Observations on different types of water bodies were carried out to study the relationship between chlorophyll and suspended organic carbon. Using the literature and proprietary material, a simple method for estimating phytoplankton carbon in situ depending on the concentration of chlorophyll a, based on classical and quantile regression analysis, is demonstrated. Calculations yielded the ordinary estimates of the carbon/chlorophyll ratios ranging from 25 to 150.

The characteristics of the biodiversity of opisthorchids and the infestation of additional hosts in various aquatic ecosystems in a metropolitan area (Novosibirsk city) are presented. The objectives of this study included determining the species composition of opisthorchids metacercariae, analyzing their occurrence and abundance in fish in each of the three groups water bodies, namely: the Ob River, its tributaries, and Berdsk Bay, located within the boundaries of Novosibirsk city and differing in the set of abiotic and biotic characteristics. The composition of the metacercariae hemipopulation in the surveyed water bodies was identical, being represented by three species, namely, Opisthorchis felineus (Rivolta, 1884), Metorchis bilis (Braun, 1890), and Metorchis xanthosomus (Creplin, 1846). However, the infestation of an additional host by opisthorchid larvae of individual species in different water localities was variable and was determined by local environmental features. The most common opisthorchid species in fish caught in the Ob River and Berdsk Bay is O. felineus, the subdominant ones are M. bilis and M. xanthosomus, respectively. In Berdsk Bay small local fish were most frequently and intensively infected with O. felineus (ide, gudgeon, and dace) and M. bilis (ide, gudgeon), while in the Ob River, O. felineus and M. xanthosomus metacercariae were more often recorded in commercial ide. In the additional host inhabiting the Ob tributaries, unlike other water bodies, M. bilis and O. felineus were dominant, with M. bilis metacercariae more often detected in small local fish, gudgeon and ide, and O. felineus, in small-sized roach. Our analysis of the diversity of opisthorchid metacercariae representatives using biological indices indicates a simplified structure of opisthorchid communities in each water body. The most complex structure of the opisthorchid hemipopulation was found in the Ob tributaries (H = 1.01), then in Berdsk Bay (H = 0.51) and in the Ob River (H = 0.32). The highest values of dominance indices (D) are characteristic of the main channel of the Ob and Berdsk Bay, which indicates the abundance of one species of opisthorchid, namely, O. felineus. Low values of the Simpson index in the Ob tributaries indicate the uniformity of the abundance of metacercariae and the absence of obvious dominance of any species.

During salt stress, plant growth is severely impaired by osmotic stress in a first phase and by specific ion toxicity in a second phase. To minimize these deleterious effects, the development of suitable management practices needs to be developed. The present study was undertaken to check whether the jasmonic acid (JA)-mediated enhancement of salt tolerance could be linked to ascorbate (AsA) concentrations and $${\text{NH}}_4^ + $$ -metabolizing enzyme activities during the second phase of salt stress. To this end, wheat seedlings cv. Karim were submitted for four weeks to 100 mM NaCl, in the presence of 1 mM JA or AsA, and analyzed for their growth-related parameters and ascorbate content as well as $${\text{NH}}_4^ + $$ -metabolizing enzymes. Obtained results showed decreased shoots’ and roots’ dry weight production and relative water contents, associated to a noteworthy reduction in leaves’ and roots’ AsA concentrations, as well as glutamine synthetase (GS), glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH) activities. Nevertheless, exogenously-supplied JA, although not affecting AsA concentrations, enhanced GS, GOGAT and GDH activities, resulting in a significant increase in all measured growth parameters. The supplementation of AsA to salt-stressed seedlings, although not affecting GS, GOGAT and GDH activities, enhanced plant growth. Overall, results of the current study indicate that the effects of JA and AsA supplementations on the activities of $${\text{NH}}_4^ + $$ -metabolizing enzymes depend on the phase of salt stress and that the JA-mediated enhancement of wheat seedlings’ tolerance to salt stress is not exerted, at the second phase, through AsA.

Abstract—The relatively large Indo-Malayan-Holarctic genus Pedetontus Silvestri, 1911 has so far included 33 described species. The genus has two subgenera including the nominative subgenus Pedetontus s. str., with seven species (6 from North America and one from Kamchatka) and Verhoeffilis Paclt, 1972, with 26 species (three species from North America, 12 from the southeastern Palearctic and 11 from the Indo-Malayan Region). Both subgenera are distinguished by the arrangement of two pairs of eversible vesicles on abdominal segments II–VI or II–V, respectively. This paper describes two new species of the latter subgenus from the Primorsky Territory of the Russian Federation: P. furuhjelmi sp. n., from Furugelm Island, and P. nigrus sp. n., from Ussuriysk environs. Both are very close to P. ussuriensis Kaplin, 1980, widespread in the Primorsky Territory, and P. silvestrii Mendes, 1993, from North Korea, but they differ well in body length, the relative length of the antennae, the structure of the antennal flagella, the compound eyes, the paired ocelli, the maxillary and labial palps, the sternites, styli and coxites of abdominal segment IX, as well as by the chaetotaxy of the legs and urocoxites IX, and the ovipositor.

Phytoplankton response to weather fluctuations is a major focus in aquatic ecology. Will the lakes unaffected by serious human disturbances experience an annual increase in water chlorophyll, and what are the relative roles of temperature and precipitation? We conducted a multi-year (2015–2023) study of chlorophyll a in the littoral of Lake Hupujarvi, a small, shallow lake in European Russia, chosen as a case study because of its autochthonous regime (drainage ratio 7.71) and slow water exchange (5.31 years). Temperature was identified as a positive driver of eutrophication, determining the interannual central tendency of chlorophyll, while precipitation had a negative effect primarily at the intra-seasonal level. A lake can attain a higher trophic status only if the mean seasonal temperature exceeds the multi-year average by more than 1°C. The effect of temperature and precipitation was greater than that of nutrients, at least for the nitrate nitrogen studied. Thus, the temperature conditions alone can trigger eutrophication in mesotrophic lakes during a single year, even with minimal phosphate concentrations in the water (in our study, under high nitrate concentrations). This study is the first to explain the conflicting data on the relative roles of temperature and precipitation in chlorophyll dynamics.

The peculiarities of morphological structure of the byssal apparatus, byssal threads, and byssal groove of the foot were studied in the commercial species of the Mediterranean mussel (Mytilus galloprovincialis) from the Sea of Japan. It was demonstrated that the byssal apparatus consists of a root, stem, and byssal threads that are elliptical in shape in cross-section. Each byssal thread consists of a corrugated, wide proximal part (which is located immediately behind the cuff and accounts for one-third of its length) and a relatively elastic, narrow distal part (accounts for two-thirds of the thread length), terminating with an oval attachment disk at the distal end. In each byssal thread, three types of byssal prepolymerized collagens (P, D, and NG) with a different block copolymer structure are contained at its different parts. The surface of the byssal threads is tuberous along its entire length. Two reinforcing cords are located on the attachment disk surface. The edges of the attachment disks are semitransparent. The byssal groove of the foot is arranged more primitively than in the studied Mytilidae species. It is noteworthy that the distal fossa is absent at the distal end of the byssal groove of the foot. The peculiarities of morphological structure of the byssus and attachment disks in M. galloprovincialis are explained by the peculiarities of the secretory organ structure.

The polymorphism of the nucleotide sequences of the trnL–trnF, rpl16 intron, and matK regions of chloroplast DNA of the medicinal plant Eleutherococcus senticosus in the southern part of the Russian Far East (RFE) has been studied. The level of genetic diversity was found to be high in the populations of Primorskii krai and average on Sakhalin Island. Hierarchical analysis of the molecular variance showed very low and insignificant genetic differentiation between the populations of these two regions (ΦCT = 0.043, P > 0.479); more than 62% of all genetic variability accounted for the intrapopulation component (ΦST = 0.377, P = 0.000). Eleven haplotypes were identified in the RFE, one of which was unique and two of which were rare for the species. All haplotypes known for E. senticosus form a single group with minimal divergence between each other.