Long-term dynamics of the proportion of left-sided individuals in the populations of the European flounder Platichthys flesus (Linnaeus, 1758) in the White Sea

Interannual variation in proportion of left-sided individuals has been studied in the populations of the European flounder from Onega (2002–2019), Mezen (2010–2016), and Dvina (2005–2019) bays of the White Sea. It was found that the flounder populations show no statistically significant and consistent changes in this character. The frequency of left-sided individuals in the local populations and the character of interpopulation differences in different years of the observation period remain relatively constant. The comparison of the results of this study with those of earlier studies reveals a similarity in proportions of left-sided fish over the past 40–60 years in flounder populations of the Kandalaksha Bay and Onega Bay. These results highlight the importance of the proportion of left-sided morphs for the analysis of population differentiation of the European flounder in the White Sea.

New petro-paleomagnetic data of Kandalaksha and Onega Bay Islands in the White Sea

<p>We have studied the AMS of metamorphic rocks (gneiss, granitoids, dykes) and soft sediments (mainly marine sediments or reworked diamicton) from the Kandalaksha and Onega Bay’s Islands of the White sea. The objects of research are located within the White sea mobile belt, represented by large tectonic nappes.</p><p>The magnetic susceptibility in soft sediment samples ranges from 78.6 E-6 to 1525E-6 (Km), and the degree (P) from 1.8% to 4.1%. Ellipsoids have a predominantly flattened type, such a distribution of AMS is typical for sedimentary rocks. At the same time, in a number of samples (from the Islands of Joker, Ipanchinikha and Olenevsky), the maximum axis is directed in a North-Westerly direction, which may indicate the flow direction. This is especially evident in flattened-triaxial ellipsoids (T=0.2-0.3). Values that have a T greater than 0.5 have a predominantly northerly direction and the orientation of minerals of the magnetic fraction and the direction of paleoflow is less pronounced.</p><p>The study of the anisotropy of the magnetic susceptibility of the Archean complexes composing the Islands of the Kandalaksha Bay of the White sea showed a high magnetic susceptibility-5E-6-1E-3 (Km), which confirms the change in the petrographic composition of gneiss. The degree of anisotropy (P) is 9% on average. It was found that the distribution of the main axes of the magnetic susceptibility ellipsoid coincides with shale and banding in the root outlets, while the maximum axis of the ellipsoid coincides with the West-North-West stretch of the regional fault. In the Onega Bay we sampled paleoproerozoic dykes, and there are AMS is coincided as contacts of studied dykes.</p><p>We done alternating field and thermal demagnetization of pilot collection which contains samples from all studied complexes. And it gives us not good results because of bad paleomagnetic record. Most of samples contain only low coercive or low temperature components and it mainly has modern direction.</p>

Hydrological and hydrochemical research of the mouths of the small rivers flowing to the White sea in the winter low water season of 2019

In the winter low water season in March and the first week of April 2019, complex hydrological and hydrochemical studies were carried out at the mouths of two small rivers of the White Sea catchment basin (the Mudyuga river, which flows into the Dvina Bay, and the Tamitsa river, which flows into the Onega Bay). The results indicate significant differences in the short-period variability of hydrological and hydrochemical parameters in the winter in the studied river mouths compared with the characteristics observed in the tidal estuaries of large and medium rivers, as well as in the mouths of small rivers of the southern seas.

Assessment of accumulation of petroleum hydrocarbons by the hydrobionts of the south-eastern part of the Onega bay of the White sea

In order to assess the current state of the ecosystem of the southeast of the Onega Bay of the White Sea affected by fuel oil spill in 2003, the accumulation of petroleum hydrocarbons was analyzed by the dominant species of aquatic organisms collected on the littoral of the most polluted coast in the areas of Purnem and Lyamts villages. In 2012, samples of aquatic organisms were taken in an area where all the species discussed in this work are represented on a small area: bivalved mollusks, attached molluscs, gastropods, polychaetes. In 2013 and 2018, samples of hydrobionts were additionally selected, in the three-kilometer strip of the coast on either sides of the givin point. In 2012 and 2013, high concentrations of HC in the tissues of bivalves were recorded. In 2018, the concentrations of hydrocarbons in the tissues of the studied hydrobionts were comparable to background values. A non-parametric test of Mann-Whitney showed a significant decrease in НС in mussel tissue from 2013 to 2018, at a significance level of 0.05. Taking into account the low levels of HC in the aqueous medium (less than 1 MPC of fishfarm) and in bottom sediments (from 0.34 to 9.03 mg/kg, the median of 1.41 mg/kg) in 2018, and is comparable with the background contents of hydrocarbons in tissues of aquatic organisms. We can conclude that after 15 years of the fuel oil spill, the condition of the Cape Deep ecosystem in terms of the content of hydrocarbons returns to the baseline state, continuing emissions of oil-sand lumps do not adversely affect the ecosystem. Based on the work done, it can also be concluded that ecotoxocological methods are priority in assessing the prolonged (or delayed) accidental impact of heavy petroleum products on aquatic ecosystems. The conclusion about the presence or absence of a negative impact on the aquatic ecosystem of hydrocarbons, based solely on the analysis of abiotic components, may not be sufficiently informative because it does not take into account the accumulative and deferred effects, especially manifested in the cold Arctic waters.

Mercury in the water of small rivers of the Onega Bay basin of the White Sea

The results of the expeditionary studies of the mercury behavior in the water of small rivers of the Onega Bay basin of the White Sea are presented. Priority forms of mercury migration have been identified and the forms of its location along the trunk of the Kyanda River have been calculated. The relationship between the content of various forms of mercury on the one hand and salinity, pH, Eh waters on the other has been analyzed. The influence of hydrological phases on the transformation of inorganic forms of mercury has been revealed. Differences in the levels of content of dissolved mercury and its connection with the salinity in the extuar areas of the marginal filters of the Subarctic rivers in natural conditions and the environment of anthropogenic impact were established.