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Ocean Science Journal
Journal Prestige (SJR): 0.262
Citation Impact (citeScore): 1
Number of Followers: 6  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1738-5261 - ISSN (Online) 2005-7172
Published by Springer-Verlag Homepage  [2467 journals]
  • A Biological Indication of Vertical Mixing of the Yellow Sea Bottom Cold
           Water

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      Abstract: Abstract The identities and origins of water masses in mixed seawater can be effectively traced by comprehensively analyzing physicochemical and biological data. In this study, distribution of an indicator species of the Yellow Sea Bottom Cold Water, Tintinnidium primitivum, was monitored to trace vertical mixing across seasons along the 35 °N line from 2019 to 2022. A bottom-oriented distribution was observed in every season except for winter. Winter vertical mixing was supported by water temperature and salinity profiles and the homogenous distribution of T. primitivum throughout the water column at Stns. 35-11 and 35-13. The absence of this species in response to the difference in the low-salinity surface water mass at Stn. 35-15 during winter indicated the invasion of shallow water mass from China. The sensitivity of this species to such hydrological changes provides a valuable insight into the vertical migration of the YSBCW.
      PubDate: 2023-01-13
       
  • Influence of Nutrient Gradient on Phytoplankton Size Structure, Primary
           Production and Carbon Transfer Pathway in a Highly Productive Area (SE
           Mediterranean)

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      Abstract: Abstract We assessed the spatial variability in the size structure of phytoplankton, community composition, primary production and carbon fluxes through the planktonic food web of the Gulf of Gabès (GG; Southeastern Mediterranean Sea) in the fall of 2017 during the MERMEX-MERITE cruise. High concentrations in nutrients, chlorophyll a (~ 2–6 µg L−1) and primary production (1816–3674 mg C m−2 d−1) revealed an eutrophic status of the studied stations in the GG. In accordance with hydrodynamic features, inorganic nutrients showed increases in concentrations from North to South and from coast to offshore, these nutrient gradients impacting the spatial distribution of phytoplankton community. Size-fractioned phytoplankton biomass and production were the lowest in the northernmost zone where they were mainly sustained by pico-sized fraction. Concomitantly, in this area, small aloricate ciliates were dominant leading to a high microbivory. Conversely, higher biomass and production were measured towards the South and offshore with prevalence of larger phytoplankton (nano- and/or micro-sized fractions) supported by diatoms. The herbivorous protozooplankton and metazooplankton were more abundant in these zones, resulting in an increase of the herbivory. The vertical particulate organic carbon flux followed also a north–south and coast-offshore increasing gradient, with a higher contribution of phytoplankton, and zooplankton fecal pellets to the sinking organic matter in the southernmost area. Our results suggest that even in nutrient-rich and highly productive waters, a continuum of trophic pathways, ranging from microbial to multivorous and herbivorous food webs, may exist, which implies different efficiencies in carbon export and carrying capacity within the ecosystem.
      PubDate: 2023-01-13
       
  • Sea Urchin Removal and Effectiveness Evaluation from the Long-Term
           Monitoring Data in Dokdo, Korea

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      Abstract: Abstract Dokdo is located 215 km away from the Korean Peninsula and is not affected by anthropogenic impacts. In this area, barren grounds developed between the late 1990s and early 2000s. The Korean government has measured the average urchin density from 1 to 10 sampling stations around Dokdo during 2006–2020 and has been conducting urchin removal projects annually since 2015 all around the bottom of Dokdo within depths of 5–20 m. Here, we implemented an additive decomposition method for time series analysis of the collected data. The timeline was divided into two periods: sample data period for predicting the urchin density (2006–2016) and intervention period (2016–2020). A trend model was estimated from the de-seasonalized data of the prediction period. Subsequently, forecasts were compared with the corresponding observations of the intervention period. While the forecasts reflected the spread of barren grounds and sea urchins, the actual urchin density during the intervention period decreased. On comparing the macroalgal coverage between the springs of 2017 and 2020, the samples with coverage less than 20% decreased from 50% in 2017 to 0% in 2020, while those with 21–40% coverage increased from 30% in 2017 to 90% in 2020. These changes confirmed the effect of urchin removal, and, based on this and other studies, an effective threshold of urchin density/biomass of two individuals and 140–150 g/m2 was suggested as the target criterion. The study proved the urchin removal as an effective solution to recover macroalgal beds in Dokdo.
      PubDate: 2023-01-04
       
  • Effects of Hydrodynamic Disturbance on Vegetation Development in Coastal
           Salt Marshes: A Model Study in Jiangsu, China

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      Abstract: Abstract Salt marshes are now known to improve coastal safety by attenuating waves and stabilizing the bed. Meanwhile, for salt marsh conservatin and restoration, a great deal of research has been done on the establishment mechanism of vegetation in salt marshes. However, research on the effects of hydrodynamic disturbance on the development of salt marsh vegetation is limited. The purpose of this paper is to investigate how the hydro-morphodynamic process affects the establishment and expansion of plants in salt marshes and to simulate the establishment process. First, we used a 2D finite-element model to simulate hydro-morphodynamics in the selected tidal flat in Jiangsu, China. We then defined the variables describing the frequency and magnitude of hydrodynamic disturbance and quantified the effects of disturbance on plant establishment using Spearman correlation coefficients. Finally, the vegetation development process was further analyzed using a logistic regression model, and the vegetation development in the study area was simulated from 2017 to 2021. The results show that salt marsh vegetation colonization has a relatively high correlation with flooding time and bed shear stress (ρ > 0.6), and bed shear stress is the main hydrodynamic disturbance parameter limiting further expansion of salt marsh vegetation. The method combining hydrodynamic modeling and logistic regression has the potential to be used to identify hydrodynamic disturbances in future salt marsh restoration and management processes and to help design appropriate restoration measures.
      PubDate: 2023-01-04
       
  • Estimating Bed Shear Stress Distribution over Bottom of a Channel on the
           Moving Vessel

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      Abstract: Abstract Shear stress is critical in the determination and estimation of bedload transport and morphological changes. Generally, the bed shear stress is estimated in fields using three-dimensional flow velocities acquired by an acoustic Doppler velocimeter and current profiler mounted on the channel bottom or anchored vessel. The temporal measurement and estimation of the bed shear stress by the conventional methods in a fixed point must be significantly close to the actual bed shear stress; however, the conventional methods may not provide sufficient information of spatial distribution of the bed shear stress over the entire domain, i.e., the measurements in several fixed points cannot guarantee that the measured values represent the entire domain of interest. Therefore, the present work proposed a framework for acquiring the spatial distributions of shear stress over a domain. Accordingly, a reach with a length and width of 5.6 km and 250 m, respectively, at the end of the Hyeongsan River in South Korea was surveyed through the moving-vessel measurement with ADCP measuring the velocities of that channel reach to estimate shear stress. To collect over a possible maximum spatial domain in a short duration, the moving-vessel technique was applied over the survey region without stopping a vessel. The measurement was conducted in a series of single zigzag transects instead of repeatedly transects over a same cross section. The spiked noises of velocity were observed in high frequencies at a single transect and so the noises were smoothed by moving average over a reasonable circular space. After the spatial interpolation, the accuracy of the spatial distributions of the bed shear stress was compared to the anchored-vessel measurement, and the reliable bed shear stress map was provided as a result.
      PubDate: 2023-01-04
       
  • Chemical Speciation of Dissolved Copper in the Nakdong River Estuary and
           Its Relationship with Humic-Like Fluorescent Dissolved Organic Matter

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      Abstract: Abstract The total dissolved copper (Cu) concentrations, chemical speciation, and intensities of humic-like fluorescent dissolved organic matter (FDOMH) components were determined in the Nakdong River Estuary. The concentrations of total dissolved Cu ranged from 4.6 to 13.3 nM and showed an inverse correlation with salinity (R2 = 0.93), indicating a conservative mixing trend in the Nakdong River Estuary. The chemical speciation of dissolved Cu was determined by competitive ligand equilibrium adsorptive cathodic stripping voltammetry, and speciation parameters were calculated using ProMCC software. The concentrations of the strong Cu-binding organic ligands (L1) ranged from 3.1 to 96 nM, whereas those of the weak ligand (L2) ranged from 10 to 3400 nM. Both L1 and L2 concentrations were relatively high at the upper sampling sites (river water sites) and decreased in proximity to the coastal sea, indicating that Cu-binding organic ligands from terrestrial sources may be dominant in the Nakdong River Estuary. Although Cu-binding organic ligands showed positive correlations with FDOMH, anomalously high concentrations of Cu-binding organic ligands were observed at river water sites, suggesting additional sources of organic ligands. Our results suggest that Cu-binding organic ligands originated from various sources in estuarine environments.
      PubDate: 2023-01-04
       
  • Sea Surface Temperature and Phytoplankton Abundance as Crucial Proxies for
           Green Noctiluca Bloom Monitoring in the Northeastern Arabian Sea: A Case
           Study

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      Abstract: Abstract Green Noctiluca scintillans (NSG) is a mixotrophic dinoflagellate that frequently forms intense blooms in the north Indian Ocean, especially in the northeastern Arabian Sea during winter. This study investigates the conducive conditions and drivers associated with NSG blooms and proposes significant models for estimating NSG based on in situ (time-series) study during the bloom cycles. Two critical factors with regard to the blooms, i.e., phytoplankton abundance and sea surface temperature (SST), were examined. The first phase of heterotrophy dominance was when moderate blooms up to ~ 2.26 × 104 cells 1–1 occurred and, when NSG cells per unit chlorophyll-a (chl-a) increased, SST decreased up to ~ 24.5 ºC. The bloom intensity was proportional to the feed (diatoms/phytoplankton) availability and the degree of cooling (by the winter convection, i.e., nutrient enrichment). In the second phase of autotrophy dominance, intense blooms up to 1.9 × 105 cells l−1 occurred and NSG cells per unit chl-a fell, when the SST increased. During this period, bloom intensity was proportional to the degree of warming, i.e., nutrient and physiological stress. Phytoplankton are related to NSG by a single linear model through this SST cycle and is likely the NSG’s essential biotic precursor. Attention is then focused on developing a remote sensing reflectance (Rrs) model for efficient synoptic monitoring of NSG using ocean color satellites. The Rrs band product ratio, a new metric, in combination with SST, notably modelled NSG abundance, which may be of potential routine application.
      PubDate: 2023-01-04
       
  • Gulf of Urabá (Caribbean Colombia), a Tropical Estuary: A Review with
           Some General Lessons About How it Works

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      Abstract: Abstract Estuaries are highly diverse ecosystems that occur at the interface between land and sea and thus possess a high degree of environmental variation over short spatial and temporal scales. The Gulf of Urabá (1800 km 2; mean depth ~ 40 m) is a semiclosed estuarine area located in the southwestern part of the Caribbean Sea (South America). This large coastal–estuarine ecosystem operates as a biogeochemical reactor due to it featuring examples of high nutrient concentrations on the surface (NO 3- = 1619 μM; NO 2- = 0.505 μM; NH 4+  = 2.938 μM; PO 4 3- = 7.603 μM), high Chl α (max = 30.17; min = 0.02; mean = 9 mg m−3), as well as blooms of toxic algae, mostly Pseudo-nitzschia pseudodelicatissima. An outbreak of Tripos fusus causes bioluminescence and about 20 events of hypoxia (< 2–4 mg O 2 L−1) within a time series of 10 years. Despite this, information regarding the biological and biogeochemical oceanography (chlorophyll α, biomass, planktonic composition, nutrient cycling, mass balance of elements, and interannual variability) remains non-existent. Therefore, elucidating an ecosystem’s thresholds for various features is necessary for managing marine ecosystems, and especially for climate change projections. We here present a review of the functioning of this estuary, evaluating and reviewing each aspect of oceanographic variability.
      PubDate: 2022-12-02
       
  • Comparing Environmental DNA Metabarcoding and Underwater Visual Census to
           Monitor Korean Coastal Fish Community

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      Abstract: Abstract This study conducted underwater visual census (UVC) and eDNA metabarcoding to survey fish fauna in the coastal waters off Busan (Cheongsapo) and Ulsan (Bangeojin), Southeast sea of Korea, after which the two survey methods were compared. A total of 49 species were identified in Cheongsapo (eDNA metabarcoding: 29 species; UVC: 29 species) and 60 were identified in Bangeojin (eDNA metabarcoding: 43 species; UVC: 30 species), which accounted for 70 species in both areas. Except for 13 species without GenBank sequence data, 80% of the species detected using UVC were detected through eDNA metabarcoding. In addition, eDNA metabarcoding enabled the detection of 33 species that were otherwise not detected by UVC. Thus, eDNA can be used to conduct fast and wide fish diversity surveys and is applicable to microhabitats in coastal areas. Therefore, eDNA could become an important complement to traditional surveys for monitoring marine biodiversity.
      PubDate: 2022-12-01
       
  • Meiofauna and Nematode Community Composition in Maxwell Bay, King George
           Island, Antarctica

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      Abstract: Abstract The Antarctic Ocean hosts several species adapted to polar environments. However, the Antarctic marine environment is rapidly changing. We studied the meiofauna and nematode communities in Maxwell Bay, King George Island, Antarctica. The meiofaunal densities ranged from 174.3 ± 6.2 to 377.9 ± 7.0 individuals/10 cm2. The nematodes and harpacticoids accounted for 89.7% of the total meiofaunal density. A total of 1448 nematode individuals across 34 genera were recorded. The dominant nematode genus was Molgolaimus. This study offers guidance for future studies on polar benthic organisms and a reference to evaluate anthropogenic effects on polar ecosystems.
      PubDate: 2022-11-09
      DOI: 10.1007/s12601-022-00092-w
       
  • Numerical Study of Influencing Factors on Tidal Wave Propagation in the
           Persian Gulf

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      Abstract: Abstract A 2D hydrodynamic model is employed to study the characteristics of tidal wave propagation in the Persian Gulf (PG). The study indicates that tidal waves propagate from the Arabian Sea and the Gulf of Oman into the PG through the Strait of Hormuz. The numerical model is first validated using the measured water levels and current speeds around the PG and the principal tidal constituents of Admiralty tide tables. Considering the intermediate width of the PG, in comparison to the Rossby deformation radius, the tidal wave propagates like a Kelvin wave on the boundaries. Whereas the continental shelf oscillation resonance of the basin is close to the period of diurnal constituents, the results show that the tide is mixed mainly semidiurnal. A series of numerical tests is also developed to study the various effects of geometry and bathymetry of the PG, Coriolis force, and bed friction on tidal wave deformation. Numerical tests reveal that the Coriolis force, combined with the geometry of the gulf, results in the generation of different amphidromic systems of diurnal and semidiurnal constituents. The configuration of the bathymetry of the PG, with a shallow zone at the closed end of the basin that extends along its longitudinal axis in the southern half (asymmetrical cross section), results in the deformations of incoming and returning tidal Kelvin waves and consequently the shifts of amphidromic points (APs). The bed friction also results in the movements of the APs from the centerline to the south border of the gulf.
      PubDate: 2022-11-07
      DOI: 10.1007/s12601-022-00091-x
       
  • Sub- and Marine Mediterranean Basin Antimicrobial Resistance and
           Environmental Concerns: A Case Study of Tunisia

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      Abstract: Abstract Antibiotics are a growing contaminant of substantial concern, principally in the aquatic environment, because of their pseudo-persistence and biological activity, and they have received a lot of attention in the recent decade. The spread of antibiotic-resistant bacteria and their antibiotic-resistant genes have showed expansion in most natural surroundings, including water, soil, and sediments, causing and presenting health problems for humans and animals. The ecological impact and environmental concerns of antibioresistance in aquatic and littoral habitats are highlighted in this review. Antibiotic pollution levels in marine, coastal water lakes, and river water flowing into the Mediterranean Sea were reported in all gathered data. Likewise, this paper showed that there was a significant lack of data and information about this pollution in seawater and general aquatic environments, revealing a substantial difficulty in following and studying these new qualities of pollutants and their main fates in natural environments. Also, their impact on the marine and lake environment in terms of the emergence of drug-resistant bacteria and drug-resistant genes was described.
      PubDate: 2022-10-25
      DOI: 10.1007/s12601-022-00090-y
       
  • Influence of the Cape Angle and Flow Speed on Eddy Formation and
           Detachment: Experimental Results and Comparison with North Brazil Current
           Eddies

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      Abstract: Abstract The quasi-periodic formation of eddies during retroflection of an initially steady surface current is addressed by experimental modeling and observations. The retroflection process was simulated for various conditions, corresponding to different combinations of a cape angle and surface current speed. The simulations were conducted on a stratified domain under rotation. Results indicate that eddy size and shape, and detaching frequency depend on cape angle, not on upstream speed. Eddies detach at a higher rate for 40 \(^\circ\) and 80 \(^\circ\) cape angles. Other configurations did not show either a regular eddy formation nor detaching. Eddy size was related to the internal Rossby radius of deformation ( \(R_{d}\) ) as predicted by theory. Current displacement toward the rotation axis in our experiments prior to eddy detachment was from 3.1 to 3.5 \(R_{d}\) . Retroflection angle was proportional to detachment T for each cape angle: 6T for 80 \(^\circ\) , and 3T for 40 \(^\circ\) , where T is the rotation period of the turn table. We conclude that eddy detachment is a result of eddy angular momentum increase from the momentum flux of the steady current. Similarity was analyzed with retroflection present in the North Brazil Current. Eddy vorticity profile and dimensionless quantities related to moving speed and eddy size in the oceanic flow agree with our results.
      PubDate: 2022-09-15
      DOI: 10.1007/s12601-022-00087-7
       
  • Study of Shoreline Changes Through Digital Shoreline Analysis System and
           Wave Modeling: Case of the Sandy Coast of Bou-Ismail Bay, Algeria

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      Abstract: Abstract This work aims to analyze the evolution of Bou-Ismail coastline in Algeria using aerial photographs and quick-bird satellite image during the elapsed period from 1959 to 2017 combined with a numerical modeling of waves, currents and sediments transport. The digital shoreline analysis system (DSAS) was used to quantify shoreline changes. Furthermore, the end point rate (EPR) and the net shoreline movement (NSM) approaches were used to study the evolution of this sandy coast. In addition, numerical modeling of waves, currents and sediment transport using SWAN and Mike 21 FM models were performed to better understand the longshore dynamic process and identify the waves characteristics that contributed to the evolution of the study area's shoreline. The shoreline change results show that the study area was in a moderate accretion state between 1959 and 1984 with an average end point rate of 0.13 m/year. This state turned negative and became alarming from 1984 to 1999 when EPR decreased to − 0.554 m/year. Nevertheless, the period between 1999 and 2017 is characterized by a stabilization state or even moderate accretion that translates into equivalent EPR of 0.02 m/year. The numerical simulation results show that the sandy coast of Bou-Ismail is directly exposed to waves coming from north and northwest with possible induced return currents which could be responsible for the coastal erosion observed in the study area, while northeast and northwest waves can produce a littoral drift contributing to the nourishment of some beaches of Bou-Ismail bay.
      PubDate: 2022-09-14
      DOI: 10.1007/s12601-022-00083-x
       
  • Erratum to: Spatio-Temporal Variation of the M2 Tidal Current from Field
           Observations in the Jeju Strait

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      PubDate: 2022-09-13
      DOI: 10.1007/s12601-022-00088-6
       
  • Reproductive and Growth Parameters of the Razor Clam, Cultellus maximus
           (Gmelin, 1791), in Southern Vietnam

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      Abstract: Abstract This study aimed to analyze the sex ratio, spawning seasons, length at first maturity, length distribution, length–weight relationship, and relative condition factor of Cultellus maximus (Gmelin, 1791) in Southern Vietnam. A total of 1037 individuals of C. maximus were collected at 3 sampling sites from June, 2019 to June, 2020. The sex ratio was found to be female biased in Can Gio and male biased in Phu Tan and Ngoc Hien. The clam spawns throughout the year, peaking at Q2 and Q3 during the rainy season. Pooled length at first maturity was 10.12 cm (9.65–10.49 cm CI 95%, P-value < 2.2·10–16). The length–weight relationship indicates positive allometric growth. This study suggests that imposing a minimum harvest size limit on C. maximus using the length at first maturity as reference and with harvest seasons in Q1 in Ngoc Hien and Can Gio and Q2 or Q3 in Phu Tan would be ideal for consumption of this species.
      PubDate: 2022-09-02
      DOI: 10.1007/s12601-022-00089-5
       
  • Estimation of Potential Habitats for Three Species of Bivalves Using the
           Habitat Variables in Gomso Bay Tidal Flat, Korea

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      Abstract: Abstract The gradual changes in the habitat of Gomso Bay negative impacted the intertidal flat aquaculture of the Manila clam Ruditapes philippinarum. The habitat evaluation of the Manila clam in Gomso Bay tidal flat that should be preceded to identify this negative impact in clam culture was conducted using the habitat variables chlorophyll-a, hydrodynamics, sediment sand, exposure time, dissolved oxygen, and salinity. Additionally, to utilize the unsuitable sites of Manila clam culture, we used the habitat suitability index by subdividing substrate variables (sorting coefficient, silt content, and mean grain size) for two species (Cyclina sinensis and Mactra veneriformis). As a result, the lower flat was chosen as the optimal habitat for Manila clam, with a habitat suitability index mean score of 0.62 and the upper flat was deemed to be the potential habitat for C. sinensis, while the middle flat was chosen for M. veneriformis. Therefore, the possibility of using unsuitable sites for Manila clam farming as alternative species was identified. These findings can be used as a reference for optimal site selection for the diversification of commercial species and decentralization of clam culture farms in the Gomso Bay tidal flat.
      PubDate: 2022-08-04
      DOI: 10.1007/s12601-022-00085-9
       
  • Spatio-Temporal Variation of the M2 Tidal Current from Field Observations
           in the Jeju Strait

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      Abstract: Abstract The variability in the tidal current in the Jeju Strait was investigated based on sea surface current fields observed by a high-frequency (HF) radar and vertical current profiles observed by three bottom-moored acoustic Doppler current profilers (ADCPs). The monthly M2 tidal current, the most dominant constituent in the study area, had significant temporal variability, and there were spatial changes in the temporal variation trend. While the semi-major axis of the M2 tidal current in winter was stronger than that in summer in some parts of the HF radar observation range, the summertime semi-major axis was stronger than that in wintertime in other parts of the observation range. Both opposite trend areas coexisted within the HF radar coverage area of several tens of kilometers. The vertical structure of the tidal currents in winter was similar to the theoretical structure in which Ekman dynamics was applied under depth-independent vertical eddy viscosity, and the year-to-year change was weak. In contrast, the vertical structure of the tidal currents in summer significantly varies over depth and years. Furthermore, the seasonal variation patterns at the three ADCP stations differed spatially. The temporal and spatial variability of tidal currents could be explained as a result of the strengthening stratification and, consequently, semidiurnal internal tides in summer. In summer, an internal tide with a wavelength of tens of kilometers could be generated in the vicinity of and propagate into the study area. The overlapping and offsetting of the barotropic and internal tidal components within the HF radar observation range caused complex spatial variations.
      PubDate: 2022-08-01
      DOI: 10.1007/s12601-022-00084-w
       
  • Multi-proxy Stratigraphy and Paleoceanographic Variations in Sediment from
           the Korea Plateau, East Sea (Japan Sea), Over the Last 500 kyr

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      Abstract: Abstract High-resolution geochemical measurements were performed on core E09-08, which was taken from the top flat area of the Korea Plateau in the East Sea (Japan Sea). Based on analyses of sedimentary lamination, high-resolution oxygen isotopes, alkenone sea surface temperature (SST) variations, and comparison with previous results from the eastern part of the East Sea, a detailed multi-proxy-based stratigraphy was reconstructed. The results demonstrated that the core bottom dates approximately 500 kyr in the late marine isotope stage (MIS) 13, and provides high-resolution data on the paleoceanographic regime in the study area. Biogenic components of total organic carbon (TOC), carbon and nitrogen isotopes of organic matter (δ13Corg and δ15Norg), and alkenone concentrations indicate a paleoceanographic regime shift within the last 500 kyr. The excursion of proxies of δ18O, δ13Corg and δ15Norg and alkenone-based SST indicate two modes of oceanographic conditions: strong negative coupled mode (SNCM) during MIS 2, 10, and 12, and normal oceanographic decoupled mode (NODM) during other MIS. These two modes were interpreted as the terrestrial organic matter source domain and high-productivity oceanographic domain, respectively. The SNCM is characterized by relatively low δ13Corg and δ15Norg, and a high C/N ratio (> 12), whereas the NODM is characterized by relatively high δ13Corg and high δ15Norg, implying that larger amounts of terrestrial material were supplied during MIS 2, 10 and 12, with enhanced productivity during other MIS. The SNCM and NODM mode are also strongly associated with eustatic sea-level changes. The δ13Corg and δ15Norg values and alkenone-based SST excursions over glacial-interglacial periods were generally consistent with global-scale paleoclimate variation, as well as local paleoclimate. This study employed multi-proxy-based stratigraphy to demonstrate dramatic oceanographic variations since MIS 13, indicating that the local oceanographic setting was superimposed on global glacial-interglacial variations.
      PubDate: 2022-06-14
      DOI: 10.1007/s12601-022-00076-w
       
  • Seasonal Growth Dynamics of Posidonia oceanica in a Pristine Mediterranean
           Gulf

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      Abstract: Abstract Seasonal growth dynamics and ecology of Posidonia oceanica were studied in a space alongshore a pristine Mediterranean gulf in 2011–2012. About one-third of the present study surface area was occupied meadows where only calcite rocks were found on bottoms between 0.5 and 29 m. Shoot density was not significantly different among seasons, and was above 364 ± 27 shoots m−2, but was different among the depths. The density variables decreased along the bottom depth gradient along which the number of leaves per shoot, inter shoot distance and the morphometrical variables tended to increase. Inferring the dynamics of biometrics (length and width of leaf, orthotropic rhizomes and leaf sheath) and density (LAI, leaf biomass and the number of leaves per shoot), the biometrics of the meadow grew seasonally between growth by March and mortality by August–September, regardless of the coverage area. Mortality occurred due to the highest annual salinity in late summer. A transition depth in space and month in time was assessed as 15 m and as August for variation of the biometrics, respectively. Rhizome related-biometrics (length, thickness, weight, sheath length and width) were dynamically initialized mainly by water nitrogen content which was high by winter-spring. A PAR in the range of 10–32%, and surface water temperature up to 28.8–29.3 °C corresponding to up to ~ 40 PSU were critical limiting factors for P. oceanica to survive in space. Water physics, chemistry, and optical properties governed the annual course of biometrics. Total organic carbon was also negatively affecting the seasonal dynamics of the rhizome.
      PubDate: 2022-06-13
      DOI: 10.1007/s12601-022-00078-8
       
 
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