Korean Coastal Waters Research Articles

Euduboscquella costata n. sp. (Dinoflagellata, Syndinea), an Intracellular Parasite of the Ciliate Schmidingerella arcuata: Morphology, Molecular Phylogeny, Life Cycle, Prevalence, and Infection Intensity.

The syndinean dinoflagellate Euduboscquella costata n. sp., an intracellular parasite of the tintinnid ciliate Schmidingerella arcuata, was discovered from Korean coastal water in November of 2013. Euduboscquella costata parasitized in about 62% of the host population, with infection intensity (= number of trophonts in a single host cell) ranging from 1 to 8. Based on morphology and nuclear 18S ribosomal RNA gene sequences, the parasite is new to science. Euduboscquella costata n. sp. had an infection cycle typical of the genus, but had morphological and developmental features that distinguished it from congeneric species. These features include: (1) episome of the trophont with 25-40 grooves converging toward the center of the shield; (2) a narrow, funnel-shaped lamina pharyngea extending from the margin of the episomal shield to the nucleus; (3) persistence of grooves during extracellular development (sporogenesis); (4) a single food vacuole during sporogenesis; (5) separation of sporocytes early in sporogenesis, regardless of type of spore formed; and (6) dinospore size (ca. 14μm in length) and shape (bulbous episome with narrower, tapering hyposome). After sporogenesis, E. costata produced four different types of spore that showed completely identical 18S rRNA gene sequences. The gene sequence was completely identical with a previously reported population, Euduboscquella sp. ex S. arcuata, from Assawoman Bay, USA, indicating that the two populations are likely conspecific. Favella ehrenbergii, a widely recorded tintinnid known to host Euduboscquella spp., co-occurred with S. arcuata, but was not infected by E. costata in field samples or during short-term, cross-infection experiments.

Vertical structure and variation of currents observed in autumn in the Korea Strait

To observe vertical structure and temporal variations of currents in the Tsushima Warm Current region of the Korea Strait, a moored buoy system was deployed in autumn 2009. The moored buoy system measured vertical profiles of current, temperature, and salinity for 24 days and a background hydrographic survey was performed. Along-strait northeastward currents were dominant in the upper layer (8–35 m). The mean current veers counterclockwise from 48 m to 74 m as much as 50°, and its speed is reduced with depth. There were distinct northward onshore currents near the bottom (65–80 m). It was demonstrated that thermal wind relation holds in the inclined pycnocline layer, which generates the counterclockwise veering current structure. Density gradient along the strait is a main factor producing the cross-strait onshore current component below the upper-layer and the cross-strait density gradient reduces the along-strait current component with depth. Previous studies have never focused on the effect of the along-strait density structure on current structure. The first Empirical Orthogonal Function mode (CM1) of current variability explains 70% of local current variations and its vertical structure is close to the mean current structure. The correlation analysis among variations of CM1 current, slope of sea level anomaly (SSLA) and local wind anomaly revealed that the variation of CM1 current is mainly related to the variation of SSLA across the strait (c-SSLA), which is known to be controlled by remote and local wind forcing. Similarity between vertical structures of mean and CM1 current suggests that thermal wind relation is the main dynamics maintaining the counterclockwise turning of CM1 current below the upper layer although the upperlayer CM1 current is controlled by c-SSLA through barotropic geostrophic relation. Time series of temperature and salinity indicate that the thermohaline front between Korean Coastal Water and Tsushima Warm Current Water meanders in time and migrates over the mooring station back and forth. The front meandering and migration also affect the local SSLA and CM1 current variations in autumn in the Korea Strait.

Description of the new phototrophic dinoflagellate Alexandrium pohangense sp. nov. from Korean coastal waters

The planktonic phototrophic dinoflagellate Alexandrium pohangense sp. nov. isolated from the coastal waters off Korea is described from living and fixed cells by light and scanning electron microscopy (SEM). DNA sequence data were collected from the small subunit (SSU), the large subunit (LSU), internal transcribed spacer regions (ITS1 and ITS2), and 5.8S of the ribosomal DNA (rDNA). The SSU and LSU rDNA sequences of the new dinoflagellate were 4–7% and 14–17%, respectively, different from those of Alexandrium minutum, Alexandrium ostenfeldii, Alexandrium tamutum, Alexandrium margalefii, and Alexandrium pseudogonyaulax, the most closely related species. In addition, the 5.8S rDNA sequence of the new dinoflagellate was also 12% different from those of A. minutum, A. ostenfeldii, A. tamutum, and Alexandrium peruvianum. In a phylogenetic tree based on LSU rDNA sequences, A. pohangense formed a clade with A. margalefii, and this clade was clearly distinct from the clade of A. minutum, Alexandrium diversaporum, A. tamutum, Alexandrium leei, A. ostenfeldii, and Alexandirum andersoni. Moreover, in a phylogenetic tree based on SSU rDNA sequences, A. pohangense was positioned at the base of the clade containing A. leei and A. diversaporum. Morphological analysis showed that A. pohangense has a Kofoidian plate formula of Po, 4′, 6′′, 6c, 8s, 5′′′, and 2′′′′, which confirmed its assignment to the genus Alexandrium. This dinoflagellate has a wide rectangular 1′ plate, the upper left side of which is slightly bent, protruding, and touching the 2′ plate, unlike A. margalefii, which has a wide rectangular 1′ plate that does not touch the 2′ plate, or A. pseudogonyaulax and Alexandrium camurascutulum, which have a narrower elongated pentagonal 1′ plate that touches the 2′ plate. Furthermore, the 1′ plate of A. pohangense meets the 1′′ plate as a straight vertical line, whereas that of A. camurascutulum meets the 1′′ plate as an inclined line because it is lifted by the intrusion of the 1′′ plate. In addition, A. pohangense had a relatively small ventral pore whose majority was located on the 4′ plate, unlike A. margalefii or A. pseudogonyaulax, which have a relatively large ventral pore whose majority is located on the 1′ plate. Furthermore, A. pohangense had pores of two different sizes on the cell surface, unlike A. margalefii and A. pseudogonyaulax, which have similar pores of only one size. On the basis of morphological and phylogenetic criteria, it is proposed that this is a new species of the genus Alexandrium.

E-navigation을 활용한 해상교통관리체계 개선방안에 관한 연구

This study proposes the improvement of maritime traffic management for domestic ships and fishing vessels by introducing the e-navigation environment. This study discusses the development of present Vessel Traffic service (VTS) in a systematic aspect and a fuctional aspect. The concept and architecture of e-navigation operation system based on the General Information Center on Maritime Safety and Security (GICOMS) are proposed as a solution for the improvement of maritime traffic management in Korean coastal waters. Especially, means of data exchange between ships and ship-shore based on the Maritime Cloud and regional e-Data Center are discussed. This study will help to the implementation of the Korean e-navigation project which focuses on the safety of small ships and fishing vessels. In the future, it is needed to study for the development and operation of accident prevention system under the e-navigation environment.

Intraspecific diversity and distribution of the cosmopolitan species Pseudo-nitzschia pungens (Bacillariophyceae): morphology, genetics, and ecophysiology of the three clades.

Three clades of Pseudo-nitzschia pungens, determined by the internal transcribed space (ITS) region, are distributed throughout the world. We studied 15 P.pungens clones from various geographical locations and confirmed the existence of the three clades within P.pungens, based on ITS sequencing and described the three subgroups (IIIaa, IIIab, and IIIb) of clade III. Clade III (clade IIIaa) populations were reported for the first time in Korean coastal waters and the East China Sea. In morphometric analysis, we found the ultrastructural differences in the number of fibulae, striae, and poroids that separate the three clades. We carried out physiological tests on nine clones belonging to the three clades growing under various culture conditions. In temperature tests, only clade III clones could not grow at lower temperatures (10°C and 15°C), although clade I and II clones grew well. The estimated optimal growth range of clade I clones was wider than that of clades II and III. Clade II clones were considered to be adapted to lower temperatures and clade III to higher temperatures. In salinity tests, clade II and III clones did not grow well at a salinity of 40. Clade I clones were regarded as euryhaline and clade II and III clones were stenohaline. This supports the hypothesis that P.pungens clades have different ecophysiological characteristics based on their habitats. Our data show that physiological and morphological features are correlated with genetic intraspecific differentiation in P.pungens.

A new gelatinous colony-forming Thalassiosira minicosmica sp. nov. (Bacillariophyta) from Korean coastal waters and a consideration of the Thalassiosira subtilis group

A new, convex-valved Thalassiosira species, T. minicosmica, was observed from Korean coastal waters between 6 May 2009 and 6 March 2014. Thalassiosira minicosmica was characterized by: (1) gelatinous colony formation by mucilage threads extruded from the fultoportulae, (2) eccentric arrangement of the areolae, (3) almost occluded foramina, (4) a short external tube of marginal fultoportulae, and (5) a single rimoportula (with a remarkably long external tube) between marginal fultoportulae. Similar species, such as T. minuscula, T. diporocyclus and T. subtilis, were compared with T. minicosmica, and their several shared characters, such as the convex valve, foramen structure and an externally larger rimoportula than fultoportula, are diagnostic for the Thalassiosira subtilis group, rather than the gelatinous colony-forming feature. Based on the morphological similarities, we recognize the Thalassiosira subtilis group including seven Thalassiosira species.

Colonization dynamics in trophic-functional patterns of biofilm-dwelling ciliates using two methods in coastal waters

The colonization dynamics in trophic-functional structure of biofilm-dwelling ciliate fauna were studied using two methods based on an artificial substratum in Korean coastal waters of the Yellow Sea during April 2007. Polyurethane foam enveloped slide (PFES) and conventional slide (CS) systems were used to collect ciliate samples at a depth of 1 m. The ciliate fauna represented similar colonization dynamics in trophic-functional patterns that were driven mainly by the algivores, bacterivores and non-selectives in both systems. Simple trophic-functional patterns (e.g. algivores and non-selectives) occurred within the ciliate fauna at the initial stage (1–3 days), while complex patterns (e.g. algivores, non-selectives and bacterivores) were established at the transitional (5–7 days) and equilibrium (9–19 days) stages. However, the time in which ciliate fauna reached a stable trophic-functional pattern was shorter in the PFES than in the CS system. Among four trophic-functional types, the algivores and bacterivores significantly fitted the MacArthur-Wilson and logistic models in colonization and growth curves in both systems, respectively. Furthermore, the species richness and diversity of algivores and bacterivores were significantly higher in the PFES system than in the CS. These results suggest that the PFES system was more effective than the conventional slide method for a colonization survey on trophic-functional patterns of biofilm-dwelling ciliate fauna in marine ecosystems.

Occurrence of large temperature inversion in the thermohaline frontal zone at the Yellow Sea entrance in winter and its relation to advection

AbstractTemperature inversion (higher temperature at a deeper depth) in winter and its relation to advection were investigated by analyzing both conductivity‐temperature‐depth data in the southern Yellow Sea (YS) and northwestern East China Sea during the winter of 2002–2003 and time series data of temperature, salinity, and currents at a buoy station at the YS entrance. Significant temperature inversions occur predominantly along the thermohaline front at the YS entrance where the Cheju Warm Current Water (CWCW) and the cold coastal waters meet. In February 2003, on the northern frontal zone along 34°N where isotherms and isohalines declined downward to the north, particularly large inversions with temperature differences of larger than 2.0°C were observed to occur more in troughs than in the crests of the wave‐like frontal meander where the cold Korean coastal water (KCW) advances farther southward. The inversion persisted until mid‐April at the buoy station in the frontal zone, and both temperature and salinity showed simultaneous variations in the same manner. During episodic occurrences of large inversions, temperature and salinity decreased sharply in the upper layer, but increased concurrently in the lower layer. These episodic inversions were found to be closely related to the westward advection of the KCW in the upper layer and the northward advection of the CWCW in the lower layer. It is considered that these advections may play an important role in maintaining baroclinicity in the northern frontal zone, which is responsible for driving the westward transversal flow across the YS entrance.

Population structure and sequence divergence in the mitochondrial DNA control region of gizzard shad Konosirus punctatus in Korea and Japan

To investigate the extent of genetic differentiation among populations, genetic polymorphism in gizzard shad Konosirus punctatus, collected from wild populations of eight locations in Korea and four locations in Japan, was examined using mitochondrial DNA (mtDNA) control region. Two distinct mitochondrial lineages were detected: Lineage A was only distributed around Korean coastal waters and dominates the western and southwestern coast group of Korea. While Japanese groups of K. punctatus were exclusively assigned to lineage B. The co-occurrence of both lineages in southeast and east coasts of Korean coastal waters indicated that the current distribution pattern of gizzard shad populations was constructed by secondary contact.

Critical criteria for identification of the genus Chaetoceros (Bacillariophyta) based on setae ultrastructure. II. Subgenus Hyalochaete

:Our objective was to select setae ultrastructure characteristics as identification criteria for Chaetoceros subgenus Hyalochaete. We sampled 53 Korean coastal water locations and three Chukchi Sea, Arctic Ocean sites, and we studied 22 species using light microscopy and scanning electron microscopy. We selected 12 criteria for species-specific identification: (1) point of fusion of the sibling setae, (2) spine form, (3) poroid shape, (4) spine arrangement, (5) poroid arrangement, (6) number of poroid rows per μm along the setae, (7) special intercalary setae, (8) connecting bridge-like structure on the basal part of the intercalary setae, (9) siliceous capilli on the basal part of the setae, (10) setae cross-sectional shape, (11) silicification of the setae wall and (12) direction of setae to the chain axis. Using these criteria, we constructed a dichotomous key to aid species-specific identification in the subgenus Hyalochaete.

전이함수모형에 의한 여수연안 표면수온 예측

In this study, single-input transfer function model is applied to forecast monthly mean sea surface temperature(SST) in 2010 at Yeosu in Korean coastal waters. As input series, monthly mean air temperature series for ten years(2000-2009) at Yeosu in Korea is used, and Monthly mean SST at Yeosu station in Korean coastal waters is used as output series(the same period of input). To build transfer function model, first, input time series is prewhitened, and then cross-correlation functions between prewhitened input and output series are determined. The cross-correlation functions have just two significant values at time lag at 0 and 1. The lag between input and output series, the order of denominator and the order of numerator of transfer function, (b, r, s) are identified as (0, 1, 0). The selected transfer function model shows that there does not exist the lag between monthly mean air temperature and monthly mean SST, and that transfer function has a first-order autoregressive component for monthly mean SST, and that noise model was identified as . The forecasted values by the selected transfer function model are generally higher than actual SST in 2010 and have 6.4 % mean absolute percentage error(MAPE). The error is 2 % lower than MAPE by ARIMA model. This implies that transfer function model could be more available than ARIMA model in terms of forecasting performance of SST.

동남아시아산 염장해파리의 이화학적 성분 특성 비교

The study investigated the chemical composition, pH, and texture of salted jellyfish processed in Indonesia, Thailand, and China as a pilot study for processing the jellyfish Nemopilema nomurai, which occurs in Korean coastal waters. The 14 samples of salted jellyfish included processed umbrella and oral arms and consisted of 68.4-78.3 g/100 g moisture, 1.79-4.37 g/100 g crude protein, and 0.07-0.41 g/100 g crude lipid. The total amino acid content was 2.30-4.69 g/100 g and glycine accounted for 20.07-37.37% of the total amino acids. Salting jellyfish reduces the possibility of microbial growth and enhances the shelf life because the samples have a pH of 3.77-4.35, salinity of 18.53-24.02%, and lower water activity of 0.77-0.80. The lightness (L), redness (a), and yellowness (b) of the samples were 53.98-61.32, 1.76-6.26, and 14.08-29.0, respectively. The springiness, strength, and hardness of the salted jellyfish differed significantly among the products. The sample processed in Indonesia had the highest springiness. While the chemical composition, pH, water activity, and color differed significantly among the products, there were no significant effects of the country of manufacture. These results will enable the determination of quality index parameters for salted processed Nemopilema nomurai caught in Korean coastal.

Harmful algal bloom (HAB) in the East Sea identified by the Geostationary Ocean Color Imager (GOCI)

Harmful Cochlodinium polykrikoides blooms have frequently appeared and caused fatal harm to aquaculture in Korean coastal waters since 1995. We investigated the applicability of GOCI, the world's first Geostationary Ocean Color Imager, in monitoring the distribution and temporal movement of a harmful algal bloom (HAB) that was discovered in the East Sea near the Korean peninsula in August 2013. We identified the existence of C. polykrikoides at a maximum cell abundance of over 6000cells/mL and a chlorophyll a concentration of over 400mg/m3. In areas of C. polykrikoides blooms, GOCI remote sensing reflectance (Rrs) spectra demonstrated the typical radiometric features of a HAB, and from the diurnal variations using GOCI-derived chlorophyll concentration images, we were able to identify the vertical migration of the red tide species. We also found that the formation and propagation of the HAB had relations with cold water mass in the coastal region. GOCI can be effectively applied to the monitoring of short-term and long-term movements of red tides.

Marine ecosystem health assessments in Korean coastal waters

Coastal pollution has long been recognized as a serious problem. Unfortunately, no simple solutions exist for sustaining a healthy ecosystem in coastal zones. Until now, approaches have only focused on affected areas and associated pollutants without much attention being paid to more preventative measures. A more comprehensive framework is appropriate for sustaining coastal marine health. Based on adequate policy making, a foundation for research could be established, and coastal environmental conditions could then be evaluated through regular assessments under new guidelines. The assessment results would provide instructive data for future decisions by policy makers concerning the restoration and maintenance of coastal health. For the purpose of developing technical tools for assessing coastal ecosystem health conditions and providing practical ecological information, a project is currently being undertaken to develop the Marine Ecosystem Health Index (MEHI) based on organizing, simplifying, and generalizing the holistic data of marine ecosystems. During the last three years, 20102012, coastal ecosystem components were monitored in Jinhae Bay and Gwangyang Bay which are known to be highly polluted and which are special management areas in the South Sea of Korea. As part of the ongoing work to increase technical development, assessment indicators dealing with the relationships between chemical pressures and biological responses were selected and a monitoring system for indicator measurements was also established. Indicator criteria for determining healthy or unhealthy conditions in the ecosystem monitored were established based on the results analyzed from past data as well as the conditions monitored in this project. Finally, a numerical expression tool applying the selected indicators and the criteria was generated for the integration of bay ecosystem health assessment. Water environments were studied in terms of eutrophication and sediment environments with regard to toxic organic compounds, and heavy metals were also monitored to understand the environmental conditions produced by chemical pollutants. Community structures and population dynamics of plankton and benthos were investigated at the same time, and these were intensely analyzed to understand the relationships with chemical factors. Each of these four subdivisions of water quality, sediment quality, plankton, and benthos was repectively expressed and integrated into a numerical expression to produce a health index or score. Finally, we were able to recognize which areas of Jinhae Bay and Gwangyang Bay are relatively healthy based on this assessment result and were able to prioritize actions to restore the health of the bay ecosystems. In a forthcoming step, the four indices will be integrated into a holistic health index of marine ecosystem assessments. The assessment results will be provided through an online service in the near future and will be shared with all concerned. The project is a pioneering effort to assess the health of marine ecosystems in Korea and is continuously making efforts to ensure technical superiority with regard to application in other special management areas and to provide technical knowhow with regard to marine ecosystem health assessment based on the work carried out in Jinhae Bay and Gwangyang Bay (Picture 1).

Resolving the intra-specific succession within Cochlodinium polykrikoides populations in southern Korean coastal waters via use of quantitative PCR assays

While the toxic dinoflagellate Cochlodinium polykrikoides is known to form blooms that are maintained for extended periods, the genetic differentiation of these blooms are currently unknown. To assess this, we developed a real-time PCR assay to quantify C. polykrikoides at the intra-specific level, and applied this assay to field samples collected in Korean coastal waters from summer through fall. Assays were successfully developed to target the large-subunit ribosomal RNA region of the three major ribotypes of C. polykrikoides: Philippines, East Asian, and American/Malaysian. Significant linear relationships (r2≥0.995) were established between Ct and the log of the copy number for each ribotype qPCR assay. Using these assays, C. polykrikoides blooms in Korean coastal waters were found to be comprised of Philippines and East Asian ribotypes but not the American/Malaysian ribotype. The Philippines ribotype was found to be highly abundant during summer bloom initiation and peak, whereas the East Asian ribotype became the dominant ribotype in the fall. As such, this newly developed qPCR assay can be used to quantify the cryptic ecological succession of sub-populations of C. polykrikoides during blooms that light microscopy and previously developed qPCR assays cannot resolve.

Observations on dinoflagellate parasites of aloricate ciliates in Korean coastal waters

Observations on dinoflagellate parasites of aloricate ciliates in Korean coastal waters

Germination rate of Phyllospadix japonicus seeds relative to storage methods and periods

To determine the optimal storage method and longest possible storage period of Phyllospadix japonicus seeds, we examined post-storage germination rates using different storage methods and periods for P. japonicus seeds harvested in Korean coastal waters. P. japonicus seeds are classified as recalcitrant seeds with an average moisture content of 45.4%. Germination rates of P. japonicus seeds stored in seawater at 4 °C, seawater at room temperature with air supply, and an aquarium with continuous seawater circulation ranged from 35.0% to 43.5%, whereas seeds stored in seawater at 30°C, a refrigerator at −20°C, and a desiccator at room temperature did not germinate. Seeds stored at 4°C maintained germination rates of 72.5∼73.0% until 30 days of storage, but showed rapidly decreasing germination rates after 60 days and no germination after 180 days. Since few studies have investigated seed storage of P. japonicus, these results will serve as useful data for seed-based P. japonicus habitat restoration.

Critical criteria for identification of the genus Chaetoceros (Bacillariophyta) based on setae ultrastructure. I. Subgenus Chaetoceros

:To propose identification criteria for Chaetoceros subgenus Chaetoceros based on setae ultrastructure, we sampled 38 Korean coastal water locations and 12 Chukchi Sea, Arctic Ocean sites and we studied 11 species using light microscopy and scanning electron microscopy. We selected seven criteria for species-specific identification: (1) spine form; (2) poroid arrangement; (3) number poroid rows between costae; (4) costae presence or absence; (5) angle of costa against the seta rim; (6) spine cross-sectional shape; and (7) seta wall silicification. On the basis of these criteria, we constructed a flowchart to enable species-specific identification. We showed that similar species within the subgenus Chaetoceros can be distinguished solely on the basis of setae criteria.

한국연안해역 와편모조류 시스트 연구에 관한 고찰

To investigate the research state and characteristics of dinoflagellate cyst along the Korean coastal waters, this work analyzed 45 studies conducted in the Korean coasts and basin, the south of Jeju, East China Sea including some part of the Yellow Sea. It was found that the research on dinoflagellate cyst began in the later half of the 1980s in Korea, and that the research areas focused on eutrophied regions where a red tide occurred or on the seas where coastal development occurred. In other words, no research on the East Sea was found. In terms of research contents, there were various studies on analysis of cyst assemblage, tracking of the changes in marine environment like process of eutrophication, roles as a seed population in occurrence of a red tide, creation of cyst by use of sediment trip and tracking of its changes, morphological changes by the change of pH concentration in the hypoxia zone of eutrophied region, germination of a specific species, and other international-level studies. Species composition and cell density also varied in the Korean coastal waters. However, much research on dinoflagellate cyst in Korea is not systematic, and is fragmentary and individual and hencesuffers from great limitations. The research results so far have focused only on specific regions, and sporadic research had been conducted by specific research groups. Dinoflagellate cyst of surface sediments represents the accumulation index of pelagic environment in the sea and is a useful index to understand the marine environment efficiently. In conclusion, Korea requires organized human resources and collaborative research on dinoflagellate cyst which in turn should be considered as a component of marine ecosystem and as an essential aspect of marine biology.

Taxonomic study on the euryhaline Cyclotella (Bacillariophyta) species in Korea

Cyclotella species were collected at 51 sites from July 2010 to June 2013 in Korean coastal waters. A total of five Cyclotella species (C. atomus var. marina, C. baltica, C. litoralis, C. meduanae, and C. meneghiniana) were identified in this study. The diagnostic characteristics for five Cyclotella species are described, focusing on the spacing, position, number of satellite pores of the mantle fultoportula and valve face fultoportula. In addition, we put the salinity ranges of five species of Cyclotella together. Of the five Cyclotella species, C. baltica, C. litoralis and C. meduanae are newly recorded in Korea.