Chemical elements in sediments and in bivalve mollusks from estuarine regions in the south of Bahia State, northeast Brazil

Estuaries receive daily inputs of chemical elements which can impact the quality of water and sediment, as well as the health of biota. In addition to the sediment, bivalve mollusks have been used in the chemical monitoring of these systems. This study investigated the presence and contents of As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in superficial sediment and in bivalves (Crassostrea gasar, C. rhizophorae and Mytella guyanensis) from estuaries in the south / extreme south of Bahia State, northeast Brazil. The samples were evaluated with inductively coupled plasma optical emission spectrometry (ICP-OES, Varian 710). Except for Cd, all other elements were found in the samples, being that Co was exclusive in the sediment. The estuaries equivalent to sampling stations #1 - Valença, #2 - Taperoá, #3 - Ilhéus and #4 - Belmonte showed levels of metals compatibles with those established by the Brazilian legislation, however, the #5 - Santa Cruz Cabrália, in addition to the presence of As, presented a high level of Pb and Cu in C. gasar, which was attributed to the impacts of nautical activities in that locality.

Detection of SARS-CoV-2 RNA in Bivalve Mollusks by Droplet Digital RT-PCR (dd RT-PCR)

Bivalve shellfish are readily contaminated by human pathogens present in waters impacted by municipal sewage, and the detection of SARS-CoV-2 in feces of infected patients and in wastewater has drawn attention to the possible presence of the virus in bivalves. The aim of this study was to collect data on SARS-CoV-2 prevalence in bivalve mollusks from harvesting areas of Campania region. A total of 179 samples were collected between September 2019 and April 2021 and were tested using droplet digital RT-PCR (dd RT-PCR) and real-time RT-PCR. Combining results obtained with different assays, SARS-CoV-2 presence was detected in 27/179 (15.1%) of samples. A median viral concentration of 1.1 × 102 and 1.4 × 102 g.c./g was obtained using either Orf1b nsp14 or RdRp/gene E, respectively. Positive results were unevenly distributed among harvesting areas and over time, positive samples being more frequent after January 2021. Partial sequencing of the spike region was achieved for five samples, one of which displaying mutations characteristic of the Alpha variant (lineage B.1.1.7). This study confirms that bivalve mollusks may bioaccumulate SARS-CoV-2 to detectable levels and that they may represent a valuable approach to track SARS-CoV-2 in water bodies and to monitor outbreak trends and viral diversity.

Peculiarities of Stratigraphic Distribution and Paleoecology of Jurassic Bivalve Mollusks of the Pre-Сarpathian Foredeep

Pre-Carpathian region is one of the oldest oil and gas producing regions of our country, which is attracting more and more attention of scientists. In the Outer zone of the Pre-Carpathian Foredeep, Jurassic deposits occur at considerable depths (up to 3,000 m), so we obtain almost all geological information about them exclusively during the study of core material selected during drilling. A comprehensive and detailed study of the Jurassic deposits of this zone during exploration drilling in the 1950s contributed to the discovery of the Kokhanivske and Sudovovyshnianske oil deposits and Rudkivske gas deposit, as well as a number of oil and gas manifestations. After that, the interest in the conditions of formation and stratification of Jurassic deposits increased. Researchers have begun to treat them as the promising objects for oil and gas exploration. Jurassic deposits in the Pre-Сarpathian Foredeep fill a single depression – the Stryi Jurassic deflection, covered by a thick layer of Cretaceous and Neogene rocks. The study of their geology and stratigraphy has acquired important applied and scientific significance, because stratigraphic research serves as a basis for clarifying the history of geological development of the region, performing tectonic constructions, reconstruction of paleogeographic and paleoecological conditions, comparison of productive horizons and specification of their stratigraphic position, search for new objects promising for hydrocarbons. Extremely rare finds of paleontological remains (which are not always well preserved) do not allow to unambiguously determining the age of the host rocks. It is still not always possible to clearly stratigraphically distinguish and correlate these rocks due to weak paleontological study and partial uncertainty in the interpretation of the geological structure of these strata. Despite the significant amount of research we have done, there are some debatable issues regarding the completeness of the section of these rocks and the presence of separate stratigraphic units in them. For many years, we have studied in detail and comprehensively bivalve mollusks found in the core of wells drilled in the Outer zone of the Pre-Carpathian Foredeep. As a result, the age of the host strata was specified and confirmed, as well as the thickness of individual stratigraphic units.

Linear growth and yield of bivalve mollusks Mya Arenaria linnaeus, 1758 in the conditions of the littoral of the barents and white seas

Mya arenaria are large bivalve mollusks burrowing into the ground. Mollusks are widespread in the northern hemisphere. The growth patterns of M. arenaria were studied in the arctic part of the species’ geographic range. As a result of the research, it was revealed that the mollusks from the Severnaya Inlet of the Kandalaksha Bay of the White Sea have the highest growth rate. The limiting shell length is L∞=174.7 mm, and the rate of growth retardation is k=0.0518 year–1. The mollusks from the Yarnishnaya Inlet of the Barents Sea have the lowest growth rates L∞=84.27 mm, and the rate of growth retardation is k=0.0721 year-1. A positive correlation was found between the nature of the soil and the limiting shell length of mollusks (r = 0.94).

ANALYSIS OF THE STATE OF THE NURA RIVER FORAGE BASE

This article presents the results of research on the state of the Nura River forage base. The species composition, total mass, and abundance of zooplankton and zoobenthos were determined in the reservoirs. The zooplankton of the studied reservoirs is also diverse and includes widespread species that can be divided into 3 groups: rotifers, branched-moustached, oar-footed crustaceans. In the studied reservoirs, 40 taxa were noted as part of zooplankton, of which 11 species are rotifers, 16 are branched crustaceans, and 13 are oar-footed crustaceans. A.priodonta, P.remata and F.longiseta are dominant in the frequency of occurrence in rotifers, D.сuclata and D.galeata in branchiformes, and representatives of the genus Mesocyclops in copepods. The total species diversity of the benthic complex of the Nura River contains more than 100 species. The abundance of small bivalve mollusks of the families Euglessidae and Pisidiidae, which form the basis of benthic biomass, is very high in the rheotic areas. The bottom population of limnic and areas close to them in terms of characteristics is more diverse in species terms. The dominant species here are the chironomids Chironomidae spp., which had a high number. The forage base of the river sections corresponds to the environmental conditions and allows a certain herd of commercial fish to exist.

Species diversity of unionid mussels (Mollusca: Bivalvia: Unionidae) as a bioindicator of the state water environment of river basins of Ukraine

Species diversity and frequency index of bivalve mollusks’ of unionid family are researched within river basins of Ukraine. The largest frequency index of mussels is identified in the Prypiat and Desna basins (84 and 79% respectively), then (as the indicator declines) – the Dnieper and Severskiy Donets basins (74 and 67%), the Southern Bug and Danube (47 and 46%), the Southern and Western Bug (47 and 28%), the Crimea (17%). No mollusks were found in the Azov basin at all. Most often (33%) there were found groups consisting of only three unpretentious species (Unio pictorum, U. tumidus, Anodonta anatina). In general, settlements from one to three species make up 70% of all researched collecting sites. Settlements formed by four species are identified only in 23% of habitats. Only 6% of settlements consisted of five aboriginal species and about 1% – of six. Locations where six species lived together were identified only in the Danube and Prypiat basins. There are no settlements of five species in the Western Bug and Desna basins at all, and there are not any even four species settlements in the Crimea. The obtained data can be used for organizing environmental activities and assessing water environment quality

Abiotic Factors Effect on the Distribution and Density of Species of the Families Unionidae, Pisididae, Euglesidae and Corbiculidae in High Mountains of the Kashkadarya Riverside Zone

As a result of the study, it has been identified that the water temperature in the Kashkadarya River is 18–24 °C, the water clarity is 0.51–0.62 m and the water flow rate is 0.72–0.84 m/sec. The species of bivalve mollusks Sinanodonta gibba, S. orbicularis, S. puerorum, Colletopterum cyreum sogdianum, Corbicula cor, C. fluminalis, C. purpurea, Corbiculina tibetensis, C. ferghanensis are widespread in the region. The abiotic factors discussed in the paper play an important role in the distribution of mollusks. There are 13 species of bivalve mollusks in the mountainous region, which is the head part of the river, 9 species in the middle part of the hill region of the river and 6 species in the lower desert region.