• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.26 no.3
• /
• pp.248-262
• /
• 2021

Marine planktonic ciliates include two major groups, loricated tintinnids and naked oligotrichs. The study of marine ciliate plankton in Korea began with taxonomic efforts on tintinnids based on the morphology of lorica, a vase-shaped shell. Despite polymorphism in the lorica, it is utilized as a key characteristic in identification of tintinnid species. However, oligotrichs have been studied only recently in Korea due to challenges associated with the observation of ciliary arrangements and the technical development for cell staining. Species diversity and phylogenetic classification of the ciliates have been informed by recent advances in morphological and molecular analyses. Illustrations of the planktonic ciliate in Korea have been published on the basis of taxonomic data of tintinnids and oligotrichs. Planktonic ciliates acting as the major consumers of pico- and nanoplankton as well as the prey of mesozooplankton, has been monitored by spatial and temporal investigations in Korean coastal waters. A practical approach addressing the limitations and potential of marine ciliate studies in Korea is proposed here to improve the data quality of planktonic ciliates, providing an enhanced basis for quality control of ciliate monitoring.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.12 no.2
• /
• pp.61-72
• /
• 2007

The relationship between North Pacific chum salmon (Oncorhynchus keta) population and climate variability was investigated in the North Pacific ecosystem. Time-series for the Aleutian Low Pressure, Southern Oscillation, Arctic Oscillation, and Pacific Decadal Oscillation (PDO) indices dating back to 1950 are compared with the chum salmon catch using a cross-correlation function (CCF) and cumulative sum (CuSum) of anomalies. The results of CCF and CuSum analyses indicated that there was a major change in climate during the mid 1970s, and that the chum salmon population responded to this climate event with a time-lag. The PDO and chum salmon returns showed a highly significant correlation with a time-lag of 3 years, while the AOI with a time-lag of $6{\sim}7$ years. The favorable environments for fry chum salmon might cause better growth in the coastal areas, but higher growth rate during the early stage does not seem to be related to the improved return rate of spawning adults. Rather, growth in the Okhotsk Sea or the Bering Sea during immature stages has a significant correlation with return rate, which implies the size-related mortality process. The development of a local climate index is necessary to elucidate the effect of climate variability on the marine ecosystem around the Korean Peninsula.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.18 no.1
• /
• pp.43-52
• /
• 2006

Numerical model tests are done in order to evaluate impact zone of low salinity water on outer region of the developing Saemankeum reservoir. Also saline mixing processes are investigated f3r the inner reservoir with consideration of Mankyoung and Donjin riverine flood discharges when sea water is passing freely through gate. In these analyses 2-d ADCIRC, 3-d TIDED3D and CE-QUAL-ICM models are used. Through models tests, it is found that inner reservoir mixing process caused by inflow of outer sea water occurs gradually. It takes at least one month for complete mixing on Mankyoung part and 6 month on Dongjin part of the reservoir. When Sinsi or Garyeok gates are opened to control inner reservoir level, discharging velocities decrease exponentially from the gates, but show very strong currents of 0.5m/sec to the 10Km region apart. These results imply that hydrodynamic circulation and ecosystem of frontal region of the Saemankeum dike might be affected in amount by gate operations, since low saline inner waters are discharged periodically at ebb tide according to tidal level.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.23 no.5
• /
• pp.393-400
• /
• 2011

The mass transport is very complicated at the area which has the macro tide and complex geometry such as Gyeonggi bay. Especially, the long period current has a strong influence on the estuarine ecosystem and the long-term distribution of substances. The long period current is caused by several external forcing, whose unique characteristic varies spatially and temporally. The variation characteristics of long period current is analysed and its generation mechanism is studied. The tidal nonlinear constituents such as overtide and compound tide are generated due to nonlinear interaction and it causes mean sea level setup. The tidal wave propagating up into estuary is transformed rapidly by decrease of cross-sectional area and depth. Therefore the mean sea level is getting rise toward upriver. The high and low tide level is similar between down-river(Incheon) and up-river(Ganghwa) during neap tide when the tidal deformation is decreased. The tidal phase difference between two tidal stations causes a periodic fluctuation of sea level difference. The low water level of Ganghwa station during spring tide does not descend under EL(-)2.5 m, but the low water level of Incheon fall down under EL(-)4.0 m. The variation of tidal range and its sea level are increased during spring tide. It is found that the long period current $M_{sf}$ is quite similar to that of sea level difference between the two tidal stations. It means that the sea surface inclination caused by the spatial difference of tidal deformation is important forcing for the generation of long period current.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.23 no.5
• /
• pp.358-368
• /
• 2011

Responses of plankton populations to nutrient enrichment in mesocosm experiments in Shihwa lake were simulated using FVCOM. Dissoloved oxygen module was added to the FVCOM to simulate impacts of its decreased levels. The ecological model included the major components of the pelagic ecosystem including nutrients, phytoplankton (pico-, nano-, micro-), zooplankton (two groups of protozoa, mesozooplankton), particulate organic matter, dissolved organic matter and bacteria, and was calibrated using trophodynamic data collected from Gyeonggi Bay and Shihwa Lake. The model was able to reproduce major responses of plankton populations to nutrient enrichment, including phytoplankton of different size groups, change of dominance of protozoa from < 20 ${\mu}m$ oligotrichs to scuticociliates, and reponses to bacteria and low levels of dissolved oxygen in water column of the mesocosms.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.3 no.2
• /
• pp.80-89
• /
• 1998

To understand the temporal variation of phytoplankton community in the Antarctic coastal ecosystem, physicochemical parameters, chlorophyll a, and primary productivity were measured as a component of the 7th KARP (Korea Antarctic Research Program) in 1994. Data were collected every month between February and December except four months (June-September) when the study area was frozen. Chlorophyll a concentrations ranged from negligible to 3.03 ${\mu}g/l$, averaging 0.63 ${\mu}g/l$. The primary productivity ranged 0.53-18.95 mg C/$m^3{\cdot}day$, and the depth-integrated primary productivity ranged 41.28-560.20 mg C/$m^3{\cdot}day$. A positive relationship was observed between the phytoplankton biomass and irradiance ($r^2$=0.29, p < 0.01). The degree of correlation between the primary productivity and irradiance ($r^2$=0.85, p < 0.001) was significantly higher than that between the phytoplankton biomass and irradiance. However, neither temperature nor inorganic nutrients seem to affect the temporal variation of primary productivity.

• Korean Journal of Environmental Biology
• /
• v.32 no.4
• /
• pp.311-318
• /
• 2014

PFOS (perfluorooctane sulfonate) is one of the perflourinated organic compound, which persist as a residual compound in the coastal environments. Intertidal mud crab Macrophthalmus japonicus mainly inhabits in coastal and bay ecosystems in Indo-Pacific region including Korea and reflects to environmental changes. In the present study, M. japonicus were exposed to different concentrations of PFOS and various ecotoxicological end-points such as survival rate, elimination of appendages, changes of the crust and internal organ color changes were investigated. Interestingly, the PFOS exposure showed concentration-dependent decrease of survival rate. High PFOS exposure ($30{\mu}gL^{-1}$) showed a low survival rate of 24% at 168 hours. Further, in comparison with the controls, the rate of elimination of appendages was also considerably increased in a time dependent manner upon PFOS exposure. Notably, with progression of time, an increased exposure to PFOS, test species showed whitening effect in a concentration-dependent manner, whereas the crab crust color was unchanged in the control. In addition, change in internal organs color and their visibility (clarity) observed in PFOS exposed crabs compared to control. Taken together, we suggest, eco-toxicology end-points of M. japonicus exposed to PFOS gave important biological information which could be useful to identify toxic contamination in the marine benthic environments.

• 한국해양학회지
• /
• v.26 no.3
• /
• pp.204-222
• /
• 1991

The annual cycles of plant major nutrients and dissolved oxygen in a nutrients-rich semi-enclosed coastal inlet, chinhae Bay, of the southern coast of the Korean Peninsula are first presented. The water column of the bay is stratified during summer (April-late September) and well0mixed during winter (October-March). During the summer stratification period, dissolved oxygen contents exceed 400uM in the surface but diminish to less than 50uM in the near bottom waters, which often results in an anoxic environment in the inner part of Chinhae Bay. After the breakdown of the stratification in October, dissolved oxygen concentration remains undersaturated until February. The evidence of allochthonous input of N-nutrients throughout the year is readily seen in the water column: however. crude budget calculations show that the nutrients are efficiently utilized within the bay ecosystem, and that export of the nutrients from the bay to the shelf must be negligible. There is no sign of the enrichment of the nutrients in the water column. The eutrophication phenomenon sensu stricto is not observed in chinhae Bay. Using the standing stock of dissolved oxygen and estimation of the oxygen fluxes across the air-sea boundary, a benthic oxygen respiration rate during winter is estimated conservatively at 21-24 mmol Cm/SUP -2/d/SUP -1/. this oxygen respiration rate accounts for about 20% of the total phytoplankton production in winter.

• Korean Journal of Ecology and Environment
• /
• v.48 no.2
• /
• pp.122-128
• /
• 2015

This study aims to figure out the vegetation status and characteristics of the spatial distribution in Taeanhaean National Park. As a result, vegetation communities were Pinus thunbergii community, Pinus densiflora community, Pinus thunbergii-Pinus densiflora community, Camellia japonica community, Carpinus turczaninowii community, Carpinus turczaninowii-Pinus thunbergii community, Kalopanax septemlobus community, Koelreuteria paniculata community, Robinia pseudoacacia community, and sand dune and coastal wetland vegetation including Vitex rotundifolia community, Elymus mollis community, Calamagrostis epigeios community, Ischaemum anthephoroides community, Zoysia sinica community, Suaeda maritima community, and Phragmites communis community. Landscape types in actual vegetation map were Pinus thunbergii community (3.92%), Pinus densiflora community (1.40%), Robinia pseudoacacia community (0.05%), sand dune and coastal wetland vegetation (0.11%), field (0.46%), seashore (0.24%), thinning area (0.08%), bareground (0.16%), and sea (93.58%). Area of Pinus thunbergii community among vegetation type was $14.797km^2$ (3.92%) and the largest. Stratification structure and species composition of Pinus thunbergii community distributed in the seashore were different as a result of disturbance and human use. On the other hand, we assumed that succession will take place to the potential natural vegetation that is Quercus serrata and Quercus dentata in undisturbed Pinus thunbergii community. Meanwhile, Erechtites hieracifolia was occupied in understory of Pinus thunbergii community around the seashore and Diodia teres was invaded to sand dune vegetation. They may affect on natural species negatively. Therefore, monitoring and management plans are necessary.

• Journal of Wetlands Research
• /
• v.26 no.1
• /
• pp.82-91
• /
• 2024

In this study, research cases related to blue carbon storage were collected and analyzed, and various definitions of blue carbon were considered in terms of spatiotemporal scope and scientific aspect. 444 papers were selected as research cases related to blue carbon storage, and analysis of the number of papers published by year/country and keywords was performed. Publication of papers related to blue carbon storage has continued to increase since 2011, and more than 50 papers have been published annually since 2018. The most publications by country were in Australia with more than 100 papers, and the United States and China also published more than 60 papers. Key terms related to "natural environment" and "storage characteristics" were analyzed in the sentences defined in the 23 papers that presented the definition of blue carbon. The natural environments where blue carbon was stored were mostly mangroves, salt marshes, and seagrass beds, and blue carbon repository included sediments and even plants themselves. The existing definition of blue carbon focused on the vegetation environment as the storage environment for blue carbon. However, since blue carbon is stored in the sediments of coastal wetlands, it would be appropriate to define the coastal ecosystem, including non-vegetated mudflats, as the storage environment for blue carbon.