• Journal of the Korean Society of Marine Environment & Safety
• /
• v.30 no.1
• /
• pp.20-31
• /
• 2024

This study was conducted to investigate the changes in the structure of benthic communities resulting from aquaculture activities and to assess the benthic health status of surface sediment in Gangjin Bay, a region known for concentrated shellfish aquaculture on the southern coast of Korea. Survey stations were divided into longline culture, bottom culture, and non-cultivation areas. The spatiotemporal distribution of physiochemical factors such as the grain size, water temperature, salinity, and total organic carbon in Gangjin Bay showed no significant differences between sampling stations. However, the species number, density, and diversity were relatively lower at the sampling stations in the bottom culture areas than at the other stations throughout the entire survey period. Cluster analysis and principal coordinates analysis also clearly distinguished the benthic communities in the bottom culture areas from those in the other sampling areas. At the sampling stations in the longline culture and non-cultivation areas, Scolectoma longifolia and Sigambra tentaculata, which are indicator species of organically enriched areas, appeared as dominant species. However, excluding some stations influenced by physical factors such as the water depth and current speed, the occupancy rate was not high. The health assessment results, conducted using the fisheries environment assessment method, revealed good conditions with Grades 1 and 2 across the entire area. However, an examination of the spatiotemporal changes in benthic communities and the benthic health index indicated that the benthic environment in the bottom culture areas was affected by physical disturbances.

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

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.8 no.3
• /
• pp.133-149
• /
• 1975

1. A quantitative ecological investigation of the intertidal sand beach at Yong-ho Bay, located about 6km NE of Busan Harbour was carried out from February, 1974 to February, 1975. Composition of the fauna, diversity, faunal affinity and distributions in time and space were studied. Some ecological factors influencing to the community also discussed. 2. The beach can be classified as a fine-sand beach which is dominated by Armandia lanceolata and Nephtys sp. (A). Thirty two species of animals representing 29 genera were found. In number, two polychaetes, A. lanceolata and Nephtys sp. (A) were dominant, while one polychaete, Neanthes japonica and one bivalvia, Laternula limicela were dominant in weight. 3. Distribution of the fauna was devided into three areas of different faunal compositions with sediment types particularly by mud fraction content, and it well agreed with faunal affinity and diversity index value. 4. Seasonal fluctuation of the three dominant species, A. lanceolata, Nephtys sp. (A) and N. japonica was studied. Except Nephtys sp. (A), the fluctuation were closely related to the brooding time. 5. There was no relationship between faunal distribution and organic matter content. Submergence time affected the distribution of some species but the influence to the whole-community was little.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.38 no.3
• /
• pp.172-183
• /
• 2005

To assess the macrobenthic community of oligohaline Youngam Lake, which is located at the Youngsan Watershed on the southwest part of Korea, macrobenthic fauna were collected at 45 stations during May, 2002. A total of 16 species of macrofauna were recorded with a mean density of 240 individuals per $m^2$ and a mean biomass of 7.07 g wet weight per $m^2$. Major dominant faunal groups were crustacean arthropods in terms of the number of species and abundance, and polychaete annelids in terms of biomass. The mean grain size was $5.7\;{\phi}$ which was dominated by silt fraction. The hydrological environment of the lake was characterised as an oligohaline environment with a mean surface water temperature of $17.8^{\circ}C$ and a mean salinity of 2.08 psu. The major dominant species were amphipods, Corophium sp. ($31\%$) and Jesogammarus sp. ($25\%$). Lowe. values of species diversity (H') with a mean of 0.81 (less than 1.0 from most stations) reflected the overall poor faunal diversity in this area. Multivariate analysis suggested that this benthic faunal community could be divided into four sub-regions such as the area from lake proper to water channel to the south, the stations located at the entrance and northern water channel, the stations near the dike, and the lake proper area. Freshwater and brackish water species which occurred in each station group were corresponded to the oligohaline salinity regime. Bottom hypoxia appeared in the entrance part of the lake between dyke and lake proper on May, which was resulted from stratification from spring season. These facts imply that marine macrobenthos were severely impacted by low salinity and a consequent hypoxia after embankment of the lake due to the restriction of water circulation.

• Journal of Environmental Science International
• /
• v.11 no.3
• /
• pp.215-225
• /
• 2002

In order to evaluate the relationship between geochemical characteristics and benthic facies of the sediments from the Oenaro Island where red tide proliferation is first observed every year including this year, surface and short multiple core sediment samples were analyzed in terms of geochemical and benthic facies variation. The contents of organic carbon, carbonate, and sulfide gas were relatively low. The variation in C/N ratios, which indicate nature of organic carbon, suggested that the organic carbon recorded in the study area is composed of mixtures of marine and terrigenous organic matters. The concentration of minor elements found at the surface and multiple core sediment samples were also low as well as the enrichment factors(Ef) for the seven heavy metals indicated that the sediment of this area is not polluted significantly. The macrobenthic faunal community comprised 61 species, and their mean density was 708 ind./m2. Polychaete worms were major taxa of this benthic community. A crustacean amphipod, Melita sp. was the most abundant species accounted for 20.7% of total abundance, and the small polychaetes such as Heteromastus filiformis, Paralacydonia poradoxa, Magelona japonica and Sigambra tentaculata were the next dominant species. The macrobenthos around the Oenaro Island were more diverse and abundant than that in Gamak Bay. The benthic communities in the study area sustained somewhat different species composition based on the cluster analysis and the MDS ordination. The benthic community health condition at three stations seemed to be unbalanced, and slightly polluted based on the biological index such as BPI and BC. There was no clear relationship between the geochemistry characteristic and the benthic faunal facies attributed by the micro-algal blooms in this coastal area.

• Ocean and Polar Research
• /
• v.41 no.2
• /
• pp.47-61
• /
• 2019

The Dokdo coast is known for its high biodiversity. However, few studies have examined the biodiversity and macrobenthic community on the subtidal soft-bottom. Therefore, we collected macrobenthos (> 1 mm) using a Smith-McIntyre grab ($0.1m^2$) at 15 stations along the Dokdo coast in September 2016. The sediments consisted of badly sorted (1.7) coarse sand with gravel and the mean sediment grain size was $-0.4{\phi}$. In total, 177 macrobenthic species were collected; their mean density was $1,566ind./m^2$. The number of species and density of macrobenthic fauna decreased significantly with the mean grain size. The dominant species were the amphipods Melita denticulata (16.5%) and Melita shimizui (5.5%), polychaete Salvatoria clavata (5.4%), bivalve Glycymeris aspersa (4.4%), and ophiuroid Ophionereis dubia (4.3%). The dominant macrobenthos species on the subtidal soft-bottom differed from the coastal areas of the East Sea, suggesting that the difference in the sediment grain size affected the macrobenthos. Cluster analysis was performed to divide the study area into four groups, and environmental factors which correlated with species composition and distribution in the study area were the combination of the four parameters of salinity, dissolved oxygen, total organic carbon and depth. A future seasonal investigation is needed to understand the species composition and characteristics of the Dokdo macrobenthos.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.19 no.4
• /
• pp.297-309
• /
• 2016

This study was carried out to investigate the differences in sedimentary environments and benthic polychaete communities between farming grounds and natural habitats (non-farming ground) in Gamak Bay. Sampling stations of natural habitats were evenly distributed in the entire bay. And mussel farm, oyster farm and ark-shell farm were selected as farming grounds. Dominant sedimentary facies was mud in most sampling stations of farming grounds and natural habitats. However organic contents were higher in the farming grounds than natural habitats of the bay. The species number and mean density of polychaetous community in the natural habitats were greater than those from the farming grounds. Lumbrineris longifolia, known as potential organic enrichment indicator species, was first dominant species both in farming grounds and natural habitats of the bay. However, the next dominant species consisted of different species between two benthic habitats. As a result of community analysis using cluster analysis and nMDS, the natural habitats were divided into several station groups, but most of stations in farming grounds were clustered into one group. Pearson' correlation analysis and PCA showed high relationships between sedimentary environmental factors and benthic polychaetous community in natural habitats, but low or no relationships in farming grounds. That means benthic polychaetous community established in farming ground was under unusual condition such as high input of organic matter. Thus it is necessary to improve the benthic environmental quality of the farming grounds as well as the north-western inner part in Gamak Bay through long-term monitoring efforts.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.22 no.4
• /
• pp.189-195
• /
• 1989

The ecological studies of the benthic polychaetes were carried out in the follow Sea for the period of August 1982 through February 1986. Special emphasis were placed on quantitative species composition and the importance of polychaetes in the benthic community. Polychaete group ranked numerically high, composing $35.1\~46.4\%$ of the total benthos. In the biomass, echinoderms or mollusks showed as a dominant group, but the range of its seasonal variation was very large. Due to the use of sampling gear, the relative importance of polychaetes was somewhat different. The case of a dredge showed a little lower composition rate of polychaetes than a grab one. This result was caused by high density of benthic animals because the dredge would tow only much more surface sediments than the grab sampler. The present studies included a total of 141 species and the representative polychaetes in this area were Spiophanes bormbyx, Ampharete arctica, Geniada maulata, Nephtys caeca, Nothria iridescens.

• 한국해양학회지
• /
• v.30 no.4
• /
• pp.250-261
• /
• 1995

This study was carried out to investigate the distribution of the benthic polychaetous community in Kamak Bay, in summer of 1993. Polychaetes, the dominant faunal group comprising 74.5% of the total number of fauna, consisted of a total of 84 species with a mean density of 112 indiv.m/SUP -2/. The number of species and density were higher in the mouth area of the bay than in the rest of the bay. The most dominant Polychaete was Tharyx sp.(31.9%), followed by Lumbrineris longifolia (27.5%), Chone sp.(4.5%) and Glycera chirori (4.2%). The correspondence analysis revealed that the study area could be divided into four regions. Northeastern channel and southern mouth region of the bay, named Tharyx-Chone assemblage, sustained higher polychaetous density and species number due to the active water exchange with the outer off-sea, whereas northwestern region of the bay had the poorest polychaetous assemblage in the species number and faunal density owing to the blocking water exchange, high organic enrichment in sediment, and low dissolved oxygen content of bottom water. The central region, named Praxillella-Terebellides assemblage and Gly-cera assemblage, was the transition zone between another two region in species composition.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.30 no.3
• /
• pp.413-422
• /
• 1997

To know the food chain of an intertidal community, feeding habits of Acanthogobius elongata were studied by analyzing stomach contents. A. elongata were monthly collected and the environment conditions of the habitat were investigated in the intertidal zone of Naecho-do, Kunsan from July 1993 to June 1994. Ratio of stomach contents to weight of A. elongata was $1.78\%$, and fullness of stomach showed a similar value to ratio of stomach contents to weight. Fullness of stomach was increased twice a day in the morning and the afternoon. The most important food item was copepods amounting to $54\%$ of the total stomach contents. Of these, Paracalanus parvus was most abundant in spring, Calanus sinicus in summer, Acartia sp. in autumn, and Calanus sinicus in winter. Degree of overlapping for the food items between seasons was not very high, except between spring and summer. There were little differences in feeding habits among the size groups. For all size groups of A. elongata, the occurrence rates of copepods, decapods, molluscs and cirriped larvae were high. As the fish grows, those of amphipods, polychaete larvae, isopods, cumaceans and stomatopods increased gradually. The importance index of the major food items was in the order of Calanus sinicus, Corycaeus affinis and Acartia sp..