Korean Coastal Waters Research Articles

Spatial and temporal distribution of tributyltin (TBT) in seawater, sediments and bivalves from coastal areas of Korea during 2001–2005

Tributyltin (TBT) concentrations were determined in seawater, sediments and bivalve samples collected from Korean coastal areas during 2001-2005, to investigate the levels and temporal variation in TBT contamination in relation to the timing of the imposition of regulations on TBT use in Korea. TBT concentrations ranged from <5.0 to 164 ng/L in seawater, from <7.0 to 9,576 ng/g dry weight in sediments, and from <7.0 to 6,296 ng/g dry weight in bivalves. The highest concentrations of TBT were found at locations close to intensive shipping traffic and industrial complexes, and the contamination at some hot spot areas was high enough to cause harmful effects on marine organisms. TBT concentrations and their occurrence in Korean coastal waters have been decreasing annually. In particular, TBT concentrations in seawater have dramatically decreased. This result is consistent with regulations and bans on the use of TBT in Korea.

Recent moon jelly (Aurelia sp.1) blooms in Korean coastal waters suggest global expansion: examples inferred from mitochondrial COI and nuclear ITS-5.8S rDNA sequences

AbstractKi, J-S., Hwang, D-S., Shin, K., Yoon, W. D., Lim, D., Kang, Y. S., Lee, Y., and Lee, J-S. 2008. Recent moon jelly (Aurelia sp.1) blooms in Korean coastal waters suggest global expansion: examples inferred from mitochondrial COI and nuclear ITS-5.8S rDNA sequences. – ICES Journal of Marine Science, 65: 443–452. The moon jelly Aurelia was found recently in Korean coastal environments, and its dense blooms caused economic losses for fisheries and power plants. The species is tentatively recognized as Aurelia aurita; yet, its identity and origin remain elusive. To find reliable molecular evidence for its identity, we determined the DNA sequence of the mitochondrial cytochrome c oxidase subunit I gene and nuclear ITS-5.8S rDNA of specimens collected from different Korean locations. We compared the nuclear and mitochondrial DNA data among specimens and demonstrated that all Korean Aurelia have an identical genotype. BLAST searches demonstrated that the Korean Aurelia matched the previously designated Aurelia sp.1. Parsimony and relevant phylogenetic analyses of the genus Aurelia demonstrated that the genotypes of Korean, Japanese, and Californian Aurelia sp.1 were nearly identical (&gt;99.6% similarity), whereas they were significantly different (&lt;84.1% similarity) from other Aurelia. This suggests that Aurelia sp.1, which occur in the three regions, are descendants of a single population and may have dispersed from one location. However, the dispersal time and origin of Aurelia sp.1 still remain uncertain.

한국 연안에 출현하는 무각와편모조류 5종에 대한 형태 및 분자계통학적 특성

Many species in Gymnodiniales, which are unarmored dinoflagellates, are responsible for marine algal blooms and some of them have potent toxin in the cell. Their taxonomy has so far been well-defined, and several genera (e.g. Akashiwo, Gymnodinium, Karenia) have recently been re-described. In Korea, few works have been carried out on their taxonomical and molecular studies. This study focused on comparison of both morphological and molecular characteristics of five unarmored dinoflagellates on Korean coastal water: Akashiwo sanguinea, Cochlodinium polykrikoides, Gymnodinium catenatum, Gymnodinium impudicum and Karenia aureolum (

Fecundity and growth-dependent mortality of Pacific anchovy ( Engraulis japonicus) in Korean coastal waters

We propose a method of estimating natural mortality of marine pelagic fishes, especially for early-life stages, based on their fecundity. To estimate size-dependent fecundity, growth and mortality of Pacific anchovy ( Engraulis japonicus), the most abundant fish species in coastal waters off the Korean peninsula, we undertook a synthesis of results from past studies and data. Assuming that the growth coefficient K varies with water temperature, we derived a modified von Bertalanffy growth equation covering all life stages based on otolith analysis of anchovies collected from southwestern coastal area of Korea in 1996. By revisting a past study on spawning and egg production of anchovies in the southern Korean coastal waters, we calculated a monthly-averaged fraction of mature females spawning per day to estimate that an average female anchovy spawns 36 times per year, and that the mean number of eggs produced by an average female is ca. 160 × 10 3 yr −1. Accepting the ‘bigger-is-better’ hypothesis, we derived a theoretical mortality curve that assumes instantaneous natural mortality as an inverse function of anchovy body length. Assuming equilibrium status of stock, estimated annual instantaneous mortality of anchovy between egg to age-1 stage was 11.3 yr −1 and estimated size-specific mortality was 1.24 d −1 mm in fork length. The derived theoretical mortality curve fit well the stage-specific mortalities, which were estimated independently based on ichthyoplankton surveys and anchovy samples collected by commercial nets, but underestimated the egg mortality (0.89 d −1 vs. 0.83 d −1).

Congener‐specific characterization and sources of polychlorinated dibenzo‐p‐dioxins, dibenzofurans and dioxin‐like polychlorinated biphenyls in marine sediments from industrialized bays of Korea

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DLPCBs) were determined in 122 coastal sediments from heavily industrialized areas in Korea. Toxic equivalent (TEQ) concentrations of PCDD and PCDF (PCDD/F) and DLPCB ranged from 0.44 to 38.5 pg/g dry weight and from 0.01 to 38.4 pg/ g dry weight, respectively. Overall PCDD/F and DLPCB concentrations were elevated in estuarine and inner bay locations close to industrial complexes, indicating that these contaminants derived from local discharges. Concentrations of PCDD/F measured in the present study were comparable to those in industrialized areas of other countries. Nonparametric multidimensional scaling ordination and congener-specific characterization showed that combustion processes occurring in industrial complexes, including the steel industry, are the major source of PCDD/Fs in Korean coastal waters. There were no significant correlations among PCDD/ Fs, DLPCBs, and total organic carbon; however, there was moderate correlation between PCDD/Fs and DLPCBs in some coastal bays, suggesting that these chemicals have similar sources and movements in these locations.

Development and field application of rRNA-targeted probes for the detection of Cochlodinium polykrikoides Margalef in Korean coastal waters using whole cell and sandwich hybridization formats

The dinoflagellate, Cochlodinium polykrikoides Margalef, has been responsible for mass mortalities of both wild and farmed fish along the Korean coast on virtually an annual basis since 1982. Economic impacts to the fishing and aquaculture industries are extensive, with a loss of USD $95 million reported in 1995 alone. The use of taxon-specific molecular probes for harmful algal species is recognized as a promising approach for the early detection of bloom formation and as part of an effective mitigation strategy. We have developed and successfully applied large subunit ribosomal RNA (LSU rRNA)-targeted probes in both whole cell and sandwich hybridization assay (SHA) formats for the species-specific detection of C. polykrikoides in Korean coastal waters. Sequences of the D1–D3 variable regions used to design probes were identical between five Korean and one Hong Kong C. polykrikoides isolates, while sequences for several N. American Cochlodinium isolates differed to varying degrees from the former. The automated SHA detected C. polykrikoides at levels as low as ∼1–3 cells/L in the field, demonstrating its suitability for detecting the target species at pre-bloom concentrations. This method should thus prove valuable to existing monitoring programs aimed at providing aquaculture interests with an early warning of frequently devastating bloom events.

마산만에서 부유원생동물의 연구

In Korea the study of marine heterotrophic protists started in the late 1980s, and since the early 1990s many studies have been conducted in various marine environments. In this article, studies on the distribution and abundance of protists and the biotic interactions (bacteria-protists, phytoplankton-protists) conducted in Korean coastal waters are reviewed, and a field study is reported and discussed. The field study in Masan Bay was carried out from February 2004 to November 2005 at seven selected stations representative of the bay. During the study, the mean abundance of heterotrophic bacteria and the mean concentration of chlorophyll-a were 2.1×10? cells mL?¹ and 9.8 ㎍ L?¹, respectively. Heterotrophic protists consisted of heterotrophic dinoflagellates, heterotrophic nanoflagellates (excluding dinoflagellates) and ciliates, and their abundances were means of 7.9×10⁴ cells L?¹, 1.2×10³ cells mL?¹, and 4.0×10⁴ cells L?¹, respectively. Generally, the chlorophyll-a concentrations and the abundances of heterotrophic bacteria and protists were higher in the inner zone of the bay, where there are high concentrations of organic matters, than in the middle and outer zones. Using the grazing rates of heterotrophic nanoflagellates on bacteria previously reported in this area, it can be calculated that about 69% of bacterial producton was removed by HNF grazing activity. About 24% of initial chlorophyll-a concentration was removed by microzooplankton grazing activity. In conclusion, this study suggests that in Masan Bay heterotrophic protists control the growth of bacteria and phytoplankton, and heterotrophic protists represent an important link of bacterial & microalgal biomass to higher trophic levels.

마산만 저서생태계를 중심으로 연안해역 건강성 평가를 위한 저서생물지수의 적용

In this work, we compared the characteristics of three benthic biotic indices (BPI, AMBI, BIBI) which indicates the health condition of benthic communities in Masan Bay, Korea where anthropogenic impacts have been concentrated. Also we evaluated the usefulness of these benthic indices and some problems if they were applied to the Korean coastal waters. For this we used the macrozoobenthos data collected using van Veen grab (<TEX>$0.1\;m^2$</TEX>) at 21 sites in Masan Bay in February and August 2004. Based on the BPI values, two stations in the inner bay were found in a very hard polluted condition and three stations in the middle bay were also in a highly polluted condition. Only one station located in the bay mouth was in a normal condition. The inner bay stations showed very high AMBI values (<TEX>${\geq}5.0$</TEX>), indicating a highly polluted condition. The bay mouth station was assessed in a moderately polluted condition. The overall BIBI values in Masan Bay were in the range between 1.0 and 3.0. The inner bay stations showed low BIBI values (<TEX>${\leq}2.0$</TEX>) in the severely degraded condition. The bay mouth station with high BIBI value over 3.0 was assessed as a normal condition. All three benthos indices showed that macrozoobenthic communities in the inner bay were in a seriously polluted condition all year round, and macrobenthic faunas in the bay mouth seemed in a bad healthy condition (slightly polluted) based on AMBI during summer season. These three benthic biotic indices showed the similar assessment result, and thus we consider that each of them is a useful tool for the assessment of coastal benthic ecosystems under the organic enrichment in sediment.

Genetic Diversity of Parasitic Dinoflagellates in the Genus Amoebophrya and Its Relationship to Parasite Biology and Biogeography

We determined 18S rRNA gene sequences of Amoebophrya strains infecting the thecate dinoflagellates Alexandrium affine and Gonyaulax polygramma from Korean coastal waters and compared those data with previously reported sequences of Amoebophrya from cultures, infected cells concentrated from field samples, and environmental 18S rRNA gene sequences obtained from a variety of marine environments. Further, we used these data to examine genetic diversity in Amoebophrya strains relative to geographic origin, host phylogeny, site of infection, and host specificity. In our analyses of known dinoflagellate taxa, the 13 available Amoebophrya sequences clustered together within the dinoflagellates as three groups forming a monophyletic group with high bootstrap support (maximum likelihood, ML: 100%) or a posterior probability (PP) of 1. When the Amoebophrya sequences were analyzed along with environmental sequences associated with Marine Alveolate Group II, nine subgroups formed a monophyletic group with high bootstrap support (ML: 100%) and PP of 1. Sequences known to be from Amoebophrya spp. infecting dinoflagellate hosts were distributed in seven of those subgroups. Despite differences in host species and geographic origin (Korea, United States, and Europe), Amoebophrya strains (Group II) from Gymnodinium instriatum, A. affine, Ceratium tripos (AY208892), Prorocentrum micans, and Ceratium lineatum grouped together by all of our tree construction methods, even after adding the environmental sequences. By contrast, strains within Groups I and III divided into several lineages following inclusion of environmental sequences. While Amoebophrya strains within Group II mostly developed within the host cytoplasm, strains in Groups I and III formed infections inside the host nucleus, a trait that appeared across several of the subgroups. Host specificity varied from moderately to extremely species-specific within groups, including Group II. Taken together, our results imply that genetic diversity in Amoebophrya strains does not always reflect parasite biology or biogeography.

Physiological responses of Ulva pertusa and U. armoricana to copper exposure

A comparative study of copper (Cu) toxicity and tolerance in two species of Ulva from Korea, the native Ulva pertusa and alien Ulva armoricana, was conducted by examining the effects on growth, pigmentation, chlorophyll fluorescence, antioxidant capacity and nitrate reductase activity. Toxic effects of Cu were less expressed in U. armoricana than in U. pertusa. At lower concentrations (25–50 μg L −1), exposure to Cu did not affect thallus growth of U. armoricana, whilst growth was significantly reduced in U. pertusa. An increase in chlorophyll concentrations was observed in U. armoricana exposed up to 100 μg L −1, whereas Cu caused a significant chlorophyll reduction in U. pertusa. Chlorophyll b was reduced to a lesser extent than chlorophyll a by higher Cu concentrations. In U. armoricana, the maximum efficiency of photosystem II, minimum fluorescence, maximum electron transport rate and non-photochemical quenching were unaffected by Cu except at the highest concentration tested. U. pertusa showed a significant decrease in those parameters at much lower Cu concentrations. It was notable that in this alga the maximum efficiency of photosystem II was reduced at higher Cu concentrations than relative electron transport rate. Elevated concentrations of Cu induced a strong activation of antioxidant activity in U. armoricana, whereas the generation of high levels of reactive oxygen species probably decreased the non-enzymatic antioxidant defense system in U. pertusa. An increase in the nitrate reductase activity of U. armoricana at 50–100 μg L −1 Cu coincided with the increase in chlorophyll contents, whereas U. pertusa showed a significant decrease at the higher Cu concentration. Differences in the sensitivity of the two species of Ulva to Cu may influence their competitive interactions in Korean coastal waters experiencing temporal increases in the loading of heavy metals.

동해안 개다시마 Kjellmaniella crassifolia Miyabe (Phaeophyta)의 초기배양과 생장특성 연구

Kjellmaniella crassifalia Miyabe is one of the valuable seaweed crops cultured in the Korean coastal waters of the East Sea. Unfortunately recent environmental changes have adversely influenced its growth, prompting the need to develop techniques for species restoration. To obtatin biological information, the growth of the species was monitored for one year. The maximum blade length, <TEX>$110{\pm}45cm$</TEX>, was attained in July, and zoospores were released in November. The optimum culture conditions allowing juvenile sporophytes to grow to young blades consisted of <TEX>$20{\mu}mol/m^2s\;at\;10^{\circ}C$</TEX> under which the blade length grew to <TEX>$1,732.5{\pm}143.3{\mu}m$</TEX> in 42 days. Sporangial sori started to form in September, reaching 85% maturity in November and 89% maturity in December. Examining the growth of the species according to depth, the individuals growing at 5 meters grew the most, reaching a blade length of <TEX>$75.9{\pm}18.9cm$</TEX> in August.

Photosynthesis and photoinhibition of two green macroalgae with contrasting habitats

We evaluated light-related traits ofUlva pertusa Kjellman from the intertidal and upper subtidal zones, and ofUmbraulva japonica (Holmes) Bae & Lee (formerlyUlva japonica) within its upper growth limit of 10 m, in Korean coastal regions.U. pertusa showed significantly higher maximum photosynthetic rates, photosynthetic efficiency, saturating irradiances, and total pigment contents. However, green light-use efficiency at limiting irradiances was notably higher inU. japonica, possibly due to the presence of green light absorbing pigments like siphonaxanthin and siphonein. Non-enzymatic antioxidation capacity as determined by DPPH (α,α-diphenyl-β-picrylhydrazyl) radical scavenging rate was markedly higher inU. pertusa (50.49%) than inU. japonica (8.85%). Both species showed a substantial decrease in optimal photosystem (PS) II efficiency (Fv/ Fm) with increasing PAR doses despite the degree of photoinhibition being more marked inU. japonica. After 24 h in dim light,U. pertusa rapidly and almost fully recovered Fv/ Fm within an hour whileU. japonica exhibited slow and incomplete PSII recovery over the full recovery period. A significant depression in photosynthetic activity with monochromatic UV-B radiation was observed inU. japonica only, followed by slight recovery in dim light. Light use efficiency and high irradiance tolerance may be important ecological axes along which the niche separation of green foliose algae occurs in Korean coastal waters.

Polybrominated diphenyl ethers (PBDEs) in marine sediments from industrialized bays of Korea

Concentrations of polybrominated diphenyl ethers (PBDEs) were determined in coastal sediments from heavily industrialized areas and major harbors in Korea. ∑PBDE 20 concentrations in sediments ranged from 2.03 to 2253 ng/g dry weight. PBDE concentrations were higher at estuarine and inner bay locations close to industrial complexes and large harbors, indicating that the PBDE contamination in the sediments is due to local discharges from industrial complexes. Deca-BDE was the predominant congener and the concentrations were comparable to or higher than those reported from other countries. Non-parametric multidimensional scaling (MDS) ordination showed that deca-BDE technical mixture is the main source of PBDE contamination in Korean coastal waters, with minor contamination by octa-BDE product. This result is consistent with the consumption pattern of brominated flame-retardants (BFRs) in Korea. Significant correlations existed among BDEs 28, 47, 99, 100, 153, and 154; however, BDEs 183 and 209 showed little correlation with less highly brominated congeners.

Size selectivity of drum-net traps for whelk ( Buccinum opisoplectum dall) in the Korean coastal waters of the East Sea

The selection of whelk by seven experimental types of drum-net trap was evaluated in a comparative fishing study in the East Sea, Korea, between July and October 2003. The experimental traps were fished in conjunction with a control trap constructed from 20 mm mesh. Three of the experimental traps used increased mesh sizes (35, 55 and 75 mm), another two employed escape rings (diameters of 3 and 5 cm), and the remaining two were constructed using double hoops to form gaps (widths of 2 and 4 cm) around the entire circumference of the trap. The minimum legal mesh size (35 mm mesh) was found to be effectively non-selective over the size range of whelk present in the fishery. The traps with 55 and 75 mm mesh and the traps fitted with escape rings all had statistically significant lower estimated efficiency than the control trap. Although the double hoop traps appear to offer the greatest potential for reducing the catch of undersized whelk, these traps are the most difficult to construct, store and deploy. Further research is required to improve the selectivity of traps fitted with escape rings.

MICROSATELLITE MARKERS REVEAL POPULATION GENETIC STRUCTURE OF THE TOXIC DINOFLAGELLATE ALEXANDRIUM TAMARENSE (DINOPHYCEAE) IN JAPANESE COASTAL WATERS1

This is the first report to explore the fine‐scale diversity, population genetic structure, and biogeography of a typical planktonic microbe in Japanese and Korean coastal waters and also to try to detect the impact of natural and human‐assisted dispersals on the genetic structure and gene flow in a toxic dinoflagellate species. Here we present the genetic analysis of Alexandrium tamarense (Lebour) Balech populations from 10 sites along the Japanese and Korean coasts. We used nine microsatellite loci, which varied widely in number of alleles and gene diversity across populations. The analysis revealed that Nei's genetic distance correlated significantly with geographic distance in pair‐wise comparisons, and that there was genetic differentiation in about half of 45 pair‐wise populations. These results clearly indicate genetic isolation among populations according to geographic distance and restricted gene flow via natural dispersal through tidal currents among the populations. On the other hand, high P‐values in Fisher's combined test were detected in five pair‐wise populations, suggesting similar genetic structure and a close genetic relationship between the populations. These findings suggest that the genetic structure of Japanese A. tamarense populations has been disturbed, possibly by human‐assisted dispersal, which has resulted in gene flow between geographically separated populations.

Characterization of cholinesterases in marbled sole, Limanda yokohamae, and their inhibition in vitro by the fungicide iprobenfos

Cholinesterases (ChEs) have been characterized in marbled sole (Limanda yokohamae) for use as a possible biomarker of pollution exposure. In brain, ChEs existed almost exclusively (>95%) as acetylcholinesterase (AChE) whereas in muscle, about 20-30% of ChE activity was in the form of butyrylcholinesterase (BChE; pseudocholinesterase). Acetylthiocholine and butyrylthiocholine (identified in mammalian studies as diagnostic substrates for AChE and BChE respectively) were hydrolyzed mainly, but not exclusively, by these enzymes. The inhibitors BW284C51 and iso-OMPA (identified in mammalian studies as diagnostic inhibitors of AChE and BChE respectively) were not specific for these enzymes in marbled sole. Brain AChE and muscle AChE and BChE were characterized in terms of their kinetic properties (KM etc.) and optimal conditions (substrate concentration, protein concentration, pH etc.) were established to allow routine assays of ChE activity to proceed under pseudo-first order conditions. The sensitivity of ChEs to a locally significant pesticide, iprobenfos (IBP; kitazin) was established in terms of IC50 concentrations. Brain AChE was relatively insensitive to IBP, but muscle AChE and BChE were sensitive to IBP concentrations in the high nM range. However, ambient IBP concentrations in Korean coastal waters are usually not high enough to cause detectable ChE inhibition in this species.

Distribution of the heterotrophic dinoflagellate Pfiesteria piscicida in Korean waters and its consumption of mixotrophic dinoflagellates, raphidophytes and fish blood cells

To explore the distribution of Pfiesteria piscicida in Korean coastal waters, we analyzed the morphology and DNA sequence of several isolates collected from 6 locations along the southern and western Korean coasts. We also investigated the prey species consumed by a Korean isolate and determined the growth and ingestion rates of P. piscicida when it fed on the dinoflagellate Amphidinium carterae, an unidentified cryptophyte species, and the raphidophyte Heterosigma akashiwo. Additionally, these parameters were measured when the isolate was fed perch blood cells and the cryptophyte Rhodomonas salina. Furthermore, we calculated grazing coefficients by combining field data on abundance of P. piscicida (and Pfiesteria-like dinoflagellates) with laboratory data on ingestion rates. The DNA sequence of a P. piscicida isolate from Masan Bay was identical to USA isolates, whereas DNA sequences of isolates from Busan, Incheon, Kunsan, Kwangyang, and Yeosu differed by 1 bp from USA isolates. Among the prey offered, P. piscicida was able to feed on all naked mixotrophic dinoflagellates, the smallest thecate mixotrophic dinoflagellates Heterocapsa rotundata, and all raphidophytes, but not on large thecate dinoflagellates. Perch blood cells were the optimal prey. Maximum growth rates of P. piscicida fed on perch blood cells, R. salina, A. carterae, the cryptophyte, and H. akashiwo were 1.74, 1.41, 1.22, 1.15, and 1.10 d -1 , respectively. The maximum ingestion rate of P. piscicida when fed perch blood cells (4.3 ng C predator -1 d -1 ) was much higher than those when fed R. salina, H. akashiwo, A. carterae, or the cryptophyte (0.4 to 1.7 ng C predator -1 d -1 ). Calculated grazing coefficients on co-occurring Amphidinium spp., H. akashiwo, and cryptophytes were up to 1.07, 0.45, and 0.22 h -1 , respectively. Our results suggest that grazing by P. piscicida potentially has a considerable effect on algal populations.

Ingestion of bacterial cells by the marine photosynthetic ciliate Myrionecta rubra

We report the first observation of fluorescently labeled bacteria (FLB) ingestion by the cells of MR-MAL01, a temperate strain of the marine photosynthetic ciliate Myrionecta rubra Jankowski 1976 (=Mesodinium rubrum Lohmann 1908). We also investigated the time course of ingestion and digestion of bacteria as well as the ingestion rates at 3 different light intensities. In the stationary phase of growth with ambient bacterial abundance (1.4 x 10 6 cells ml -1 ) under conditions of 15°C and 60 μE m -2 s -1 , the rates of FLB uptake and disappearance of M. rubra MR-MAL01 cells were 7.6 and 5.3 FLB grazer -1 h -1 , respectively. The ingestion rate of M. rubra in cultures was calculated to be 53 bacteria grazer -1 h -1 . The initial abundance of M. rubra (ca. 1.0 x 10 4 cells ml -1 ) in the ingestion-digestion experiment was comparable to the natural abundance during the M. rubra red tide in Korean coastal waters. The bacterivory rate of M. rubra increased gradually as light intensity decreased from 200 to 0 μE m -2 s -1 ; this might enable the photosynthetic M. rubra to survive under intermittently light-limiting conditions. The present study showed a novel phenomenon of the ingestion of bacterial cells by M. rubra and the light-affected bacterivory rates of the common red tide ciliate.

The effect of seawater CO2 concentration on growth of a natural phytoplankton assemblage in a controlled mesocosm experiment

We examine the effects of seawater pCO2 concentration of 25, 41, and 76 kPa (250, 400, and 750 matm) on the growth rate of a natural assemblage of mixed phytoplankton obtained from a carefully controlled, 14‐d mesocosm experiment. Throughout the experiment period, in all enclosures, two phytoplankton taxa (microflagellates and cryptomonads) and two diatom species (Skeletonema costatum and Nitzschia spp.) account for approximately 90% of the phytoplankton community. During the nutrient‐replete period from day 9 to day 14 populations of Skeletonema costatum and Nitzschia spp. increased substantially; however, only Skeletonema costatum showed an increase in growth rate with increasing seawater pCO2. Not all diatom species in Korean coastal waters are sensitive to seawater pCO2 under nutrient‐replete conditions.

Polybrominated diphenyl ethers (PBDEs) in sediment and bivalves from Korean coastal waters

Concentrations of polybrominated diphenyl ethers (PBDEs) were determined in sediment and bivalves collected from 25 coastal locations in Korea. Twenty major PBDE congeners were found in all sediment and bivalve samples. ∑PBDE 20 concentrations ranged from 0.45 to 494 ng/g, dry weight (average 27.8 ng/g dry weight) in sediments, and from 0.38 to 9.19 ng/g, wet weight (average 2.94 ng/g wet weight) in bivalves. The highest concentrations were found at locations near industrial complexes and large harbors, suggesting that human activities contribute to PBDEs contamination in Korean coastal environment. PBDE concentrations measured in our study, excluding BDE congener 209 (deca-BDE), in sediment and bivalves were lower than those reported from other countries; whereas BDE 209 concentrations were comparable to or higher than those reported from other countries. The predominant PBDE congener in sediments and bivalves was deca-BDE, which accounted for >90% and >60% of the total PBDE concentrations in sediment and bivalves, respectively. This is consistent with high consumption of deca-BDE for the flame-retardant market in Korea. Significant correlations existed among BDEs 28, 47, 99, 100, 153 and 154 in sediments and bivalves; however, BDEs 183 and 209 showed little correlation compared with less highly brominated congeners.