scholarly journals Phytoplankton Bloom Dynamics in Incubated Natural Seawater: Predicting Bloom Magnitude and Timing

2021 ◽  
Vol 8 ◽  
Author(s):  
Jin Hee Ok ◽  
Hae Jin Jeong ◽  
Ji Hyun You ◽  
Hee Chang Kang ◽  
Sang Ah Park ◽  
...  
Keyword(s):  
Growth Rate ◽  
South Korea ◽  
Coastal Waters ◽  
Phytoplankton Bloom ◽  
Economic Losses ◽  
Natural Seawater ◽  
Initial Ratio ◽  
Phytoplankton Blooms ◽  
Best Fit ◽  
Linear Regressions

Phytoplankton blooms can cause imbalances in marine ecosystems leading to great economic losses in diverse industries. Better understanding and prediction of blooms one week in advance would help to prevent massive losses, especially in areas where aquaculture cages are concentrated. This study has aimed to develop a method to predict the magnitude and timing of phytoplankton blooms using nutrient and chlorophyll-a concentrations. We explored variations in nutrient and chlorophyll-a concentrations in incubated seawater collected from the coastal waters off Yeosu, South Korea, seven times between May and August 2019. Using the data from a total of seven bottle incubations, four different linear regressions for the magnitude of bloom peaks and four linear regressions for the timing were analyzed. To predict the bloom magnitude, the chlorophyll-a peak or peak-to-initial ratio was analyzed against the initial concentrations of NO3 or the ratio of the initial NO3 to chlorophyll-a. To predict the timing, the chlorophyll-a peak timing or the growth rate against the natural log of NO3 or the natural log of the ratio of the initial NO3 to chlorophyll-a was analyzed. These regressions were all significantly correlated. From these regressions, we developed the best-fit equations to predict the magnitude and timing of the bloom peak. The results from these equations led to the predicted bloom magnitude and timing values showing significant correlations with those of natural seawater in other regions. Therefore, this method can be applied to predict bloom magnitude and timing one week in advance and give aquaculture farmers time to harvest fish in cages early or move the cages to safer regions.

scholarly journals Detection of Rhodococcus fascians, the Causative Agent of Lily Fasciation in South Korea

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 241
Author(s):  
Joon Moh Park ◽  
Jachoon Koo ◽  
Se Won Kang ◽  
Sung Hee Jo ◽  
Jeong Mee Park
Keyword(s):  
Phylogenetic Analysis ◽  
South Korea ◽  
Nicotiana Benthamiana ◽  
Economic Value ◽  
Virulence Gene ◽  
Economic Losses ◽  
Herbaceous Perennials ◽  
Rhodococcus Fascians ◽  
Different Strains

Rhodococcus fascians is an important pathogen that infects various herbaceous perennials and reduces their economic value. In this study, we examined R. fascians isolates carrying a virulence gene from symptomatic lily plants grown in South Korea. Phylogenetic analysis using the nucleotide sequences of 16S rRNA, vicA, and fasD led to the classification of the isolates into four different strains of R. fascians. Inoculation of Nicotiana benthamiana with these isolates slowed root growth and resulted in symptoms of leafy gall. These findings elucidate the diversification of domestic pathogenic R. fascians and may lead to an accurate causal diagnosis to help reduce economic losses in the bulb market.

scholarly journals Genetic Characteristics of Avian Influenza Virus Isolated from Wild Birds in South Korea, 2019–2020

Viruses ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 381
Author(s):  
Eun-Jee Na ◽  
Young-Sik Kim ◽  
Sook-Young Lee ◽  
Yoon-Ji Kim ◽  
Jun-Soo Park ◽  
...  
Keyword(s):  
Avian Influenza ◽  
South Korea ◽  
Basic Amino Acid ◽  
Histopathological Change ◽  
Amino Acid Sequences ◽  
Wild Birds ◽  
Influenza Viruses ◽  
Economic Losses ◽  
Active Monitoring ◽  
Genetic Characteristics

Wild aquatic birds, a natural reservoir of avian influenza viruses (AIVs), transmit AIVs to poultry farms, causing huge economic losses. Therefore, the prevalence and genetic characteristics of AIVs isolated from wild birds in South Korea from October 2019 to March 2020 were investigated and analyzed. Fresh avian fecal samples (3256) were collected by active monitoring of 11 wild bird habitats. Twenty-eight AIVs were isolated. Seven HA and eight NA subtypes were identified. All AIV hosts were Anseriformes species. The HA cleavage site of 20 representative AIVs was encoded by non-multi-basic amino acid sequences. Phylogenetic analysis of the eight segment genes of the AIVs showed that most genes clustered within the Eurasian lineage. However, the HA gene of H10 viruses and NS gene of four viruses clustered within the American lineage, indicating intercontinental reassortment of AIVs. Representative viruses likely to infect mammals were selected and evaluated for pathogenicity in mice. JB21-58 (H5N3), JB42-93 (H9N2), and JB32-81 (H11N2) were isolated from the lungs, but JB31-69 (H11N9) was not isolated from the lungs until the end of the experiment at 14 dpi. None of infected mice showed clinical sign and histopathological change in the lung. In addition, viral antigens were not detected in lungs of all mice at 14 dpi. These data suggest that LPAIVs derived from wild birds are unlikely to be transmitted to mammals. However, because LPAIVs can reportedly infect mammals, including humans, continuous surveillance and monitoring of AIVs are necessary, despite their low pathogenicity.

scholarly journals Visibility Prediction over South Korea Based on Random Forest

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 552
Author(s):  
Bu-Yo Kim ◽  
Joo Wan Cha ◽  
Ki-Ho Chang ◽  
Chulkyu Lee
Keyword(s):  
Random Forest ◽  
South Korea ◽  
Correlation Coefficients ◽  
Predictive Performance ◽  
Air Pollutant ◽  
Economic Losses ◽  
Observation Data ◽  
Local Data ◽  
Weather Forecasts ◽  
Monitoring Service

In this study, the visibility of South Korea was predicted (VISRF) using a random forest (RF) model based on ground observation data from the Automated Synoptic Observing System (ASOS) and air pollutant data from the European Centre for Medium-Range Weather Forecasts (ECMWF) Copernicus Atmosphere Monitoring Service (CAMS) model. Visibility was predicted and evaluated using a training set for the period 2017–2018 and a test set for 2019. VISRF results were compared and analyzed using visibility data from the ASOS (VISASOS) and the Unified Model (UM) Local Data Assimilation and Prediction System (LDAPS) (VISLDAPS) operated by the Korea Meteorological Administration (KMA). Bias, root mean square error (RMSE), and correlation coefficients (R) for the VISASOS and VISLDAPS datasets were 3.67 km, 6.12 km, and 0.36, respectively, compared to 0.14 km, 2.84 km, and 0.81, respectively, for the VISASOS and VISRF datasets. Based on these comparisons, the applied RF model offers significantly better predictive performance and more accurate visibility data (VISRF) than the currently available VISLDAPS outputs. This modeling approach can be implemented by authorities to accurately estimate visibility and thereby reduce accidents, risks to public health, and economic losses, as well as inform on urban development policies and environmental regulations.

scholarly journals Evaluation of the Variability of the ORF34, ORF68, and MLST Genes in EHV-1 from South Korea

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 425
Author(s):  
Hyung-Woo Kang ◽  
Eun-Yong Lee ◽  
Kyoung-Ki Lee ◽  
Mi-Kyeong Ko ◽  
Ji-Young Park ◽  
...  
Keyword(s):  
Nucleotide Sequence ◽  
South Korea ◽  
Molecular Level ◽  
Economic Losses ◽  
Equine Herpesvirus ◽  
Equine Herpesvirus 1 ◽  
Mlst Analysis ◽  
Herpesvirus 1 ◽  
First Time ◽  
Group 1

Equine herpesvirus-1 (EHV-1) is an important pathogen in horses. It affects horses worldwide and causes substantial economic losses. In this study, for the first time, we characterized EHV-1 isolates from South Korea at the molecular level. We then aimed to determine the genetic divergences of these isolates by comparing them to sequences in databases. In total, 338 horse samples were collected, and 12 EHV-1 were isolated. We performed ORF30, ORF33, ORF68, and ORF34 genetic analysis and carried out multi-locus sequence typing (MLST) of 12 isolated EHV-1. All isolated viruses were confirmed as non-neuropathogenic type, showing N752 of ORF30 and highly conserved ORF33 (99.7–100%). Isolates were unclassified using ORF68 analysis because of a 118 bp deletion in nucleotide sequence 701–818. Seven EHV-1 isolates (16Q4, 19R166-1, 19R166-6, 19/10/15-2, 19/10/15-4, 19/10/18-2, 19/10/22-1) belonged to group 1, clade 10, based on ORF34 and MLST analysis. The remaining 5 EHV-1 isolates (15Q25-1, 15D59, 16Q5, 16Q40, 18D99) belonged to group 7, clade 6, based on ORF34 and MLST analysis.

scholarly journals Testing the effect of H0 on fσ8 tension using a Gaussian Process method

2020 ◽  
Author(s):  
En-Kun Li ◽  
Minghui Du ◽  
Zhi-Huan Zhou ◽  
Hongchao Zhang ◽  
Lixin Xu
Keyword(s):  
Growth Rate ◽  
Dark Energy ◽  
Cosmological Constant ◽  
Gaussian Process ◽  
Dark Energy Model ◽  
Hubble Space Telescope ◽  
Λcdm Model ◽  
Space Distortion ◽  
Best Fit ◽  
Process Method

Abstract Using the fσ8(z) redshift space distortion (RSD) data, the $\sigma _8^0-\Omega _m^0$ tension is studied utilizing a parameterization of growth rate f(z) = Ωm(z)γ. Here, f(z) is derived from the expansion history H(z) which is reconstructed from the observational Hubble data applying the Gaussian Process method. It is found that different priors of H0 have great influences on the evolution curve of H(z) and the constraint of $\sigma _8^0-\Omega _m^0$. When using a larger H0 prior, the low redshifts H(z) deviate significantly from that of the ΛCDM model, which indicates that a dark energy model different from the cosmological constant can help to relax the H0 tension problem. The tension between our best-fit values of $\sigma _8^0-\Omega _m^0$ and that of the Planck 2018 ΛCDM (PLA) will disappear (less than 1σ) when taking a prior for H0 obtained from PLA. Moreover, the tension exceeds 2σ level when applying the prior H0 = 73.52 ± 1.62 km/s/Mpc resulted from the Hubble Space Telescope photometry. By comparing the $S_8 -\Omega _m^0$ planes of our method with the results from KV450+DES-Y1, we find that using our method and applying the RSD data may be helpful to break the parameter degeneracies.

Mechanical scarification technique breaks seed coat-mediated dormancy in wild oat (Avena fatua)

2021 ◽  
pp. 1-25
Author(s):  
Roberto Lujan Rocha ◽  
Yaseen Khalil ◽  
Aniruddha Maity ◽  
Hugh J. Beckie ◽  
Michael B. Ashworth
Keyword(s):  
Growth Rate ◽  
Seed Coat ◽  
Research Effort ◽  
Economic Losses ◽  
Wild Oat ◽  
Weed Species ◽  
Physical Dormancy ◽  
No Donor ◽  
Seedling Growth Rate ◽  
Oat Seeds

Abstract Wild oat is a herbicide resistance-prone global weed species that causes significant economic losses in dryland and horticultural agriculture. As a result, there has been a significant research effort in controlling this species. A major impediment to this research is the seed coat-mediated dormancy of wild oat, requiring a labor-intensive incision or puncturing of the seed coat to initiate seed germination. This study defines the most efficient settings of a mechanical thresher to overcome wild oat seed dormancy and then validates these settings using multiple populations collected from the Western Australian grain belt. We also compare the effects of rapid mechanical scarification and known germination stimulus tactics such as scarification with sulfuric acid (H2SO4), partial endosperm removal, sandpaper scarification of the seed coat, and immersion in sodium nitroprusside (NO donor SNP) solution on wild oat seedling growth rate. Threshing treatment of 1,500 rpm for 5 s provides equivalent germination compared with manually puncturing individual wild oat seeds, with no difference in seedling relative growth rate. The mechanical scarification of seeds using the thresher resulted in greater germination (66%) than H2SO4 scarification (0%), partial endosperm removal (10%), sandpaper seed coat scarification (25%), and exposure to NO donor SNP (34%). This study demonstrates that the physical dormancy of wild oat can be rapidly overcome using a commercially available mechanical thresher.

scholarly journals Phytoplankton blooms on the western shelf of Tasmania: evidence of a highly productive ecosystem

Ocean Science ◽  
2015 ◽  
Vol 11 (1) ◽  
pp. 1-11 ◽  
Author(s):  
J. Kämpf
Keyword(s):  
Satellite Data ◽  
Coastal Upwelling ◽  
Phytoplankton Bloom ◽  
Hot Spot ◽  
Marine Ecosystem ◽  
Austral Summer ◽  
Phytoplankton Blooms ◽  
Study Region ◽  
Upwelling System ◽  
Fluorescence Line

Abstract. Satellite-derived chlorophyll a data using the standard NASA-OC3 (ocean colour) algorithm are strongly biased by coloured dissolved organic matter and suspended sediment of river discharges, which is a particular problem for the western Tasmanian shelf. This work reconstructs phytoplankton blooms in the study region using a quadratic regression between OC3 data and chlorophyll fluorescence based on the fluorescence line height (FLH) data. This regression is derived from satellite data of the nearby Bonney upwelling region, which is devoid of river influences. To this end, analyses of 10 years of MODIS-aqua satellite data reveal the existence of a highly productive ecosystem on the western Tasmanian shelf. The region normally experiences two phytoplankton blooms per annum. The first bloom occurs during late austral summer months as a consequence of upwelling-favourable coastal winds. Hence, the western Tasmanian shelf forms a previously unknown upwelling centre of the regional upwelling system, known as Great South Australian Coastal Upwelling System. The second phytoplankton bloom is a classical spring bloom also developing in the adjacent Tasman Sea. The author postulates that this region forms another important biological hot spot for the regional marine ecosystem.

scholarly journals ECONOMIC ENVIRONMENT OF ARCTIC LIQUEFIED NATURAL GAS SUPPLIESTO THE ASIAN-PACIFIC REGION COUNTRIES UNDER THE END OF THE “TRADE WAR” BETWEEN THE USA AND CHINA

2020 ◽  
Vol 68 (2/2020) ◽  
pp. 12-21
Author(s):  
M. V. Ulchenko ◽  
Keyword(s):  
United States ◽  
Growth Rate ◽  
Natural Gas ◽  
South Korea ◽  
The United States ◽  
Liquefied Natural Gas ◽  
Asia Pacific ◽  
Russian Arctic ◽  
Pacific Region ◽  
Asia Pacific Region

Currently, the Asia-Pacific market is a priority goal for almost all major producers of liquefied natural gas(LNG). This is due to the relatively high price that local consumers are willing to pay, as well as the accelerated growth rate of natural gas consumption. At the same time, China is the main driver of growth in demand for LNGin the world, has concluded a trade agreement with the United States, which involves the purchase of energy resources worth more than $ 52 billion over two years. Given the decline in LNG prices, as well as increased competition, the issue of the prospects for sales of Russian Arctic gas on the market of the Asia-Pacific region becomes particularly relevant.The study provides a generalized assessment of the needs of the main importers of LNG ––China, South Korea and Japan, with a planning horizon of 4–5 years. The relatively high growth rates of the economy, partial rejection of nuclear energy, struggle to improve the environmental situation, as well as the desire to diversify supply routes explain the needs of the countries in the Asia-Pacific region for additional volumes of LNGin the near future. The analysis showed that both Japan and South Korea are interested in increasing the volume of imports of Russian arctic LNG, whose key advantages over most competitors are the price and relative proximity of sales markets. At the same time, the reduction in the number of operating gas drilling rigs in the United States indicates that it will not be possible to maintain the growth rate of LNG production at the level of 2018 and 2019.

Technological progress, non-price factors competitiveness, and changes in trade income elasticities: empirical evidence from South Korea and Hong Kong

2020 ◽  
pp. 1-26
Author(s):  
Marco Flávio Cunha Resende ◽  
Vitor Leone ◽  
Daniele Almeida Raposo Torres ◽  
Simeon Coleman
Keyword(s):  
Growth Rate ◽  
Hong Kong ◽  
South Korea ◽  
Empirical Evidence ◽  
Technological Progress ◽  
Innovation System ◽  
Balance Of Payments ◽  
Income Elasticities ◽  
Long Run ◽  
Catch Up

In the balance-of-payments-constrained growth model literature, income elasticities (IEs) are considered as the crucial element determining a country's long-run growth rate. Although the extant literature accepts that technology matters for IEs magnitude, explanations linking technology and IEs magnitude are limited. In this paper, we make use of the National Innovation System (NIS) concept from the Evolutionary School to explain the channels through which the size of a country's IEs is influenced by the level of development of its NIS, which in turn is a channel through which the non-price competitiveness factors work. Additionally, we empirically test the hypothesis that the catch-up allowed by NIS developments achieved in South Korea and Hong Kong improved their IEs over the 1980–1995 period. Our empirical results suggest a link between the level of NIS development and the size of the IEs.

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