Observations of a cycle of intense coastal upwelling and downwelling at the research site of the Shirshov Institute of Oceanology in the Black Sea

The paper presents the results of joint analysis of the response of vertical temperature and current velocity profile distributions in the coastal zone of the Gelendzhik region of the Black Sea to strong wind forcing in the third ten-day period of September 2013. This forcing was caused by the propagation of an atmospheric cyclone, which first initiated coastal upwelling that was later replaced by downwelling. We formulate a criterion for the development of full coastal upwelling and demonstrate its efficiency. We assume that frequent events of incomplete coastal upwelling and downwelling are associated with changes in the water dynamics (variations in the intensity and direction of the alongshore current) generally not related to local wind forcing.     

Modeling photosynthesis and the growth of marine phytoplankton

The paper analyzes the most popular models of photosynthesis and growth of marine phytoplankton in the literature and demonstrates their limitations. A new approach to modeling is proposed and used to obtain new models of marine phytoplankton photosynthesis and growth. An important feature of the proposed models is their ability to describe coupled multisubstrate cyclical interactions typical of biochemical and physiological processes. As a first approximation, the mathematical models are represented by equations of nonrectangular hyperbolas. The models describe the stoichiometry of extraction of elements from the medium, whatever the degree of their limitation, an important feature in describing biogeochemical cycles of elements. This stoichiometry is governed by measurable internal parameters of an organism (substrate parameters) and can be a key cause of stoichiometric formation of elements in the ambient medium, described, for example, by the Redfield ratio. The substrate constants are fundamental characteristics of the models, which form “automatically” in the construction of model equations in arbitrary units.     

Viruses,bacteria, and heterotrophic nanoflagellates in Laptev Sea plankton

The paper considers the concentrations and functional characteristics of viruses, bacteria, and heterotrophic nanoflagellates determined for the first time in the Laptev Sea in August-September, 2014. The abundance of bacteria, viruses, and heterotrophic nanoflagellates varied from 110.1 × 10³ to 828.4 × 10³ cells/mL, from 384.2 × 10³ to 2932.8 × 10³ particles/mL, and from 108 to 651 cells/mL, respectively. The daily bacterioplankton production varied from 4.2 × 10³ to 381.7 × 10³ cells/mL, with an average of 117.6 × 10³ cells/mL. Electron transmission microscopy has for the first time shown that the frequency of visibly infected bacterial cells varied from 0.2 to 2.0% (0.8% on average) of N_B. The average virus-induced mortality of bacteria was 6.3% of bacterioplankton production, with variations ranging from 1.4 to 16.9%. Grazing on bacteria by heterotrophic nanoflagellates contributed more to bacteria mortality than virus-induced bacterial lysis. By grazing on bacteria, heterotrophic nanoflagellates consumed large quantities of viruses located on the surface and inside bacterial cells.     

Protection of marine birds and turtles at St Brandon’s Rock,Indian Ocean,requires conservation of the entire atoll

A survey of seabirds and turtles at St Brandon’s Rock, 400 km north of Mauritius, was undertaken in 2010. We estimated that 1 084 191 seabirds comprising seven breeding species and excluding non-breeders were present at the archipelago and we counted 279 turtle tracks and nesting pits of green turtles Chelonia mydas. Hawksbill turtles Eretmochelys imbricata were also present. Analyses of 30 different islets that make up the atoll showed that the seabird species mostly partitioned their use of islets based on islet size, with four species preferring larger islets and two species preferring smaller islets. Alien species introduced historically are still present and other threats, such as shipwrecks, remain. We propose conservation and other measures that should adequately protect the birds, turtles and coral reef by treating the atoll as a system.     

Influence of anthropogenic pressure and seasonal upwelling on coral reefs in Nha Trang Bay (Central Vietnam)

The growing coastal development, dredging and dumping activities, overfishing and expansion of marine cage culture in Nha Trang Bay (NTB) of Central Vietnam since the beginning of the 2000s have resulted in a dramatic decrease of live coral cover. Surveys conducted in April–May 2013 and the same period in 2014 revealed that with an increase in distance from the outer part of the bay towards the mainland, the rivers’ influxes and dredged areas, coral cover decreased from 75% to 0.6% and species richness from 63 to 5, while the abundance of macroalgae increased from 0% to 56%. These changes correlate with differences in the concentration of suspended sediments on the same gradient. The abundance of the crown‐of‐thorns starfish Acanthaster planci and of the echinoid Diadema setosum significantly increased between the first estimation in 1998 and the survey in 2014, from 0 to 1.7 individuals (ind.) per 100 m^?2 and from 50.8 to 94.5 ind. per 100 m^?2, respectively, contributing to coral loss and intensive bioerosion of the reef framework in the bay. The large sizes of adult colonies of tabulate Acropora on the remote stations with negligible sedimentation and eutrophication loads were inconsistent with the assumptions that temperature‐induced coral bleaching or cyclones could be the major impacts in Nha Trang Bay. Analysis of the 16‐year thermal history of the bay did not reveal any instances in which the coral thermal bleaching threshold had been exceeded up to the present study. Seasonal upwelling, which occurs annually in the vicinity of Central Vietnam, may contribute to mitigation of thermal anomalies within NTB and to the maintenance of healthy coral communities on the remote reefs with relatively low anthropogenic impact.     

Experiment of Wind Wave Parameter Research on the Black Sea Shelf

The article presents information on the current experiment of research on wind wave parameters in the Black Sea coastal zone. Two wave-meter devices are the part of the measuring equipment of the Black Sea testing site Gelendzhik of the Shirshov Institute of Oceanology (IO RAS). The integral characteristics of wind waves accumulated and obtained in real time may be in demand by experts in operational and satellite oceanography.

     

Components of Oil Pollution in Water and Bottom Sediments of the Northeastern Part of the Russian Black Sea Region

Oceanology - The results of studies of oil pollution (by the sum of hydrocarbons and resinous substances) of water and bottom sediments in the northeast Black Sea in spring and autumn are...     

Assessment of Pollution of the Kerch Strait and Adjacent Black Sea Area Based on Field Measurements of 2019–2020

Oceanology - The paper presents the results of an analysis of the main pollutants (heavy metals, pesticides, detergents, hydrocarbons) in water, suspended particulate matter, and bottom sediments,...     

Concentration and Isotopic and Elemental Composition of Organic Matter in Subsea Thawed and Permafrost Deposits of Buor-Khaya Bay

Oceanology - A comparative analysis of the content and composition of organic matter (OM) in samples of bottom sediments and subaqueous permafrost rocks by the concentration of organic carbon (OC),...     

Geophysical Studies of the Seymour Sewell Seamount on the Flank of the Central Indian Ridge

Oceanology - The volcanic structure of the Seymour Sewell seamount appears to have formed over a relatively long time in at least two stages. Its main massif was formed as a result of volcanic...