The characteristic pattern of multiple colored layers in coastal stratified lakes in the process of separation from the White Sea

An unusual feature of the saline stratified lakes that were formed due to ongoing postglacial uplift on the White Sea coast is the presence of several differently colored thin layers in the zone with sharp gradients. Colored layers in five lakes at various stages of separation from the sea were investigated using optical microscopy, spectrophotometry, spectrofluorimetry, and photobiology. The upper greenish colored layer located in the aerobic strata of all lakes near the compensation depth of 1% light penetration contains green algae. In the chemocline, another layer, brightly green, red or pink, is dominated by mixotrophic flagellates. Despite the very low light intensities and the presence of H 2 S, active photosynthesis by these algae appears to be occurring, as indicated by high values of the maximum quantum yield of primary photochemistry, electron transport activity, photosynthetic activity of photosystem II, the fraction of active centers, and low values of heat dissipation. In the reduced zone of the chemocline, a dense green or brown suspension of anoxygenic phototrophs(green sulfur bacteria) is located.     

One-dimensional theory of the wave boundary layer

Results obtained in a 2-D modeling of the statistical structure of the wave boundary layer (WBL) are used for elaboration of the general approach to 1-D modeling taking into account the spectral properties of wave drag for an arbitrary wave field. In the case of the wave field described by the JONSWAP spectrum, the momentum and energy spectral density exchange, vertical profiles of the wave-induced momentum flux and dependence of total roughness parameter and drag coefficient on peak frequency are given. The reasons that the total roughness parameter increases with decreasing fetch are explained. The role of wind waves as an active element of the ocean-atmosphere dynamic system is also discussed.     

Spatial distribution of the phytoplankton in the White Sea during atypical domination of dinoflagellates (July 2009)

The species composition and biomass of phytoplankton, concentrations of chlorophyll a (Chl a) and nutrients, and accompanying hydrophysical conditions have been studied in the White Sea on July 6–11, 2009. The temperature of the surface water layer was lower than the multiyear average in July. Dinoflagellates dominated in the entire studied area; this was not the typical event for July. We suggest that domination of dinoflagellates was caused by low water temperature, when the nutrient regeneration rate was insufficient to support diatom growth. The abundance of microalgae and the structure of the phytoplankton community depended on the water structure. Variations in the phytoplankton community structure were caused not by substitution of specific species but rather by variability of the abundance of a single species, Heterocapsa triquetra. The highest phytoplankton biomass has been recorded in weakly stratified waters, where tidal mixing supplied the income of inorganic nutrients. The income of nutrients to the photic layer was limited in the stratified waters of Dvina Bay during the summer low-water period, so the phytoplankton abundance was low. We suggest that the lens of surface desalinated water presumably originated from the outlet of the Dvina River was registered in the central part of the White Sea.     

Long-term sea level changes along the lagoon shores of the Baltic and Black Seas

We examine the data on the mean annual sea level dynamics for 1875–2005 along the eastern coast of the Baltic Sea (Baltiisk and Kronstadt) and along the northern coast of the Black Sea (Odessa, Sevastopol’ and Kerch) which have coastal lagoons. The study revealed a generally positive trend for the period (from 0.7 to 1.8 mm/year at different points), a similarity of changes in the level for separate 30-year-long intervals, and a significant increase in sea level growth rate at the turn of the 20^th century (up to 8.6–13.3 mm/year at different points). High values of the correlation coefficient (0.71–0.87) were recorded between the variations in the mean yearly level (with the temporal trend excluded) within the lagoon coasts of the Baltic and Black Seas as well as the absence of a correlation between data series for the two seas. Analysis (after excluding a linear trend from the variation of the values) showed an actual absence of a correlation between mean yearly level variations and North Atlantic atmospheric circulation indices, while the previously recorded correlation was due to a correlation between trend components. It is suggested that the sea level oscillations include only a small component which responds oppositely for the two seas to the resultant influence of the eastward and westward components of the atmospheric circulation. On the basis of the similar absolute values of the linear trend and of the range of long-term fluctuations in mean yearly sea level values in the area of the lagoon coasts of the Baltic and Black Seas, the conclusion is drawn about the similar conditions under which over the course of the last 100 years the coastal lagoons have been evolving in these two, relatively remote, zones of the drainage basin of the Atlantic Ocean.     

Picophytoplankton Distribution at the Ob River Section and in the Western Part of the Kara Sea

Oceanology - The spatial distribution of picophytoplankton abundance, biomass, chlorophyll a and the contribution of picoalgae to the total chlorophyll a was studied in the outer Ob River estuary...     

On the Role of Small Photosynthetic Flagellates in the Fall Phytoplankton Community of Onega Bay,White Sea

Oceanology - The abundance, biomass, size structure of small photosynthetic flagellates (SPF; 3–10 µm), chlorophyll a (Chl a), and the contribution of SPF to the total phytoplankton...     

Picophytoplankton of the Laptev Sea in Autumn

Doklady Earth Sciences - The abundance and biomass of picophytoplankton, the total concentration of chlorophyll a, and the contribution of the picofraction to chlorophyll a were studied in the...     

Inter-annual variability of the hydrological-chemical characteristics in the north-western Black Sea shelf area over recent decades (1960–1990)

A number of significant hydrologicla and chemical parameters of the Black Sea shelf area have been identified and investigated: the inter-annual variability of the mean annual and seasonal (winter and summer) values of the air and seawater temperatures and salinity in the vicinity of Odessa; silicon and phosphate concentrations averaged over the north-western Black Sea shelf area (NWBS); discharges of the Danube and Dnieper rivers; mean surface and near-bottom oxygen concentrations in summer acquired through the analysis of the summarized data collected at three oceanographic stations occupied between Bolshoi Fontan and the Tendra isthmus from the early 1950s up to date. From these data, the variability of the areas subject to oxygen deficit in the near-bottom layer of the NWBS shelf during the summers of 1973–1994 has been assessed. Predominant oscillation periods and trends in the inter-annual variability of the studied parameters have been revealed and their relationship and climatic dependence has been demonstrated. Translated by Vladimir A. Puchkin.