of its area corresponds to the model of a local stock. Interaction of the North Atlantic and the Norway-Barents Sea populations well correspond to the model of fluctuating stocks. Redfish aggregations in different biotopes (mesobenthal and mesopelagial) are intrapopulational epigenetic groups. In the period of warm and anomalously warm years, a part of mature specimens from the pelagial of the North Irminger Sea make an irreversible migration to the southern part of the Norwegian Sea and form there mixed aggregations of fish from the North Atlantic and Norway-Barents Sea populations. With consideration of the effect of climatic–oceanological processes, a principally new scheme is elaborated describing the process of seasonal migrations of redfish in the mesobenthal and mesopelagial. The previous views on direction of return migrations of redfish of the Norway-Barents Sea population are reconsidered. Juveniles from the western part of the Barents Sea and Spitsbergen not only supplement the demersal aggregations but also migrate to the pelagial of the Norwegian Sea.

Feeding peculiarities of mass pelagic ichtyophagous fish from the Canary upwelling waters and frontal zones of Mauritania have been investigated: vadigo Campogramma glaycos, false scad Caranx rhonchus, bluefish Pomatomus saltatrix, Atlantic bonito Sarda sarda, West African Spanish mackerel Scomberomorus tritor, large-eyed hairtail Trichiurus lepturus and pompano Trachinotus ovatus. These species feed on epipelagic fish living or forming temporary agglomerations at the depths up to 200–250 m from the surface.

Specific biological features, morphology, and genetic variation of an invasive species, the Chinese sleeper Perccottus glenii, in several lake and river ecosystems of the Tyumen oblast have been studied. This species displays relatively high rate of linear and weight growths. The main feed of the Chinese sleeper in both the river and lake ecosystems is the chironomid larvae. The diet is richer in the river ecosystem; predation plays an important role; and cannibalism is observed. As has been shown, the qualitative and quantitative characteristics of the Chinese sleeper infestations with local helminth species are by one order of magnitude lower as compared with the native fish species. A significant infestation rate is observed only for Nippotaenia mogurndae, a parasite specific for the Chinese sleeper. The population of this introduced species displays a high genetic variation for DNA markers. The rate of polymorphic ISSR bands is 73% and Nei’s genetic diversity is 0.26. The Chinese sleeper populations in the not directly connected river and lake (distance, 90 km) display a genetic identity of 99.5%, suggesting the absence of genetic differentiation of local populations, explainable by their recent origin from a single source of invasion. Morphological differences of the Chinese sleeper in different ecosystems appear on the same genetic basis and suggest a wide reaction norm characteristic of this species, underlying its ecological plasticity.

The effect of pH on the activity of proteinases of intestine mucosa, chyme, and enteral microbiota was studied in three piscivorous fish species of the Rybinsk Reservoir differing in their ecological traits: pike Esox lucius, burbot Lota lota, and zander Sander lucioperca. In all fish species, studied pH of ten is optimal for the functioning of proteinases of intestine mucosa; in chyme proteinases, optimal pH values vary from six to ten. Optimal pH for functioning of proteinases of enteral microbiota is seven for zander and pike; pH of nine, for burbot. High activity of chyme and microbiota proteinases within the diapason of pH values of six to nine is a characteristic of burbot. Relative activity of proteinases of intestine mucosa in all fish species is not more than 15% of the maximal activity; that of chyme and enteral microbiota is lower than 40% in zander, close to 50% in burbot, and 80 and 50%, respectively, in pike. It is suggested that diversity of the patterns of pH-dependence of enteral microbiota proteinases relates to the specificity of microbiota in various ecological zones of the reservoir (littoral, sublittoral, and bathyal).

Butterflyfishes (Chaetodontidae) from the reefs of Ly Son Archipelago (northern Central Vietnam) are reviewed. In total, 16 species of chaetodontids from three genera (Chaetodon, Forcipiger, and Heniochus) are found. All species are documented by underwater photos, and they have not been registered off Ly Son Islands before. A comparison of chaetodontid faunas off Ly Son, Cu Lao Cham, and Paracel islands; in the Gulf of Tonkin; and in southern Central Vietnam is conducted.

The first reliable finding of Gobius cruentatus in Russian waters of the Black Sea coast of the Caucasus is reported.

In the light gradient installation, the larvae of European river lamprey Lampetra fluviatilis of 0+ age, migrating downstream (downstream migrants), are distributed predominantly over the zone of dusk illumination (150–1 lx) and less so over the daylight zone (2500–150 lx) and night illumination zone (<1 lx). In 0+ larvae that passed over to the sedentary lifestyle, the photopreferendum changes: they avoid the dusk and daytime illumination and prefer nighttime illumination. Such photopreferendum is retained in later larvae of lamprey (1+ and older).