• Title/Summary/Keyword: neritic

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Three Miraciid Copepods (Harpacticoida, Miraciidae) from South Korea

  • Chang, Cheon-Young
    • Animal Systematics, Evolution and Diversity
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    • v.25 no.3
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    • pp.215-225
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    • 2009
  • Three harpacticoid species of the family Miraciidae are reported from neritic and brackish waters in Korea: Amphiascus kawamurai Ueda and Nagai, 2005, Schizopera clandestina (Klie, 1924) and Schizopera neglecta Akatova, 1935. Amphiascus kawamurai is newly recorded from Korea. Redescription is provided with the systematic accounts and illustrations of them.

Biological Oceanography Of The Gamagyang Bay-The Yeoja Bay Water System(I)

  • Shim, Jae Hyung
    • 한국해양학회지
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    • v.15 no.2
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    • pp.89-99
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    • 1980
  • The major source of nutrients in both the Gamagyang Bay and the Yeoja Bay is mixing. However, water discharges also seem to contribute significant quantities which may influence local phytoplankton growth. Data collected inn the study area shows that natural fluctuations in the environmental conditions of the entire area play a dominant role in determining the phytoplankton populations of the two Bays. The predominating phytoplankton forms are neritic diatom species including some dinoflagellate species in summer. Neritic groups are relatively more abundant in inner areas of the Bays. The oceanic groups and species are seasonal, and associated with advective effects. One neritic species is of overwhelming numerical importance and occurs when a specific seasonal conditions is formed. Species cycles in the two Bays may be regarded as largely the result of successional changes or cycles of autochthonous species introduced by advective processes.

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Using Tintinnid Distribution for Monitoring Water Mass Changes in the Northern East China Sea (북부 동중국해 수괴 변화 감시를 위한 유종섬모류 분포 적용)

  • Kim, Young-Ok;Noh, Jae-Hoon;Lee, Tae-Hee;Jang, Pung-Guk;Ju, Se-Jong;Choi, Dong-Lim
    • Ocean and Polar Research
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    • v.34 no.2
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    • pp.219-228
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    • 2012
  • Tintinnid species distribution has been monitored in the northern East China Sea (ECS) in the summer of 2006 through 2011. This is used to understand the water mass movements in the northern ECS. The warm oceanic tintinnid species had largely spread in 2007 in the area, indicating that there was greater warm water extension into the northern ECS. However the extension of neritic water within the Changjiang diluted water mass has strengthened in 2008 and 2010 because the neritic species distribution had relatively grown in both years. These annual results based on the biological indicators of tintinnid species are well matched with the salinity change in the area. The warm oceanic species, Dadayiella ganymedes had frequently occurred over the study years and had shown a significant relationship with the salinity change. This is valuable as a key stone species for monitoring the intrusion of the Kuroshio within the northern ECS. Information from tintinnid biological indicators can support physical oceanography data to confirm ambiguous water mass properties.

The Paleoenvironment of the Northern Part of the Nagdong River Delta (낙동강 삼각주 북부의 고환경)

  • 오건환
    • The Korean Journal of Quaternary Research
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    • v.8 no.1
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    • pp.33-42
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    • 1994
  • The study area is filled up by alluvium which can be classified into lower and upper beds by the facies of deposits and their degree of weathering. The lower bed is not of marine but of fluvial. The upper bed is mainly composed of clay and silt or fine sand beds col-ored dark or dark gray which are of neritic or brackish yielding mollusca fossils. The oyster(Crassostrea ariakensis) obstained from the depth of 3m below the present sea level in the upper bed was dated at 4,100 110Y.B.P. and the veneridae(Meretrix lamarck) 1m height above the present delta plain in the old sand bar was dated at 1,700 85Y,B,P. It is therfore concluded that the study area a small kern col of terrestri-al basin prior to postglacial age had experienced the Holocene transgression. Consequently the study area is considered to have been progressively formed under neritic or brackish circumstance before 1,700Y.B.P.

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Species Composition and Occurrence Patterns of Zooplankton in Gamag Bay (가막만에 출현하는 동물플랑크톤의 종조성과 계절별 출현 양상)

  • 서호영;이인태;윤양호;최상덕;이삼노;한명일;김병섭;강윤호;이우범
    • Korean Journal of Environmental Biology
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    • v.20 no.2
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    • pp.118-129
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    • 2002
  • Zooplankton was sampled vertically with a Norpac net from Gamag Bay in April, July, September and December, 2001. Copepods were predominant in April and December, and cladocerans in July and Noctituca scintillans in September, respectively. There are high spatio-temporal fluctuations in the abundance of zooplankton with a range of 22-17,197 indiv.$m^3$. In the copepod community, neritic species, Eurytemora pacifica, Acartia omorii, Centropages abdominalis and Calanus sinicus were predominant in April ; Labidocera rotunda and A. erythraea in July; A. erythraea and Paracalanus parvus s. 1. in September; A. omorii and E. pacifica in December. However, oceanic species Eucalanus sp. and Neocalanus sp. were abundant in September. It indicates that although Gamag Bay is semi-closed, the distribution pattern of zooplankton is seasonally strongly affected by oceanic waters in addition to neritic ones.

Neritic Paleocurrent Analysis of Pennsylvanian Tethyan Sea at Samcheog Coalfield, Korea (후기(後期) 석탄기(石炭紀) 테티스해내(海內) 한국 삼척탄전(三涉炭田)의 천해류(淺海流) 분석(分折))

  • Kim, Haang Mook
    • Economic and Environmental Geology
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    • v.11 no.1
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    • pp.21-37
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    • 1978
  • The depositional environment of the Manhang and the Geumcheon Formation of the Pennsylvanian Gomog Croup is revealed to the shallow neritic marine milieu in this paper also as the results of Park (1963), Cheong(1975) and Kim (1976), through the analyses of stratigraphy, paleocurrent, properties of cross-beddings and sedimentational features. The formations contains some possible terrestrial sediments suggesting the paralic environment, which are however not recognized definitely within them. The paleocurrent analysis is made to the Manhang Formation only. The paleocurrent of the formation is known to belong to the shallow neritic longshore current. The paleocurrent analysis is based chiefly on the cross-bedding analysis, and subordinately on the texture of elastic coarse sediments. The paleocurrent mean is determined to $269^{\circ}$, that is, from east to west, of which direction is interpreted to the right angle to the slope of the basinal depository plane and also the parallel with die depositional strike, according to Klein (1960) and Selley's (1968) criteria. The variance value of paleocurrent directions of the Manhang Formation in the whole area studied is 6,374, and the values range from 3,394 to 6,957 according to the dirstricts. The paleocurreut pattern of the whole area shows polymodel, and the patterns in each district range from trimodel to quadrimodel. Those models approach to the shallow marine or paralic model of Tohill and Picard (1966), Picard and High (1968 a), Pisnak (1957) and Pettijohn (1962). The mean value of maximum inclinations of cross-beddings of the whole area is $19.9^{\circ}$ with the standard deviation of 8.4, and ranges from $15.6^{\circ}$ to $21.7^{\circ}$ in the districts. Comparing the histogram showing the frequency distribution of the maximum inclinations of cross-beddings of the Manhang Formation with the Pettijohn's (1962) histogram, it is found that the model approaches to his marine model. The Pennsylvanian Gomog Group of the coalfield is considered to have had been deposited in the pseudogeosynclinal zone on the plateau by the transgression of the Tethyan sea caused by the epirogenic movements during the Pennsylvanian Period.

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Effects of Environmental Factors on the Seasonal Variations of Zooplankton Communities in the Semi-enclosed Yeoja Bay, Korea (반폐쇄적 여자만 동물플랑크톤 군집의 계절변화에 따른 환경요인의 영향)

  • Seong Yong Moon;Heeyong Kim;Mi Hee Lee;Jin Ho Jung;Se Ra Yoo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.56 no.1
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    • pp.54-65
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    • 2023
  • Effect of environmental factors on the seasonal variations of zooplankton communities was investigated in the semi-closed Yeoja Bay, Korea from February, April to August, and November 2021. Out of a total 49 species of zooplankton were collected with a predominant of neritic copepods (mainly Paracalanus orientalis, Acartia omorii, Acartia ohtsukai, Centropages abdominalis, Ditrichocorycaeus affinis, and Oithona sp.), accounting for 58.9% of the total abundance of zooplankton. The diversity indices indicated a relatively highest in July, suggesting that diversity is influenced by seasonal temperature, N. scintillans, and neritic copepods species. A cluster analysis with non-metric multidimensional scaling revealed four groups of zooplankton communities. The February sample clustered into Group A, having the lowest mean total abundance and species diversity of zooplankton, consisting mainly of N. scintillans located the whole region. Cluster Group B from the spring season (April to May) and contained the species diversity with some neritic copepods. Cluster Group C from the summer season (June to August) mainly comprised P. orientalis, A. ohtsukai, Oithona sp., and hydromedusae. Cluster Group D from the autumn season (November) mainly comprised P. orientalis, Temora discaudata. Redundancy analysis indicated that abundance is positively correlated with temperature, salinity, and pico chlorophyll-a concentrations. This study showed that planktonic larvae (such as branchyura larvae) and some copepods (including A. omorii, A. ohtsukai, C. sinicus, and C. abdominalis) were significantly vulnerable to zooplankton community of temperature, salinity, and pico chlorophyll-a concentrations.

Stratigraphy and Paleoenvironment of Domi-1 and Sora-1 Wells, Domi Basin (도미분지 도미-1, 소라-1공의 층서와 고환경)

  • Yun, Hye-Su;Byun, Hyun-Suk;Oh, Jin-Yong;Park, Myong-Ho;Lee, Min-Woo
    • Economic and Environmental Geology
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    • v.45 no.4
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    • pp.407-429
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    • 2012
  • There has been much debates on the geologic age of the sediments of the Domi Basin, since age results varied after research methods and fossil groups. This study carried out palynological analysis and seismic interpretation to establish a stratigraphy and environmental reconstruction mainly based on fossil dinoflagellates and Seismic data from the Domi-1 and Sora-1 wells. The dinocyst assemblages found enabled zonation of the well sediment sequence resulting in 4 ecozones. Index fossils among dinocysts and palynomorphic substances indicate geologic age of the well ranges from Eocene to Pleistocene, and paleoenvironment varies from freshwater to inner-neritic marine. The fossil association also suggests strong relationship to Japanese Tertiary basins in Kyushu area in terms of stratigraphy and basin developmental history.

Temporal Variations and Species Composition of Planktonic Tintinnids (Protist, Ciliophora) in the Korea Strait (대한해협에서 유종섬모충류의 종조성과 시간적 변동)

  • Han, Gook-Bo;Lee, Won-Je
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.15 no.4
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    • pp.176-183
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    • 2010
  • In order to understand the temporal variations and species composition of tintinnids, at two stations of the Korea Strait, this study was carried out from January to December 2007 (n=17). Fifty-one species from 22 genera were encountered: 27 neritic species (9 genera) and 24 oceanic species (14 genera). The species composition was different between two stations, and neritic species frequently appeared at St. 1, while oceanic species more frequently appeared at St. 2. According to the frequency in appearance of species, the most dominant species were neritic species such as Stenosemella nivalis and S. pacifica, that appeared in all seasons. Also, Acanthostomella norvegica, Amphorellopsis acuta, Epilpocyloides ralumensis, Protorhabdonella curta and other many oceanic species appeared intensively during the low salinity (${\leqq}33\;psu$) and high water temperature (${\geqq}24^{\circ}C$) period (July~October). The abundance of tintinnids ranged from 0 to 1,845 cells $L^{-1}$. It was higher in the seasons (summer and autumn) of low salinity and high water temperature than in other seasons. The abundance was relatively higher at St. 1 than at St. 2. On the basis of correlation and multiple regression analyses, the tintinnid abundance was not correlated with chi-a, but significantly correlated with water temperature and salinity, suggesting to be the primary abiotic factors influencing the abundance. This study suggests that the complex hydrographic conditions of the study area might influence the temporal distribution and species composition of tintinnids.

Slope Sedimentation and Organic Carbon Content in the Late Quaternary West Florida Slope Sediments

  • Lee, Eun-Il;Park, Soo-Chul
    • Journal of the korean society of oceanography
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    • v.34 no.3
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    • pp.144-150
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    • 1999
  • Slope sedimentation on the modern west Florida continental margin is controlled by pelagic carbonate accumulation and off-shelf sedimentation of neritic carbonates and terrigenous fines. Production and deposition of pelagic carbonates by planktonic foraminifera and coccoliths have played a significant role in the total slope sedimentation and are mainly promoted by sea-surface productivity. Organic carbon data reflect the relatively high biological productivity in surface waters, indicating high accumulation of biogenic calcareous sediments. The surface-water productivity in the study area is supported by the relation among microfossil assemblages, carbonate mineralogy and sedimentary organic carbon.

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