• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.619-624
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• 2003

Genital organs and gonad development in kishi velvet shrimp (Metapenaeopsis dalei) were studied based on morphological and histological observations. The samples were collected monthly around the Ochongdo area on the western coast of Korea, from April 1997 to December 1998. Thelycum appear structurally complete after females reach a length of about 12.0 mm CL. Petasma rarely Join after males reach a length of 10.6 mm CL and a fully developed petasma shows up to a length of 12.0 mm CL. The ovaries lie on the dorsal side of the female shrimps thorax. The ovary cavity is located below the heart and above the hepatopancreas. The anterior part of the ovary is round and fused, and the posterior part shows a pair of tubule-like structures. Testes are bilaterally symmetrical, the anterior part shows a convoluted tubule, and the posterior part consists of a pair of tubules. In histological observations, ripe eggs and spermatozoon show when mature females and males reach a length of about 12.0 mm CL.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.6
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• pp.867-874
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• 2016

Although shrimps belonging to family Crangonidae are known to be genetically divergent and ecologically important among the various benthos, any of their mitochondrial genome has not been reported yet. We here determined the complete mitochondrial genome sequence of Crangon hakodatei (Rathbun, 1902), which was collected from East China Sea ($124^{\circ}E$ and $34.5^{\circ}N$). Total mitochondrial genome length of C. hakodatei was 16,060 bp, in which 13 proteins, 2 ribosomal RNAs, 22 transfer RNAs and a putative control region were encoded. Secondary structure prediction analysis showed that twenty tRNA genes exhibit the conserved structure but two genes, $tRNA^{Cys}$ and $tRNA^{Ser}$ (AGN), lack T and D arm, respectively. Based on the sequence similarity of the COI region from the currently reported five species belonging to genus Crangonidae, C. hakodatei was most closely related to Crangon crangon. Phylogenetic analysis of full COXI genes belonging to infraorder Caridea showed that only crangonid shrimps were clustered together with those of Dendrobranchiata. Gene order were well conserved from Penaeoidea to Caridea but $tRNA^{Pro}$ and $tRNA^{Thr}$ in Palaemonid shrimp were flipped each other by the recombination. Further study about mitochondrial genome sequences of shrimps belonging to Crangonidae should be made to know better about their evolutional relationships with other those in infraorder Caridea.

• 한국해양학회지
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• v.30 no.2
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• pp.138-146
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• 1995

Present study was performed to describe the growth of Leptochela gracilis (STIMPSON, 1860), the dominant species of the coastal water near Kanghwa Island, Korea. Samples were collected from 1 sampling point by long bag seine net at monthly interval from April 1993 to January 1994 except for August 1993. In the population study of Leptochela gracilis, ovigerous female has appeared from April to September 1993 and the ratio (egg-bearing female/female) showed over 70% from May to July 1993. Female individuals were predominant from May 1993 to January 1994 and it was found that sex ratios were not significantly different between pregnant and non-pregnant period(p>0.05). The population of Leptochela gracilis was divided into 2 types of generation; i) short term generation. and ii) long term generation. Longevity of the long term generation was presumed to vary from 12 to 15 months. In the case of short term generation, spawned by egg-bearing stock of September, however, it was not certain whether they absorbed in the long term generation, thus overcome winter season or die after December by environment factors. The growth in cavalcade length of the long term generation was better fitted to Pauly and Gaschutz model than Von Bertalanffy.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.535-544
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• 1998

Seasonal variation of the crab community in the eelgrass (Zostera marina) bed in Kwangyang Bay was studied based on the monthly collections through a year of 1994. The crab community in the eelgrass bed was composed of 21 species representing 12 families. The community was dominated by Charybdis Japonica, Telmessus acutidens, Hemigrapsus penicillatus, and Pugettia quadridens. Crabs collected in the study area were primarily small-sized species or early juveniles of large crab species. Most individuals had carapace width smaller than 25 mm except C. japonica and T. acutidens which had maximum carapace width over 85 mm. More than 5 species were collected every month except January and February (4 and 3 species, respectively). The peak abundance occurred in August and low abundances in autumn and winter. Species diversity indices showed that more diverse crabs were collected In spring and summer, and lesser ones in autumn and winter. The crabs in the study area can be grouped into three groups on the basis of their occurrence patterns: resident species, seasonal species, and temporary species. More abundant and more diverse crabs were collected during nighttime than daytime.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.5
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• pp.432-442
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• 1992

To identify the histological site of synthesis of yolk protein precursor, vitellogenin, by immunocytochemical method in the freshwater crab Eriocheir japonicus, we purified the yolk protein, vitellin, from crude egg extracts, and prepared the anti-rabbit serum against vitellin. Then, the site of vitellogenin synthesis was demonstrated by immunotytochemical method with PAP(peroxidase-antiperoxidase) reaction using the rabbit antiserum aganist vitellin. Female specific serum protein was identified in female serum by immunoelectrophoresis and Ouchterlony's immunodiffusion test for mature male and female sera. Based on the immunoelectrophoresis and Ouchterlony's diffusion test for mature male and female sera and crude egg extracts using antiserum against vitellogenic female serum absorbed with male serum, the female specific serum protein was identified as vitellogenin, detected in female serum only. The major yolk protein, vitellin, was purified from the crude egg extracts by DEAE-cellulose ion exchange chromatography, followed by sepharose CL-4B gel filteration chromatography. The molecular weight of vitellin was estimated to be about 245,000 dalton by sepharose CL-4B gel filteration chromatography. from the results of immunological analysis for vitellin, it was found that the vitellin antiserum contained the antibody against vitellogenin. In the results of immunocytochemical reaction by PAP method with the rabbit antiserum against vitellin, the vitellogenic oocytes and the hepatopancreas of mature female showed positive PAP reaction, but not in follicle cells and previtellogenic oocytes nf ovary, muscle of female and mature male hepatopancreas. Therefore, it showed that the hepatopancreas of mature female is the site of vitellogenic synthesis.

• Korean Journal of Ichthyology
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• v.9 no.1
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• pp.61-70
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• 1997

The spawning season, growth and feeding habit of tubesnout, Aulichthys japonicus were examined from the samples collected by a small beam trawl in the Zostera marina belt at the coastal water off Hamduck, Cheju Island, from May 1993 to May 1994. Tubesnout was the dominant species of overall 58 species collected in the study area throughout the year. The larvae and juvenile of tubesnout in the frequency distributions of body length began to appear in the Z. marina belt in March, and adults disappeared after May in the following year. The gonad weight index (GWI) and the condition factor (K) were high from November 1993 to January 1994 for males, while females were high from February to May 1994. Although tubesnout is an oviparous fish, males have the urogenital papilla. These results suggest that they were fertilized between November and January, and then males seemed to be died or move into other places. Females were examined to spawn from February to May. The stomach contents of tubesnout were dominated by copepoda smaller than ca. 1mm, Paracalanus, Oithona, Acartia, Oncaea and Harpacticoidae, accounting for 97% of total food items. The feeding habit of tubesnout did not vary by size. The fishes fed on Calanus, Euchaeta and decapoda larvae larger than ca. 3mm in March and April during the spawning season.

• Animal Systematics, Evolution and Diversity
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• no.nspc2
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• pp.233-241
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• 1988

The crab, Macrophthalmus (Mareotis ) japonicus , collected in 1983 from CHojijin tidal flat, southeastern part of Kangwha Island , Korea, was studied. Its caraace breadth, the carapace length , and body height were checked , and the measured raw data were analysed for the growth ratios by the mode subtraction method from the frequency distribution compared with the probability graphs. The growth rate of the crab rose more in summer than in fall and exceeded 10% during the same period on Chojijin tidal flat in Kangwha Island , Korea. Four size groups of the crab appeared in June, 1983 , but they were put together into only on emixed group by autumn. The rapid growth of the crab in summer in middle latitude comes from the seasonal bio-rhythm and the best conditions for food. But the physiological activities of the crab are reduced from autumn and the growth rate reaches the upper limits in many individuals on this tidal flat. The more the crabs grow, the more the breadth ratios to the carapac length become larger and the slopes of correlation curve get smaller. The measured values from the carapace breadth of the crab are more useful for morphological studies than those values from the carapace length or body height.

• Journal of Wetlands Research
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• v.21 no.2
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• pp.95-101
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• 2019

In tidal flats that lack plants, methane ($CH_4$) fluxes are both positive (gas emission) and negative (gas "sinking") in nature. The levels of methanotroph populations significantly affect the extent of $CH_4$ sinking. This preliminary study examined $CH_4$ flux in tidal flats using a circular closed-chamber method to understand the effects of macroinvertebrate burrowing activity. The chamber was deployed over decapods (mud shrimp, Laomedia astacina and crab, Macrophthalmus japonicus) burrows for ~ 2 h, and the $CH_4$ and $CO_2$ concentrations were continuously monitored using a closed, diffuse $CH_4/CO_2$ flux meter. We found that Laomedia astacina burrow (which is relatively long) site afforded higher-level $CH_4$ production, likely due to diffusive emission of $CH_4$ in deep-layer sediments. In addition, the large methanotrophic bacteria population found in the burrow wall sediments has $CH_4$ oxidation (consumption) potential. Especially, nitrite-driven anaerobic oxidation of methane (AOM) may occur within burrows. The proposed $CH_4$-oxidation process was supported by the decrease in the ${\delta}^{13}C$ of headspace $CO_2$ during the chamber experiment. Therefore, macroinvertebrate burrows appear to be an important ecosystem environment for controlling atmospheric $CH_4$ over tidal flats.

• Korean Journal of Ecology and Environment
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• v.55 no.4
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• pp.368-375
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• 2022

Gut contents analysis is essential to predict the impact of organisms on food source changes due to variations of the habitat environment. Previous studies of gut content analysis have been conducted using traditional methods, such as visual observation. However, these studies are limited in analyzing food sources because of the digestive process in gut organ. DNA metabarcoding analysis is a useful method to analyze food sources by supplementing these limitations. We sampled marine fish of Pennahia argentata, Larimichthys polyactis, Crangon affinis, Loligo beka and Sepia officinalis from Gwangyang Bay and Yeosu fisheries market for analyzing gut contents by applying DNA metabarcoding analysis. 18S rRNA v9 primer was used for analyzing food source by DNA metabarcoding. Network and two-way clustering analyses characterized the relationship between organisms and food sources. As a result of comparing metabarcoding of gut contents for P. argentata between sampled from Gwangyang Bay and the fisheries market, fish and Copepoda were analyzed as common food sources. In addition, Decapoda and Copepoda were analyzed as common food sources for L. polyactis and C. affinis, respectively. Copepoda was analyzed as the primary food source for L. beka and S. officinalis. These study results demonstrated that gut contents analysis using DNA metabarcoding reflects diverse and detailed information of biological food sources in the aquatic environment. In addition, it will be possible to provide biological information in the gut to identify key food sources by applying it to the research on the food web in the ecosystem.

• Journal of Ecology and Environment
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• v.47 no.4
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• pp.200-210
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• 2023

Background: Cambaroides similis is an endangered candidate species living in the stream of South Korea. Freshwater crayfish is known to decline rapidly not only domestically, but also internationally. Its decline is projected to be further exacerbated due to climate change. Understanding physical characteristics of the habitat is crucial for the conservation of an organism. However, comprehensive data regarding the distribution and physical habitat characteristics of C. similis are currently unavailable in South Korea. Thus, the objective of this study was to ascertain preferred ranges for water depth, current velocity, and streambed substrate of C. similis using Weibull model. Results: In this study, C. similis was found at 59 sites across 12 regions in South Korea. Its optimal water depth preferences ranged from 11.9 cm to 30.1 cm. Its current velocity preferences ranged from 9.8 cm s^-1 to 29.1 cm s^-1. Its substrate preferences ranged from -5.1 𝜱_m to -2.5 𝜱_m. Median values of central tendency were determined as follows: water depth of 21.4 cm, current velocity of 21.2 cm s^-1, and substrate of -4.1 𝜱_m. Mean values of central tendency were determined as follows: water depth of 21.8 cm, current velocity of 22.0 cm s^-1, and substrate of -4.4 𝜱_m. Mode values of central tendency were determined as follows: water depth of 21.7 cm, current velocity of 20.1 cm s^-1, and substrate of -3.7 𝜱_m. Conclusions: Based on habitat suitability analysis, physical microhabitat characteristics of C. similis within a stream were identified as Run section with coarse particle substrate, low water depth, and slow current velocity. Due to high sensitivity of these habitats to environmental changes, prioritized selection and assessment of threats should be carried out as a primary step.