The state‐of‐the‐art in marine navigation

Tide gauges distributed all over the world provide valuable information for monitoring mean sea level changes. The statistical models used in estimating sea level change from the tide gauge data assume implicitly that the random model components are stationary in variance. We show that for a large number of global tide gauge data this is not the case for the seasonal part using a variate-differencing algorithm. This finding is important for assessing the reliability of the present estimates of mean sea level changes because nonstationarity of the data may have marked impact on the sea level rate estimates, especially, for the data from short records.     

Nitrogenase activity and estimates of nitrogen fixation by freshwater benthic blue‐green algae

The sandy substrate of Lake Taharoa (west coast, North Island, New Zealand ‐ 35°50'S, 173°41'E) is covered by communities of filamentous algae that extend from the exposed beach down to 21 m depth. The algae bind the sand to form crusts and mats which may break off as discrete plates. The dominant species are the blue‐greens Microcoleus, Nostoc, Phormidium, Lyngbya, Oscillatoria, Scytonema, Stigonema, Shizothrix, Calothrix, Dichothrix, Tolypothrix, and Anabaena, with occasional high concentrations of the desmid Cylindrocystis. Nitrogenase activity, measured by acetylene reduction, showed a wide range of rates (4–150 μmol C₂H₄ m^‐2h^‐1). Estimates of annual rates of nitrogen fixation by the Taharoa communities are comparable with those for periphytic blue‐green algae‐dominated systems reported elsewhere.     

State‐of‐the‐art sea level and meteorological monitoring systems in the intra‐Americas sea

State‐of‐the‐art technology is presently being used for the acquisition of water level and meteorological data in the Intra‐Americas Sea to support the Global Sea Level Observing System (GLOSS) network of sea‐level monitoring stations. GLOSS stations provide data for the investigation of regional relative sea level change in areas of complex tectonic motion, national geodetic vertical datums, near real‐time data for input to climatic diagnostic numerical models, calibration of satellite altimeter and scatterometer data, and the evaluation of the feasibility of producing synoptic mean sea level charts for the prediction of climatic trends, long‐range weather forecasts, and ocean processes.     

Velocity measurements in the East Auckland Current north‐east of North Cape,New Zealand

Flow in the East Auckland Current (EAUC) system to the north‐east of North Cape, New Zealand is examined using data from two current meter mooring arrays, with supporting data from conductivity/temperature/depth (CTD) and satellite altimetry. Variable currents up to 45 cm s_–1 were observed. The variability was partly attributable to changes in position and strength of the North Cape Eddy whose centre lies some 150 km offshore. The observed flows across the mooring line correlate well with those estimated from satellite altimetry. This gives confidence in the use of the satellite data to estimate the transport variability in the EAUC in the 1992–2001 period. No seasonal cycle was found in the volume transports but rather broadband variability at periods longer than 100 days.     

Drift currents in the southern New Zealand region as derived from Lagrangian measurements and the remote sensing of sea‐surface temperature distributions

Four drift bottles, cast adrift south of the Subtropical Convergence at 48°S, 156°E in November 1980, landed within 123 days of release at a short stretch of coast north of Banks Peninsula. A high degree of coherence in the responsible drift pattern is indicated. The contemporary surface circulation inferred from satellite‐derived sea‐surface temperature distributions indicates that the bottles were entrained in a meridionally‐converging flow after drifting across the southern Tasman Sea without crossing the Convergence. They were prevented from further eastward drifting because of a marked southward flexing of the Convergence east of the Southland Current during February 1981. Because of local weather and tide effects, the bottles finally beached in Pegasus Bay.     

Stress–Strain State and GPS Kinematics of the Lithosphere in the Northern Part of Eurasia

Izvestiya, Atmospheric and Oceanic Physics - The neomobilist plate tectonic concept is currently at the forefront of geotectonics. This concept is based on the idea of the division of the...     

A simple method for the detection of hepatitis A virus in the environmental samples by polymerase chain reaction

Hepatitis A virus (HAV) is very persistent in the environment and is especially difficult to detect in the seafoods. In recent years, molecular cloning of the genome of HAV has led to sensitive polymerase chain reaction (PCR) method for the detection of HAV RNA. Here we describe a new and simple procedure to extract RNA from contaminated clams and the PCR method for detection of HAV in environmental samples. The specificity and efficiency of PCR amplification were studied using cDNA and RNA of HAV. Three primer couples gave satisfactory results. Some basic parameters of the PCR were modified to perform a highly specific and sensitive test.     

Analysis of state of the carbonate system of waters and variations of the content of organic carbon in bottom sediments of the Sevastopol bay in 1998–2005

On the basis of the experimental data accumulated in 1998–2005, we analyzed the space and time variations of the carbonate system of waters and the content of organic carbon in bottom sediments of the Sevastopol Bay. The intensity of gas exchange through the water-atmosphere interface was quantitatively estimated. It was shown that the partial pressure of carbon dioxide pCO₂ in waters of the bay became much higher for the period of observations. The maximum changes were observed in summer. They were especially pronounced for the bottom layer of waters. For the entire period of observations, the invasion of carbon dioxide CO₂ was predominant in the major part of the bay, and the content of organic carbon in the bottom sediments increased. The ability of waters in the bay to absorb CO₂ is explained by the synthesis of organic substances, which becomes possible due to the presence of the equivalent load of nutrients. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 57–67, March–April, 2008.     

Fishery characteristics and abundance estimates of the mangrove crab Scylla serrata in southern Tanzania and northern Moçambique

The mud crab Scylla serrata is lightly exploited along the East African seaboard. This study reports on fishing practices and gives preliminary estimates of abundance and size structures of the mud crab populations in Utende, Chole Island and Juani Island, Tanzania, and west of Quirimba and Ibo Island, Moçambique. Estimates for three mangrove habitats (in Tanzania); open channel (<1 per 25 m²), mangrove fringe (3 per 25 m²) and inner forest (1 per 25 m²) were obtained using burrow density and from burrow occupancy from fisheries data. Mud crabs from Tanzania were significantly smaller (carapace width) and less abundant (in terms of mass) than those from Moçambique. This newly exploited resource provides a potential alternative source of income, but local management and monitoring plans need to be implemented early.     

Coastal upwelling in the Baltic Sea—Satellite and in situ measurements of sea-surface temperatures indicating coastal upwelling

Satellite data (AVHRR) and in situ data of sea-surface temperatures have been used to describe wind-induced upwelling along the Swedish coast of the Baltic. The satellite data, transformed to isotherm charts, points out three sections of the coast where the upwelling is especially intense. The cold upwelled water, normally found within 10–20 km from the coast, sometimes spreads out in finger-like filaments. There are indications of propagation of upwelling fronts and centers, which may be associated with coastal-trapped waves. Ten years of in situ measurements of sea-surface temperature have been used for a statistical compilation of upwelling events. The statistics reveal that upwelling is a common feature along certain sections of the coast, occurring for about one-fourth to one-third of the time. Some information of time scales and temperature anomalies associated with the upwelling events are also given. A wind analysis shows a correlation between upwelling and winds parallel to the shore line, in accordance with the Ekman theory of upwelling generation.     

The spreading of eutrophication in the eastern coast of the Gulf of Bothnia,northern Baltic Sea – An analysis in time and space

In the Baltic Sea, the Gulf of Bothnia is the only sub-basin with only minor effects of eutrophication mainly due to physical factors. Most evaluations of the state of the Gulf of Bothnia are based on offshore investigations. In the present study the coastal zone of the eastern Gulf of Bothnia is analysed. Long-term data (1980–2007) of total nitrogen and phosphorus, turbidity and oxygen are analysed using principal component analysis (PCA) for spatial and temporal patterns in the trophic situation. The coastal zone is divided into six regions: inner and outer areas of the Bothnian Sea and the Quark, and the outer areas of the southern and northern Bothnian Bay. The results show a degradation of water quality from north to south, and from outer to inner coastal areas. Eutrophication changes from an almost non-existing problem in the Bothnian Bay in the north to clear signs of nutrient over-enrichment in the Bothnian Sea. This shows that even if eutrophication in the Gulf of Bothnia is not serious, the increasing trends in nutrient levels should be seen as warning signals for the future, and remedies to combat eutrophication should be taken rapidly.     

Optical backscattering in the Arabian Sea—continuous underway measurements of particulate inorganic and organic carbon

Continuous surface measurements of temperature, salinity, fluorescence and optical backscattering were made during R/V Thompson cruise no. TN053 in the northern Arabian Sea (“Bio-Optical cruise”; October–November, 1995). The cruise covered the early NE monsoon period. Optical measurements involved alternate estimates of total backscattering and acidified backscattering approximately every 1.5–2 min (measured after addition of a weak acid to dissolve calcium carbonate). The difference between total and acidified backscattering equals “acid-labile backscattering”. Total and acid-labile backscattering were converted to the concentration of particulate organic carbon (POC) and particulate inorganic carbon (PIC; calcium carbonate), respectively, and discrete samples taken along the cruise track were used for calibration. Backscattering data were frequently coherent with temperature, salinity, and density variability. Acid-labile backscattering values revealed that calcium carbonate accounted for 10–40% of the total optical backscattering in the region, and the semi-continuous records demonstrated distinct patches of coccolith-rich water. The northern Arabian Sea had the highest acid-labile backscattering. Results suggest that PIC : POC ratios can vary over about four orders of magnitude. Highest surface values of PIC : POC approached one in several places. We also report qualitative observations of phytoplankton community structure made aboard ship, on fresh samples.     

Reproduction of the large-scale state of water and sea ice in the arctic ocean in 1948–2002: Part I. Numerical model

Calculations were performed using a model of the combined circulation of the Atlantic Ocean (from 20° S), the Arctic Ocean, and the Bering Sea with a resolution of 0.25° by latitude and longitude for 1958–2006. The results are compared with observational data and results obtained by other models. Model estimates were obtained for the evolution of the Atlantic water inflow into the Arctic basin through the Fram Strait and the Barents Sea. Increased transports of Atlantic water inflow into the Arctic basin were found for the first half of the 1990s and 2004–2006. The relation between Atlantic water transports into the Arctic basin and variations in the North Atlantic oscillation is shown. A positive trend of Atlantic water inflow into the Arctic basin through the Fram Strait (0.061 Sv per year) was revealed. The evolution of the freshwater-layer thickness in the Beaufort Circulation (BC) is considered. There are three periods of its increased values combined with the increased anticyclonic vorticity of BC currents: the 1960s, the 1980s, and from 1999 until now. The model estimate for a statistical mean timescale of the cycle of freshwater concentration and sink from the BC is 16 years, which is close to currently existing estimates. The evolution of anticyclonic vorticity of currents leads the variations in the freshwater-layer thickness of the BC by 1.75 years. Since the mid-1970s, there have been long positive trends of both the freshwater-layer thickness and anticyclonic vorticity of currents in the BC. In the same time period, there has been a satellite-registered negative trend in the ice area in the Arctic, which was reproduced by the model.     

Oxygen consumption in the epilimnia and hypolimnia of two eutrophic,warm‐monomictic lakes

Oxygen consumption was estimated for two eutrophic New Zealand lakes using a simple 2‐layer model, from estimates of net changes in oxygen, phytoplankton photosynthesis, inflow and outflow, diffusion, eddy diffusion, and changes in the depth of the thermocline. Of the total oxygen consumption, 75–85% occurred in the epilimnia. Epilimetic oxygen consumption per m³ and per m² in Lake Johnson were higher than in Lake Hayes, reflecting known differences in the trophic status of the lakes, but estimates for the hypolimnia of the two lakes were similar. Daily hypolimnetic areal deficits were sensitive to both the depths and time intervals chosen.

In the epilimnia, monthly oxygen production by photosynthesis averaged 1.1 and 1.8 times the initial oxygen content in Lakes Hayes and Johnson respectively. Diffusion appeared to be of similar magnitude to photosynthesis in the isothermal period, but was less important during stratification. Losses to the hypolimnia by eddy diffusion were less than 10% of photosynthesis. Photosynthesis in the hypolimnia contributed 30–40% of the oxygen consumed there and eddy diffusion supplied a further 20%.

In Lake Johnson a 3–5 m stratum of water in the metalimnion became anoxic for 2–3 months each summer while there were still up to 5.2 g.rer³ of oxygen remaining in the hypolimnion. Metalimnetic anoxia is attributed largely to oxygen consumption in situ, resulting from the highly eutrophic state of the lake and intense thermal stratification. Zooplankton respiration accounted for less than 10% of the maximum net decline in metalimnetic oxygen in 1970–71, but was more important in the other 2 years.

Changes in the oxygen content of the hypolimnion indicate that Lake Hayes has become more eutrophic since 1954–55. In Lake Johnson low oxygen concentrations at the autumn overturn (<5 g.m^‐3) represent a threat to the trout population.     

Modern Horizontal Movements in the Zones of Strong and Moderate Earthquakes of the Early 21st Century in the Central Sector of the Greater Caucasus: Characteristics Inferred from GPS Observations and Connection with Neotectonics and Deep Structure of the Earth’s Crust

Izvestiya, Atmospheric and Oceanic Physics - Analysis of GPS-measurements made for the first time along the geodesic profile crossing all the main geological structures in the Ossetian region of...     

Interannual variations and trend of the production of inorganic carbon by coccolithophores in the arctic in 2002–2010 based on satellite data

Based on MODIS data, a significant decline in the intensity and spatial extension of blooms of coccolithophore E. huxleyi in Arctic waters in 2002–2010 is revealed and quantified. This 9-year tendency has been unfolding against a background of negative trends in the dynamics of SST and levels of incident PAR and summer-time NAO, which collectively, but with a predominance of the NAO influence, are believed to be the main drivers of the decline of E. huxleyi blooms and the associated decline in inorganic carbon production in the Arctic Basin.     

Daily and seasonal dynamics of suspended particles in the Rhône River plume based on remote sensing and field optical measurements

Satellite ocean colour remote sensing can serve as a powerful tool to assess river plume characteristics because it provides daily mapping of surface suspended particulate matter (SPM) concentration at high spatial resolution. This study’s ultimate objective was to better understand daily and seasonal particle dynamics in a coastal area strongly influenced by freshwater discharge and wind—the Rhône River (France), this being the major source of terrestrial input to the Mediterranean Sea. SPM concentrations and biogenic composition (chlorophyll a, organic carbon) were investigated during several bio-optical field campaigns conducted in spring–autumn of 2010 both from aboard a research vessel and by means of an autonomous profiling float. Freshwater discharge and wind velocities varied significantly during the year, associated with marked fluctuations in surface SPM (upper 1 m), even within hours and not restricted to any specific season. Thus, the range was ca. 12–25 g m^–3 (dry mass basis) on 9 April (spring), and ca. 3–39 g m^–3 on 4–5 November (late autumn). Short-term variations were observed also in SPM composition in terms of POC (albeit not chl a), with POC/SPM ratios ranging between ca. 3 and 11% over ca. 3 weeks in spring. Nevertheless, the particulate backscattering coefficient (b _bp) proved to be a robust proxy of SPM concentration in the river plume (b _bp(770)?=?0.0076?×?SPM, R²?=?0.80, N?=?56). It has recently been demonstrated that 80% of the Rhône’s terrestrial discharge occurs during flood events. The results of the present study revealed that, under these conditions, SPM is constrained largely within surface waters (i.e. at depths <5 m), with only weak daily vertical variability. By implication, ocean colour satellite data are highly suitable in meaningfully estimating the overall SPM load exported by the Rhône River to the Mediterranean. These findings make a solid contribution to future improvements of three-dimensional sediment transport models for the region and similar settings.     

Studies on the absorption and utilization of amino acids in the test diets by the prawn Penaeus orientalis

This experiment was conducted to study the characteristics of absorption of amino acids by different regions of the alimentary tract and the utilization of free amino acids in the test diets of the prawn, Penaeus oricntolis.The midgut gland is the principal site of nutrient absorption. In the foregut, the digestibility coefficient of 15 amino acids tested accounted for 52.5% of the total digestibility coefficient in the entire alimentary tract. In the midgut, the digestibility coefficient was 47.5 % of the total. There was no evidence of the hindgut assimilating amino acids.The free amino acid in the test diet, methionine, was almost absorbed before entering the midgut. Methionine could not be absorbed synchronously with other amino acids bound in the dietary protein, but it did affect the synchronization of other essential amino acids. [3H]-lysine, incorporated into the test diet, was almost totally assimilated within the midgut gland. Five and a half hours after feeding, the labelled amino acid had be     

Currents in the Luzon Strait during the spring of 2002: observation and computation by modified inverse model

On the basis of the current measurements at 200,500 and 800 m from moored current meters with the time series data from March 17 to April 15 at the mooring station (20°49′57″N, 120°48′ 12″E) and the hydrographic data obtained in the Luzon Strait during the spring of 2002 cruise, the circulation in the investigated