• ALGAE
• /
• v.32 no.3
• /
• pp.199-222
• /
• 2017

Occurrence of Cochlodinium polykrikoides red tides have resulted in considerable economic losses in the aquaculture industry in many countries, and thus predicting the process of C. polykrikoides red tides is a critical step toward minimizing those losses. Models predicting red tide dynamics define mortality due to predation as one of the most important parameters. To investigate the roles of heterotrophic protists in red tide dynamics in the South Sea of Korea, the abundances of heterotrophic dinoflagellates (HTDs), tintinnid ciliates (TCs), and naked ciliates (NCs) were measured over one- or two-week intervals from May to Nov 2014. In addition, the grazing impacts of dominant heterotrophic protists on each red tide species were estimated by combining field data on red tide species abundances and dominant heterotrophic protist grazers with data obtained from the literature concerning ingestion rates of the grazers on red tide species. The abundances of HTDs, TCs, and NCs over the course of this study were high during or after red tides, with maximum abundances of 82, 49, and $35cells\;mL^{-1}$, respectively. In general, the dominant heterotrophic protists differed when different species caused red tides. The HTDs Polykrikos spp. and NCs were abundant during or after C. polykrikoides red tides. The mean and maximum calculated grazing coefficients of Polykrikos spp. and NCs on populations of co-occurring C. polykrikoides were $1.63d^{-1}$ and $12.92d^{-1}$, respectively. Moreover, during or after red tides dominated by the phototrophic dinoflagellates Prorocentrum donghaiense, Ceratium furca, and Alexandrium fraterculus, which formed serial red tides prior to the occurrence of C. polykrikoides red tides, the HTDs Gyrodinium spp., Polykrikos spp., and Gyrodinium spp., respectively were abundant. The maximum calculated grazing coefficients attributable to dominant heterotrophic protists on co-occurring P. donghaiense, C. furca, and A. fraterculus were 13.12, 4.13, and $2.00d^{-1}$, respectively. Thus, heterotrophic protists may sometimes have considerable potential grazing impacts on populations of these four red tide species in the study area.

• Journal of Environmental Science International
• /
• v.11 no.4
• /
• pp.297-308
• /
• 2002

Field observations for research of oceanographic characteristics in waters adjacent to fish farm on land and water quality at area where water is supplied to fish farm and area where water is discharged from fish farm are carried out in coastal waters of Pyoson located in the southeastern region of Jeju Island in March, May, August and November of 2000. Semidiurnal tides to the northeast and southwest dominate. The mean velocities of current around neap tides and spring tides are 8.52cmㆍs$^{-1}$, 28.63cmㆍs$^{-1}$, respectively. The difference of temperature between area where water is supplied to fish farm and area where water is discharged from fish farm is about 0.6$^{\circ}C$. Seasonal variation range for temperature and salinity is 13.5$^{\circ}C$ and 3.5psu, individually. Concentrations of nitrate(NO$_3$$^{-}$), phosphate(PO$_4$$^{3-}$ ), silicate(SiO$_2$) and COD(chemical oxygen demand) are high in autumn. Particularly, concentrations of nitrate and COD in winter and spring at station where water is supplied to fish farm are higher than these at station where water is dischared from fish farm. However, concentration of phosphate and silicate at station where is supplied to fish farm in spring, summer and autumn is higher than that at station where water is dischared from fish farm. Water quality in the study area is grade 1 and this level is kept up in the whole year.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.29 no.5
• /
• pp.228-238
• /
• 2017

In coastal region, tidal harmonic constants of semi-diurnal tides and nonlinear tides were collected. The observed tide data of KHOA were analyzed by a tide harmonic analysis method. In the southwestern coasts and Han river estuary, nonlinear tides are clearly generated. The generation of tide non-linearity and tide asymmetry is closely related with tide form factor in Korean coastal zone. Tide non-linearity and asymmetry in Mokpo harbour have increased by a series of coastal development projects. The increase has caused rise of high water level and drop of low water level, and increase of tidal range. In Kunsan Outport, tidal range has been declined due to inter-annual change of nonlinear tides after completion of Samangeum sea-dyke.

• ALGAE
• /
• v.32 no.2
• /
• pp.101-130
• /
• 2017

The ichthyotoxic Cochlodinium polykrikoides red tides have caused great economic losses in the aquaculture industry in the waters of Korea and other countries. Predicting outbreak of C. polykrikoides red tides 1-2 weeks in advance is a critical step in minimizing losses. In the South Sea of Korea, large C. polykrikoides red tide patches have often been recorded offshore and transported to nearshore waters. To explore the processes of offshore C. polykrikoides red tides, temporal variations in 3-dimensional (3-D) distributions of red tide organisms and environmental parameters were investigated by analyzing 4,432 water samples collected from 2-5 depths of 60 stations in the South Sea, Korea 16 times from May to Nov, 2014. In the study area, the vegetative cells of C. polykrikoides were found as early as May 7, but C. polykrikoides red tide patches were observed from Aug 21 until Oct 9. Cochlodinium red tides occurred in both inner and outer stations. Prior to the occurrence of large C. polykrikoides red tides, the phototrophic dinoflagellates Prorocentrum donghaiense (Jun 12 to Jul 11), Ceratium furca (Jul 11 to Aug 21), and Alexandrium fraterculus (Aug 21) formed red tides in sequence, and diatom red tides formed 2-3 times without a certain distinct pattern. The temperature for the optimal growth of these four red tide dinoflagellates is known to be similar. Thus, the sequence of the maximum growth rates of P. donghaiense > C. furca > A. fraterculus > C. polykrikoides may be partially responsible for this sequence of red tides in the inner stations following high nutrients input in the surface waters because of heavy rains. Furthermore, Cochlodinium red tides formed and persisted at the outer stations when $NO_3$ concentrations of the surface waters were < $2{\mu}M$ and thermocline depths were >20 m with the retreat of deep cold waters, and the abundance of the competing red-tide species was relatively low. The sequence of the maximum swimming speeds and thus potential reachable depths of C. polykrikoides > A. fraterculus > C. furca > P. donghaiense may be responsible for the large C. polykrikoides red tides after the small blooms of the other dinoflagellates. Thus, C. polykrikoides is likely to outgrow over the competitors at the outer stations by descending to depths >20 m and taking nutrients up from deep cold waters. Thus, to predict the process of Cochlodinium red tides in the study area, temporal variations in 3-D distributions of red tide organisms and environmental parameters showing major nutrient sources, formation and depth of thermoclines, intrusion and retreat of deep cold waters, and the abundance of competing red tide species should be well understood.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2004.05a
• /
• pp.111-116
• /
• 2004

We surveyed the coastal structure damages due to the typhoon 'Mae-mi' which heavily struck Korean peninsula in September 12, 2003. The survey revealed the typhoon induced high tides and strong winds were the main causes especially in Busan areas. Though some experimental real time coastal monitoring stations captured the typhoon movements at the critical time, more systematic and complete systems should be implemented to save human lives and properties from huge typhoon disasters.

• Korean Journal of Environmental Biology
• /
• v.31 no.2
• /
• pp.165-171
• /
• 2013

The distribution patterns of estuarine copepods were investigated in the Seomjin River estuary of southern Korea after heavy rains in August 2006. Tidal influence extended 16 km from the estuary mouth. Each estuary zone (Oligohaline salinity <5, mesohaline salinity 5~18, polyhaline salinity >18) changed within a range of about 5~6 km between low and high tides. A total of ten species were recorded, of which Pseudodiaptomus koreanus, Sinocalanus tenellus, and Tortanus dextrilobatus were predominant in the oligohaline zone; Acartia ohtsukai and Acartia forticrusa in the mesohaline zone; and A. erythraea, Calanus sinicus, Centropages dorsispinatus, Labidocera rotunda and Paracalanus parvus s. l. in the polyhaline zone. Their density was fastly reduced in the other zones. In particular, the oligohaline species migrated and aggregated into deeper water during ebb tides in order to retain their populations, while the same tendency was weaker for polyhaline species, suggesting that evolutionary traits primarily control population retention behaviors in estuarine environments.

• Korean Journal of Environmental Biology
• /
• v.17 no.3
• /
• pp.271-278
• /
• 1999

In order to clarify water quality, dynamics and structure of phytoplankton communities, and red tides, the present study was carried out monthly from July to September 1998 at 19 stations in Deukryang Bay. Water temperature varied from 24.$0^{\circ}C$ to 28.6$^{\circ}C$, and salinities ranged from 25.0$\textperthousand$ to 28.6$\textperthousand$. During red tides in July, chlorophyll-$\alpha$ contents were rather high in August, it showed that phytoplankton controlled primary production in this bay. Phytoplankton was composed of 89 diatoms, 19 dinoflagellates, and 3 silicoflagellates. Phytoplankton standing crops varied from a minimum of 1.3$\times$10$^4$cells/ι(Sept., St. 17) to a maximum of 3.8$\times$10$^{6}$ cells/ι (July, St. 10). Red tides occurred in July when the standing crops averaged 1.8$\times$10$^{6}$ cells/ι. Leading the causative organisms of red tide were Prorocentrun minimum in the upper bay, Chaetoceros curvisetus in the mouth and middle part of the bay, Ceratium furca and Thazassio- sira sp. around Nokdong Harbour. Concentration of nutrients such as nitrogen was high in the upper bay, during red tides, water temperatures varied from 23.8$^{\circ}C$ to 29.7$^{\circ}C$ and salinity were 23.l$\textperthousand$ to 27.0$\textperthousand$.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.36 no.5
• /
• pp.343-353
• /
• 2018

Ocean tides in Antarctica are not well constrained mostly due to the lack of tidal observations. Especially, tides underneath and around ice shelves are uncertain. InSAR (Interferometric Synthetic Aperture Radar) data has been used to observe ice shelf movements primarily caused by ocean tides. Here, we demonstrate that it is possible to estimate tidal constituents underneath the Sulzberger ice shelf, West Antarctica, solely using ERS-1/2 tandem mission DInSAR (differential InSAR) observations. In addition, the tidal constituents can be estimated in a high-resolution (~200 m) grid which is beyond any tidal model resolution. We assume that InSAR observed ocean tidal heights can be derived after correcting the InSAR data for the effect of atmospheric loading using the inverse barometric effect, solid earth tides, and ocean tide loading. The ERS (European Remote Sensing) tandem orbit configuration of a 1-day separation between SAR data takes diminishes the sensitivity to major tidal constituents including $K_1$ and $S_2$. Here, the dominant tidal constituent $O_1$ is estimated using 8 differential interferograms underneath the Sulzberger ice shelf. The resulting tidal constituent is compared with a contemporary regional tide model (CATS2008a) and a global tide model (TPXO7.1). The InSAR estimated tidal amplitude agrees well with both models with RMS (root-mean-square) differences of < 2.2 cm and the phase estimate corroborating both tide models to within $8^{\circ}$. We conclude that fine spatial scale (~200 m) Antarctic ice shelf ocean tide determination is feasible for dominant constituents using C-band ERS-1/2 tandem mission InSAR.

• Nuclear Engineering and Technology
• /
• v.45 no.4
• /
• pp.539-552
• /
• 2013

To establish an aging management plan considering seawater influx and changes in groundwater within nuclear power plant sites, the characteristics of groundwater flow must be understood. This study investigated the characteristics of groundwater flow within the site and analyzed groundwater level recorded by monitoring wells to evaluate groundwater flow characteristics and elements that affected these characteristics for supplying the information to conduct the appropriate aging management for ensuring the safety of the safety-related structures in Shin Kori Unit 1 and 2. The increase in groundwater level during the wet season results from high sea-level conditions and the large amount of precipitation. As a result of the analysis of groundwater distribution and change characteristics, the site could be divided into a rainfall-affected area and a tide-affected area. First, the rainfall-affected area can further be divided into areas that are affected simultaneously by excavation, backfill, and a permanent dewatering system. Secondly, areas that are not affected by excavation, or the dewatering system, or by structure arrangement and excavation. Analysis of the spectrum for wells affected by tides resulted in confirmation of the M2 component (12.421 hr) and S2 component (12.000 hr) of the semidiurnal tides, and the O1 component (25.819 hr) of the diurnal tides. In the cross-correlation results regarding tides and groundwater levels, the lag time occurred diversely within 1-3 hours by the effect of the well location from sea, the distribution of the backfill material with depth, and the concrete structure.

• Journal of Astronomy and Space Sciences
• /
• v.21 no.2
• /
• pp.101-108
• /
• 2004

The terrestrial nightglow emission in near infrared region were obtained using a Fourier Transform Spectrometer(FTS) at Esrange, Sweden ($67.90^{\circ}$N, $21.10^{\circ}$E) and the OH(4- 2) bands were used to derive temperature and airglow emission rate of the upper mesosphere. For this study, we analyzed data taken during winter of 2001/2002 and performed spectral analysis to retrieve wave information. From the Lomb-Scargle spectral analysis to the measured temperatures, dominant oscillations at various periods near tidal frequency are found. Most commonly observed waves are 4, 6, and 8 hour oscillations. Because of periods and persistence, the observed oscillations are most likely of tidal origin, i.e. zonally symmetric tides which are known to have their maximum amplitudes at the pole.