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Saifullin R.R.,Kazan Federal University | Shakirova F.M.,State Research Institute of Lake and River Fisheries
Journal of Ichthyology

The analysis of the size composition, age structure, linear growth, and fecundity of the Volga zander Sander volgense has been performed in the Kuibyshev reservoir. To date, the growth rates of the species have decreased slightly compared to the 1970s. Over the period from 2000 to 2013, catch volumes of Volga zander tended to increase. © 2016, Pleiades Publishing, Ltd. Source

Maximov A.A.,Russian Academy of Sciences | Eremina T.R.,Russian State Hydrometeorological University | Lange E.K.,RAS Shirshov Institute of Oceanology | Litvinchuk L.F.,Russian Academy of Sciences | Maximova O.B.,State Research Institute of Lake and River Fisheries

The changes in the concentrations of the mineral nitrogen (nitrates and nitrites) and phosphorus and in the state of the planktic communities in the eastern Gulf of Finland following a large-scale invasion of the polychaete Marenzelleria arctia were analyzed. The bioirrigation and bioturbation of the bottom deposits by polychaetes resulted in a dramatic increase in the nitrogen/phosphorus ratio in the waters of the gulf, thus leading to cascade changes in the plankton. As a result of the decrease in the abundance of colonial nitrogen-fixing cyanobacteria, which cause "blooming" in surface waters, the total biomass of the phytoplankton and chlorophyll a concentration decreased. Because of the disappearance of large colonies of cyanobacteria and the surge of small algae, the food supply for the zooplankton improved and its biomass increased. According to our calculations, the amount of phosphorus deposited in the bottom sediments as a result of the polychaete activity markedly exceeded the external phosphorus load on the Gulf of Finland from the Russian coast. We conclude that the invasion of Marenzelleria arctia resulted in the cardinal reconstruction of the entire ecosystem of the eastern Gulf of Finland. © 2014 Pleiades Publishing, Inc. Source

Issi I.V.,Russian Academy of Agricultural Sciences | Tokarev Y.S.,Russian Academy of Agricultural Sciences | Voronin V.N.,State Research Institute of Lake and River Fisheries | Seliverstova E.V.,RAS Sechenov Institute of Evolutionary Physiology and Biochemistry | And 2 more authors.
Acta Protozoologica

The ultrastructure and molecular phylogeny of a new microsporidium Mrazekia macrocyclopis sp.n., a parasite of the copepod Macrocyclops albidus (Jur.) in North-West of Russia are described. All stages of its life cycle are diplokaryotic. Fresh spores are rod-shaped and 7.3-10.5 × 1.6-2.3 μm in size. Spore ultrastructure is typical of Mrazekia. The polar tube consists of the anterior clavate manubrium followed by a thin filament arranged in 3.5-4.5 nearly vertical coils. Spores are enclosed in individual sporophorous vesicles. SSU rDNA sequence analysis showed attribution of the new species to a cluster of microsporidia infecting insects (Cystosporogenes, Endoreticulatus), microsrustaceans (Glugoides), vertebrates (Vittaforma) and ciliates (Euplotespora) nested within the clade IV sensu Vossbrinck, Debrunner-Vossbrinck (2005). Mrazekia macrocyclopis is not therefore closely related to Bacillidium vesiculoformis, another microsporidium with rod-shaped spores, and the polyphyletic nature of the family of Mrazekiidae is obvious. Source

The study of the genetic structure of the coregonid populations in the eastern part of the Gulf of Finland based on 30 enzyme loci revealed the poor differentiation of the majority of the samples from the Coregonus lavaretus L. populations that were caught close to the mainland's shoreline (DN = 0. 000-0. 005). The genetic differences between the anadromous whitefishes of the Gulf of Finland and the populations of whitefishes from the Ladoga and Onega lakes also turned out to be minimum. The sea populations of the species that populate the open part of the Gulf of Finland near the Russian islands have significantly diverged genetically from the main pool of the populations of the Gulf of Finland (DN = 0. 018-0. 037). The presence of the CK-Al,2*c allele with a high frequency (p ≥ 0. 5) in the gene pool of the sea whitefish implies the probable origin of the island populations from a separate evolution lineage of whitefish of Western Europe or a taxon of complex evolution origin as a result of the introgressive hybridization between different species of coregonids. The phylogenetic closeness and common character of the origin of all the investigated samples of the vendace Coregonus albula L. from the Gulf of Finland and the Ladoga and Onega lakes are supported by the low values of the genetic distances between them (DN = 0. 000-0. 008). © 2012 Pleiades Publishing, Ltd. Source

Sayfullin R.R.,Kazan Federal University | Shakirova F.M.,State Research Institute of Lake and River Fisheries
Inland Water Biology

For the first time over the past 50 years, an analysis of the size composition, age structure, and linear population growth of ide in the Kuibyshev Reservoir has been made. The increase in the growth rates of young ide has been recorded in the reservoir when compared with the river conditions at the initial stage of existence of the reservoir. © 2014, Pleiades Publishing, Ltd. Source

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