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1.
Salinity tolerance, energy metabolism, buoyancy, and passive sinking and swimming speeds have been studied for comparative assessment of the adaptive potential of two species of cyclopoid copepods in the Black Sea, the native Oithona similis and new invader Oithona davisae. Both species were considered marine euryhaline copepods, but the range of salinity tolerance of O. davisae was much broader (5–55‰). The energy metabolism, locomotor activity, mean body mass density, and speed of passive sinking at the same temperature were significantly higher in O. davisae than in O. similis. The relationship between the physiological and behavioral parameters and ecological characteristics of the species are discussed. 相似文献
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S. N. Moshonkin V. B. Zalesny A. V. Gusev 《Izvestiya Atmospheric and Oceanic Physics》2018,54(5):495-506
The algorithm for splitting k–ω turbulence equations is used to parameterize viscosity and diffusion coefficients in the ocean general circulation model. The k–ω equations are split into stages describing the transport-diffusion and generation-dissipation of the turbulent kinetic energy and frequency function ω. At the generation-dissipation stage, the equations are solved analytically. Calculations of circulation in the North Atlantic–Arctic Ocean for 1948–2009 have been carried out. The experiments demonstrate an adequate reproduction of hydrophysical characteristics and high efficiency of the algorithm. It is shown that considering the climatic annual mean buoyancy frequency in the turbulence equations at the generation-dissipation stage is an important factor in improving the accuracy of simulated fields. 相似文献
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The results of the analysis of the stable oxygen isotopes content in shell carbonates for the purpose of the individual age
determination of the Rapana venosa gastropod (Valenciennes 1846) are presented. The data acquired via this method agreed with the number of spawning marks on
the shell surface. Additionally, the duration of the seasonal extrema can indicate the velocity of the shell’s growth throughout
the mollusk life, and the relative δ18O value in the shell’s near-apex increments, the season when a young shell comes out of its cocoon. It has been shown that
the common method of growth rings counting at the operculum is unreliable for a shell’s age determination. The distinguishing
of modal classes is ineffective as well, since the corridor of the variations in size for coeval individuals is very broad.
Apparently, such variable characteristics as the growth rate, the wall’s thickness, and the relative weight are greatly dependent
on the alimentary conditions, which are unequal even in the same biotope. 相似文献
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This paper presents an artificial neural network (ANN)-based response surface method that can be used to predict the failure probability of c-φ slopes with spatially variable soil. In this method, the Latin hypercube sampling technique is adopted to generate input datasets for establishing an ANN model; the random finite element method is then utilized to calculate the corresponding output datasets considering the spatial variability of soil properties; and finally, an ANN model is trained to construct the response surface of failure probability and obtain an approximate function that incorporates the relevant variables. The results of the illustrated example indicate that the proposed method provides credible and accurate estimations of failure probability. As a result, the obtained approximate function can be used as an alternative to the specific analysis process in c-φ slope reliability analyses. 相似文献
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This study investigated the sexual maturation process, release of spermatozoa or eggs and oocyte diameter of the rhizostomid medusae Nemopilema nomurai using samples collected from August 2006 to June 2008 from the waters around Korea and Japan, including peripheral areas outside the species’ usual habitat. Immature medusae were observed from June to October only in the western sector of the study area. The onset of spermatozoa and egg release occurred in September and October, respectively, and peaked in December and January. Medusae migrated eastward from source areas with the Tsushima Warm Current, where they formed gametes and spawned. Peak position and maximum oocyte diameter increased as the gonads developed according to the size-frequency distribution of oocytes. No fertilized eggs or embryos were found in the gonads. The correlation was analyzed with bell diameter, maximum oocyte diameter, sampling date, surface water temperature and gonad color to estimate which environmental factors and maturation indices were related to the maturation stage of females. Maturation stage correlated well with maximum oocyte diameter, which correlated negatively with surface water temperature. There was no significant correlation between bell diameter and maturation stage. Therefore, bell diameter was inappropriate for determining maturation index. Sex could not be distinguished clearly by gonad color. However, light pink gonads were more prevalent in males and various deep colors such as orange and brown were more frequent in female medusae. 相似文献
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In Kievka Bay of the Sea of Japan, the population of the Japanese sea cucumber Apostichopus japonicus inhabits the areas of coarse sediments and complex bottom topography. These distributional patterns are closely related to
the species’ ecology, i.e., to the demand for protection against the wave turbulence. The aggregationing coverage of the sea
cucumber population is about 80 hectares, where ∼200 thousand animals were accounted for in the last years. The aggregation’s
area varies during the year, which is closely related to the species’ biological peculiarities, such as their behavioral patterns
and the redistribution of their food resources. A significant increase of the juvenile population occurred after the farm-reared
sea cucumber spat were released in 2003. 相似文献
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The age and growth of filefish, Thamnaconus modestus (Günther 1877) in the southern waters of Korea were investigated. Samples were collected with commercial trawl catches during the period from May 2009 to December 2011. Of the 2,626 specimens collected, the sex ratio was not significantly different from 1:1 (P > 0.05). The total length ranged from 11.3 to 42.1 cm. The gonadosomatic index for both sexes was the highest in May to June, indicating that May to June is the main spawning period. The length of females at sexual maturity was 25.92 cm. The length-weight relationship of the filefish was TW = 0.0121TL3.0536 (n = 1,692, r2 = 0.9034, P < 0.001). The age of the sampled individuals was estimated by counting growth rings recorded on the 5th vertebrae; ages ranged from 0 to 9 years. The filefish of the same age displayed a high individual variation in total length. Length-at-age data were fitted by using the Von Bertalanffy growth model. The estimated Von Bertalanffy growth parameters were L∞ = 42.04 cm, k = 0.21 year?1 and t0 = ?1.56 for females, L∞ = 41.20 cm, k = 0.18 year?1 and t0 = ?2.36 for males, and L∞ = 43.16 cm, k = 0.17 year?1 and t0 = ?2.18 for the combination of both male and female. These data can be used as useful biological information for the future fishery management of filefish resources in Korean waters. 相似文献
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A total of 25 surficial sediment samples (Peterson grab, gravity and piston cores), collected during the Pilot Expedition
to Southern Ocean (PESO) 2004 cruises 199C and 200 onboard the ORV Sagar Kanya along a N–S transect between 9.69°N and 55.01°S, and 80 and 40°E in the Indian Ocean sector of the Southern Ocean (SW Indian
Ocean), have been investigated for various morphological features—test size, mean proloculus size and coiling direction (dextral/sinistral
forms)—of the planktic indicator species Neogloboquadrina pachyderma (Ehrenberg). The results show that the coiling directions co-vary with temperature and salinity, the abundances of sinistrally
coiled forms increasing towards higher latitudes (south of 40°S), whereas dextrally coiled forms show a reverse trend. Similarly,
overall test and proloculus sizes depend largely on the physicochemical properties (salinity, temperature, nutrients, calcium
saturation) of the ambient water masses. These observations suggest that, particularly at the boundaries between different
water masses, variations in morphological features of N. pachyderma can meaningfully be used to reconstruct paleoceanographic conditions from Indian Ocean sediments. 相似文献
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It is shown that, in 2002–2005, the mass development of the coccolithofore Emiliania huxleyi on the Gelendzhik shelf occurred annually and in May–June its abundance reached 1.5 × 106 cells/l. In 2004–2005, the bloom of E. huxleyi was accompanied by a mass development of the diatom alga Chaetoceros subtilis var. abnormis f. simplex (0.6–0.9 × 106 cells/l); for the first time, it was registered as a dominating form of the Black Sea phytoplankton. Small flagellates and picoplankton algae played a noticeable role in the phytoplankton throughout the entire period of the studies. Meanwhile, in the early summer period, the bulk of the biomass consisted of coccolithophores (50–60%), while, in the late summer period, diatomaceous algae dominated (50–70%). Among the ecological factors that favor the coccolithophore development one may note the microstratification of the upper mixed layer at a high illumination level and high temperature in the surface waters (18–21°C). The terrigenous runoff during the rainy period had a negative effect on the E. huxleyi development, while storms dispersed the population over the upper mixed layer. The wind-induced near-shore upwelling stimulated the development of diatoms. 相似文献
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With increasing anthropogenic impact on the environment, investigations of organism’s response to the contamination of natural habitats, are especially relevant. In the present study, we sought to identify the correlation between the bottom sediments and local variability in histopathology of Anadara kagoshimensis (Bivalvia) in four sites of the north-eastern coast of the Black Sea. Bottom sediment grain size, redox potential of pore water, heavy metals, benzo-α-pyrene and DDT concentrations have been used as characteristics of bottom sediments. Analysis of the data revealed differences in the geochemical background of the studied sites and the histopathological state of the molluscs from these areas. Among the 10 studied elements as well as benzo-α-pyrene and DDT, only Ni has shown an exceedance of statutory limits of concentration in bottom sediments. The study reveals a relationship between Ni concentration in the bottom sediments and frequency of heavy histopathologies in the molluscs. In addition to causes directly related to pollution, mild pathology may be influenced by “natural” causes; in particular, the high content of brown cells in the connective tissue of the digestive gland may be due to the age of molluscs. 相似文献
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Nineteen surface sediment samples, collected onboard ORV Sagar Kanya during the 199C and 200th (the pilot expedition to Southern Ocean) cruises along a north-south transect between 1.92° S to 55.01° S latitude and 67.88° E and 44.89° E longitude, were studied for total planktonic foraminiferal assemblage, relative abundance and the oxygen isotopic values of the indicator planktic species Globigerina bulloides. These profiles were compared with the latitudinal variations in the average salinity and nutrient (phosphate) contents of the top 100 meters water column. The initial results have traced the signatures of salinity linked variations of different water masses in the study region. The influence of Australian Mediterranean Water (AAMW) has been noticed in the present dataset. 相似文献
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In February and April 2000, in the Southern Ocean between Africa and Antarctica, the concentration of chlorophyll (C chs) in the surface layer was not high (0.1–0.3 mg/m3). The zones of increased C chs values (0.6–2.0 and over 2.0 mg/m3) were located between the Southern Subtropical and Subantarctic fronts, near the Polar front, and to the south of the Antarctic Divergence. From February to April, in the open areas of the Southern Ocean, a general C chs decrease was observed. A similar trend was also noted in the near-shore seas of the East Antarctic. At the shelf of the Sea of Cosmonauts, within the upper mixed layer, the content of chlorophyll amounted to 0.34–0.37 mg/m3. In the area of the continental slope, we registered the formation of a subsurface chlorophyll maximum (0.52–0.56 mg/m3) at a 20-m depth, which deepened to 70 m when passing to the deep-water area. The positive correlation with a high coefficient (r = 0.939) between the field and satellite data (C chs and C sat, respectively) allows one to conclude about the applicability of the SeaWiFS algorithm for the estimation of the chlorophyll content within the surface layer in the Antarctic areas studied. In the course of the ice formation in Prydz Bay, during five days, the content of chlorophyll in different phases of the new ice increased by a factor of 2.9, whereas the values of this parameter in the surrounding waters remained quite invariable. The C sat values were 6.3 times as high as those obtained experimentally for the sludge ice. Because of the large areas occupied by floating ice, the sole usage of satellite data may cause great errors in the productivity estimation of the East Antarctic seas. 相似文献
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Time series changes in sea surface temperature (SST), chlorophyll a (Chl a), nutrients (PO4, NO3), and sea winds, which correlated with the passage of Typhoon Shanshan in the East/Japan Sea (EJS), are illustrated using satellite data for Chl a, SST, sea winds, and in situ data for nutrients and water temperature. The sea-surface cooling (SSC) effect by the passage of the typhoon was higher at stations nearer to the center compared to stations further from the center. The SSC effect at stations in the colder water region (on the left side of the typhoon’s track) was higher than at stations in the Tsushima Warm Current region (on the right side of the typhoon). The SSC effect continued for approximately 10 days after the passage of the typhoon. The Chl a concentration at all stations increased after the passage of the typhoon. This increase continued for a period of approximately 10 days, but the duration period at each station varied with distance from the typhoon center. Changes in Chl concentrations at stations within a 2° distance on both sides from the typhoon’s center were higher than that at other stations. The changes in Chl a by the passage of the typhoon were measured at approximately 0.3–1.0 mg/m3 along the moving path of the typhoon. Phosphate and nitrate changes were inversely correlated with the water temperature changes; the nutrient concentration increased with the passage of the typhoon. Like the changes in SST, changes in nutrient concentrations on the left side of the typhoon’s track were higher compared to those at the center and the right side. 相似文献
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Chlorophyll-a concentration (C chl) variations in the cross section within and outside the Peter the Great Bay shelf during different stages of the winter–spring phytoplankton bloom in 2003–2005 has been considered based on a ship (obtained during the R/V Akademik M.A. Lavrent’ev voyage of February 26 to March 9, 2003) and MODIS-Aqua spectroradiometer and the SeaWiFS color-scanner satellite data. A comparison of the C chl variability obtained from the ship and satellite data indicates that these data are inconsistent. According to satellite data obtained at the MUMM atmospheric correction, the C chl variability is distorted less than the NIR-correction data. Studying the variations in the coefficients of light absorption by the detritus and yellow substance (a dg) and light backscattering by suspended particles (b bp), C chl, chlorophyll-a fluorescence (F chl) according to the satellite data allow us to state that the variations in the discrepancy between the satellite and ship C chl values are mainly caused by the variations in the content of the detritus and yellow substance in water. Based on the satellite data, it has been revealed that the a dg values increase with increasing wind mixing after the phytoplankton bloom (about 2–5 km areas where the a dg, C chl, F chl, and bbp values abruptly increased in 2005, apparently due to eddy formation). It has been indicated that the F chl characteristic, which is close to C chl, increases when the favorable conditions for the phytoplankton bloom deteriorate. Therefore, this characteristic cannot be used to identify C chl under the indicated conditions. 相似文献
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Sayaka Yasunaka Yukihiro Nojiri Taketo Hashioka Chisato Yoshikawa Taketoshi Kodama Shin-ichiro Nakaoka Sanae Chiba Fuminori Hashihama Masahide Wakita Ken Furuya Daisuke Sasano Akihiko Murata Hiroshi Uchida Michio Aoyama 《Journal of Oceanography》2018,74(1):1-11
We used more than 25,000 nutrient samples to elucidate for the first time basin-scale distributions and seasonal changes of surface ammonium (NH4 +) and nitrite (NO2 ?) concentrations in the Pacific Ocean. The highest NH4 +, NO2 ?, and nitrate (NO3 ?) concentrations were observed north of 40°N, in the coastal upwelling region off the coast of Mexico, and in the Tasman Sea. NH4 + concentrations were elevated during May–October in the western subarctic North Pacific, May–December in the eastern subarctic North Pacific, and June–September in the subtropical South Pacific. NO2 ? concentrations were highest in winter in both hemispheres. The seasonal cycle of NH4 + was synchronous with NO2 ?, NO3 ?, and satellite chlorophyll a concentrations in the western subtropical South Pacific, whereas it was synchronous with chlorophyll-a but out of phase with NO2 ? and NO3 ? in the subarctic regions. 相似文献