• Title/Summary/Keyword: chemical diversity

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Effects of Fire on Vegetation and Soil Nutrients in Mt. Chiak (치악산의 식생과 토양에 미친 산불의 영향)

  • 박봉규;김종희
    • Journal of Plant Biology
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    • v.24 no.1
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    • pp.31-45
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    • 1981
  • The purpose of this study aimed to study effects of fire on vegetation and soil properties after the first growing season in Mt. Chiak. 1. With the basis of importance value of species in each stand, status of species was assessed for three categories; Increaser species, Decreaser species, and Neutral species. 2. Biomass was 2.2 times higher on burned area than unburned. This indicates that biomass was remarkably increased after fire. 3. To evaluate similarity, coefficients of similarity among communities were obtained, and correlation coefficients were also estimated. These indices showed that burned and unburned community were markedly different.. $B_1$-stand and $B_1$-stand appeared most similar to each other among stands. 4. Species diversity was greater in burned than unburned stands. 5. Soil pH value and organic matter content in burned area were significantly higher than those in unburned area. However, soil water content was lower in burned area. There was no effect of burning on soil pH value and water content at 15~20 cm depth of soil. 6. All chemical compositions except sodium were much higher in soil surface. The decreases in sodium levels at surface were probably resulted from the rapid leaching due to the increased solubility and decreased capacity for adsorption of sodium in comparison with potassium or calcium. Among chemical compositions of soil amount of nitrogen showed least difference between the burneb and unburned surfaces soil.

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Secondary Science Teachers' PCK Components and Subcomponents Specific to the Learning Environment in an Online-offline Mixed Learning Environment (온-오프라인 혼합 학습환경에서 중등과학교사의 학습환경 특이적인 PCK 요소 및 하위요소)

  • Jisu, Kim;Aeran, Choi
    • Journal of the Korean Chemical Society
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    • v.66 no.6
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    • pp.472-492
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    • 2022
  • The purpose of this study was to investigate secondary science teachers' PCK components and subcomponents that are specific to online and offline learning environment. Data collection consisted of survey, class observation, and individual interviews of twelve science teachers. This study used a theoretical framework of PCK for deductive data analysis and articulated codes and themes through the following inductive analysis. Data analysis revealed that each of PCK components showed different specificity to the online and offline learning environment. And subcomponents of each PCK component were different according to the specificity of the online and offline learning environment. Teaching orientation toward science had a specific orientation for the online learning environment, i.e., 'learning science concept' and 'lecture centered instruction.' Knowledge of the science curriculum had online-offline mixed learning environment specific knowledge, i.e., 'reorganization of curriculum' and online learning environment specific knowledge, i.e., 'development of learning goal' and 'science curricular materials.' Knowledge of science teaching strategies had online learning environment specific knowledge, i.e., 'topic-specific strategy', 'subject-specific strategy', and 'interaction strategy' and COVID-19 offline learning environment specific knowledge, i.e., 'topic-specific strategy' and 'interaction strategy'. Knowledge of student science understanding had online learning environment specific knowledge, i.e., 'student preconception', 'student learning difficulty', 'student motivation and interest', and 'student diversity' and COVID-19 offline learning environment specific knowledge, i.e., student learning difficulty'. Knowledge of science assessment had online-offline mixed learning environment specific knowledge and online learning environment specific knowledge, i.e., assessment contents and assessment methods for each.

Morphological Characteristics of Weed Seed Fibers (잡초 종자섬유의 형태적 특징 비교)

  • Yoon, A Ra;Lee, Min Woo;Kim, Seul Ki;Kim, Jin-Seog
    • Weed & Turfgrass Science
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    • v.3 no.3
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    • pp.196-205
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    • 2014
  • In this study, to obtain basic data for searching potential resources as new natural fibers, we investigated morphological and classificatory characteristics of 21 weed seed fibers. According to classification keys in this study, the collected weed seed fibers could be classified into total 13 types, showing their diversity. Seven species among them belonged to BOT3 type. Two species belonged to B2N0 and DOS3 type, respectively. Many of weed seed fibers had not branched. However, three species had various branched fibers at one main fibers on the seed. Three species had various branched fibers at several main fibers on the seed. Eight species had a smooth fiber surface but 13 species had a weakly or significantly developed-corniculum on the fiber surface. In the fiber cell shape, fiber cells of eight weed species were composed of one long cell without septum. But others had a fiber cell shape composed of a bunch of several long cells. Based on the easiness of harvesting, productivity of fibers, and morphological characteristics of seed fiber, it seemed that five seed fibers (TYPLA, METJA, HEMLY, IMPCK, and EREHI) should be additionally investigated if they are practically applicable as renewable resources for new natural fibers.

Selection of Indicator Insects for the Evaluation of Agricultural Environment (농업환경 평가를 위한 지표곤충 선발)

  • Choi Young-Cheol;Park Hae-Chul;Kim Jong-Gill;Sim Ha-Sik;Kwon Oh-Seok
    • Korean journal of applied entomology
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    • v.43 no.4 s.137
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    • pp.267-273
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    • 2004
  • To select indicator insects, the abundance of which is one of the major criteria for the evaluation of agricultural environment, was designated and monitored in the three sites (Hongcheon A, B, and Yangpyeong) from 2001 to 2003. Characteristics of rice cultivation are usual cultivation with 2 or 3 times sprayed chemical agents per year in Hongcheon A site, duck cultivation with non-sprayed chemical agent, green manure and mowing in Hongcheon B site, and pond snail with non-sprayed chemical agent, green manure and mowing in Yangpyeong site. Dominant floral species are Digitaria ciliaris (Retz.) Koel., Persicaria thunbergii (Siebold & Zuccarini) H. Gross, Echinochioa crus-galli (L.) Beauvois, and Humulus scandens (Lour.) Merr. in Hongcheon A site, Digitaria ciliaris (Retz.) Koel., Persicaria thunbergii (Siebold & Zuccarini) H. Gross, and Echinochloa crus-galli (L.) Beauvois in Hongcheon B site, and Digitaria ciliaris (Retz.) Koel., Setaria viridis (L.) Beauv., and Persicaria langiseta (De Btuyn) Kitagawa in Yangpyeong site. Degree of green naturality (DGN) was higher in Hongcheon B site (2.0) and Yangpyeong site (3.6) than in Hongcheon A site (1.6). Number of species and individual of insects collected in the three sites were abundant on August and September. The species diversity was higher in Hongcheon B and Yangpyeong than in Hongcheon A. And Coleoptera was dominant in the all sites. The dominance index (DI) was the lowest, but diversify index (H'), evenness index (E) and richness index (RI) were the highest in Hongcheon B site. Based on three results, indicator insects for the evaluation of agricultural environment were selected as Dolichus halensis in Hongeheon A site, as Pheropsophus. javanus and Polionemobius mikado in Hongcheon B and Yangpyeong sites.

Soil Microbial Community Analysis using Soil Enzyme Activities in Red Pepper Field Treated Microbial Agents (토양효소활성을 이용한 미생물제제 처리 고추경작지의 토양미생물군집 분석)

  • Kim, Yo-Hwan;Lim, Jong-Hui;An, Chang-Hwan;Jung, Byung-Kwon;Kim, Sang-Dal
    • Journal of Applied Biological Chemistry
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    • v.55 no.1
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    • pp.47-53
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    • 2012
  • Increasing concerns over green farming technology, plant growth promoting rhizobacterium (PGRP) having growth promoting as well as plant disease suppressing properties was recently preferred to use for biological control of plant pathogens infecting plant. We measured the influence of the selected microbial consortium agents-a mixture of PGPR strains-, commercial bio-fungicide, and chemical pesticides on soil microbial community in red pepper field. The activities of soil enzyme such as dehydrogenase, urease, phosphatase, ${\beta}$-glucosidase, and cellulase were analyzed to investigate that of soil microbial community. We also measured plant length, main stem, stem diameter, number of branches and yields of red-pepper in order to observe the red pepper growth promotion. The results of measuring enzyme activities were dehydrogenase 3.5584 ${\mu}g$ TPF $g^{-1}h^{-1}$, urease 15.8689 ${\mu}g$ $NH_4{^-}N$ $g^{-1}h^{-1}$, phosphatase 0.5692 ${\mu}g$ PNP $g^{-1}h^{-1}$, ${\beta}$-glucosidase 2.4785 ${\mu}g$ PNP $g^{-1}h^{-1}$, and cellulase 86.1597 ${\mu}g$ glucose $g^{-1}h^{-1}$ in the soil treated with the microbial consortium agents, so it came out to be very active in the soil. Observing the growth of red-peppers, the main-stem length and the stem diameter were 6.1% and 8.1% higher in the soil treated with the selected microbial consortium agent than the chemical pesticides. After harvesting, yields were 7.3% higher in the soil treated with selected microbial consortium agents than the chemical pesticides. These results showed that microbial consortium agents contribute to increasing soil microbial diversity, growth promoting, and yield of red pepper.

Brief Introduction of Research Progresses in Control and Biocontrol of Clubroot Disease in China

  • He, Yueqiu;Wu, Yixin;He, Pengfei;Li, Xinyu
    • 한국균학회소식:학술대회논문집
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    • 2015.05a
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    • pp.45-46
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    • 2015
  • Clubroot disease of crucifers has occurred since 1957. It has spread to the whole China, especially in the southwest and nourtheast where it causes 30-80% loss in some fields. The disease has being expanded in the recent years as seeds are imported and the floating seedling system practices. For its effective control, the Ministry of Agriculture of China set up a program in 2010 and a research team led by Dr. Yueqiu HE, Yunnan Agricultural University. The team includes 20 main reseachers of 11 universities and 5 institutions. After 5 years, the team has made a lot of progresses in disease occurrence regulation, resources collection, resistance identification and breeding, biological agent exploration, formulation, chemicals evaluation, and control strategy. About 1200 collections of local and commercial crucifers were identified in the field and by artificiall inoculation in the laboratories, 10 resistant cultivars were breeded including 7 Chinese cabbages and 3 cabbages. More than 800 antagostic strains were isolated including bacteria, stretomyces and fungi. Around 100 chemicals were evaluated in the field and greenhouse based on its control effect, among them, 6 showed high control effect, especially fluazinam and cyazofamid could control about 80% the disease. However, fluzinam has negative effect on soil microbes. Clubroot disease could not be controlled by bioagents and chemicals once when the pathogen Plasmodiophora brassicae infected its hosts and set up the parasitic relationship. We found the earlier the pathogent infected its host, the severer the disease was. Therefore, early control was the most effective. For Chinese cabbage, all controlling measures should be taken in the early 30 days because the new infection could not cause severe symptom after 30 days of seeding. For example, a biocontrol agent, Bacillus subtilis Strain XF-1 could control the disease 70%-85% averagely when it mixed with seedling substrate and was drenching 3 times after transplanting, i.e. immediately, 7 days, 14 days. XF-1 has been deeply researched in control mechanisms, its genome, and development and application of biocontrol formulate. It could produce antagonistic protein, enzyme, antibiotics and IAA, which promoted rhizogenesis and growth. Its The genome was sequenced by Illumina/Solexa Genome Analyzer to assembled into 20 scaffolds then the gaps between scaffolds were filled by long fragment PCR amplification to obtain complet genmone with 4,061,186 bp in size. The whole genome was found to have 43.8% GC, 108 tandem repeats with an average of 2.65 copies and 84 transposons. The CDSs were predicted as 3,853 in which 112 CDSs were predicted to secondary metabolite biosynthesis, transport and catabolism. Among those, five NRPS/PKS giant gene clusters being responsible for the biosynthesis of polyketide (pksABCDEFHJLMNRS in size 72.9 kb), surfactin(srfABCD, 26.148 kb, bacilysin(bacABCDE 5.903 kb), bacillibactin(dhbABCEF, 11.774 kb) and fengycin(ppsABCDE, 37.799 kb) have high homolgous to fuction confirmed biosynthesis gene in other strain. Moreover, there are many of key regulatory genes for secondary metabolites from XF-1, such as comABPQKX Z, degQ, sfp, yczE, degU, ycxABCD and ywfG. were also predicted. Therefore, XF-1 has potential of biosynthesis for secondary metabolites surfactin, fengycin, bacillibactin, bacilysin and Bacillaene. Thirty two compounds were detected from cell extracts of XF-1 by MALDI-TOF-MS, including one Macrolactin (m/z 441.06), two fusaricidin (m/z 850.493 and 968.515), one circulocin (m/z 852.509), nine surfactin (m/z 1044.656~1102.652), five iturin (m/z 1096.631~1150.57) and forty fengycin (m/z 1449.79~1543.805). The top three compositions types (contening 56.67% of total extract) are surfactin, iturin and fengycin, in which the most abundant is the surfactin type composition 30.37% of total extract and in second place is the fengycin with 23.28% content with rich diversity of chemical structure, and the smallest one is the iturin with 3.02% content. Moreover, the same main compositions were detected in Bacillus sp.355 which is also a good effects biocontol bacterial for controlling the clubroot of crucifer. Wherefore those compounds surfactin, iturin and fengycin maybe the main active compositions of XF-1 against P. brassicae. Twenty one fengycin type compounds were evaluate by LC-ESI-MS/MS with antifungal activities, including fengycin A $C_{16{\sim}C19}$, fengycin B $C_{14{\sim}C17}$, fengycin C $C_{15{\sim}C18}$, fengycin D $C_{15{\sim}C18}$ and fengycin S $C_{15{\sim}C18}$. Furthermore, one novel compound was identified as Dehydroxyfengycin $C_{17}$ according its MS, 1D and 2D NMR spectral data, which molecular weight is 1488.8480 Da and formula $C_{75}H_{116}N_{12}O_{19}$. The fengycin type compounds (FTCPs $250{\mu}g/mL$) were used to treat the resting spores of P. brassicae ($10^7/mL$) by detecting leakage of the cytoplasm components and cell destruction. After 12 h treatment, the absorbencies at 260 nm (A260) and at 280 nm (A280) increased gradually to approaching the maximum of absorbance, accompanying the collapse of P. brassicae resting spores, and nearly no complete cells were observed at 24 h treatment. The results suggested that the cells could be lyzed by the FTCPs of XF-1, and the diversity of FTCPs was mainly attributed to a mechanism of clubroot disease biocontrol. In the five selected medium MOLP, PSA, LB, Landy and LD, the most suitable for growth of strain medium is MOLP, and the least for strains longevity is the Landy sucrose medium. However, the lipopeptide highest yield is in Landy sucrose medium. The lipopeptides in five medium were analyzed with HPLC, and the results showed that lipopeptides component were same, while their contents from B. subtilis XF-1 fermented in five medium were different. We found that it is the lipopeptides content but ingredients of XF-1 could be impacted by medium and lacking of nutrition seems promoting lipopeptides secretion from XF-1. The volatile components with inhibition fungal Cylindrocarpon spp. activity which were collect in sealed vesel were detected with metheds of HS-SPME-GC-MS in eight biocontrol Bacillus species and four positive mutant strains of XF-1 mutagenized with chemical mutagens, respectively. They have same main volatile components including pyrazine, aldehydes, oxazolidinone and sulfide which are composed of 91.62% in XF-1, in which, the most abundant is the pyrazine type composition with 47.03%, and in second place is the aldehydes with 23.84%, and the third place is oxazolidinone with 15.68%, and the smallest ones is the sulfide with 5.07%.

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A Study of Fish Community on Up and Downstream of Hwabuk Dam Under Construction in the Upper Wie Stream. (위천 상류에 건설 중인 화북댐 상 하류 어류군집에 관한 연구)

  • Seo, Jin-Won;Kim, Hee-Sung
    • Korean Journal of Ecology and Environment
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    • v.42 no.2
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    • pp.260-269
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    • 2009
  • Hwabuk Dam has been under construction to reduce flood damage in Nakdong River watershed and to supply stable water for middle area of Gyeongbuk Province. Therefore, fish investigation in up and downstream of the dam was conducted from 2004 to 2008 in order to determine any negative effect on fish community due to dam construction and to use as fundamental data for conserving species diversity and maintaining stream health. According to data analysis on water quality, temperature, dissolved oxygen, pH, suspended solids, and total E-coli had seasonal variation, but they did not significantly differ in sites. However, biological and chemical oxygen demand, chlorophyll-a, nitrogen, and phosphorus representing organic matter and nutrient concentration were higher in upper site and decreased to lower site so that they differed by site. Concentration of arsenic among the heavy metals was less than 0.05 mg $L^{-1}$, which is regulated for protection of human health in water quality standard, except for 0.092 mg $L^{-1}$ in June 2005. During the study period, the total number of fish caught from the 6 sites was 10,263 representing 7 families 19 species. Among them, dominant and subdominant species were Korean chub (Zacco koreanus, 62.5%) and Chinese minnow (Rhynchocypris oxycephalus, 10.6%) which inhabit mostly in mid and upper streams, Korea. Among the 19 species, Korean endemic species were 9 species (47.4%) including Korean slender gudgeon (Squalidus gracilis majimae), Korean dark sleeper (Odontobutis platycephala), and Korean shiner (Coreoleuciscus splendidus). There was several individuals of the $1^{st}$-class endangered species, Naktong nose loach (Koreocobitis nahtongensis), caught in 2005${\sim}$2007, and no introduced species of fish was found in entire sampling period. According to result of community analysis, dominance index decreased toward lower site, but diversity and richness indices increased toward lower site. The equation of length-weight relationship on the dominant species was TW=0.000003$(TL)^{3.2603}$. The parameter b in the equation was greater than 3.0 indicating good nutritional condition in the populations. Compared to populations of Korean chub in other streams, the population in Hwabuk Dam watershed had higher mean of condition factor by size indicating better growth rate. With fish fauna and multi-metric health assessment model in each sampling attempt, index of biotic integrity (IBI) was evaluated and it resulted mostly in good (26${\sim}$35) and excellent (36${\sim}$40) condition in all sites, and the mean of IBI was the highest in site 5. The results indicate that it is very important to study not only environmental impact assessment with fish composition but also stream health assessment in order to conserve healthy aquatic ecosystem.

Fish Community Characteristics in Hwapocheon Wetland, Korea (화포천 습지의 어류군집 특성)

  • Ko, Myeong-Hun;Choi, Kwang-Seek;Lim, Jeong-Cheol
    • Korean Journal of Environment and Ecology
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    • v.36 no.2
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    • pp.165-176
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    • 2022
  • This study surveyed the characteristics of fish communities in Hwapocheon Wetland, Korea, from May to September 2020. The survey collected 735 objects in 21 species belonging to 7 families from 8 survey stations. The dominant and subdominant species were Hemiculter eigenmanni(23.8%) and Micropterus salmoides(10.3%), respectively. The next most abundant species were Zacco platypus(9.5%), Carassius auratus(9.4%), Pseudorasbora parva(9.0%), Squalidus chankaensis tsuchigae(6.7%), Acheilognathus macropterus(5.4%), Lepomis macrochirus(5.2%), Pseudogobio esocinus(4.1%), Opsariichthys uncirostris amurensis(3.7%), and Carassius cuvieri(3.3%). Among the fish species collected, one species, Culter brevicauda, was class II endangered wildlife designated by the Ministry of Environment, and one species,S. c. tsuchigae(4.8%), was endemic to Korea.Additionally, three exotic species (M. salmoides, L. macrochirus, and C. cuvieri) and one landlocked species (Rhinogobius brunneus) were collected. Compared to previous studies, the proportion of fish living in the running water area tended to decrease, the proportion of fish living in the water purification area tended to increase, and ecosystem-disturbing species (M. salmoides and L. macrochirus) tended to increase gradually. Results of fish community analysis showed that the mainstream stations (St. 1, 3, 4, 5, 6, and 8) had low dominance, but high diversity and richness, and other stations (St. 2 and 7) had high dominance but low diversity and richness. The river health (index of biological integrity) evaluated using fish was assessed as bad (6 stations), normal (1 station), and very bad (1 station). The water quality grade was assessed as slightly bad due to the chemical oxygen demand (COD), total organic content (TOC), suspended solid (SS), and total coliforms (TC). The annual water quality showed a gradually increasing trend of biological oxygen demand (BOD), COD, SS, and chlorophyll-a. The stable life of fish and the improvement of river health in Hwapocheon Wetland require water quality improvement and the systematic management of ecosystem-disturbing species (M. salmoidesand L. macrochirus).

Fish Community Structure and Biodiversity of the Korean Peninsula Estuaries (한반도 하구의 어류군집 구조 및 다양성)

  • Park, Sang-Hyeon;Baek, Seung-Ho;Kim, Jeong-Hui;Kim, Dong-Hwan;Jang, Min-Ho;Won, Doo-Hee;Park, Bae-Kyung;Moon, Jeong-Suk
    • Korean Journal of Ecology and Environment
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    • v.55 no.1
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    • pp.35-48
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    • 2022
  • Fish assemblage of total 325 of Korean peninsula estuaries were surveyed to analyze the characteristics of community structure and diversity by sea areas for three years from 2016 to 2018. The scale (stream width) of Korean estuaries were various (14~3,356 m), and 68.9% of all estuaries showed salinity of less than 2 psu. Total 149 species classified into 52 families of fish were identified, and the dominant and sub-dominant species were Tribolodon hakonensis (relative abundance, RA, 12.5%) and Mugil cephalus (RA, 9.5%), respectively. The estuary of the Korean Peninsula had different physical and chemical habitat environments depending on the sea area, and accordingly, fish community structure also showed statistically significant differences (PERMANOVA, Pseudo-F=26.69, P=0.001). In addition, the NMDS (nonmetric multidimensional scaling) results showed the patterns that indicating fish community difference by sea areas, even though low community similarity within sea area (SIMPER, 21.79~26.39%). The estuaries of east sea areas were distinguished from the others in the aspects of which, the higher importance of migratory fishes and endangered species, and that of brackish species were characterized at south sea estuaries. However, the estuaries of west sea showed higher importance of species that have a relation with freshwater (primary freshwater species, exotic species), which is the result that associating with the lower salinity of west sea estuaries because of the high ratio of closed estuaries(78.2%). The SIMPER analysis, scoring the contribution rates of species to community similarity, also showed results corresponding to the tendency of different fish community structures according to each sea area. So far, In Korea, most studies on fish communities in estuaries have been conducted in a single estuary unit, which made it difficult to understand the characteristics of estuaries at the national level, which are prerequisite for policy establishment. In present study, we are providing fish community structure characteristics of Korean estuaries in a national scale, including diversity index, habitat salinity ranges of major species, distribution of migratory species. We are expecting that our results could be utilized as baseline information for establishing management policies or further study of Korean estuaries.

Changes in Fermentation Characteristics and Bacterial Communities of Whole Crop Rice Silage during Ensiling Period (저장기간에 따른 사료용 벼 사일리지의 발효특성 및 미생물상 변화)

  • Mirae Oh;Hyung Soo Park;Bo Ram Choi;Jae Hoon Woo;Seung Min Jeong;Ji Hye Kim;Bae Hun Lee
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.44 no.1
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    • pp.1-5
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    • 2024
  • Understanding changes in fermentation characteristics and microbial populations of forage silage during ensiling is of interest for improving the nutrient value of the feed for ruminants. This study was conducted to investigate the changes in fermentation characteristics and bacterial communities of whole crop rice (WCR) silage during the ensiling period. The chemical compositions, pH, organic acids and bacterial communities were evaluated at 0, 3, 6, and 12 months after ensiling. The bacterial communities were classified at both the genus and species levels. The dry matter content of WCR silage decreased with the length of storage (p<0.05), but there was no significant difference in crude protein and NDF contents. Following fermentation, the pH level of WCR silage was lower than the initial level. The lactic acid content remained at high levels for 3 to 6 months after ensiling, followed by a sharp decline at 12 months (p<0.05). Before fermentation, the WCR was dominated by Weissella (30.8%) and Pantoea (20.2%). Growth of Lactiplantibacillus plantarum (31.4%) was observed at 3 months after ensiling. At 6 months, there was a decrease in Lactiplantibacillus plantarum (10.2%) and an increase in Levilactobacillus brevis (12.8%), resulting in increased bacteria diversity until that period. The WCR silage was dominated by Lentilactobacillus buchneri (71.2%) and Lacticaseibacillus casei (27.0%) with a sharp reduction in diversity at 12 months. Overall, the WCR silage maintained satisfactory fermentation quality over a 12-month ensiling period. Furthermore, the fermentation characteristics of silage were found to be correlated to bacterial microbiome.