Lagoon ecosystems: peculiarities of the species, spatial and trophic structure of macrobenthos (Kandalaksha bay, White sea)

Изучены видовое разнообразие, пространственная и трофическая структура макробентосных сообществ сублиторали и нижних горизонтов литорали в 5-ти лагунных экосистемах Кандалакшского залива Белого моря. Всего в исследованных экосистемах было обнаружено 52 вида бентосных беспозвоночных животных и 6 видов морских трав и водорослей. В сублиторали наибольшим видовым разнообразием, общей плотностью и биомассой макробентоса характеризуется наиболее открытая к морю лагуна, расположенная на выходе из кутовой области Кислой губы, а наименьшим - наиболее закрытая и заиленная лагуна Никольской губы, где преобладали солоноватоводные и морские эвригалинные виды. Промежуточное положение занимали лагуна Ермолинской губы, лагуна, расположенная рядом с Ершовским озером и лагуна на Зеленом мысу. В нижней литорали общие показатели структуры сообщества макробентоса (общая плотность, биомасса и в меньшей степени видовое разнообразие) в отличие от сублиторали увеличивались от менее зарегулированных и открытых экосистем к более закрытым системам. Исключением является лагуна Никольской губы, значительное заиление которой приводит к существенному уменьшению видового разнообразия и снижению общей плотности и биомассы сообщества макробентоса. The species diversity, spatial and trophic structure of macrobenthos communities in the sublittoral and lower littoral horizons in five lagoon ecosystems of the Kandalaksha Bay of the White Sea have been studied. In total, 52 species of benthic invertebrates and 6 species of sea grasses and algae were found in the studied ecosystems. In the sublittoral zone, the highest species diversity, total density and biomass of macrobenthos is characterized by the lagoon most open to the sea, located at the exit from the innermost area of Kislaya Bay. The lowest diversity is found in the most closed and silted lagoon of Nikolskaya Bay, where brackish water and marine euryhaline species predominated. The lagoon of the Ermolinskaya Bay, the lagoon located next to the Ershov Lake and the lagoon on Cape Verde hold an intermediate position. In the lower littoral zone, the general indicators of the structure of the macrobenthos community (total density, biomass, and, to a lesser extent, species diversity), in contrast to the sublittoral one, increased from less regulated and open ecosystems to more closed systems. An exception is the lagoon of Nikolskaya Bay, the significant siltation of which leads to a significant decrease in species diversity and a decrease in the total density and biomass of the macrobenthos community.

SEISMICITY of the RUSSIAN PART of EAST EUROPEAN PLATFORM and ADJACENT TERRITORIES in 2015

It is reported that 41 stationary seismic stations, 2 arrays, and 7 temporary seismic stations, located in the area of Novovoronezh and Kursk nuclear stations, monitored seismicity of the Russian territory of the East European Platform (EEP) in 2015. The registration capabilities of the seismic network at the EEP as a whole were estimated based on the average station noise level and the equation for the energy decay of seismic phases. Zones with the best capabilities have been allocated. A feature of seismicity in 2015 is the manifestation of earthquakes of moderate magnitudes (ML=2.7–3.9) in the peripheral regions (in the southwest, west, and northwest) and in zones associated with paleorift structures: in the southwest – with the Dnieper Donetsk and in the northeast – with the Kirov-Kazhim and Soligalich (Central Russian) aulacogenes. The results of the macroseismic survey are given for the earthquake in Poltava on February 2, 2015, with M=3.7; focal mechanisms of two earthquakes (03.02.2015 and 12.06.2015) are constructed. According to the data of the Latvian Center, an earthquake was recorded in the region of Lithuania bordering the Kaliningrad region. Weaker natural seismicity with ML≤2.5 was recorded in Karelia and the regions bordering with Finland, near the Kandalaksha Bay, near the Khibiny, and Lovozersky massifs on the Kola Peninsula, and on the territory of the Voronezh crystalline massif.

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).

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.

THE RESULTS OF THE FUNCTIONAL STATE OF THE MEIOBENTHIC FAUNA RESEARCH IN HIGH-SULFIDE BIOTOPES OF COASTAL LAKES-LAGOONS OF THE KANDALAKSHA BAY (WHITE SEA)

The article presents the results of the studies of physiological state of meiofauna taken from the bottom sediments of two meromictic lakes which had different stages of geological isolation from the White Sea. It was concluded that active living benthic organisms of these high-sulfide biotopes could penetrate no deeper than the upper boundary of the hemocline. Organisms living at the depth of the upper redox-chemocline boundary (nematodes, chironomids and oligochaetes) in the lakes-lagoons of the Kandalaksha Bay (White sea) have high locomotor activity characteristics. Nematodes and rotifers were found on the lower edge of the chemocline, but they were motionless and did not show signs of active life. Therefore, they, with a high degree of probability, could be attributed to the dead component of the community. No meiobenthos was found in the anoxic zone at the bottom of the sulfide lake at a depth of 7.5 m. Finding abundant motionless benthic ciliates, belonging to the family Tintinnidae at the upper edge of the chemocline of Lake Trekhtsvetnoe does not allow researchers to make unambiguous conclusion about their physiological state. The main factor limiting the penetration of zoobenthic oxybionts into the redox zone of the studied meromictic White Sea lagoons is obviously the combined effect of deficiency of dissolved oxygen with simultaneous contamination of the aquatic environment and benthal with hydrogen sulfide. On the contrary, the positive properties of this habitat can be attributed to the high content of potential food resources (biomass of photo-and chemolithotrophic microorganisms), and, probably, the previously observed layer of the chemocline with an increased temperature. It is noteworthy that the latter phenomenon, which is observed in most of the stratified lakes-lagoons of the polar region, is most developed in the winter period.

EAST EUROPEAN PLATFORM. RUSSIAN PART

It is reported that 22 stationary seismic stations, 2 arrays and 7 local seismic stations, located in the area of Novovoronezh and Kursk nuclear stations, monitor seismicity of the Russian territory of the East European platform (EEP). A new station Belogornoe with high registration class has been opened, which also belongs to the International Monitoring System for the Comprehensive Nuclear-Test-Ban Treaty (IMS CTBTO). The results of the microseismic noise study at the Pulkovo network stations and assessment of maximum distance of earthquake registration in the Voronezh crystalline massif are presented. In 2014, relatively strong earthquakes with М3.0 were not recorded on the Russian territory of the EEP. Weaker natural seismicity with M≤2 was recorded in Karelia and the border areas with Finland, near Kandalaksha Bay, near the Khibiny Massif on the Kola Peninsula and on the territory of the Voronezh Crystalline Massif. Observations of local networks near nuclear stations are aimed at updating the information on seismicity previously considered as an aseismic territory of the EEP. Man-made events were recorded in permanent quarries, the most powerful of them (M=3.1–3.3) were produced in the quarries on the territory of the Kursk magnetic anomaly.