• Journal of Environmental Impact Assessment
• /
• v.9 no.2
• /
• pp.109-117
• /
• 2000

The dynamics of physico-chemical factors and biomass of epilithic attached algae was determined by bimonthly sampling in the Kyechon and Yudongchon situated in the upper part of Som River from March 1998 to February 1999. Among environmental factors, average of $NH_4$, $NO_3$, SRP and SRSi concentration ranged $8.9{\sim}86.6{\mu}g$ N/l, $663.9{\sim}2,018.1{\mu}g$ N/l, $0{\sim}15.0{\mu}g$ P/l and 1.6~2.6 mg Si/l, respectively. The contents of chlorophyll-a and organic matter per unit area, which ranged from 21.1 to 231.8 $mg/m^2$ and ranged from 5.2 to 52.6 $g/m^2$, respectively, showed very high in the spatial and temporal variations. Both were high in February and May and low in March seasonally. The fluctuation of epilithic biomass related the concentration of $NH_4$, SRP and current velocity. In relationship between biomass and current velocity, >200 and 100~200 mg chl-a/$m^2$ corresponded to <0.2 and <0.8 m/s, respectively. The evaluation of water quality with chl-a and organic matter of periphyton resulted on over eutrophic condition. Periphytic algae in a small stream were more effective as indicator of water quality than planktonic algae. More researches on periphytic algae in relation to water quality evaluation are needed.

• Journal of Aquaculture
• /
• v.10 no.2
• /
• pp.213-218
• /
• 1997

Experiments on the feeding activity and environmental tolerance of geoduck clam, Panope japonica caught at the coastal water of Kangwon province located in the East Sea of Korea were performed from January to December, 1994. Twenty genera and 33 species of plankton were found in the digestive tract, and most of them are phytoplankton. In spring, 21 species of planktonic foods were indentified, but in sumer, only 11 species were identified. Nitzschia longissima and Rizosolenia alata were present evey month. Weight of the digestive tract was fluctuate seasonally : higher winter and spring, and lower summer. Adult geoduck clams could be tolerated within the range of 5 to $20^{\circ}C$ water temperature, and they could tolerated considerably well temperature than higher temperature within the range.

• The Korean Journal of Malacology
• /
• v.6 no.1
• /
• pp.1-10
• /
• 1990

The occurrence of the larvae, the size of the spats daily attached to the collectors, the difference of the spat size with temperature, and the darly growth of a mussel, Mytilus edulis, were investigated at the off Songpo, Chinhae Bay, the southern part of Korea during the period from March 1 to August 30 in 1986. The water timperature and specific gravity ranged from 7.0 $^{\circ}C$ to 27.4$^{\circ}C$ (mean 17,24$\pm$5.9$0^{\circ}C$), and from 1.0126 to 1.0126(mean, 1.0242$\pm$0.0023), respectively. D-shaped larvae had two peak occurrences in March 8, April 19, Umbo-shaped larvad three peaks in March 8, April 21 and June 17, and full grown larvae two peaks in May 13 and June 23, respectively. Therefore, it is assumed that the mussel had two mass spawning time in early March and mid April and two mass settling time in mid May and alte June. The maximum size of the planktonic mussel larvae ranged from 375-400${\mu}{\textrm}{m}$ and most larvae sizing below 300${\mu}{\textrm}{m}$ long settled in adquate substrate. Spats just after settlement had the range from 26.5 to 547.3${\mu}{\textrm}{m}$ with the minimum of 225.0 ${\mu}{\textrm}{m}$ in mean shell length. The spats settled in summer season, when the water temperature raised above $25^{\circ}C$, were smaller than those settled in spring season in mean shell length. The early growth of the mussel spat had been assumed considerably fast.

• Animal Systematics, Evolution and Diversity
• /
• v.18 no.1
• /
• pp.75-84
• /
• 2002

MtDNA cyt b gene was used to investigate the geographic variation of 11 populations (106 individuals) of the planktonic developing, periwinkle Littorina brevicula, throughout Eastern, Western, and Southern coastal regions in Korea. The sequence of 500 base pairs and 13 different haplotypes were determined. Haplotype LbA was predominated through the populations studied with frequence of 0.877. Haplotypes were shown different frequencies in each coastal region (0.82, 0.90, and 1.00, respectively). enetic analysis of the 61 individuals of L. brevicula from the polluted and unpolluted sites yielded 8 distinct haplotypes. Haplotype LbA also was most common, and it was shared by 0.872 of frequency among specimens.

• Journal of Life Science
• /
• v.17 no.11
• /
• pp.1453-1463
• /
• 2007

This study presents a molecular phylogenetic analysis of the harmful dinoflagellate Cochlodinium polykrikoides, by use of partial sequence of small subunit (SSU) rRNA gene from most of the major taxa(24 species) in dinoflagellates. The class Dinophyceae clade formed a strong monophyletic relationship with C. polykrikoides and several taxa. On the basis of deeper nodes, the phylogenetic relationships placed C. polykrikoides closer to the order Prorocentrales rather than to the order Gymnodiniales, which was supported by a strong bootstrap value (100%) in the analyses of Neighbor-Joining and Parsimony methods. There is strong support for C. polykrikoides being placed in the same branch as Gymnodiniaceae and being connected in a clade with Prororcentrum micans among Prorocentrales. Morphological data show that C. polykrikoides is well associated with the genus Gyrodinium; however, this species is genetically closer to Gymnodinium than to Gyrodinium. The placement of C. polykrikoides always formed an independent branch separated from other dinoflagellates. In conclusion, planktonic P. micans plays an important role as an ancestor of Gymnodinium, whereas C. polykrikoides appears to be used an intermediate position between P. micans and Gymnodinium based on evolution.

• Korean Journal of Environmental Biology
• /
• v.27 no.1
• /
• pp.1-5
• /
• 2009

This study was to investigate the habitat conditions and growth of right eye flounder (Kareius bicoloratus) in the Saemangeum Reseorvoir during 1995$\sim$2007. The planktonic larvae of K. bicoloratus appeared in early March, and then the juveniles started the benthic life in the tide-pools inside the reservoir, being 1.5$\sim$2.5cm in total length in early April and 6.0$\sim$7.2cm in mid-July. This species was not collected in the tide-pools after July, indicating that the juveniles began to move to outer seas for growing. When the tide barrier of Saemangeum was constructed, the juveniles of K. bicoloratus decreased as the tidal pools were covered continuously, then they could not be collected after 2005. Thus, it is concluded that the environmental change has taken important influence on distribution and spawning of K. bicoloratus since the reservoir was constructed.

• 한국해양학회지
• /
• v.30 no.2
• /
• pp.69-76
• /
• 1995

A turbidite core sediment (RN88-PC5) from 2051 m on the deep-sea floor at the southern margin of Okinawa Trough was examined. Sedimentological characteristics were quite different between sandy sediments and hemipelagic sediments and hemipelagic sediments in terms of benthic foraminiferal assemblage, grain-size and chemical composition. All turbidite sandy sediments were clearly transported from shallow area as they include typical coral reef dwelling benthic foraminifera which were not found in the background hemipelagic sediments. These layers also suggest that the sediments were transported by turbidity-related currents and implies that sedimentological mechanisms were different between sandy sediments and hemipelagic sediments. The result of the /SUP 14/ C age dating and the stable oxygen isotopic fluctuation of planktonic foraminifera show a gradual warming trend of the surface water from about 10 Ka to present. Also Termination lb as well as two fresh water input events were recognized at ca2 and 7 ka.

• 한국해양학회지
• /
• v.22 no.2
• /
• pp.87-104
• /
• 1987

The middle Cretaceous stratigraphec section of Deep Sea Drilling Project (DSDP) Site 530 in the Angola Basin is characterized by cyclic interbeds of organic-carbon-rich black shales and organic-carbon-poor red and green claystones, namely the black shale sequence. A number of samples from the black shale sequence were analyzed for the typesand distribution of insoluble sedimentary organic matter(kerogen) in order to give more information on the depositional conditions of the black shales in the Angola Basin. The dominant type of kerogen in the black shale sequence at Site 530 is amorphous organic matter mainly of marine planktonic algal origin. It probably consists of remains of some unfossiliqed dinoflagellates. The cyclic preservation of organic-carbon-rich black shales in the Angola Basin during the mid-Cretaceous could be explained by the low dissolved-oxygen concentration in the warm, saline deep and bottom waters combined with the sluggish circulation within the highly restricted basin, and the periodic high productivity in the surface waters.

• Journal of The Geomorphological Association of Korea
• /
• v.21 no.4
• /
• pp.165-180
• /
• 2014

Embankment of reservoir Gonggeomji in Sangju has been continuously added since the construction. After approximately 1220 yr BP of late Unified Silla dynasty when the embankment was firstly constructed, there were piled up four times with an interval of approximately 50 years until ca. 980 yr BP of late Goryeo dynasty. The first two times were relatively piled up high, while another two times were made slightly high. After addition of embankment, water level gradually became low and the quality also bad with increase of benthic- and epipitic diatoms than planktonic ones. Shoaling of reservoir was probably resulted from severe vegetation destructions on the small river basins flowing into Gonggeomji. After approximately 980 yr BP, water level rose during approximately 50 years due to precipitation increase.

• Korean Journal of Ecology and Environment
• /
• v.52 no.3
• /
• pp.231-244
• /
• 2019

Zooplankton is essential biological assemblage in understanding the structure and function of aquatic ecosystems, since it plays as a linkage between primary producers and higher trophic level organisms such as fish. Although zooplankton has planktonic characteristics, the sampling and treatment methods for its community analyses are more complicated and variable compared with phytoplankton due to its high diversity in body size and species-specific depth selection behaviors. In the present paper, we reviewed representative classical methods for field sampling and treatments of freshwater zooplankton in relation with quantification of its community structure, and suggested appropriate methods depending on various research objectives.