A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  

  Subjects -> WATER RESOURCES (Total: 160 journals)
We no longer collect new content from this publisher because the publisher has forbidden systematic access to its RSS feeds.
Similar Journals
Journal Cover
Journal of Oceanology and Limnology
Journal Prestige (SJR): 0.301
Citation Impact (citeScore): 1
Number of Followers: 3  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2096-5508 - ISSN (Online) 2523-3521
Published by Springer-Verlag Homepage  [2469 journals]
  • Reconstruction of large complex sand-wave bathymetry with adaptive
           partitioning combining satellite imagery and sparse multi-beam data

    • Free pre-print version: Loading...

      Abstract: Abstract Shallow marine sand waves are formed on the seabed and are widely distributed within tidal environments. However, the use of multibeam echo sounding (MBES) is costly to obtain the bathymetric mapping of large complex sand waves. Therefore, we propose a new method that employs a combination of multiangle sun glint images and sparse MBES data to achieve comprehensive bathymetric mapping of large and complex sand waves. This method involves estimating sea surface roughness, automatically extracting sand-wave crests, conducting adaptive subregion partitioning, estimating the water depth at auxiliary points, and generating digital bathymetric models. The method was employed in a case study of sand waves on the Taiwan Bank. Bathymetric mapping was implemented for large complex sand waves over an area spanning approximately 350 km2 using multiangle sun glint images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer and MBES data. The results show that mapped and measured water depths were well-matched; the root-mean-square error of water depths was 1.77 m, and the relative error was 5.03%. These findings show that bathymetric mapping of large complex sand waves can be effectively conducted using the new method, and as such, the workload of MBES is reduced and efficiency is improved.
      PubDate: 2022-05-31
       
  • UV-B irradiation and allelopathy by Sargassum thunbergii affects the
           activities of antioxidant enzymes and their isoenzymes in Corallina
           pilulifera

    • Free pre-print version: Loading...

      Abstract: Abstract Intertidal macroalgae can cope with the dual effects of UV-B irradiation and allelopathy. To study the impacts of the two stressors, we co-cultured Corallina pilulifera with Sargassum thunbergii in 1:1 and 1:10 ratios under different doses of UV-B radiation. The response of the antioxidant defense system, focusing on activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POX) and glutathione reductase (GR), was monitored. In addition, isoenzyme patterns were analyzed using non-denaturing polyacrylamide gel electrophoresis. The results show that the activities of SOD, APX, and GR were all significantly affected by both UV-B radiation and allelopathy, and the effect of their interaction was significant. However, POX activity was only influenced by UV-B radiation. The enzymatic assay revealed four distinct bands of SOD. The SODIII band weakened significantly when the co-cultures were exposed to extremely high dosage of UV-B irradiation under both co-culturing ratios of 1:1 and 1:10. When the co-culturing ratio was 1:10, both POXII and APXII enzyme activities increased with different UV-B doses. GR activity was at its greatest when the co-culture ratio was 1:10 and exposure was to the higher UV-B doses. The activities of GRIII and GRIV were elevated under all UV treatments whereas the activities of GRI and GRII were reduced under the lower UV-B treatments but were elevated under the higher UV-B treatments. However, lipid peroxidation, as indicated by the thiobarbituric acid-reacting substance (TBARS) assay, increased significantly under the dual stressors. Our data suggest that allelopathy and UV-B radiation stress can each affect the antioxidant enzyme activities of C. pilulifera. Critically, the adverse effects of UV-B on C. pilulifera were intensified by the compounding effects of allelopathy.
      PubDate: 2022-05-31
       
  • Stoichiometric flexibility regulates the co-metabolism effect during
           organic carbon mineralization in eutrophic lacustrine sediments

    • Free pre-print version: Loading...

      Abstract: Abstract Several studies have suggested the pivotal roles of eutrophic lakes in carbon (C) cycling at regional and global scales. However, how the co-metabolism effect on lake sediment organic carbon (OC) mineralization changes in response to integrated inputs of labile OC and nutrients is poorly understood. This knowledge gap hinders our ability to predict the carbon sequestration potential in eutrophic lakes. Therefore, a 45-day microcosm experiment was conducted to examine the dominant mechanisms that underpin the co-metabolism response to the inputs of labile C and nutrients in lacustrine sediments. Results indicate that the labile C addition caused a rapid increase in the positive co-metabolism effect during the initial stage of incubation, and the co-metabolism effect was positively correlated with the C input level. The positive co-metabolism effect was consistently higher under high C input, which was 152% higher than that under low C input. The higher β-glucosidase activity after nutrient addition, which, in turn, promoted the OC mineralization in sediments. In addition, different impacts of nutrients on the co-metabolism effect under different C inputs were observed. Compared with the low nutrient treatments, the largest co-metabolism effect under high C with high nutrient treatment was observed by the end of the incubation. In the high C treatment, the intensity of the co-metabolism effect (CE) under high nitrogen treatment was 1.88 times higher than that under low nitrogen condition. However, in the low C treatment, the amount of nitrogen had limited impact on co-metabolism effect. Our study thus proved that the microorganisms obviously regulate sediment OC turnover via stoichiometric flexibility to maintain a balance between resources and microbial requirements, which is meaningful for evaluating the OC budget and lake eutrophication management in lacustrine sediments.
      PubDate: 2022-05-31
       
  • Influence of nitrate concentrations on EH40 steel corrosion affected by
           coexistence of Desulfovibrio desulfuricans and Pseudomonas aeruginosa
           bacteria

    • Free pre-print version: Loading...

      Abstract: Abstract Nitrate addition is a common bio-competitive exclusion (BCE) method to mitigate corrosion in produced water reinjection systems, which can affect microbial community compositions, especially nitrate and sulfate reducing bacteria, but its effectiveness is in controversy. We investigated the influence of nitrate concentrations on EH40 steel corrosion affected by coexistence of Desulfovibrio vulgaris and Pseudomonas aeruginosa bacteria. Results demonstrate that only mixed bacteria or nitrate had little effect on EH40 steel corrosion, and nitrate could accelerate the corrosion of EH40 steel through the action of microorganisms. The corrosion promotion of nitrate was dependent on its concentrations, which increased from 0 to 5 g/L and decreased from 5 to 50 g/L. These differences were believed to be related to the regulation of nitrate in the growth of bacteria and biofilms. Therefore, care must be taken to BCE method with nitrate when nitrate reducing bacteria with high corrosive activity are present in the environments.
      PubDate: 2022-05-31
       
  • Diverse habitat preferences of two sea cucumber species and the seasonal
           change in a coral reef area

    • Free pre-print version: Loading...

      Abstract: Abstract Different sea cucumbers have different preferred habitats and seasonal changes, which is still lack of detailed research. This study selects two common tropical sea cucumbers (Holothuria edulis and Stichopus chloronotus) to explore the reasons that affect their habitat selection and seasonal changes, so as to provide support for the spatial planning of sea cucumbers reserve in coral reef area. The study area is a compound distribution area of living coral reefs and sandy bottom in the north of Wuzhizhou Island. The survey time is January, April–September, 2019. Three fixed transects (G, H, and Q) were selected to reveal the population ecological characteristics of them in the typical dry season (January, April, May, and June) and rainy season (July, August, and September). The variation range of density for H. edulis and S. chloronotus were 2.0–8.9 inds./10 m2 and 0.2–0.7 inds./10 m2, respectively. The population density in rainy season was significantly higher than that in dry season (P<0.05). H. edulis tends to be distributed in deeper water. The distribution of H. edulis was significant positively correlated with the sand coverage and sand continuity in G transect (P<0.05), and significant negatively correlated with live coral coverage in three transects (P<0.01). The shift from dry season to rainy season is a key factor affecting their habitat preference. In dry season, the preferred habitats of S. chloronotus are small rock (SR), sand (S), and small coral reef (SCR), while the H. edulis is S, SR, and dead coral rubbles (DCR). In rainy season, the preferred habitats of S. chloronotus are shift to SCR and SR, while the H. edulis is SCR, DCR, and sand.
      PubDate: 2022-05-31
       
  • Seasonal co-occurrence patterns of bacteria and eukaryotic phytoplankton
           and the ecological response in urban aquatic ecosystem

    • Free pre-print version: Loading...

      Abstract: Abstract Microorganisms play a key role in aquatic ecosystems. Recent studies show that keystone taxa in microbial community could change the community structure and function. However, most previous studies focus on abundant taxa but neglected low abundant ones. To clarify the seasonal variation of bacterial and microalgal communities and understand their synergistic adaptation to different environmental factors, we studied the bacterial and eukaryotic phytoplankton communities in Fenhe River that runs through Taiyuan City, central China, and their seasonal co-occurrence patterns using 16S and 18S rDNA sequencing. Results indicate that positive interaction of eukaryotic phytoplankton network was more active than negative one except winter, indicating that the cooperation (symbiotic phenomenon in which phytoplankton are interdependent and mutually beneficial) among them could improve the adaption of microbial community to the local environmental changes and maintain the stability of microbial network. The main genera that identified as keystone taxa in bacterial network were Salinivibrio and Sphingopyxis of Proteobacteria and they could respond to the variation of nitrite and make use of it, while those that identified as keystone taxa in eukaryotic phytoplankton network were Pseudoschroederia and Nannochloris, and they were more susceptible to nitrate and phosphate. Mychonastes and Cryptomonas were closely related to water temperature. However, the loss of the co-occurrence by environmental factor changes affected the stability of network structure. This study provided a reference for analyzing relationship between bacteria and eukaryotic phytoplankton and revealing potential importance of keystone taxa in similar ecological domains in carbon, nitrogen, and phosphorus dynamics.
      PubDate: 2022-05-31
       
  • Estimating the evolution of sea state non-Gaussianity based on a
           phase-resolving model

    • Free pre-print version: Loading...

      Abstract: Abstract The occurrence of rogue waves is closely related to the non-Gaussianity of sea states, and this non-Gaussianity can be estimated using corresponding two-dimensional wave spectra. This paper presents an approach to non-Gaussianity estimation based on a phase-resolving model called the high-order spectral method (HOSM). Based on numerous HOSM simulations, a set of precalculated non-Gaussianity indicators was established that could be applied to real sea states without any calibration of spectral shapes. With a newly developed extraction approach, the indicators for given two-dimensional wave spectra could then be conveniently extracted from the precalculated dataset. The feasibility of the newly developed approach in a real wave environment is verified. Using the estimation approach, phase-resolved non-Gaussianity can now be illustrated throughout the evolution of sea states of interest, not just at a few specific times; and the level of non-Gaussianity at any time in a duration can be identified according to the statistics (e.g., quantities) of the phase-resolved indicators, that are obtained throughout the duration concerned.
      PubDate: 2022-05-31
       
  • Changes in embryonic development, juvenile growth and physiological
           adaptation of the cuttlefish Sepia pharaonis in response to photoperiod
           manipulation

    • Free pre-print version: Loading...

      Abstract: Abstract Photoperiod is a key environmental indicator for regulating embryonic development, individual growth and physiological processes in aquatic animals. In this study, differences in embryonic development and performance of newly hatched cuttlefish juvenile exposed to five different cycles of lightdark (L:D): constant light, 18L:6D, 12L:12D, 6L:18D cycles, and constant darkness were evaluated. Prolonged exposure to light induced an accelerated rate of embryonic development, particularly after the red-bead stage. Principal component analysis (PCA) revealed that red-bead stage, heartbeat, endoskeleton formation, pigment appear, and six increments of cuttlebone were the main factors contributing to the embryonic development. Meaning that the duration time of these five stages were significantly different when exposed to photoperiod regimes, which may determine the duration of the incubation period of the embryos. Long term light has also affected the incubation parameters with an increased rate in hatching and shortened the incubation and hatching periods in the 12–24-h day length range. However, constant light and darkness environment appeared to have a greater effect on the stress of embryonic development, mainly reflected in the yolk shed ratio and the inking rate in the egg capsule. Moreover, the increase in the day length has contributed to improve the growth and survival of juveniles in the 12–18-h day length range; however, juveniles exposed to constant light and darkness experienced worse results in terms of growth, tissue glycogen content, digestive enzymes of the digestive glands, and metabolic enzymes of the muscles. These finding suggest that prolonged light exposure accelerates the process of embryonic development, maximum feeding time is not necessarily a condition of optimal growth, and inappropriate light cycles can disturb the body’s endogenous controls. Therefore, the optimal photoperiod for the embryos development and juvenile growth of Sepia pharaonis were 12 h and 12–18 h of day length, respectively. These results are useful for increasing the production of this species during embryo incubation and juveniles rearing in aquaculture practice.
      PubDate: 2022-05-31
       
  • Chloride-binding capacity of mortars composed of marine sand subjected to
           external chloride penetration

    • Free pre-print version: Loading...

      Abstract: Abstract In order to explore the interactional relations of internal chloride and external chloride-binding amongst the cementitious materials, the chloride-binding capacity of mortars composed of marine sand (MS) or washed marine sand (WMS) were investigated. Results indicate that more external chloride can penetrate and diffuse more deeply into the WMS mortar than that in the MS mortar. This phenomenon suggests that the external chloride migration resistance due to WMS is lower than that caused by MS. The distribution trends of the bound chloride content in the two types of mortars are the same at different immersion times. However, a significantly decreased area of the bound chloride content exists at the border of the external penetration area (EPA) and the external unaffected area (EUA) at the immersion ages of 3 and 7 d, and then it disappears gradually with immersion time. The WMS mortar can bind more external chloride, whereas the MS mortar can bind more internal chloride, at different immersion times. The distributions of bound chloride conversion rate in the EPAs of the two types of mortars differ across immersion times. The distribution firstly decreases, and then it increases at the immersion ages of 3 and 7 d. The distribution was from increase, then decreases, and increase again at the immersion ages of 28 and 56 d. The bound chloride conversion rate in the WMS mortar is affected more greatly by external chloride penetration than that in the MS mortar. The amounts of the Friedel’s salt tend to increase with prolonged immersion time. Finally, the penetration of external chloride can increase the amount of fine capillary pores smaller than 100 nm in the WMSmortar exposed for 56 d in the chloride salt solution (WMS-E) specimen.
      PubDate: 2022-05-31
       
  • Global air-sea CO2 exchange flux since 1980s: results from CMIP6 Earth
           System Models

    • Free pre-print version: Loading...

      Abstract: Abstract The ocean could profoundly modulate the ever-increasing atmospheric CO2 by air-sea CO2 exchange process, which is also able to cause significant changes of physical and biogeochemical properties in return. In this study, we assessed the long-term average and spatial-temporal variability of global air-sea CO2 exchange flux (FCO2) since 1980s basing on the results of 18 Coupled Model Intercomparison Project Phase 6 (CMIP6) Earth System Models (ESMs). Our findings indicate that the CMIP6 ESMs simulated global CO2 sink in recent three decades ranges from 1.80 to 2.24 Pg C/a, which is coincidence with the results of cotemporaneous observations. What’s more, the CMIP6 ESMs consistently show that the global oceanic CO2 sink has gradually intensified since 1980s as well as the observations. This study confirms the simulated FCO2 could reach agreements with the observations in the aspect of primary climatological characteristics, however, the simulation skills of CIMP6 ESMs in diverse open-sea biomes are unevenness. None of the 18 CMIP6 ESMs could reproduce the observed FCO2 increasement in the central-eastern tropical Pacific and the midlatitude Southern Ocean. Deficiencies of some CMIP6 ESMs in reproducing the atmospheric pressure systems of the Southern Hemisphere and the El Niño-Southern Oscillation (ENSO) mode of the tropical Pacific are probably the major causes.
      PubDate: 2022-05-31
       
  • Decadal variation and trend of the upper layer salinity in the South China
           Sea from 1960 to 2010

    • Free pre-print version: Loading...

      Abstract: Abstract Ocean salinity is an essential measurable indicator of water cycle and plays a crucial role in regulating ocean and climate change. Using Simple Ocean Data Assimilation (SODA) reanalysis product, substantial decadal variability of the salinity in the upper layer of the South China Sea (SCS) from 1960 to 2010 was examined. Results show that a decadal variation of the upper layer salinity is clear. The upper layer (100 m) waters are found to freshen from 1960, become saltier during 1975 to 1995, and freshen again from 1995 to 2010. The strongest anomalies appear in the northeastern, northern, and northwestern regions in the three periods, respectively. The salinity variation trends become weaker below the upper layer, except the salinification trend in the northern SCS extends to at least 300 m during the salinification period. Diagnosis of the salinity budget over the top 100 m shows that during the first freshening period horizontal advection, vertical advection, and surface freshwater forcing all contribute to salinity freshening, and horizontal advection is relatively larger. The contribution of horizontal advection and surface freshwater forcing to the positive salinity anomaly is comparable, while the vertical advection is the secondary factor in the salinification period. Horizontal advection, especially zonal advection, plays a crucial role during the second freshening period. Moreover, horizontal advection is more important than that in the first freshening period. In addition, the contribution of horizontal advection is mainly in zonal direction controlled by Kuroshio intrusion. Further analysis shows the upper-layer salinity variations have a Pacific Decadal Oscillation (PDO)-like signal, with freshening during the negative PDO years, and salinification during the positive PDO years. PDO mainly influences the upper-layer salinity changes through both atmospheric bridge and oceanic bridge.
      PubDate: 2022-05-31
       
  • Involvement of the ammonium assimilation mediated by glutamate
           dehydrogenase in response to heat stress in the scleractinian coral
           Pocillopora damicornis

    • Free pre-print version: Loading...

      Abstract: Abstract Glutamate dehydrogenase (GDH) plays an important role in the ammonium assimilation and nitrogen metabolism by catalyzing the reversible oxidative deamination of L-glutamate to α-ketoglutarate. In the present study, the potential functions of GDH in response to heat stress were explored in the scleractinian coral Pocillopora damicornis (designated as PdGDH). The cDNA of PdGDH contained an open reading frame of 1 611 bp encoding a polypeptide of 536 amino acids, which exhibited the highest sequence identity to GDH of Stylophora pistillata (96% identity), and the deduced PdGDH protein was predicted to contain one GdhA domain (from Val95 to Tyr525). The recombinant protein of PdGDH (rPdGDH) was expressed in Escherichia coli BL21 (DE3)-Transetta, and its catalytic activity was measured under different temperatures, pH conditions and epigallocatechin-3-gallate (EGCG, a GDH inhibitor) concentrations. The purified rPdGDH only used reduced coenzyme nicotinamide adenine dinucleotide (NADH) as coenzyme, and its highest activity was observed at 35 °C and pH 7.5, respectively. The rPdGDH activity was negatively correlated with the concentration of EGCG, and was inhibited by more than half (65%, P<0.05) at 10−4 mol/L EGCG. No significant alteration of PdGDH mRNA expression was detected at 12 h after exposure to heat and ammonium (P>0.05). Furthermore, the activities of NADH-GDH in the scleractinian coral P. damicornis increased significantly at 12 h after the heat and ammonium stress, and the NADH-GDH activity in the heat stress group (32.66 U/mg, P<0.05) was significantly higher than that in the heat and ammonium stress group (11.26 U/mg). These results collectively suggested that PdGDH, as a homologue of glutamate dehydrogenase in the scleractinian coral P. damicornis, could respond to heat stress at the protein level, which would have ability to further promote ammonium assimilation to increase the heat acclimatization of the coral-Symbiodiniaceae symbiotic association.
      PubDate: 2022-05-31
       
  • Observation of physical oceanography at the Y3 seamount (Yap Arc) in
           winter 2014

    • Free pre-print version: Loading...

      Abstract: Abstract Seamounts affect the surrounding physical oceanography and form unique dynamic processes. The influences of these processes on biological and sedimentary distributions are quite different in seamount areas at different depths. The Y3 seamount is located in the Yap Arc of the tropical Western Pacific Ocean. The water depth of its summit is ∼280 m. Based on field data obtained in December 2014 and other open-access data, the physical oceanography around the Y3 seamount was preliminarily analyzed. The results show that the upper layer (0–150 m) was under the influence of the westward-flowing North Equatorial Current (NEC), while the eastward-flowing North Equatorial Undercurrent (NEUC) controlled the water between 200–800 m. The NEC was strong and steady, but the NEUC was disturbed by the Y3 seamount. The cold dome above the Y3 seamount was not caused by a Taylor cap or tidal rectification but probably by upwelling during the survey time. Tidal currents were squeezed against topography and greatly amplified in the Y3 seamount. The thicknesses of the surface turbulent layers were greatly influenced by the spring-neap tidal cycle. The turbulent diffusivities in the sea surface layer above the Y3 seamount were much larger than those in the open ocean. Calculations showed that the surface wind stress greatly affected the turbulent mixing in the surface layer of the Y3 seamount. The reciprocal action between the amplified tidal currents and topography was the most likely cause of the turbulent mixing near the bottom of the Y3 seamount. This study can provide a scientific basis for further study of biological and depositional characteristics at the Y3 seamount.
      PubDate: 2022-05-31
       
  • Erratum to: Impact of typhoon Lekima (2019) on material transport in
           Laizhou Bay using Lagrangian coherent structures

    • Free pre-print version: Loading...

      PubDate: 2022-05-01
       
  • Erratum to: Chinia gen. nov.—the second diatom genus simonsenioid raphe
           from mangroves in Fujian, China

    • Free pre-print version: Loading...

      PubDate: 2022-05-01
       
  • Examination of seasonal variation of the equatorial undercurrent
           termination in the Eastern Pacific diagnosed by ECCO2

    • Free pre-print version: Loading...

      Abstract: Abstract Seasonal variations of the equatorial undercurrent (EUC) termination in the Eastern Pacific, and their mechanism were examined using the Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2). The ECCO2 reproduced a weak and shallow eastward EUC east of the Galapagos Islands, with annual mean transport of half of EUC to the west of the Islands. The diagnosis of zonal momentum equation suggests that the zonal advection (nonlinear terms) drives the EUC beyond the Islands rather than the pressure gradient force. The EUC in the Far Eastern Pacific has the largest core velocity in boreal spring and the smallest one in boreal summer, and its volume transport exhibits two maxima in boreal spring and autumn. The seasonal variability of the EUC in the Eastern Pacific is dominated by the Kelvin and Rossby waves excited by the zonal winds anomalies in the central and Eastern Pacific that are associated with the seasonal relaxation or intensification of the trade wind. In the Far Eastern Pacific to the east of 120°W, the eastward propagation Kelvin waves play a dominate role in the seasonal cycle of the EUC, results in a semiannual fluctuation with double peaks in boreal spring and autumn. A construction of water mass budget suggests that approximately 24.1% of the EUC water east of 100°W has upwelled to the mixed layer by 0.35 m/d. The estimated upwelling is strongest during boreal autumn and weakest during boreal winter. It is also found that approximately 42.6% of the EUC turns westward to feed the south equatorial current (SEC), 13.2% flows north of the equator, and 20.1% flows south of the equator, mainly contributing to Peru-Chile undercurrent.
      PubDate: 2022-05-01
       
  • A low-cost in-situ CO2 sensor based on a membrane and NDIR for long-term
           measurement in seawater

    • Free pre-print version: Loading...

      Abstract: Abstract The multi-point simultaneous long-term measurement of CO2 concentration in seawater can provide more-valuable data for further understanding of the spatial and temporal distribution of CO2. Thus, the requirement for a low-cost sensor with high precision, low power consumption, and a small size is becoming urgent. In this work, an in-situ sensor for CO2 detection in seawater, based on a permeable membrane and non-dispersive infrared (NDIR) technology, is developed. The sensor has a small size (Þ 66 mm×124 mm), light weight (0.7 kg in air), low power consumption (<0.9 W), low cost (<US$1 000), and high-pressure tolerance (<200 m). After laboratory performance tests, the sensor was found to have a measurement range of (0–2 000)×10−6, and the gas linear correlation R2 is 0.99, with a precision of about 0.98% at a sampling rate of 1 s. A comparison measurement was carried out with a commercial sensor in a pool for 7 days, and the results showed a consistent trend. Further, the newly developed sensor was deployed in Qingdao nearshore water for 35 days. The results proved that the sensor could measure the dynamic changes of CO2 concentration in seawater continuously, and had the potential to carry out long-term observations on an oceanic platform. It is hoped that the sensor could be applied to field ocean observations in near future.
      PubDate: 2022-05-01
       
  • Description of two new species of Pseudoaliinostoc (Nostocales,
           Cyanobacteria) from China based on the polyphasic approach

    • Free pre-print version: Loading...

      Abstract: Abstract Two cyanobacterial strains CHAB5870 and CHAB5871 morphologically identified as Nostoc-like species were isolated from different habitats in China, and they were phylogenetically and taxonomically characterized based on a polyphasic approach combining morphological, ecological, and molecular data. In the 16S rRNA gene phylogeny inferred using maximum likelihood, maximum-parismony, and bayesian inference methods, these two strains clustered within the Pseudoaliinostoc clade. The 16S rRNA gene sequences of these two strains displayed ≥95.5% and ≤98% similarity to Pseudoaliinostoc species, which indicated them to represent new species of the genus Pseudoaliinostoc. Furthermore, the unique pattern of D1–D1′ and Box-B helix of the 16S–23S rRNA internal transcribed spacer (ITS) secondary structure also revealed that two strains represented novel species. These results supported the establishment of two new Pseudoaliinostoc species with the name P. jiangxiense sp. nov. and P. yunnanense sp. nov.
      PubDate: 2022-05-01
       
  • Coastal buoy observation of air-sea net heat flux in the East China Sea in
           summer 2020

    • Free pre-print version: Loading...

      Abstract: Abstract The full fluxes and associated air-sea variables based on three months of operational buoy observations in the East China Sea (ECS) in summer 2020 were analyzed for the first time. The surface net heat flux (Qnet) was positive (139.7±77.7 W/m2) and was dominated by the combined effects of solar shortwave radiation (SW) and latent heat fluxes (LH). The mean heat flux components of 4 reanalysis datasets (NCEP2, MERRA-2, CFSR, and ERA5) and buoy data were compared to assess the mean ability of the modeling/reanalysis simulation. Among the four components of air-sea flux, SW was the best simulated, while LH was the worst simulated. The longwave radiation (LW) and LH values from reanalysis were higher than those from buoy data, especially LH. The high LH resulted in low Qnet. Furthermore, the 4 reanalysis datasets were compared with the buoy dataset. Among all flux products, the difference in radiation flux was the smallest, while that in the turbulent flux was the greatest. The observed variables related to turbulent flux were analyzed to help determine the cause of the flux discrepancies. High wind speeds were the main cause of this difference. Using the variables provided by the reanalysis data and the same bulk formulas of the Coupled Ocean-Atmospheric Response Experiment (COARE 3.0), we found that the recalculated sensible heat flux (SH) and LH were closer to the observed heat fluxes than the direct model outputs. The significant differences between these methods could account for the discrepancies among different data. Among all air-sea flux products, the air-sea flux in ERA5 was closer to the in-situ observations than the other products. The comparison results of reanalysis data provide an important reference for more accurate studies of the summer heat flux in the ECS at the synoptic and climatic scales.
      PubDate: 2022-05-01
       
  • Characterization of Amphidinium (Amphidiniales, Dinophyceae) species from
           the China Sea based on morphological, molecular, and pigment data

    • Free pre-print version: Loading...

      Abstract: Abstract Amphidinium species are amongst the most abundant benthic dinoflagellates in marine intertidal sandy ecosystems. Some of them are able to produce a variety of bioactive compounds that can have both harmful effects and pharmaceutical potentials. The diversity of Amphidinium in shallow waters along the Chinese coast was investigated by isolating single cells from sand, coral, and macroalgal samples collected from 2012 to 2020. Their morphologies were subjected to examination using light microscopy (LM) and scanning electron microscopy (SEM). A total of 74 Amphidinium strains were morphologically identified, belonging to 11 species: A. carterae, A. gibbosum, A. operculatum, A. massartii, A. cf. massartii, A. fijiensis, A. pseudomassartii, A. steinii, A. thermaeum, A. theodori, A. tomasii, as well as an undefined species. The last seven species have not been previously reported in Chinese waters. Amphidinium carterae subclades I, II, and IV were found in the South China Sea, while subclade III was only found in the Yellow Sea. Threadlike body scales were observed on the surface of subclades III and V, supporting the idea that A. carterae might contain several different species. Large subunit ribosomal RNA (LSU rRNA) sequences-based phylogeny revealed two groups (Groups I and II) within Amphidinium, which is consistent with the relative position of sulcus (in touch with cingulum or not). In addition, large differences in morphology and molecular phylogeny between A. operculatum (the type species of Amphidinium) and other species, suggest that a subdivision of Amphidinium might be needed. The pigment profiles of all available strains were analyzed by high performance liquid chromatography (HPLC). Eleven pigments, including peridinin, diadinoxanthin, diatoxanthin, pheophorbide (and pheophorbide a), antheraxanthin, β-carotene, and four different chlorophylls were detected. The high pheophorbide/pheophorbide a ratio in Amphidinium implies that it may be a good candidate as a natural source of photosensitizers, a well-known anticancer drug.
      PubDate: 2022-05-01
       
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
 


Your IP address: 18.207.133.27
 
Home (Search)
API
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-