Strong Paleoearthquakes along the Aksuu Border Fault according to the Results of Dating the Offset Terrace Complex of the Chon-Aksuu River,Northern Tien Shan

The study and radiocarbon dating of the low alluvial terraces of the Chon-Aksuu River, in the Northern Issyk-Kul region, which were broken by the Kebin (Kemin) earthquake of 1911 (Ms = 8.2, Io = 10 to 11), are carried out. The obtained radiocarbon dated ages refer to the second half of the Holocene. Since that time, at least eight strong earthquakes took place along this (Chon-Aksuu) segment of the Aksuu border fault. Three seismic events, including the earthquake of 1911 occurred in the second millennium A.D. This outburst of seismic energy was preceded by two millennia of seismic quiescence, which set in after another pulse of seismic activation. The latter lasted for 1.5 millennia and included five strong earthquakes. The recurrence period of seismic events during the activations is 300–600 years. Hence, the seismic regime along the Chon–Aksuu segment of the Aksuu border fault in the second half of the Holocene was a succession of two seismic activations, each with a duration of 1.0–1.5 ka, which were separated by a 2-ka interval of seismic quiescence. Therefore, the absolute datings of the river terraces of different ages which have been broken by a seismogenic rupture can serve as a reliable source of information about the age of the strong earthquakes that occurred along the seismogenic fault.     

Plant Morphofunctional Response to Environmental Changes in Active Fault Zones of the Kurai Ridge (Gorny Altai)

Izvestiya, Atmospheric and Oceanic Physics - Integrated geological, geophysical, geochemical, and botanical studies in the Kuraika River Valley (Kurai Ridge, Gorny Altai) have revealed sharp...     

The rates of organic matter destruction in the central part of the Arctic Basin

The intensity of the processes of organic matter (OM) destruction in the deep-water part of the Arctic Basin is considered in terms of the activities of hydrolytic enzymes (alkaline phosphatase and proteases) and of redox enzymes of the electron transport system (ETS). High concentrations of mineral phosphorus are shown to cause low phosphatase activity (0.000–0.005 μM P/l h). The average time of the phosphate recycling amounted to about 240 h. The ranges of the total and specific activity of protease are 0.000–0.192 mg of azocasein/(l h) and 0.00–3.57 mg of azocasein/h mg of protein, respectively. It is found that the microplankton production of exo- and endopeptidase in the Arctic Basin is controlled by the concentration of nitrates in the water. The values of the total and the specific activities of the ETS enzymes vary within 0.27–8.96 μl O₂/(l h) and 8.4–583 μl O₂/mg of protein h, respectively. It is shown that the maximum values of the total activities of the hydrolytic and redox enzymes are characteristic for the photic layer. The vertical fluxes of organic carbon from the photic layer, being calculated by the activity of the ETS enzymes, amounted to 220–600 g of C_org/year m². The presence of ice intensifies the redox processes by factors of 2–15.     

Elemental and biochemical composition of organic matter in the waters of the Russian sector of the Arctic Basin under the present conditions

The considered area of the Russian sector of the Arctic Basin was characterized in August–September of 2008 by the wide horizontal and vertical variability of the concentrations of dissolved and particulate organic matter (OM), as well as of its elemental and biochemical composition. The concentration ranges amounted to 51.6–434 and 2.2–18.6 μM, respectively, for the dissolved and particulate C_org; up to 1.9–30.2 μM for N_org; and up to 0.08–1.53 μM for P_org. The maximum values were characteristic for the Russian Arctic shelf. The analysis of the authors’ and published data showed that a pronounced accumulation of OM, mainly in the dissolved form, took place in the Arctic Basin within the past 12 years. The concentrations of dissolved OM were higher in the western sector of the Russian Arctic than those in the eastern sector. The main biochemical components in all the waters constituting the Arctic Ocean are carbohydrates and lipids for dissolved OM and proteins and carbohydrates for particulate matter.     

Radiocarbon chronology of Holocene glacial and climatic events in southeastern Altai (Central Asia)

The geomorphological studies and radiocarbon dating of moraine complexes and the tree line within the North Chuya Ridge, along with active slope processes, soil formation, and peat formation in southeastern Gorny Altai, constrain the age of the main glacial and climatic events in this area at 7 ka to the first half of the 19th century. It is for the first time in the history of Altai studies that 57 absolute dates were obtained for glaciation in a vast but climatically and neotectonically homogeneous area. The new data refute the conventional idea that the Holocene glaciation in this mountain land comprised eight stages of the gradual retreat of the Late Würm (Sartan) glaciation. Also, they evidence that glaciation in the upper parts of the troughs retreated almost completely no later than 7 ka and valley glaciers in southeastern Altai were activated many times in the second half of the Holocene. Data are given on the morphology and age of three moraine generations reflected in the topography. A combination of temperature minima and humidity maxima led to a catastrophically rapid and the largest (up to 5–6 km) ice advance at the Akkem Stage (4.9–4.2 ka). In addition to the radiocarbon data, the time limits of the Historical stage (2.3–1.7 ka) were defined more precisely using dendrochronological and archaeological data from Scythian burials of Pazyryk culture in SE Altai. The moraines closest to the present-day glaciers formed at the Aktru Stage (late 13th–middle 19th century). During warm interglacials, the glaciers waned considerably or retreated completely and the zone of recent glaciation was reforested. As a result of progressive aridization in the Holocene, the glaciers in southeastern Altai waned at each successive stage, and their mass balance was not positive during the greatest temperature minimum of the last millennium (middle 19th century).     

Tag loss and movement of stocked yearling rainbow trout (Oncorhynchus mykiss) in southwestern Australia

Rainbow trout, Oncorhynchus mykiss, have been stocked in southwestern Australia since the 1930s. Trials at a research station maintained 868 tagged yearling O. mykiss (age: 14 months; standard length: 208 mm) for up to 375 days. The mean tag loss rate was 0.12% ± 0.040% per day for both single- and double-tagged fish. The tag loss rate was used to interpret tag return data from 7030 single-tagged yearlings stocked into three river systems in southwestern Australia. Recaptures indicated that O. mykiss survived into their second season in all rivers, with the maximum time at liberty of 21 months (longevity of at least 35 months). Upstream and downstream movements of O. mykiss increased with time, although 29% of recaptures were reported from the stocking site. Significantly more O. mykiss were recaptured from the Warren River, and differences remained even when corrected for stocking levels; angler effort had a marginal effect on return rates. Higher return rates from the Warren River may be due to availability of suitable habitat (stream cover, cooler water) for O. mykiss. Results allow the stocking regime to be reviewed to improve fishery performance.     

Organic matter of the Kiziltashskie Limans

Data on biochemical ecosystem monitoring of Kiziltashskie Limans are given. The limans are the only natural water bodies in the Russian Black Sea where pascual breeding of very valuable commercial fish is implemented. The presented concentrations of dissolved and particulate organic matter are 2–5 times greater than the values typical of the coastal zone of the Black Sea (from 7.9 to 27.7 mg/L and from 0.3 to 1.5 mg/L, respectively). The main biochemical component of the dissolved organic matter is carbohydrates, and that of particulate matter is protein. The share of particulate organic matter in the Kiziltashskie Limans never exceeds 7%. The elemental (C, N, P) and biochemical composition of organic matter is studied (carbohydrates, proteins, lipids). The rates of enzymatic reactions vary from season to season. Thus, processes of hydrolytic splitting of phosphor-organic compounds during primary production are very intensive in the spring, while processes of organic matter oxidation, catalyzed by enzymes of electron-transport system, are intensive in the summer.     

Significant genetic differentiation among meroplanktonic barrel jellyfish Rhizostoma pulmo (Cnidaria: Scyphozoa) in the Mediterranean Sea

Molecular data have shown that jellyfishes are more geographically restricted and evolutionarily divergent than previously thought. We examined genetic variation and divergence within the meroplanktonic barrel jellyfish Rhizostoma pulmo in the Mediterranean Sea; specific sampling areas were the northern Adriatic, western Mediterranean and Tunisian coast. A total of 19 sampling sites and 68 sequences of the mtDNA cytochrome c oxidase subunit I (COI) gene were used. Of the 68 COI sequences, 45 were newly collected specimens which originated from nine sampling sites along the Tunisian coast. A total of 24 haplotypes were obtained and the specimens sampled were characterised by relatively high levels of haplotype diversity (h = 0.866) and low levels of nucleotide diversity (π = 0.004). Haplotype network analysis showed the presence of three distinct phylogenetic lineages (populations), with separate geographic ranges in the northern Adriatic, western Mediterranean and Tunisian coast. The observed genetic differentiation between these three lineages was supported by the presence of significant genetic differentiation between the 19 populations (F_ST = 0.757, p < 0.001). The high level of genetic differentiation detected in the barrel jellyfish investigated could be attributed to either intrinsic and/or extrinsic barriers to genetic exchange between different populations that may have adapted to different environmental conditions.     

A multi‐dating approach applied to proglacial sediments attributed to the Most Extensive Glaciation of the Swiss Alps

Dehnert, A., Preusser, F., Kramers, J. D., Akçar, N., Kubik, P. W., Reber, R. & Schlüchter, C. 2010: A multi‐dating approach applied to proglacial sediments attributed to the Most Extensive Glaciation of the Swiss Alps. Boreas, Vol. 39, pp. 620–632. 10.1111/j.1502‐3885.2010.00146.x. ISSN 0300‐9483. The number and the timing of Quaternary glaciations of the Alps are poorly constrained and, in particular, the age of the Most Extensive Glaciation (MEG) in Switzerland remains controversial. This ice advance has previously been tentatively correlated with the Riss Glaciation of the classical alpine stratigraphy and with Marine Isotope Stage (MIS) 6 (186–127 ka). An alternative interpretation, based on pollen analysis and stratigraphic correlations, places the MEG further back in the Quaternary, with an age equivalent to MIS 12 (474–427 ka), or even older. To re‐evaluate this issue in the Swiss glaciation history, a multi‐dating approach was applied to proglacial deltaic ‘Höhenschotter’ deposits in locations outside the ice extent of the Last Glacial Maximum. Results of U/Th and luminescence dating suggest a correlation of the investigated deposits with MIS 6 and hence with the Riss Glaciation. Cosmogenic burial dating suffered from large measurement uncertainties and unusually high ²⁶Al/¹⁰Be ratios and did not provide robust age estimates.