Long-term changes in the meiobenthos of the eastern part of the Black Sea

The results of meiobenthic surveys undertaken in 1991, 1999, and 2005 off the Caucasian coasts of the Black Sea are presented. During the period of 1991 to 1999, the number of free-living nematodes increased significantly at all the sampling stations. The mean nematode abundance values grew from 85 ind./10 cm² in 1991 to 1167 ind./10 cm² in 1999. Proportionally, the total metazoan meiofauna density increased from 171 to 1283 ind./10 cm². The abundance of other meiofaunal groups including harpacticoid copepods did not change significantly. As a result of these changes, the ratio of nematodes to copepods (the nematodes-copepods index) increased from 2.5: 1 in 1991 to 26: 1 in 1999 and to 70: 1 in 2005. The number of foraminifers increased twofold. In 1991, they were found only at five stations out of 25. In 1999, foraminifers were presented at all ten stations with a mean density of 212 ind./10 cm². Such changes in the meiobenthic communities could have resulted from cascade transformations of the ecosystem leading to among other changes to a decline in the macrobenthos biomass and the release of nonutilized organic matter in the bottom ecosystems. The differences in the procedures of the sampling and the samples’ processing in the different years may be responsible for the 20–30% variation in the assessment of the meiobenthos’ number.     

Optical characteristics of coastal waters and atmosphere near the south coast of the crimea at the end of summer 2008

We present the results of measurements of optical characteristics of waters (the beam attenuation coefficient, volume scattering function, sea water reflectance, and Secchi depth) and optical characteristics of the atmosphere (aerosol optical thickness, content of vapors, and the ?ngstr?m exponent) carried out in September 2008 on the oceanographic platform near Katsiveli. We carried out the comparative analysis of hydrooptical characteristics measured in various years. The optical type of sea waters in the period of observations is determined.     

Circulation in the southwestern part of the Kara Sea in September 2007

During cruise 54 of the R/V Akademik Mstislav Keldysh to the southwestern Kara Sea (September 6 to October 7, 2007), a large amount of hydrophysical data with unique spatial resolution was obtained on the basis of measurements using different instruments. The analysis of the data gave us the possibility to study the dynamics and hydrological structure of the southwestern Kara Sea basin. The main elements of the general circulation are the following: the Yamal Current, the Eastern Novaya Zemlya Current, and the St. Anna Trough Current. All these currents are topographically controlled; they flow over the bottom slopes along the isobaths. The Yamal Current begins at the Kara Gates Strait and turns to the east as part of the cyclonic circulation. Then, it turns to the north and propagates along the Yamal coast over the 100-m isobath. The Eastern Novaya Zemlya Current (its core is located over the eastern slope of the Novaya Zemlya Trough) flows to the northeast. Near the northern edge of Novaya Zemlya, it encounters the St. Anna Trough Current, separates from the coast, and flows practically to the east merging with the continuation of the Yamal Current. A strong frontal zone is formed in the region where the two currents merge above the threshold that separates the St. Anna Trough from the Novaya Zemlya Trough and divides the warm and saline Arctic waters from the cooler and fresher waters of the southwestern part of the Kara Sea. This threshold, whose depth does not exceed 100–150 m, is a barrier that prevents the spreading of the Barents Sea and Arctic waters to the southwestern part of the Kara Sea basin through the St. Anna Trough.     

The potential of wetlands in reducing storm surge

A critical component of flood protection in some coastal areas is expected to be the potential contribution of wetlands to the lowering of surges as they propagate inland from the coast. Consequently, an accurate method to quantify the effect of wetlands on coastal surge levels is required. The degree to which wetlands attenuate surge is the subject of debate and difficult to assess. The potential of wetlands to reduce storm surge has typically been expressed as a constant attenuation rate, but the relationship is much more complex. A numerical storm surge model was applied to assess the sensitivity of surge response to specified wetland loss. Results suggest that wetlands do have the potential to reduce surges but the magnitude of attenuation is dependent on the surrounding coastal landscape and the strength and duration of the storm forcing. Numerical models that simulate the relevant physical processes can provide valuable information on how to best integrate wetlands into coastal protection plans. However, while the model applied for this study has displayed skill in estimating surges over wetlands, the formulations are missing key processes and model advancements are necessary.     

Geochemical and microbiological characteristics of sediments near the Malenky mud volcano (Lake Baikal, Russia), with evidence of Archaea intermediate between the marine anaerobic methanotrophs ANME-2 and ANME-3

Detailed lithological, biogeochemical and molecular biological analyses of core sediments collected in 2002–2006 from the vicinity of the Malenky mud volcano, Lake Baikal, reveal considerable spatial variations in pore water chemical composition, with total concentrations of dissolved salts varying from 0.1 to 1.8‰. Values of methane δ¹³С in the sediments suggest a biogenic origin (δ¹³С_min. ?61.3‰, δ¹³С_max. ?72.9‰). Rates of sulphate reduction varied from 0.001 to 0.7 nmol cm^?3 day^?1, of autotrophic methanogenesis from 0.01 to 2.98 nmol CH₄ cm^?3 day^?1, and of anaerobic oxidation of methane from 0 to 12.3 nmol cm^?3 day^?1. These results indicate that methanogenic processes dominate in gas hydrate-bearing sediments of Lake Baikal. Based on clone libraries of 16S rRNA genes amplified with Bacteria- and Archaea-specific primers, investigation of microbial diversity in gas hydrate-bearing sediments revealed bacterial 16S rRNA clones classified as Deltaproteobacteria, Gammaproteobacteria, Chloroflexi and OP11. Archaeal clone sequences are related to the Crenarchaeota and Euryarchaeota. Baikal sequences of Archaea form a distinct cluster occupying an intermediate position between the marine groups ANME-2 and ANME-3 of anaerobic methanotrophs.     

Spectral contributions of the components of seawater to the beam attenuation coefficient in surface waters of the Mediterranean Sea

We compute model spectra of the beam attenuation coefficient in surface waters of the Mediterranean Sea. These spectra are used to determine the contribution of the components of seawater (suspended matter, yellow substance, pigments of phytoplankton, and pure water) to the beam attenuation coefficient in different types of seawater. For the surface waters, we establish the relationship between the light scattering coefficient and the attenuation coefficient at a wavelength of 547 nm and determine the background (limiting minimum) value of the coefficient of absorption by the yellow substance in waters of the Mediterranean Sea. It is compared with the values of the same parameter for some other basins (Black Sea, Lake Baikal, Baltic Sea, and oceanic waters).     

The geochemistry of deepwater particulate matter over the hydrothermal field at 9°d50′ N (the East Pacific Rise)

The results of geochemical studies of particulate matter in the water mass over the hydrothermal field at 9°50′ N on the East Pacific Rise are presented. The particulate matter was tested in background waters, in the buoyant plume, and in the near-bottom waters. The contents of Si, Al, P, C_org, Fe, Mn, Cu, Zn, Ni, Co, As, Cr, Cd, Pb, Ag, and Hg were determined. No definite correlations were found between the ele-ments in the background waters. Many of the chemical elements correlated with Fe and associated with its oxyhydroxides in the buoyant plume. In the near-bottom waters, microelements are associated with Fe, Zn, and Cu (probably, to their sulfides formed under fluid mixing with seawater). The matter precipitated in a sed-imentation trap was similar to the near-bottom particulate matter in the elemental composition.     

Spatial variability of the chlorophyll <Emphasis Type="Italic">a</Emphasis> and the specific structure of the phytoplankton in the northwestern part of the Sea of Japan during the winter period

To evaluate the structure and photosynthetic activity of the phytoplankton of the northwestern part of the Sea of Japan, the results of the surveys conducted from February 26 to March 9, 2003, during the 30th cruise of the R/V Akademik Lavrentyev were used. The species composition was considered taking into account the influences of the hydrological conditions. In particular, the studied water area was divided into four zones with various sizes of the mixed layer depth (MLD). An inverse relationship between the MLD and the content of chlorophyll a (Chl a) in various zones was established. The diatom algae were the basic dominants of the composite structure of the phytoplankton everywhere. It is revealed that, at a MLD increase, smaller forms of microalgae receive development. The intrapopulation relations are caused by the adaptation of various species of phytoplankton to the influence of external factors, among which the size of MLD is fundamental.     

Thermal anomalies associated with shallow gas hydrates in the K-2 mud volcano, Lake Baikal

Thermal measurements and hydrate mapping in the vicinity of the K-2 mud volcano in Lake Baikal have revealed a particular type of association of thermal anomalies (29–121?mW?m^–2) near hydrate-forming layers. Detailed coring within K-2 showed that hydrates are restricted to two distinct zones at sub-bottom depths exceeding 70–300?cm. Temperature data from stations with hydrate recovery and degassing features all display low thermal gradients. Otherwise, the thermal gradients within the mud volcano are generally increased. These findings imply a more complicated thermal regime than often assumed for mud volcanoes, with important roles for both fluids and hydrates. The coexistence of neighbouring low and high thermal anomalies is interpreted to result from discharging and recharging fluid activity, rather than hydrate thermodynamics. It is suggested that hydrates play a key role in controlling the fluid circulation pattern at an early stage. At a later stage, the inflow of undersaturated lake water would favour the dissolution of structure I hydrates and the formation of structure II hydrates, the latter having been observed on top of structure I hydrates in the K-2 mud volcano.     

Interference of the mechanisms of influence that weak extremely low-frequency electromagnetic fields have on the human body and animals

This review is devoted to the problem of interference between the mechanisms of biological action of natural and artificial electromagnetic fields (EMFs) for different levels of the organization of life. We discuss the problem of specific and nonspecific responses of the human body and animals to the action of EMFs on cellular and organismal levels.