• Ocean and Polar Research
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• v.38 no.4
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• pp.315-324
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• 2016

In this study, we investigated changes in the macrobenthic community in Sihwa tidal flat before and after the operation of a Tidal Power Plant (TPP). In order to investigate changes in the macrobenthic community structure, field surveys were conducted at eighteen stations in 4 transect lines every September from 2011 to 2015. Mean density of macrobenthos decreased to $116ind./m^2$ in 2015 from $1,602ind./m^2$ in 2011. While the mean density of macrobenthos has decreased, species richness and biomass have gradually increased. The species diversity and SEP (Shannon-wiener Evenness Proportion) have also gradually increased over time since the operation of the TPP. The macrobenthic community in Sihwa tidal flat was divided into 4 groups on a yearly base. Before the operation of TPP, opportunistic species such as Neanthes succina and Polydora cornuta largely contributed to the structure of the macrobenthic community, while equilibrium species such as Periserrula leucophryna and Scopimera globosa contributed after the operation. With the operation of TPP, the macrobenthic community has rapidly recovered and this might be related to improvement in the quality of water and sedimentary environments as a result of an increase in water mass volume exchanged through the TPP gate.

• Korean Journal of Veterinary Service
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• v.40 no.2
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• pp.119-131
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• 2017

Among different types of spoilage, microbial contamination can cause feed decomposition, which results in decreases in feed intake and productivity, infection, and breeding disorder. During the storage time, various microbes have a chance to inoculate with depreciation of feed and to infect the animals. We investigated bacteria that inhabit diverse feed ingredients and complete feed which have been stored for a few months. We isolated and identified 30 genera and 62 species of bacteria. Among these 62 species, 21 species were of non-pathogenic bacteria, 18 species were of pathogenic bacteria, 9 species were of opportunistic pathogens, and 14 species were of unknown bacteria. Pantoea allii and 24 species showed proteolytic enzyme activity. We also confirmed that 6 species including Pseudomonas psychrotolerans showed ${\alpha}$-amylase activity, and 29 species including Burkholderia vietnamiensis showed cellulase activity. Microbacterium testaceum and 3 species showed resistance to Ampicillin, Kanamycin, Streptomycin, Gentamicin, Carbenicillin, and Erythromycin ($50{\mu}g/mL$). Using mealworm larvae (Tenebrio molitor L.) as a model for pathogenicity, we confirmed that 8 species including Staphylococcus xylosus had pathogenicity for mealworm larvae. Especially, Enterobacter hormaechei, Staphylococcus xylosus, and Staphylococcus hominis were reported as being pathogenic for humans. This research suggests that hygienic management of animal feed is essential because beneficial and harmful bacteria can inhabit animal feed differently during storage and distribution.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.4
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• pp.378-382
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• 2011

The feeding ecology of bluefin searobin Chelidonichthys spinosus around Jeju Island was examined. Specimens were caught every autumn from 2004 to 2007. The primary prey items of C. spinosus included fish, shrimp, and crabs. Chelidonichthys spinosus preyed upon a wide range of sub-pelagic crustacean groups(e.g., Leptochela gracilis, Leptochela sydniensis). This species was also an opportunistic feeder, exploiting the available prey groups in each area(i.e., L. gracilis in the South Sea and East China Sea groups and L. gracilis and L. sydniensis in the Yellow Sea group). The main prey group of this species changed from demersal shrimp to pelagic shrimp with prey environmental changes. Observed ontogenetic shifts in diet were relatively clear despite substantial overlap between the 10 cm and 20 cm C. spinosus groups.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.1
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• pp.273-283
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• 2015

This study was carried out to examine the species composition and community structure of benthic marine algae at the subtidal zones of Daepo, Wolpyeong, Wimi and Jigwido in south Jeju, Korea from March to December 2009. Total 87 species including 14 green algae, 23 brown algae, and 50 red algae were collected and identified. Among these species, 9 species were found throughout the year. The dominant species which contributed significantly to the total biomass were Ecklonia cava, Undaria pinnatifida, Peyssonnelia capensis, Cladophora wrightiana, Sargassum serratifolium, Grateloupia angusta, Codium coactum, Plocamium cartilagineum, and Sargassum macrocarpum. The average seaweed biomass was 7,578.2 g wet weight $m^{-2}$ and maximum biomass was recorded seasonally in spring ($9,627.6g\;m^{-2}$), while minimum was recorded in autumn ($5,963.0g\;m^{-2}$), by sites maximum biomass Jigwido ($12,889.9g\;m^{-2}$), while minimum was recorded in Daepo ($5,403.8g\;m^{-2}$). The seasonal and regional flora were investigated as six functional groups. A coarsely branched form was the most dominant functional group constituting from 42.9~52.8% of the total flora. Ecological state group (ESG) II, as an opportunistic species, including sheet form, filamentous form, and coarsely branched form, consisted of 31~59 species, constituting 77.5~84.9%.

• Journal of Animal Science and Technology
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• v.56 no.5
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• pp.16.1-16.9
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• 2014

Fatty acids (FA) have recently been used in several studies to infer the diet in a number of species. While these studies have been largely successful, most have dealt with predators that have a fairly specialized diet. In this paper, we used FA analysis as a tool to infer the diet of the nearctic river otter (Lontra canadensis). The river otter is an opportunistic predator known to subsist on a wide variety of prey including, fishes, crayfish, molluscs, reptiles and amphibians, among others. We analyzed the principle components of 60 FA from otters and 25 potential prey species in Illinois, USA. Prey species came from 4 major taxonomic divisions: fishes, crayfish, molluscs and amphibians. Within each division, most, but not all, species had significantly different profiles. Using quantitative FA signature analysis, our results suggest that, by mass, fish species are the most significant component of Illinois River otters' diet ($37.7{\pm}1.0%$). Molluscs ranked second ($32.0{\pm}0.8%$), followed by amphibians ($27.3{\pm}4.3%$), and finally, crayfish ($3.0{\pm}0.6%$). Our analysis indicates that molluscs make up a larger portion of the otter diet than previously reported. Throughout much of the Midwest there have been numerous otter reintroduction efforts, many of which appear to be successful. In regions where mollusc species are endangered, these data are essential for management agencies to better understand the potential impact of otters on these species. Our analysis further suggests that quantitative FA signature analysis can be used to infer diet even when prey species are diverse, to the extent that their FA profiles differ. Better understanding of the otter's metabolism of FA would improve inferences of diet from FA analysis.

• Ocean and Polar Research
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• v.23 no.3
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• pp.255-264
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• 2001

Development process of benthic community on experimental substrata attached on a newly installed artificial reef complex in Jeju Island was observed for 27 months from 1992 to 1994. Among 34 species of algae and 64 species of zoobenthos obtained from the study, Ecklonia cava dominated with a maximum biomass of about $10kg/m^2$. It was able to smother the other animals, however it provided a new substrate for the new settlers. Opportunistic bryzoans such as Likenopora radiata and Dexiospira spirillum occurred during the early stage were substituted by poriferans, banacles and other bryzoans. Young barnacles were smothered by bryozoans, on the contrary, bryozoans were bulldozed by adult barnacles. No apparent differences have been observed between vertically and horizontally installed substrates in terms of species composition and biomass during the early stage of succession. Thereafter owing to the rapid growth of E. cava, the horizontal substrata carried on a higher biomass while the vertical showed a higher coverage. The benthic process on the experimental substrata can be classified into three stages: initial stage, build up stage and regulatory stage. Important mechanisms involved were canopying of E. cava, suffocation by bryozoans and poriferans, and bulldozing of adult barnacles.

• Ocean and Polar Research
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• v.33 no.4
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• pp.421-434
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• 2011

Although thermal effluent from coastal power plants affects marine ecosystems, few studies have examined the spatiotemporal distribution of macrobenthic communities in a coastal area of Korea with thermal discharge. This study analyzed the species composition and abundance of a macrobenthic community in relation to environmental variables for a period of 1 year. In total 334 macrobenthic faunal species were collected; the mean density was 3,221 ind/$m^2$. The number of species and the density of macrobenthic fauna increased with distance from the thermal discharge site. Cluster analysis indicated that the macrobenthic community could be divided into two groups: group I in shallow (< 30 m deep) and group II in the outer areas (> 30 m deep). Group I showed the lowest species density and diversity. Four polychaetes, including Magelona japonica, Spiophanes bombyx, Scolotoma longifolia and Chaetozone setosa, all of which have been dominant species since 1987, exhibited higher mean densities in the area distant from the thermal discharge (the outer and north areas). Conversely, the warm-adapted and opportunistic species, such as the amphipods Urothoe convexa and Mandibulophoxus mai, the bivalve Felaniella sowerbyi, and the polychaete Rhynchospio sp., were more abundant in the thermal discharge region. The results of this study indicate that thermal effluent influences macrobenthic communities in the shallow area, while other environmental variables, such as depth, sediment grain size, and TOC, are more important determinants of the macrobenthic communities in deeper regions (> 30 m deep).

• Ocean and Polar Research
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• v.43 no.2
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• pp.73-88
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• 2021

The community structure and health status of macrobenthos assemblages were investigated in the subtidal area of the Nakdong River estuary, Southern Coast of Korea. Benthic fauna samples were collected seasonally at 8 stations in the subtidal area of the Nakdong River estuary from February 2013 to October 2015. During the survey, a total of 380 species and 4,603 ind./m² of macrobenthos in all sampling areas were collected. The major dominant species were the polychaetes Minuspio japonica, Pseudopolydora kempi, Heteromastus filifomis, Capitella capitata, the amphipod Grandidierella japonica and the bivalvia Arcuatula senhousia. Some species of polychaetes found in the study area consisted of opportunistic species that showed high densities when habitat condition was poor. On the other hand, macrobenthos assemblages in the study area were divided into brackish water and marine groups. Abundance was high in the brackish group, while the number of species and diversity index were high in the oceanic group. The three indices (AMBI, M-AMBI, and BHI) in the assessment of health levels based on the ecological characteristics and number of species in macrobenthic were commonly shown to be in good condition in the group of oceanic stations, while relatively poor conditions were reflected in the group of brackish stations. Compared to other indices, the M-AMBI index of the three indices for health assessment was considered to be a relatively more suitable one to assess benthic ecological conditions.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.882-895
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• 1997

Changes in the benthic communities have been studied to investigate the environmental effects before and after the construction of Shihwa Dike in the West coast of Korea. It is suggested that sequential changes in macrofaunal assemblages progressed in two sucressional directions. In the Shihwa lake under the influence of organic enrichment. First, the appearance of 'azoic tone' or 'grossly polluted zone' developed in the area of less than 6 m in depth resulted from the severe dissolved oxygen depletion due to the eutrophication from the increased organic loading. Second, the 'polluted zone' characterized by the proliferation of the opportunistic species in organically enriched area, was found in the vicinity of the industrial discharges and nearby fluvial inputs. This benthic community succession in the Shihwa lake seemed to be caused by the various ecological events such as an eutrophication in this organically enriched environment after construction of the dike and other physico-chemical parameters like salinity and dissolved oxygen in the bottom water, which may be influenced by the irregular surface water discharge and dilution by outer seawater inflow through the water gate of the dike. On the other hand, the benthic communities in the outside of the dike showed that the species richness was more than doubled and the abundance increased almost seven times more than that before the dike construction. This may be a typical characteristics of the initial phase in benthic eutrophication, suggesting that an increased organic input area may have been reponsible for this faunal change in the study area.

• Journal of fish pathology
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• v.32 no.2
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• pp.69-80
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• 2019

We performed MLSA (multilocus sequence analysis) and phenotypic characterization of Aliivibrio species isolated from walleye pollock (Gadus chalcogrammus) maintained in 3 different facilities of Gangwon Province, the east coast of Korea. Of 38 Aliivibrio species identified by 16S rDNA sequences, 12 strains were randomly selected and MLSA was conducted with 5 house-keeping genes (gapA, gyrB, pyrH, recA and rpoA) and 16S rDNA gene. Phylogenetic analysis and homology of the concatenated sequences (4,580 bp) with other Vibrionaceae genera revealed that 4 strains (GNGc16.1, YYGc16.1, YYGc16.2, GSGc18.1) were identified as Aliivibrio logei and one strain (GSGc16.1) as A. wodanis. One strain (GSGc17.1) was tentatively identified as A. logei, but needs further analysis because it did not belong to the same clade with A. logei type strain. 6 strains (GSGc17.2, GNGc16.2, GSGc16.2, GSGc17.3, GSGc18.2, GSGc17.4) need further investigation as potential novel species. Either phenotypic characterization or 16S rDNA sequence alone did not provide enough information for identification of Aliivibrio strains at the species level. A. logei and A. wodanis are generally known as non-pathogenic bacteria, but also known as opportunistic or secondary pathogens of cold water fishes. Cares should be taken to prevent potential outbreaks due to these bacteria, although there was no outbreaks during the sampling period.