• Journal of the korean society of oceanography
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• v.32 no.2
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• pp.63-68
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• 1997

Stable isotope profiles with fine-scale resolution were constructed from the fossil mollusk shells, Mercernaria mercernaria, obtained from the late Pleistocene transgressive deposits of Gomez Pit, Virginia, USA. Incremental sampling were made along the axis of maximum growth to provide high-resolution ${\delta}^{18}$O and ${\delta}^{13}$C records. The ${\delta}^{18}$O shell profiles exhibit a series of pronounced cycles in the overall amplitude, corresponding to strong seasonal variations in temperature, which is apparently positive environmental variable. Contrasts between the patterns of ${\delta}^{18}$O and ${\delta}^{13}$C profiles reflect the relationship influencing the seasonal carbon cycling in the shallow marine environment. Positive anomalies of the ${\delta}^{13}$C values during the summer were observed to be out of phase with the ${\delta}^{18}$O profile. Such relatively heavier carbon source may be alternated due to seasonal methanogenesis during the summer. A hypothesized methane-based system may be operated in the shallow and marginal marine environment, resulting in a ${\delta}^{13}$C enriched bicarbonate pool, in which the heavier isotope seems to be incorporated to the shell carbonate.

• Fisheries and Aquatic Sciences
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• v.26 no.5
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• pp.336-343
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• 2023

This study aimed to know the response of deep-sea squid Sthenoteuthis oualaniensis to the light colors of the artificial bait. This experiment used the commercial artificial flashlight baits commonly sold in the fishing shop. The bait has several different light color combinations. The light colors were modified into several light colors by inactivating certain colors and used as treatments. The study is expected to be able to find flashlight bait's most effective color for squid fishing. We applied red-green, green, blue, and commercial bait lights in this study. Each treatment has 3 replications. The effect was expressed as the amount of squid caught. Data were analyzed by one-way analysis of variance. Results showed a significant effect on the number of squid catches. There was significantly different squid catches among the treatments. It indicates that this artificial flashlight bait could be developed to maximize squid catches. This finding can be used for the local fishermen's income and the squid fisheries development.

• 한국해양학회지
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• v.30 no.5
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• pp.480-492
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• 1995

Petrographic investigation has been carried out to determine the composition of the beach sediments and the affecting factors which have controlled their compositional variations from Hyupjae, Aeweol, Iho, Samyang, Hamdeok, Sehwa, Pyoseon, Jungmun, and Hwasun areas along the coast of the Cheju Island. Average mean sizes of the beach sediments are Hyupjae 2.2ø, Aeweol 0.8ø, Iho 1.4ø, Samyang 2.4ø, Hamdeok 1.6ø, Sehwa 1.5ø, Pyoseon 2.1ø, Jungmun 0.4ø, and Hwasun 0.9ø, thus, aries from 0.4 to 2.4ø. The beach sediments from Pyoseon and Hwasun areas are poorly sorted, those from Aeweol and Jungmun areas are moderately sorted and those from the rest of the areas are moderately well sorted. While-colored beach sediments in Hyupjae, Aeweol, Hamdeok, Sehwa, and Pyoseon areas are mostly composed of calcareous shells (more than 85%) such as mollusk, red algae, benthic foraminiferas, etc., whereas volcanic rock fragment is the dominant component of the black-colored beach sediments in Iho, Samyang, and Hwasun areas. Especially, the relatively white-colored beach sediment in Jungmun area, which is on e of the carbonate-dominant areas, shows a higher content of rock fragments than the other carbonate-dominant areas. The beach sediments in Pyoseon area show a high content of carbonate intercalates. Considering the contributions by organisms according to grain size, grains with the size range of 1∼2ø are mostly composed of calcareous red algae fragments, and grains with the size range of 2∼3ø consist of mollusk fragments. It is also notable that bryozoan fragments comprise about 48% of the sediment in Samyang area with the size range of 0∼1ø. The composition of the beach sediments in Cheju Island appears o be controlled by the riverine supply rate of volcanic rock fragments, the lithology of the rocks distributed ear the beaches, the direction of alongshore currents, and the direction of storms, etc.. It is suggested that the beach sediments in Iho and Samyang areas show black color because of the higher supply rate of the volcanic rock fragments from the nearby rivers, whereas those in the rest of the areas show white color due to the relatively lower content of volcanic rock fragments and higher content of carbonate components transported from shallow marine environment. In Hwasun area, the content of volcanic rock fragments is high, and they are directly from the tuffaceous rocks distributed nearby. Also, the volcanic rock fragments in Jungmun area are transported not only from the rivers nearby but also from the nearby tuffs by storm activities. The beach sediment in Pyoseon area contains a high content of carbonate intercalates, which formed in the nearby shallow marine environment through marine cementation. This indicates that active marine cementation occurs in shallow marine environment near Pyoseon area.

• Ocean and Polar Research
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• v.44 no.4
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• pp.331-338
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• 2022

The high latitude scleractinian coral Alveopora japonica Eguchi, 1965 occurs in high density in the shallow rocky subtidal in Jeju Island, forming coral carpets. Despite its ecological role providing a unique habitat for other benthic organisms, the benthic fauna associated with the A. japonica coral carpet is poorly known. To identify fauna associated with the coral carpet, we explored three sites dominated by A. japonica and one control site on northwestern Jeju Island in May 2013. Using SCUBA, we collected A. japonica and the epibenthic mega-fauna associated with the colonies in 1×1 m² and identified them to the species level. At a depth of 10 to 15 m, A. japonica colonies heavily covered the seafloor, forming a layer called a coral carpet, with a density of 94 (Keumneung-ri), 133 (Biyangdo), and 155 (Gwidok-ri) colonies/m². Thirty-four molluscan species were identified from the four sites, including 20 bivalves and 14 gastropods. The coral carpets were enriched with sessile bivalves compared to the control site, as we identified twenty bivalve and eight gastropod species from the coral carpets. Most bivalve species associated with the coral carpets had tropical-subtropical affinities, while gastropods were mainly subtropical and subtropical-low boreal species. Leiosolenus lischkei M. Huber, 2010, in the family Mytilidae and Barbatia steamsi (Pilsbry, 1895), in the family Arcidae, were the two most abundant bivalve species in the coral carpet, L. lischkei being a borer, and B. stearnsi a nestler. The tropical to subtropical Pacific star shell Astralium haematragum (Menke, 1829)was the most abundant gastropod at the study sites. The bivalves and gastropods associated with the coral carpet were small-sized juveniles or sub-adults, suggesting that the coral carpet provides a micro-habitat for the bivalves and gastropods.

• Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.76-82
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• 2005

We analyzed the paralytic shellfish poisoning (PSP) toxins of the toxic marine dinoflagellate Alexandrium tamarense collected from Dadaepo and Gaduck-do in Busan and from Sujeong-ri in Jinhae Bay, Korea, in April 2003. We also analyzed the PSP toxin of mussels (Mytilus galloprovincialis) and oysters (Crassostrea gigas) collected around Busan and Jinhae Bay. PSP toxin analyses were conducted by high performance liquid chromatography (HPLC). Fifteen cultured A. tamarense isolates contained 2.78 to 57.47 fmol/cell, with nearly identical toxin profiles: major components C2, GTX4; minor components C1, GTX1, NEO; and trace components GTX2, GTX3, STX. PSP toxin contents were 0 to $492\;\mu{g}$ STXeq/100 g in mussels and 0 to $48\;\mu{g}$ STXeq/100 g in oysters. Mussels at Gijang and Sujeong-ri contained the most PSP toxin contents ($492\;\mu{g}\;STXeq/100\;g\;and\;252\;\mu{g}\;STXeq/100\;g,\;respectively$), exceeding the quarantine level ($80\;\mu{g}$ STXeq/100 g). Their dominant toxin components were C2, C1, GTX2, and GTX3; the minor components GTX1, GTX4, GTX5, and NEO were sporadically detected. Phytoplankton contained 0.774 fmol/L seawater and 1.228 fmol/L seawater at Gijang and Sujeong-ri in April. At that time, Alexandrium cells were present in the water column at Gijang at 2,577 cells/mL and at Sujeong-ri at 6,750 cells/mL. Overall, we found the high and similar PSP toxin contents in AZexandrium isolates and mussels, and a correlation between occurrence of toxic Alexandrium cells in the water column and mussel intoxification. High densities of toxic Alexandrium cells in the water column immediately preceded shellfish intoxification at Gijang and Sujeong-ri in April.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.685-690
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• 2021

Harmful shell-boring species of the genus Polydora (Polychaeta: Spionidae) were frequently reported from commercially important mollusk species in Korea, Japan and China. The traditional approach based on the morphological characteristics showed limitations for species discrimination among shell-boring species. Therefore, DNA barcoding was adopted to identify Polydora species using molecular markers. Two Polydora species (P. haswelli and P. hoplura) in abalone shells were reported from our previous molecular phylogenetic study. In this study, we additionally reported the presence of shell-boring Polydora haswelli in commercially sold shellfish. The taxon-specific cox1 marker used in this study successfully allowed the isolation of P. haswelli from cockle Scapharca subcrenata, mussel Mytilus galloprovincialis, oyster Crassostrea gigas and scallop Argopecten irradians. Polydora hoplura was not found in these shellfish species. The genetic variations were found on the intraspecific level of P. haswelli and the same genotype was also detected in different shellfish species. This result can provide information on a new host and accurate parasitic Polydora species. Moreover, this report can be used as the biodiversity data of Polydora species on the invasion and transition of harmful Polydora species in mollusk aquaculture farms.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.2
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• pp.124-128
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• 2005

Marine reservoir correction $({\Delta}R)$ values are measured using two species of mollusk tests collected by NFRDI in 1942 before nuclear bomb testing to convert the radiocarbon age to calendar age in Korean coastal waters more accurately. The ${\Delta}R$ values are calculated to be $-117\pm45\;^{14}C\;yr$ in the southwestern coast of Korea and $-160\pm35\;^{14}C\;yr$ in southeastern coast. These values are similar to those in Chinese coast of the Yellow Sea $(-81\pm60\~-178\pm50\;^{14}C\;yr$, indicating that regional reservoir $^{14}C$ ages of these areas are lower than mean global reservoir $^{14}C$ age. The lower ${\Delta}R$ values in these areas are presumed to be mainly caused by influence of fresh-water inflow. The ${\Delta}R$ values presented In this study enhance the accuracy in converting radiocarbon age to calendar age in Korean coastal waters.

• Fisheries and Aquatic Sciences
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• v.20 no.6
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• pp.8.1-8.18
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• 2017

Background: Metallothionein (MT) is a multifunctional protein playing important roles in homeostatic regulation and detoxification of metals. Mollusk species have been considered as useful sentinel platforms for MT-based biomarker approaches, and they have been reported to display an extraordinary structural diversity of MT proteins. However, potential diversity of molluskan MTs has not been fully explored and recent updates have suggested the need of revision of evolutionary hypothesis for molluskan MTs. Results: Based on bioinformatic analysis and phylogenetic evidences, novel divergence mechanisms and paths were hypothesized in both gastropod and bivalve MT groups. Our analyses are suggestive of the taxon- or lineage-specific domain multiplication/duplication from the ancestral or prototypic MT. Diversification and selection of molluskan MTs might be driven by the needs for acquiring metal selectiveness, specialized novel function, and improved capacity of metal detoxification under environmentally stressed conditions. Conclusion: The structural diversity and variations of molluskan MTs are significantly larger than previously understood. Undoubtedly, molluskan MTs have undergone dynamic divergent processes in their evolutionary histories, giving rise to the great diversity of domain structures in extant MT isoforms. Novel evolutionary paths for molluskan MTs newly proposed in this review could shed additional light onto the revision of the hypothesis for evolutionary differentiation of MTs in the molluskan lineage.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.45 no.1
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• pp.1-13
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• 2009

Experimental fishing operation by the shrimp beam trawl was carried out to investigate the bycatch in order to develop the selective fishing gear of the shrimp beam trawl fishery. The experimental trawling was performed by the prototype fishing gear in coast sea of Boryeong, Buan, Kangjin, Tongyeong and Geoje from 30 April to 13 November 2005. Bycatches of the experimental trawling were analyzed species composition, total length composition. The results obtained can be summarized as follows; Target fishes caught by the shrimp beam trawl were Palaemon gravieri, Crangon Hakodatei, Trachysalambria curvirostris, Parapenaeopsis tenellus, Rhynchocinetes uritai and Matapenaeus joyneri. And their fishing rate and total length range were 50.0%, 46.0%, 2.6%, 0.4%, 0.3%, 0.3% and 40-80mm, 40-80mm, 120-150mm, 60-80mm, 60-80mm, 60-120mm respectively. Bycatches caught by the shrimp beam trawl consisted of fishes of 30 kinds, 6 kinds of mollusk, 5 kinds of shellfishes and 3 kinds of crabs. The main fish was Engraulis japonicus, Platycephalus indicus, Paralichthys olivaceus, Leiognathus nuchalis and Conger myriaster, their occupied rate were 47.0%, 16.6%, 13.6%, 5.5%, 2.7% respectively, and their total length range were 60-150mm, 80-410mm, 80-600mm, 30-80mm and 150-460mm respectively. A number bycatch rates of shrimp beam trawl fishery were 99.7% in Buan, 60.0% in Kangjin, 14.6% in Boryeong, 10.6% in Tongyeong and 2.7% in Geoje, The weight bycatch rate were 99.9% in Buan, 75.1% in Kangjin, 57.1% in Tongyeong, 47.4% in Boryeong and 15.4% in Geoje.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.349-356
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• 2017

The catch composition of commercially important species of the stationary lift net at Barangay Gines, Miagao, Iloilo, the Philippines was investigated from December 2013 to May 2014 during the different phases of the moon. A total of 486 kg of fish coming from 12 different genera, including mollusk and crustaceans, was caught and identified from the catch of the stationary lift net. Among the 12 genera identified from the catch of stationary lift net, anchovy (Stolephorus), sardines (Sardinella), squid (Loligo) and mysid shrimp (Acetes) were considered to be commercially important due to their value. Acetes catch was highest during the new moon in the month of January. Loligo catch was also high during the new moon except in the month of May. Stolephorus catch was also highest during the new moon except in the month of January. Sardinella catch was highest during the first quarter in the month of February. Full moon had the lowest catch all throughout the duration of the study while new moon had the highest catch during December 2013 to March 2014 and first quarter was the highest in the months of April and May.