• Animal Systematics, Evolution and Diversity
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• 제39권4호
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• pp.218-247
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• 2023

In our ongoing efforts to explore the species diversity of the harpacticoid fauna in Korea, we present findings on four newly identified species from family Tegastidae Sars, 1904. Although this family is frequently encountered in phytal communities, the diversity of tegastid copepod species within Korean waters largely remains to be elucidated. Drawing from our collections of tegastid harpacticoids from Chuja-do and Geomun-do Islands, we provide morphological descriptions for Tegastes lobus sp. nov., T. tresetosus sp. nov., T. pilosus sp. nov., and Syngastes acutus sp. nov., and propose their taxonomic relationships in relation to other species within the genus. Finally, we update the list of tegastid harpacticoids found in Korea and provide a key for identifying the six confirmed species from this region.

• Journal of Species Research
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• 제13권2호
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• pp.178-184
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• 2024

Two species (Lucicutia clausi, L. flavicornis) of Lucicutia (Lucicutiidae Sars, 1902) have been reported in Korean waters and one species(L. gaussae) is newly added the Tsushima Warm Current realm. Specimens from Korean waters are morphologically consistent with previous morphological characteristics of L. gaussae, but these differ in the following characteristics: 1) the male antennule with one process on segments XIX-XX, one process on segment XVIII, and three processes on segments XXI-XXIII; 2) in male leg 5, basis of left leg in the Korean specimen with small spine processes on the protrusion; 3) in male leg 5, the third exopodal segment of left leg without an inner marginal spine. In this study, we provide a redescription of L. gaussae insufficiently described by previous authors.

• Korean Journal of Environmental Agriculture
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• 제32권1호
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• pp.24-34
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• 2013

BACKGROUND: This study was carried out to compare population size of mudfish (Misgurnus mizolepis) between the agricultural practices and to investigate the causes of its differences. We also provided basic information for sustainable use of mudfish population in paddy fields. METHODS AND RESULTS: Mudfish and benthic invertebrates which are diet of mudifish were investigated from 8 sites of organic and conventional rice paddy fields in South Korea. Total number of mudfish were 1,882 individuals in survey sites. Mudfish population were 2.4 times larger in organic paddy fields (1,333 individuals) than in conventional paddy fields (549 individuals). The population size of mudfish was larger in Mungyeong-si, Gyeongsangbuk-do and Anseong-si, Gyeonggi-do with relatively better environmental conditions than the other 5 sites including Suwon-si, Gyeonggi-do, Cheongyang-gun, Chungcheongnam-do, Gunsan-si, Jeollabuk-do, Gimje-si, Jeollabuk-do, Hwasun-gun, Jeollanam-do, Hamyang-gun, Gyeongsangnam-do. Benthic invertebrates collected from survey sites were 74 species, 68 genera, 46 families, 19 orders, 6 classes and 3 phyla. According to agricultural practices, benthic invertebrates were identified 66 species, 62 genera, 41 families, 17 orders, 6 classes and 3 phyla in organic paddy fields while there were 66 species, 60 genera, 42 families, 18 orders, 6 classes and 3 phyla in conventional paddy fields. Dominant invertebrates were Chironomidae sp., Branchiopoda sp., Ostracoda sp., and Copepoda sp. There were no differences in dominant species between organic and conventional paddy fields. Population size of mudfish tended to increase with the population size of Chironomidae sp., Branchiopoda sp., Ostracoda sp., and Copepoda sp. But, only population of Chironomidae sp. and Copepoda sp. statistically related to population size of mudfish. The number of individuals of mudfish (Misgurnus mizolepis) was higher at the low rate of urban area than any other surveyed region and was affected by appearance ratio of main preys such as Chironomidae sp. and Ostracoda sp. CONCLUSION(S): The population size of mudfish in rice paddy fields could be affected by environmental conditions and agricultural practices such as organic and conventional methods.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제10권4호
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• pp.243-258
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• 1977

1 The coastal area between Youngdo and Jodo was a common coastal water not much different from other coastal waters before the construction of the breakwater between them. 2. The breakwater between the two islands shuts off the tidal currents and divides the area . into the two small isolated bays to create quite different environments. 3. To understand the differences between then, present study examined some environmental factors such as water temperature, salinity, dissolved oxygen, transparency, and major nutrients, phosphates, sillicates and nitrites and the phytoand zooplankton. The samplings were carried out monthly from March 1976 to February 1977 at 4 stations: 2 stations in each bay. 4. Some differences were observed in the environmental factors such as water temperature, salinity, dissolved oxygen and transparency between the two bays. 5. The distribution and occurence of nutrient salts of the two bays were distinctly different each other. Northern Bay had $138\%$ of nutrients in comparison with Southern Bay. 6. Phytoplankton in Northern Bay was about $200\%$ plentier than in Southern Bay. 7. Zooplankton in Southern Bay was about $180\%$ richer than in Northern Bay. 8. One of the pollution indicator species, Synedra ulna, was observed in Northern Bay and the occurence of Euglena sp. and ciliates were much higher in Northern Bay than in Southern Bay, but, in contrast, Sagitta sp. was more abundant in Southern Bay than in the other. 9. The areas of the two bays seem to be in its way to eutrophication especially in Northern Bay. 10. The two bays have been differentiated enough to identify each other.

• Korean Journal of Environmental Biology
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• 제27권3호
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• pp.297-305
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• 2009

The Asian paddle crab, Charybdis japonica (A. Milne-Edwards) is an important fishery resource in Korea. Despite its common occurrence and commercial importance, few studies have been carried out on the life cycle and trophic ecology of these populations inhabiting on the tidal flat. Food habits of C. japonica populations were investigated on the Jangbong tidal flat, Incheon, Korea. Monthly samples were taken using a modified otter trawl from November 1999 to January 2001. Based on the examination of stomach contents from 257 individuals, the frequencies of occurrence and the relative volumes of food items were analysed. As a result, the crustaceans (the brachyura, the cirripedia and the harpacticoid copepoda), the echinoderms (the ophiuroidea) and the molluscs (the cephalopoda Loligo beka, the bivalves Bivalvia unid. and Mytilus galloprovincialis) were important food for this species. To examine ontogenetic shifts in diets, individuals of C. japonica were categorized into 2 different size classes (${\leq}60mm$ and ${\geq}61mm$ in carapace width) representing sexually premature and mature stages. The food items of the small crabs (${\leq}60mm$) were dominated by the crustaceans with the harpacticoid copepods constituting 84.6% of total prey number. The next group was the bivalves and the brachyurans. On the other hand, the large crabs (${\geq}61mm$) mainly feed on the bivalvia (Mytilus galloprovincialis and Bivalvia unid.), the brachyurans (Crab unid.) and occasionally the cephalopods and fishes. The difference in proportions of the main prey items among these two size classes was statistically significant. Therefore, the feeding habits of the portunid crab, C. japonica changed with growth.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• 제5권3호
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• pp.238-244
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• 2000

The complete postembryonic developments of copepodid stages of Paramphiascella vararensis T. Scott(Copepoda: Harpacticoida) are described and illustrated based on specimens cultured in laboratory. The copepodites of P. vararensis feed on powder of one of green macro-algae species Ulva pertusa. Developmental time from copepodid stage to adult (copepodid stage) is about 15 days with culture conditions of 33-34 ppt of salinity, 22-23$^{\circ}$C of temperature and feed on algae powder. Sexual characters of the species are distinct on the copepodid stage. Sexual characters appear in size, antennule, pereiopods of second and bases of the fifth and sixth legs. Males are considerably smaller than females in size. In the antennule, the fourth segment of the male extremely is modified and swollen for female. In the segment number of the endopod of second pereiopod, female has 3 segments while male bears 2 segments. The female has 3 setae while the male bears 2 setae on the inner lobe of basis of fifth leg. In the basis of sixth leg, the female has 2 setae while the male has 3 setae.

• Journal of Food Hygiene and Safety
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• 제23권3호
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• pp.233-238
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• 2008

To evaluate biochemical safety of gejang distributed in Korea, 33 samples were collected and analyzed for indicator microorganisms, pathogen, parasite, pH, volatile basic nitrogen(VBN), salinity, 3-MCPD, histamine, and synthetic food colors. Total plate counts of gejang were the range of 3 to 7 log cfu/g and coliform were the range of ND to 4 log cfu/g. Vibrio parahaemolyticus was detected from 4 samples, and Escherichia coli(1 log cfu/g) and copepoda were detected from 1 sample among those. pH and VBN value of samples were the range of 6.69 to 8.10 and 21.99 to 94.55 mg%, respectively. The ranges of salinity concentration for ganjang chamgejang, ganjang ggokgejang, and ganjang dolgejang were $11.6{\sim}32.6%,\;2.8{\sim}20.5%$, and $11.6{\sim}13.3%$, respectively. But, the range of salinity concentration of yangnum gejang was $2.6{\sim}9.4%$, which was lower than ganjang gejang. Besides, 3-MCPD, histamine and synthetic food colors were not detected. From the results, most of gejang was appropriate for Korea national standard for food regulation, but still biological hygiene control for raw materials, processing, and distribution should be improved.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제29권4호
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• pp.415-430
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• 1996

Spatio-temporal variations in zooplankton community and ropepod indicator species were investigated along with the interaction between zooplankton distribution and environmental factors in Chinhae Bay. Zooplankton samples were monthly collected at 7 stations from February to September in 1993. A NORPAC net was vertically hauled from bottom to surface, At the same station, environmental factors such as temperature, salinity and COD (chemical oxygen demand) were measured at two different water layers, surface and bottom. In August and September, salinity declined below 30.00‰ , while eutrophic parameters such as COD showed the higher concentrations than those in other months, with higher concentrations at inner bay stations. Salinities were, however, higher at bay mouth areas. These distributional patterns were believed to be caused by input and dispersion of organic matters from nearby land. Zooplankton communities were composed of 7~14. Of these, Noctiluca scintillans was predominant and occupied 90.6‰ of total zooplankton abundance. Cladocera and Copepoda were secondly abundant taxa. Among 6 to 10 copepod species appeared, Acartia omorii and A. hudsonics were most common species during the survey months except March and September. Species diversities were greater, in general, at inner bay than outer bay. The lowest diversity index was observed in February, while the highest in July. Cluster analysis could divide the study area into 2 or 4 zones for each month. Zone 1, mouth area of the bay, was characterized by the influence of offshore waters. Zone II was mixing area. Zone III and IV seemed to be affected by nearby land.

• Korean Journal of Environment and Ecology
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• 제30권5호
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• pp.888-895
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• 2016

The population ecology (Ecological characteristics) of Squalidus chankaensis tsuchigae were investigated at Geum River from March to November, 2013. This species inhabited midstream of the river where was mostly covered with cobble and sand. The depth of the habitat was 30~60 cm and velocity of stream was 2.27~4.88 cm/sec. The sex ratio of female to male was 1 : 0.86. They were sexually mature when they were over two years of age. The spawning period was from June to July with water temperatures from $25^{\circ}C$ to $25^{\circ}C$. Sexually matured individuals appeared over the two year of age. Frequency analysis of total length indicated that the group with 55~70 mm in total length was one year old, the 71~90 mm was two years old, and the group over 91 mm was three years old. The average number of eggs in the ovaries was estimated as 2,219 per matured female. The number of matured eggs size in ovaries was 0.64~0.98 (mean: 0.85) mm. Calulation length-weight relation of S. chankaensis tsuchigae show the value of contant a as 0.0002 and b as 2.81, and condition factor (K) was 1.06 on average. The stomach contents were Cyanophyta, Chlorophyta, Bacillariophyta, Crustaceae, Copepoda, Nematota, Actithocephala, and Ephemeroptera, Hemiptera, Diptera, and Trichoptera that belong to Aquatic insect, and dormant bud of Pectinatella that belongs to Phylactolaemata. The diet of S. chankaensis tsuchigae was omnivorous, mainly vegetable feed on attached algae (filament form), and mainly animality feeded on benthic invertebrates such as Chironomidae larvae.

• Journal of Ecology and Environment
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• 제37권3호
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• pp.147-153
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• 2014

Structural heterogeneity results in different spatial distributions of microcrustaceans. Thus, in ecosystems with excessive macrophyte development, it may be difficult to determine the microcrustacean species composition. Given the importance of microcrustaceans in the food web, the elucidation of microcrustacean diversity is essential. In vegetated habitats, bluegill sunfish can prey on microcrustaceans, and therefore have a potential role as microcrustacean monitoring agents. In the present study, we compared microcrustacean species compositions in the field with those in the guts of bluegill, in Jangcheok Lake, South Korea. Our results showed that the number of microcrustacean species was higher in bluegill guts than in the field. Further, microcrustacean species, such as Daphnia galeata, Graptoleveris testudinaria, Leydigia leydigii, Rhynchotalona sp., and Simocephalus exponisus, were found only in bluegill guts. Our findings verify the validity of the fish gut analysis to monitor microcrustacean species compositions and to clarify spatial distributions of microcrustacean species in structurally heterogeneous ecosystems with excessive macrophyte development.