• Ocean and Polar Research
• /
• 제30권4호
• /
• pp.419-426
• /
• 2008

Ciliate plankton samples were collected biweekly from July 2006 to June 2008 in Jangmok Bay of Geoje Island. Species composition and abundances were analyzed by quantitative protargol stain and environmental parameters were also examined. A total of 88 ciliate species occurred during the study period, consisting of 22 tintinnids, 51 oligotrichs, and 15 other species. Higher ciliate abundances appeared from June to October during the warm season ($<20^{\circ}C$) and the maximum ($4.0{\times}10^4\;cells\;L^1$) in August, while the lower abundances were found during the cold season. The minimun ciliate abundance was found in November when water temperature rapidly decreased. The temporal succession of dominant species was very clear and opportunistic. Pelagostrombidium sp., Tontonia simplicidens, Helicostomella subulata, and Myrionecta rubra were co-dominant in summer while Rimostrombidium orientale occurred abundantly in winter. Strombidium tressum and S. compressum, eurythermal species, were observed during all seasons. Based on the species-specific ecology of ciliate plankton, it is suggested that the indicative ciliate species can be applied as a biological tool to detect environmental change in the southern coastal waters of korea.

• 한국수산과학회지
• /
• 제55권5호
• /
• pp.625-637
• /
• 2022

The southern coast of the East Sea is an important area affected by large warm currents as it connects the coastal waters of Jeju Island, the South Sea, and Dokdo. From 2017 to 2021, the average catch per unit effort (CPUE; kg/day/ship) of set net fishery at six ports in the Gyeongbuk region off the southern coast of the East Sea was the highest in Gampo, Gyeongju, and the lowest in Hupo, Uljin. Although the seasonal variation in the CPUE differed by region and year, it was generally high in autumn. In the set net fishery in Pohang from 2019 to 2021, we identified 72 species, which decreased to 56 species in 2019, 46 in 2020, and 41 in 2021. The species diversity index slightly increased over the three-year periods. We found positive correlations between the total catch (kg) of subtropical species in autumn and the water temperature at 50 m. Among the most abundant species, we found substantially positive correlations between the CPUE of Scomber japonicus, Scomberomous spp. and Carangids. We also noted positive correlations between the CPUE of Todarodes pacificus, Seriola spp. and Carangids.

• Ocean and Polar Research
• /
• 제33권spc3호
• /
• pp.349-358
• /
• 2011

In order to ascertain latitudinal variation of lipid contents and compositions in copepods, we collected warm water copepod species (Euchaeta sp. and Pleuromamma spp.) from four different regions from low (sub-tropical) to mid (temperate) latitudes in the Northwest Pacific Ocean. Total lipid contents of Pleuromamma spp. were about 11 $ug{\cdot}ind^{-1}$ with little latitudinal variation, whereas Euchaeta sp. showed slightly higher lipid content (20 $ug{\cdot}ind^{-1}$) than Pleuromamma spp. with latitudinal gradient (low at subtropic and high at temperate). Wax esters, known as the major storage lipid classes, were found to be the dominant lipid classes (accounting for more than 35% of total lipids) in Euchaeta sp., whereas in Pleuromamma spp., phospholipids, known as cellular membrane components, were the dominant lipid classes. However, the exception was specimens from warm pool region exhibiting dominance in storage of lipids as a form of triacylglycerols. Among fatty acids, polyunsaturated fatty acids (PUFA), especially docosahexaenoic acid (DHA : 22:6(n-3)) (about 35% of total fatty acids), were most abundant in Euchaeta sp., while saturated fatty acids (SAFA), specially hexadecanoic acid (16:0) (about 30% of total fatty acids), were most abundant in Pleuromamma spp.. Among the neutral fraction of lipids, phytol, originated from the side chain of chlorophyll, was found in all samples which generally indicate active copepods feeding on algae. While only trace amounts of short-chain fatty alcohols were found in Pleuromamma spp., significant amounts of fatty alcohols were found in Euchaeta sp.. Particularly, significant amounts of long chain monounsaturated fatty alcohols (20:1 and 22:1), generally found in cold water species, were found in Euchaeta sp. from low latitudes. The latitudinal variation of trophic lipid markers in these copepods could be significantly related with in-situ food availability and species-specific diet preference. The result of this study suggests that the lipid contents and compositions in copepods may not only indicate their nutritional condition and feeding ecology but also provide insight into species-specific living strategies under different environmental conditions (i.e. water temperature, food availability).

• 한국패류학회지
• /
• 제22권1호
• /
• pp.63-86
• /
• 2006

A list of species of bivalve mollusks, their local distributions and relative abundance in Yeongil Bay were analysed. Species richness ranging from 1 to 37 species was low (less than 10) in some stations at the entrance and in the central part of the bay. Fifteen species (Acila insignis, Nucula tenuis, Yoldia notabilis, Mytilus galloprovincialis, Arca boucardi, Axinopsida subquadrata, Felaniella usta, Mactra chinensis, Raeta pulchella, Nitidotellina hokkaidoensis, Theora fragilis, Alvenius ojianus, Callithaca adamsi, Ruditapes philippinarum and Laternula anatina) were most frequently encountered, and seven of them were most abundant numerically (per sample): Th. fragilis in the inner bay, A. insignis, N. tenuis, and A. ojianus in the outer bay, and C. adamsi, A. subquadrata, R. puichella in both parts. Local distributions of common species were described and presented in plotted data, and three distribution patterns were recognized. Biogeographical analysis shows that a majority of species (55%) belongs to the subtropical group, tropical-subtropical species (16%) play a relatively significant role, and the percentage of boreal (temperate) and boreal-arctic species is 18% which characterizes the whole fauna as subtropical. Zonal-biogeographical composition and number of species in families in Yeongil Bay are compared with those of some Japanese (Wakasa and Mutsu) and Russian (Peter the Great, Possjet and Amursky) bays of the East Sea. The absence of a number of typical warm-water embaymental mollusks in Yeongil Bay found in the north further East Sea and Japan, and the similar zonal-biogeographical structure of the inner and outer bay faunas are explained by active water exchange due to the openness of the bay, relatively low summer temperatures, and presence of upwelled cold waters.

• Journal of the korean society of oceanography
• /
• 제39권4호
• /
• pp.207-211
• /
• 2004

We used long time series of hydrographic and biological variables to examine the ecosystem consequences of a rare, anomalous event in the south sea of Korea. The highest zooplankton biomass in 36 years of sampling occurred in April 1997. Zooplankton biomass exceeded 2 times than the long-term mean at 35% of the stations. Copepod abundance was low in April and June and also failed to show a seasonal peak in 1997. Mackerel (Scomber japonicus) catches were very low in spring 1997 and 1999, in spite of a positive correlation between zooplankton biomass and mackerel catches at lags of 0, 12 and 24 months. It was discussed that a high zooplankton biomass with low copepod abundance in April 1997 resulted from unusual high temperature and salps abundance. Water temperatures were ca. $2^{\circ}C$ higher than the long-term mean at the surface. Salps and doliolids (thaliaceans), especially the warm-water species Doliolum nationalis, dominated the zooplankton. An unusual incursion of the Tsushima Warm Current may have transported the thaliaceans into the area and/or produced favorable conditions for a bloom. This study suggested that taxonomic composition of zooplankton was important to decide mackerel catches.

• Ocean and Polar Research
• /
• 제35권2호
• /
• pp.157-170
• /
• 2013

We investigated the seasonal succession of phytoplankton assemblages in the eastern part of the South Sea of Korea in relation to surface water masses. The study areas are under the direct influence of the Tsushima Warm Current (TCW) throughout the whole year, with its strength known to be seasonally variable. The region is also influenced by coastal waters (CW) driven from the South Sea of Korea and East China Sea, particularly in summer, as indicated by low salinity in the surface water. Nutrient property of the TCW can reveals whether the origin of the TCW is the nutrient-rich Kuroshio Current or the oligotropic Taiwan Warm Current. Surface chlorophyll-a (Chl-a) concentrations displayed a large seasonal variation for all stations, with high values found in spring and autumn and low values in summer and winter. At station M (offshore) and P (intermediate location between M and R), Chl-a concentrations in October were higher than those in March, when spring bloom normally occurs. This may be related to deeper mixed layer depths in October. Diatoms dominated under conditions of high nutrient supply in which Chaetoceros spp. and Skeletonema costatum-like spp. were abundant. S. costatum-like spp. dominated at stations R (onshore station) and P in December when there was greater nutrient supply, especially of phosphate. Flagellates and dinoflagellates dominated at all three stations after diatoms blooms. Dominant species were Scrippsiella trochoid in April and Ceratium furca in October at station R, and Gyrodinium spp. and Gymnodinium spp. at station M during summer, when the effect of the oligotropic Taiwan Warm Current and the oligotropic coastal water from East China Sea were strong. Redundancy analysis showed clear seasonal successions in the phytoplankton community and environmental conditions, in which both principal components 1 and 2 accounted for 69.6% of total variance. Our results suggested that environmental conditions seemed to be determined by the origin of the TCW and the relative seasonal strength of the water masses of the TCW and CW, which may affect phytoplankton growth and compositions in the study area.

• 환경생물
• /
• 제27권1호
• /
• pp.48-57
• /
• 2009

The characteristics of physico-chemical factors and the species compositions of phytoplankton were investigated to analyze the marine ecosystem at the depths during summer in the coast of Dokdo (stations DOK1$\sim$3). The mean values of conductivity (32 mS cm$^{-1}$), total dissolved solids (45 mg L$^{-1}$), salinity (35.5 psu), total suspended solids (39 mg L$^{-1}$) were the highest in DOK1. The biomass (chl-${\alpha}$) of phytoplankton was the highest in the surface of station DOK1 (3.1 ${\mu}g$ L$^{-1}$). By means of physico-chemical factors (salinity, turbidity, chl-${\alpha}$, T-N, T-P and Si), the coast of Dokdo was estimated to be more polluted than the previous results in 2000. A total of 72 species in Dokdo were composed of 54 species (76.1%) for Bacillariophyceae and 13 species (18.3%) for Dinophyceae, 3 species (4.2%) for Chrysophyceae and 1 species (1.4%) for Cyanophyceae. The standing crops of phytoplankton were the highest (8.5 $\times$ 10$^4$ cells L$^{-1}$) at 20 m of station DOK1, while they were the lowest (1.65 $\times$ 10$^4$ cells L$^{-1}$) at 30 m of station 1. The dominance index was maximum (0.73) at 10 m of station DOK1 and was minimum (0.4) at 30 m of station 1. The diversity index was the highest (2.92) in the surface of station 2, while it was the lowest at 20 m (1.58). The dominant species of phytoplankton were Chaetoceros affinis (3.3 $\times$ 10$^4$ cells L$^{-1}$) at 20 m, Climacosphenia moniligera (2.8 $\times$ 10$^4$ cells L$^{-1}$) at 40 m and Melosira juergensii (1.7 $\times$ 10$^4$ cells L$^{-1}$) at 10 m of station DOK1. At the surface of station DOK2, the dominant species were Bacillaria paxillifer and Richelia intracellularis (1.4 $\times$ 10$^4$ cells L$^{-1}$, respectively), while it was Paralia sulcata (1.6 $\times$ 10$^4$ cells L$^{-1}$) at the surface of station DOK3. The station DOKl, where affected by upwelling, turbulence and convection due to the East Korean Warm Current, was the most eutrophicated water body in three stations. The monitoring of marine ecosystem in the coast of Dokdo should be continued to show the alternatives for water and species conservation and to purify the eutrophicated water body due to artificial pollutants as well as physico-chemical factors by the global warming, the climatic change, CO$_2$ etc.

• 한국해양바이오학회지
• /
• 제3권1호
• /
• pp.1-6
• /
• 2008

Angola has a coastline of about 1,650 km long. Two diverging current namely, the Angola current with its warm water from the north and the cold Benguella Current in the south create a strong up-welling with a high productive ecosystem for marine resources. The area from Lobito to the mouth of the Cunene River, also known as the Southern fishing zone is by far the most productive of Angola's fishing zones. In 1977, the total potential of its marine fisheries sector was estimated at more than 700,000 tonnes per annum. In 2003, the Total Allowable Catch (TAC) established for demersal species was 57,600 tonnes and 160,000 tonnes for pelagic species. The most important resources are various marine demersal and pelagic fish including pilchard and the Cape and Cunene horse Mackerel (Tranchurus capensis and T. trecae). Sardinellas (Sardinella aurita and S. maderensis) are fished in parallel with horse mackerel. The rest of the catches are mainly demersal spp. and some deep water crustaceans. The demersal sppecies consist of Hake (Merluccius polli and M. capensis) and the large eye dentex spp. Tunas are caught at certain times of the year whilst some marine shrimp are also harvested from the Angolan waters. Angola also has several high value freshwater fish species, exploited by about 255 fishers. Tilapia sp. is among the most important and abundant fresh water fish found in Angola. Other species include the catfish (Clarias gariepinus) and fresh water prawns (Macrobrachuin rosenbergii). Some aquaculture ponds have been established in the country side, but due to lack of investment, proper training and the impact of civil war have seriously limited developments in the sub sector.

• 환경생물
• /
• 제36권2호
• /
• pp.217-231
• /
• 2018

2007년 2월부터 2008년 11월까지 국내의 4개 주요 항만(부산항, 울산항, 인천항, 광양항)에 분포하는 유종섬모충류의 계절적 출현양상과 선박평형수 벡터종(Coos Bay 벡터종 기준)의 계절적 출현양상을 조사하였다. 조사 기간 중 부산항과 울산항에서 유종섬모충류 난류종인 Ascampbeliella urceolata, Codonellopsis morchella, C. ostenfeldi, Dadayiella ganymedes, Eutintinnus stramentus, Protorhabdonella curta가 8월과 11월에 출현하였다. 인천항과 광양항에서는 전 계절을 통해 연안종이 출현하였고 특히 저수온기와 고수온기에 연안종의 출현이 뚜렷하였다. 광양항에서는 2007년 5월에 난류종 Tintinnopsis ampla의 출현과 2008년 11월에 C. ostenfeldi가 출현을 보였지만 인천항에서는 난류종의 출현이 관찰되지 않았다. 유종섬모충 출현분포의 특성은 연안종이 주로 출현하였으며, 부산항과 울산항에서 8월과 11월에 난류종이 중점적으로 출현하고 있는 것은 쿠로시오 해류(Kuroshio current)의 지류인 대마난류(Tsushima Warm Current)의 영향에 의한 유입되는 것으로 판단된다. 또한 조사 기간 중 주요 항만에서 출현한 유종섬모충류의 벡터종은 총 13종이었다. 광양항에서 13종으로 가장 많은 종이 출현하였고 인천항에서 6종으로 가장 적은 종수가 관찰되었으며 부산항과 울산항에서 각각 10종과 11종이 관찰되었다. 이들 벡터종은 부산항, 울산항, 광양항의 고수온기에 가장 많은 출현종수를 보인 반면, 인천항에서는 저수온기 2월에 가장 많은 출현종수를 보여 항만에 따른 차이를 보였다. 그러나 우리나라에 해역에 영향을 주는 서로 다른 해류에 의한 유입종 연구와 선박 평형수에 의해 유입된 벡터종의 연구가 매우 부족하기 때문에 주요 항만의 유종섬모충류의 종조성 차이에 대한 정확한 결론을 내리기에는 어려움이 있어 앞으로 이에 대한 체계적인 연구가 필요하다고 판단된다.

• 환경생물
• /
• 제17권4호
• /
• pp.379-387
• /
• 1999

최근 우리나라에서는 산업이 급속도로 발전하면서 급증하는 전력수요를 충당하기 위하여 원자력발전소의 건설과 가동이 증가 추세에 있다. 수년에 걸친 발전소의 건설 과정에서 부지의 매립과 준설은 저서 해조류의 서식처를 교란시키고 이는 나아가서 종조성의 변화를 야기한다. 발전소가 정상 가동하게 되면 필연적으로 다량의 온배수를 주변으로 방출하는데, 고착성 해조류는 수온의 상승에 민감하게 반응한다. 국내 원자력발전소에서는 냉각수가 복수기를 통과하면서 수온이 7~12$^{\circ}C$ 상승하게 되며, 짧은 거리의 배수로를 거쳐 주변으로 방출된다. 배수로에 인접한 구역에서는 저서 해조류의 종조성과 다양성 이 감소하는 것으로 조사되었다. 한편 발전소 냉각계통의 가동은 해조류 개체군 수준에서 생장률과 생장주기에 영향을 미치는 것으로 확인되었다. 연안수와 혼합되기 전의 배수로에 출현하는 해조류는 높은 수온에서도 견딜 수 있는 내열종으로 간주될 수 있으며, 동해안에 위치한 3개 원자력발전소의 배수로에서 1992~1998년에 걸쳐 출현한 해조류 중 출현빈도 20%이상의 내열종 해조류는 총 35종(남조류 4종, 녹조류 9종, 갈조류 8종, 홍조류 14종)이었다. 해조류가 우리 민족에게 귀중한 자원이 되고 있음을 고려해 볼 때, 발전소로부터 방출되는 폐열이 해조식생에 미치는 영향을 저감시킬 수 있는 대책 수립이 요망된다.