Okeanologiâ

Based on National Oceanic and Atmospheric Administration (NOAA, USA) and Japan Meteorological Agency (JMA) climate data sets for 1982–2021, regional features and trends of interannual changes of water temperature in the upper 2200-m layer of the Pacific Ocean tropical part were investigated, as well as their possible relationships with variations of climatic characteristics. Obtained results provide description of three-dimensional structure of the temperature anomalies and heat content variability in the water column and rate of warming in the various areas for specific phases of the resent global warming.

The results of studies of internal waves in the shelf zone of the Black Sea in the water area near the mouth of the Kodor River, conducted in June 2021, are presented. Spatial surveys were carried out with ADCP “Rio Grande 600 kHz”, which revealed the main characteristics of currents and the presence of internal waves generated by the river inflow in to the sea. Internal waves were recorded in two sections oriented along the normal to the coastline and extending to depths of 100 m. The observed waves had the features of nonlinear waves, were located on the near-surface thermocline, and had a height of up to 3–6 m. Also short-period internal waves in the form of a train of waves with an apparent period of about 3.5 min were recorded by a chain of thermistors in the coastal zone of the sea. The dispersion curves and eigenfunctions of internal waves were calculated by numerically solving the equation of internal waves, taking into account the velocity shift in the sea. Theoretical data are compared with experimental ones. A significant influence of the river inflow on the parameters of the generated internal waves moving with the flow was revealed. The experimentally observed decrease in wave periods and an increase in their group and phase velocities were confirmed.

The latitudinal distribution of the ctenophores Mnemiopsis leidyi A. Agassiz, 1865 and Beroe ovata Bruguière, 1789 in the Russian sector of the Caspian Sea has different borders of their ranges. Studies on the occurrence of ctenophores in the water column have demonstrated that each species has a characteristic temperature limit of its vertical distribution. Investigations into interactions between ctenophores showed a considerable abundance suppression of M. leidyi (particularly of smaller individuals) by B. ovata.

The work is devoted to the study of the bottlenose dolphin community in the coastal waters of the Karadag Reserve (southeastern Crimea). Observations and acoustic recordings were carried out in 2015–2017 and in 2020–2022 As the main method for identifying bottlenose dolphins, we used the method developed by us for acoustic recording of bottlenose dolphins by individual sound signals “signature whistles”. This method of identification makes it possible to fairly accurately count the population, observe the movements of bottlenose dolphins, and also reveal the association of individuals with each other.

The ferromanganese crusts found in the Bering Sea on the Volcanology Massif, the Alpha Fault Zone, and the Shirshov Submarine Ridge that cover the surface of rocky volcanic structures are most likely the product of post-volcanic activity. The present results indicate that the studied ferromanganese formations were formed under the influence of two factors: on the one hand–as a result of slow precipitation of metals from ordinary seawater, on the other hand–under the possible influence of metal-enriched hydrothermal solutions. In microstructural and mineralogical terms, the composition of Fe–Mn crusts of the Bering Sea turned out to be rather monotonous. The ore part is represented mainly by ferruginous vernadite and rarely hematite in combination with amorphous silica, to a lesser extent montmorillonite, calcite, and aragonite. The manganese mineral todorokite, considered a reliable sign of hydrothermal origin of ore crusts, was not detected in our samples. In the studied samples the reduced cerium anomaly (0.87) was established only in one sample, and in other samples its value varies within 1.08–1.89, which is typical for the upper horizons of the ocean water column. At the same time, the europium anomaly is close to neutral, so in 7 samples its value is 0.96–1.03 (average 1.0) and only in three samples it is slightly increased (1.05–1.07), which can be considered a very weak sign of hydrothermal activity. In addition, the presence of gold microinclusions in the ferromanganese phase can indirectly indicate the possible influence of hydrothermal factor on the crust composition.

Changes in the coastal zone under the influence of currents of different nature and wind waves are being investigated. A sandy beach located in the water area of the “Park of the 300th Anniversary of St. Petersburg”, the Neva Bay of the Gulf of Finland of the Baltic Sea, is considered as an object. The beach is actively affected by wind waves and eventually washes away with the intensity of the retreat of the shore of about 4 m per year. For numerical modeling, a set of models is used: SWAN–wind-wave model and COASTOX-UN–a two-dimensional model of currents, sediment transport and bottom reformation. It was developed a model of the Neva Bay and the mouth of the Neva River from the Flood Prevention Facility Complex in the west to the river Neva near the Liteiny Bridge in the east. Based on the reanalysis of wind data, 36 strong storms were selected for a five-year period from 2014 to 2018, for the sequence of which numerical modeling of waves, currents and lithodynamic processes was carried out. It was obtained balances of alluvial and washouts after a ten-years simulated period for beach sectors. To verify the results, satellite images of the modeling area are used, it was found that the model adequately describes the main observed trends in the development of the beach.

The bioelectrogenic activity of sediments of natural microbial association of the Peter’s Bay of Japanese sea research was performed in a year-round experiment with parallel temperature, illumination and water electrical conductivity monitoring by means of benthic microbial fuel cell (MFC) and automatic online-monitoring. Several variants of underwater devices, including benthic microbial fuel cells, monitoring water environment sensor,information collection and transmission systems, have been developed. This device make electrical voltage up to 216 mV, specific power up to 239 mW/m². Electrogenic activity of natural microflora depends on water temperature and reach maximum on summer with temperature about 20–25°C. The introduction of toxicants in form as hydrocarbons and cadmium into the sluge led to the suppression of microbial electrogenesis. However the introduction of inductor substances of microbial sulfidogenesis led to the stimulation of microbial electrogenesis. The possibility of functioning of the benthic MFC in the field of the Peter’s Great Bay in various climatic periods is shown. It is shown that such experimental devices serve as a basis for autonomous stations monitoring the state of the aquatic environment for a long time and in a wide range of conditions change. Thus, automatic registration of temperature, illumination and salinity of water with a frequency of 48 times a day was carried out for 13 months (11/28/2019–12/31/2020). The electrogenic activity of this microbiota upon MFC scaling can potentially become a new renewable energy source for low-power marine electronics, including those used in mariculture.

This paper provides information on the integrated geophysical, sedimentological, and hydrophysical investigations, passing meteorological and biological observations in the Eastern Tropical Atlantic during the cruise 63d of the R/V “Akademik Ioffe” in October–December 2022. The preliminary scientific results are discussed.

In the cruise No. 80 of the R/V Professor Gagarinskiy, from June 15 to July 18, 2022, complex hydrographic and hydrochemical studies were carried out in the Avachinskiy Bay of Kamchatka Peninsula, on the northeastern shelf of Sakhalin Island and in Peter the Great Bay to assess current environmental risks in the coastal zone of key areas of the Far Eastern seas of Russia and, in particular, to study possible abiotic factors that caused the mass mortality of marine organisms in Kamchatka in the fall of 2020. Comprehensive observations including CTD, hydrochemical water sampling, moorings deployment as well as sampling of plankton and bottom sediments were performed. An increased content of nutrients was found, both in subsurface and intermediate Pacific waters, in comparison with the data of the 1990–2000s. Intensive snowmelt on the adjacent mountain slopes during the survey period showed a significant effect of continental runoff on the hydrochemical characteristics of Avachinskiy Bay waters, causing a decrease in salinity and a significant increase in the concentration of nutrients and chlorophyll-a in the coastal zone. The dynamics of mesoscale eddies ensures the transport of coastal waters to the ocean over a distance of more than 100 miles. The obtained results suggest that the catastrophic phenomenon off Kamchatka, associated with anomalous harmful algae bloom, is due to the conjugation of biogeochemical and hydrographic factors – river runoff and the intrusion of deep waters on the shelf caused by coastal wind and dynamic upwelling during the period of maximum warming and eutrophication of the waters of the subarctic Pacific, as well as orographic and topographic features of Avachinskiy Bay.