Nº 5 (2023)

In this study, we investigated a species composition of the water fleas (Crustacea: Cladocera) in the water bodies of the left bank of the Lena River near Yakutsk and its vicinities. Local faunistic associations characteristics of this region were identified using a statistical approach based on the binomial distribution function. As a result of the study, 68 taxa were identified and eight very distinct groups of taxa constituting the cores of local faunistic associations of the branchiopod crustaceans in various water bodies and/or various biotopes within one water body were drawn out. We have demonstrated that the water bodies of the Lena River valley and the watershed differ both in species composition and in associations of the Cladocera. At least one species association of the Cladocera is confined to the ponds with a visible anthropogenic influence. Thus, it is possible to identify not only species that are typical for urban water bodies, but also local faunistic associations, the presence of which in the city indicates a significant anthropogenic pressure. At the same time, the identified clusters can be interpreted in terms of our knowledge of the individual species preferences to water bodies of different types and different ecological zones of a certain water body.

The paper presents the results of the study the qualitative and quantitative composition of the planktonic Crustacea of Dood Tsagaan Lake (northwestern Mongolia) (Cladocera, Diaptomidae, Cyclopidae) in modern times. Comparative analysis of the species composition of crustaceans according to new data and data obtained in the last century (1962–1963) showed that during our studies the composition of crustaceans was increased by five species of Cladocera and by three species of Copepoda, 2 species of them are from the order Cyclopoida and one from the order Calanoida. Ultrastructural studies of the main morphological parts of the copepods crustaceans Mixodiaptomus incrassatus (Sars, 1903), Acanthodiaptomus paulseni (Sars, 1903) and Cyclops glacialis Flossner, 2001 were carried out for the first time using a scanning electron microscope (SEM). Detailed study of morphometric and morphological characters including the use of SEM showed that C. glacialis inhabiting Dood Tsagaan Lake is identical to the species described in lakes (Turgun Kharhiraa Uvs aimag and Nogoon nuur) in northwestern Mongolia. The biomass of M. incrassatus, an important food object for whitefish and other fish species, was found to reach 1100 mg/m³ in the modern period.

In 2021 Acanthocyclops trajani Mirabdullayev et Defaye, 2002, was first record in the Vistula Lagoon of the Baltic Sea. This species quickly spread throughout the water area of the Lagoon. In summer, A. trajani reached its maximum development (up to 92 thousand ind./m³, 2.4 g/m³), was a dominant and forming a particularly high proportion of zooplankton in the most polluted, desalinated and eutrophicated eastern part of the Vistula Lagoon. As a result of predatory feeding, A. trajani exerted significant pressure on the planktonic communities of the Lagoon; its diet in August exceeded the production of non-predatory zooplankton. The pressure on zooplankton increased even more due to the mass development of Cercopagis pengoi (Ostroumov, 1891), with which the new species entered into competitive relationships. The main reasons for the successful naturalization of A. trajani in the Vistula Lagoon, apparently, include some features of its biology, the structure of the plankton community with the presence of unoccupied trophic niches, the continued eutrophication this waterbody, decreasing the pressure of the invasive mollusk Rangia cuneata (G.B. Sowerby, 1831), as well as local climate warming, noted in recent decades.

For the first time, the presence of the invasive amphipod Gmelinoides fasciatus (Stebbing, 1899) was established in the watercourse of the basin of Lake Vodlozero (Novguda River, a tributary of the Ileksa River), which is located on the territory of the National Park “Vodlozersky” (North-West Russia). The new habitat is at a considerable distance from the previously known ones. The shortest route through water bodies (Ileksa River–Vodlozero Lake–Sukhaya Vodla River–Vodla River–Onega Lake) is about 180 km. This raises questions about the path and mode of spread of the invasive species. Along with migration through water bodies, it is proposed to consider the version of introduction of amphipods by tourists, in particular fishermen, with equipment or bait. A detailed survey of the littoral zone of Lake Vodlozero is recommended to determine the extent of the invasive settlement.

The structure of olfactory sensilla was compared in amphipods from the Baikal region, namely in nine Baikal species (Ommatogammarus carneolus melanophthalmus Bazikalova, 1945, O. flavus (Dybowsky, 1874), O. albinus (Dybowsky, 1874), Eulimnogammarus verrucosus (Gerstfeldt, 1858), E. vittatus (Dybowsky, 1874), E. cyaneus (Dybowsky, 1874), Acanthogammarus godlewskii (Dybowsky, 1874), Pallasea cancelloides (Gerstfeldt, 1858) and Gmelinoides fasciatus (Stebbing, 1899)) and a Holarctic species Gammarus lacustris Sars, 1863. The results of the study demonstrate the comparison of aesthetasc lengths and numbers, as well as SEM images of the aesthetascs for Baikal amphipods for the first time. Our results confirm and complement the previously obtained data on the number of aesthetascs per segment for three deep-water Baikal amphipod species of the genus Ommatogammarus. Within the studied deep-water amphipods with different habitat depth ranges, Ommatogammarus albinus (Dybowsky, 1874), inhabiting maximum habitat depth, had the highest number of aesthetascs. The size and number of aesthetascs did not differ in males and females of the littoral Eulimnogammarus verrucosus (Gerstfeldt, 1858) and deep-water species. The littoral amphipods were shown to have equipped with more mechanoreceptors antennae I than deep-water amphipods.

Crustaceans are one of the biosphere’s most diverse and successful groups, also inhabiting various extreme habitats. Summing up our data and 203 literary sources, we analyzed how the degree of environmental extremeness can limit the potential taxonomic richness of crustaceans using the example of hypersaline waters. An analysis showed that, with an increase in salinity, the number of classes and orders of the Crustacea subtype decreased linearly, while the number of genera and species decreased exponentially. It has been established that with an increase in environmental salinity, the contribution of Arthropoda species to the total species richness of animals in hypersaline waters increases from 49 to 100%, the gift of Crustacea species to the total species richness of Arthropoda increases from 66 to 78%, and the contribution of Branchiopoda to the species richness of Crustacea from 19 to 71%. In the Crimean hypersaline water bodies, in the range from 35 to 120 g/L, salinity is not the main factor determining the species richness and composition of the fauna, the combination of all other factors, primarily biotic ones, plays a more critical role. Only at higher values, salinity itself begins to play the role of a hard-environmental filter. Salinity growing above 35 g/L reduces the comfort of the environment for animals and filters out the pool of species that can exist in the ecosystem. In particular water bodies, the realization of this possibility depends not only on salinity but also on the existing biotic relationships and the entire set of abiotic factors.

Physiological parameters objectively reflect the health state of the organism and can serve as effective auxiliary criteria in determining the quality of the environment. However, significant variability of physiological and biochemical parameters is known in invertebrates, and, in particular, in crustaceans. In order to overcome these limitations and increase certainty in the assessment of the biological effects of toxicants, the authors proposed approaches and methods for the selection of reference groups of crayfish based on monitoring of their heart rate at rest and under the short-term standardized functional tests, allowing to assess the functional state of crayfish and their adaptive capabilities.

The effect of exposure on the hematological parameters of the red claw crayfish Cherax quadricarinatus Von Martens 1868 was studied. Hemolymph was taken immediately after extraction from the water after 2, 4, 8 hours of exposure on the shore and 24 and 72 hours after returning to the water. Determined total hemocyte counts (THC), hemogram, general protein and hemocyanin disease. The dynamics of the growth of hematological parameters in the temporal aspect was revealed: THC and the proportion of granulocytes increased to reveal the entire pattern of growth, the proportion of agranulocytes and the total content of protein and hemocyanin. After exposure on the shore, the color of the hemolymph changed from bluish with a grayish tint to cloudy gray-green (deviation from the norm). The data obtained indicate the development of compensatory factors and pathological properties in response to stress, the occurrence of symptoms in the air, which can be used in practice in assessing the state of the red claw cancer in the process of transport.