Vol 10, No 2 (2017)

The species composition of centrohelid heliozoa (Centrohelida) in saline and brackish inland water bodies and watercourses with salinity 2.0–42.2‰ was studied in the subarid zone of Russia. Nine species (Polyplacocystis ambigua, Pterocystis foliacea, Choanocystis ebelii, Acanthocystis astrakhanensis, A. dentata, A. myriospina, A. pectinata, A. taurica, A. turfacea) are new for saline and brackish inland waters. A. astrakhanensis and A. taurica are new for the fauna of Orenburg region. The first data on centrohelidian fauna in saline rivers of Elton region were obtained. The fauna comprises Polyplacocystis ambigua, Pterocystis foliacea, A. turfacea and Choanocystis ebelii. C. ebelii is new for the protist fauna of Russia. Five species (Polyplacocystis ambigua, Pterocystis foliacea, A. pectinata, A. dentata, A. taurica) were recorded for the first time in saline and brackish waters and described as eurihaline. Morphological diagnoses of Acanthocystis dentata and A. taurica were completed.

Taxonomy and geographical distribution of diatom taxa from the genus Eunotia are discussed. Fourteen Eunotia species are found in aquatic ecosystems of Central and South-Eastern Vietnam: E. indosinica, E. karveerensis, E. sulcata, E. cf. vumbae, E. novaecaledonica, E. naegelii, E. paramuscicola, E. rabenhorstii, E. tropica, E. sioliopsis, E. australominor, E. mucophila. Two species which are new for science are described Eunotia skvortzovii Glushchenko & Kulikovskiy sp. nov. and Eunotia fogedii Glushchenko & Kulikovskiy sp. nov. Eunotia sulcata Hustedt ex Glushchenko & Kulikovskiy is validated. The species are illustrated by original LM and SEM microphotographs. The main qualitative and quantitative taxonomic data are given. The distribution is found species is discussed.

A new genus of nematodes, Valvaelaimoides gen. n., from the family Linhomoeidae Filipjev, 1922 has been validated. The genus is characterized by very large and circular amphidial fovea with edges strongly sclerotized, as well as a rather complex vulva structure of the pharynx bulb. The new genus includes two species: Valvaelaimoides macramphis sp. n. (type species) and Valvaelaimoides leptus sp. n. Their illustrated description has been given. V. leptus sp. n. is distinguished from V. macramphis sp. n. by a shorter body, relatively longer cephalic setae, and shorter spicules.

The species diversity of planktonic diatoms in thanatocenoses of bottom sediments in Lake Bol’shoe Miassovo (Southern Urals) has been studied and a reconstruction of the thermal regime of the lake for the last 1000 years is made. It is established that the restructuring of the diatom assemblage and decrease in species diversity in thanatocenoses are caused by rapid climate warming that began in the 19th century in the Southern Urals.

Long-term (1953–2004) published and original data on the taxonomic composition and ecological and geographical characteristics of planktonic crysophytes have been systematized and the degree of similarity of the crysophyte flora in nine reservoirs of the Volga River basin has been assessed. Patterns of changes in the specific species richness and biomass of golden algae along the longitudinal profile of the Volga River reservoirs are identified. The relationship between species richness and some abiotic and biolimnological parameters has been analyzed. The decline in diversity and biomass of golden algae in direction from the Upper to the Lower Volga in accordance with the geographical zoning is revealed. The long-term dynamics (1954–2011) of the species richness, abundance, and biomass of golden algae has been analyzed. A positive correlation between the diversity and biomass of golden algae and the amount of precipitation and water temperature is demonstrated.

The accumulation of heavy metals (Cu, Ni, Zn, Mn, and Fe), parameters of the photosynthetic apparatus, and flavonoid content in leaves of two widespread species of submerged hydrophytes (Elodea canadensis Michx. and Potamogeton perfoliatus L.) from habitats with different levels of pollutions have been studied. The investigations are carried out in the surroundings of the metallurgical plant in the town of Revda, Sverdlovsk oblast, Russia (Revda River, upstream and downstream the confluence of the sewage). It is shown that hydrophytes from polluted habitats (impact site) differ from the plants of a less polluted zone (background site) by a higher accumulation of heavy metals (HMs), greater leaf thickness, and larger cells and chloroplasts. Plants from the polluted site are characterized by a high content of photosynthetic pigments, while flavonoid content in the leaves is lower. The identified trends indicate a high adaptive potential of these species of plants and their ability to inhabit in an aquatic environment polluted with metals and other pollutants.

The species composition and external morphology of heterotrophic flagellates in four sphagnum bogs and six lakes in the Usman pine forest in Voronezh oblast has been studied. A total of 71 species from five supergroups (Amoebozoa, Opisthokonta, Rhizaria, Archaeplastida, and Excavata) have been recorded. The faunal similarity of the flagellate complexes is extremely low in the studied water bodies. The maximum species wealth is recorded in the terrace dammed lake with a marsh watershed, while the minimum species wealth is detected in the driest sphagnum bog. Different floodplain lakes are characterized by the maximum and minimum species specificity, while the terrace lakes and bogs occupy the intermediate position. Most species are represented by Rhizaria and Excavata. Rhizaria are dominated by Cercomonadida and Glissomonadida, while Excavata are dominated by Euglenoidea and Kinetoplastida. Only three predatory flagellates were found: Rhynchobodo armata Brugerolle, 1985, Goniomonas truncata (Fresenius, 1858), and Alphamonas edax (Klebs, 1892). Some of the revealed species also occur in sea waters, which indicates their euryhalinity. Bordnamonas tropicana was found in a fresh water body for the first time. The descriptions, drawings, and photographs of 16 species are given, taking into account the morphological features of their cells.

The composition and structure of zooplankton in small water bodies (ponds and puddles) of Pechora Bay coastal marshes have been studied. The investigated water bodies are confined to three ecotopes (low, medium, and high marshes), distinguished on the coastal strip according to the degree of soil salinity and vegetation quality along the ecological profile perpendicular to the coast. It has been revealed that the species composition and zooplankton abundance are dependent on the type of ecotope and water salinity. The trophic structure of the community shows the difference in food resources between the studied ecotopes.

Mechanisms of the initial dispersion of early larvae resident and anadromous forms of the European river lamprey have been experimentally explored. The flow (channel flow and underflow), type of bottom, and illumination are the key factors influencing the beginning and the end of downstream migration. Larvae leave the pebble ground of the spawning area when there is underflow and illumination is reduced to the night level, and then they migrate downstream in the channel stream. It is shown that the individuals dispersing from the spawning areas have switched to exogenous feeding. The end of the dispersion occurs after larvae reach oozy habitats of the riverbed, where they can find optimal feeding conditions.

All of the 166 Clarias gariepinus catfishes in Lake Tana, Ethiopia, were examined for trematode infestation in 2006—2009. Seven trematode species—Eumasenia bangweulensis, Astiotrema reniferum, Orientocreadium batrachoides, Paralecithodendrium chilostomum, Phyllodistomum bavuri, P. tana, and Cladorchiidae gen. sp.—as adult were found. The common catfish parasites were Eumasenia bangweulensis (20% prevalence and 1—62 intensity of invasion), Orientocreadium batrachoides (30% prevalence and 1–31 intensity of invasion), Phyllodistomum bavuri (24.8% prevalence and 1–8 intensity of invasion), Ph. tana (17.6% prevalence and 1–23 intensity of invasion), and Ph. bavuri. Astiotrema reniferum (three specimens were only found) was a rare species; Paralecithodendrium chilostomum was an accidental parasite of catfish. All these trematodes were first recorded in Ethiopia and Eastern Africa.

The effects of phenol and its derivatives (4-chlorophenol, 4-nirophenol and 2,4-dinitrophenol) on the activity of peptidases in five species of fish differing in feeding modes have been studied. The power of the effects depends on the fish species and localization of the enzyme (mucosa or chyme). As a rule, in the in vitro conditions the phenols in concentrations of 0.06−0.5 μM/L considerably decreases activities of the intestinal peptidases in bream; silver bream; and, especially, in pike. In some cases, phenol and its derivatives induce an inconsiderable increase in peptidase activities. In zander and perch, in fact, no changes in the enzymatic activity under impact of phenols are observed. It is suggested that the effect of phenol and its derivatives depends to a high extent on the species specificity of peptidases: in the fish of fam. Percidae, the enzymes are relatively tolerant; in fam. Cyprinidae and Esocidae, they are sensitive to the studied toxicants.

Concentrations of heterotrophic bacteria have been measured in the epiphyton of seven species of higher aquatic plants in the Ivankovo Reservoir. The abundance and biomass of the bacterioepiphyton range from 64.1 × 10⁶ to 283.7 × 10⁶ cells/сm² and from 1.6 to 6.7 μg С/сm². Maximum values are recorded in the epiphyton of emergent aquatic plants.