• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.1
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• pp.56-64
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• 2012

Polychaete community structure and its spatial distribution was investigated in 2008 from inshore and offshore of Lake Shihwa, Korea, in order to evaluate status of the benthic environment according to construction of the dike and the water gate. In the present study, the number of species, density, and diversity of polychaete community in inshore was significantly different from those in offshore. The density of polychaete community in offshore increased with the number of species whereas the diversity in inshore increased with the number of species. Dominant species in offshore were 13 species, higher than 1% of the total polychaete individuals. Heteromastus filiformis, known as the most dominant species before the construction of the dike, was the most dominant species in offshore, which collectively account for 54% of the total polychaete individuals. In inshore, the seven species were dominant, higher than 1% of the total individuals. Lumbrineris longifolia, Polydora sp., Capitella capitata, Pseudopolydora paucibranchiata, known as pollution tolerant species, contributed to higher than 75% of the total individuals in inshore. Multivariate statistical analyses, non-metric multidimensional scaling, showed apparent difference in polychaete community structure between inshore and offshore, and also difference between inner sites and outer sites of inshore around the water gate. Sediment characteristics (total organic carbon and nitrogen, ignition loss, and acid volatile sulfide) measured in this study also supported to this result. Therefore, this indicates that the offshore provides better benthic environments for polychaete habitation than the inshore, and the inshore around the water gate shows improving benthic environment, compared to the inner inshore.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.spc1
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• pp.151-164
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• 2006

We monitored the current macrozoobenthic community structure after the Sea Prince oil spill around Keumo-do and Sori-do, Korea. Macrobenthic animals were collected seasonally around Sori-Keumo do using a van Veen grab ($0.1m^2$) from October 1999 to April 2000. In total, 196 species were identified at 46 sites around Keumho-do. The mean density was 1,460 individuals/$m^2$, and polychaetes comprised 80% of the total density of the macrozoobenthic. Dominant species were the polychaete Tharyx sp. (51%), the echinoderm Amphioplus megapomus (5%) and the polychaete Lumbrineris longifolia (3%). We identified 176 macrobenthic species at 36 sites around Sori-do. The mean density was 1,068 individuals/$m^2$, and polychaetes was the most abundant faunal group, comprising 41%, followed by mollusks (24%) and echinoderms (20%). Dominant species in Sori-do were the mollusk Potamocorbula amurensis (23%), the chinoderm Amphioplus megapomus (14%), and the polychaete Tharyx sp. (10%). The overall community structures in the study area showed few seasonal changes, although there was a gradual change in the species composition within each benthic community. Tharyx sp. was the most abundant species in the study area. Because this species has not been found in the other coastal areas except during recent investigations, it is considered to have increased during the course of community succession after the oil spill. The macrozoobenthic around Keumo-do showed little change in species richness, whereas around Sori-do, it showed a few increases in species richness after the summer of 1998. The overall density showed the same trend as species richness. Based on improved community indices, we suggest that the macrozoobenthic communities around Sori-Keumo Islands are gradually recovering from the oil-spill damagecaused by the oil spill.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.22 no.1
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• pp.18-30
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• 2017

The East Sea is almost entirely composed of sandy facies, and the facies type is the major factor influencing benthic polychaete communities. There have been few studies of the effects of environmental factors on benthic polychaetes in thermal discharge areas consisting of different sediment types. This study identified the spatial distribution patterns based on the species composition and distribution of benthic polychaete communities, and the environmental factors influencing benthic polychaetes near power plants were investigated. The polychaete communities in the Uljin, Hupo, and Gori coastal areas near the power plants in the East Sea were seasonally investigated from August 2006 to February 2013. As a result, 283 species were collected. The dominant species were Spiophanes bombyx, Magelona japonica, Lumbrineris longifolia, and Sternaspis scutata. Spiophanes bombyx was the dominant species at Uljin and Hupo, but M. japonica was the dominant species at Gori. Two dominant species from the coastal waters of the East Sea, Lumbrineris longifolia and M. japonica, were rare in the power plant water intake or drainage areas. Cluster analysis was performed to divide the study area into groups by the total organic carbon content, sediment grain size and facies patterns. This study suggests that the community structures of polychaetes are more affected by the total organic carbon, grain size of sediment and facies than by disturbance from thermal discharge, which only affected the polychaete community near power plant drainage areas.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.730-743
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• 1997

Community structure and distribution patterns of benthic polychaetes were studied in Aug. 1983 and Feb. 1984 in Kwangyang Bay, Korea. During the study period, the large-scale reclamation and dredging operations were taking place. Polychaetes were composed of 76 species with a mean density of $342\;ind.{\cdot}m^{-2}$ during the summer 1983 and 77 species with a mean density of $437\;ind.{\cdot}m^{-2}$ during the winter 1984. Community structure indices were applied to the seasonal data. The stations influenced by the Seomjin river are characterized by a low species number and low diversity, while the stations located in channel regions represent high species richness and highdiversity. The inner bay stations showed the intermediate level in terms of species richness and diversity. On the basis of taxa composition and abundance in summer, the cluster analysis indicated that the study area was divided into live regions. The main factors that govern the polychaete distributions appeared to be the fresh water run-off and bottom sediment composition. However, a slight difference was observed in winter community, and changes in composition of the dominant species were found from Lagis bocki and Chone teres to Glycinde gurjanovae and Heteromastus filiformis. As a result, the broad scale reclamation and dredging activities may have played a role in changes of the polychaete community structure and the dominant species composition in Kwangyang Bay.

• Ocean and Polar Research
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• v.26 no.2
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• pp.367-376
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• 2004

Macrobenthos were collected at 7 stations located from $5^{\circ}N$ to $10^{\circ}N$ with 1o interval along the longitude of $131^{\circ}W$ using a box corer with sampling area of $0.25\;m^2$ in July, 1999. In order to see the vertical distribution of macrobenthos in sediments, each subcore sample was divided into 5 layers with 1 cm interval up to 6 cm depth. Each subcore sample was sieved through 0.3 mm mesh screen and fixed with 10% Rose Bengal added formalin. A total of 22 faunal groups in 11 phyla were sampled and the average density was $959\;{\pm}\;584\;ind./m^2$. Foraminiferans comprised 34.8% of total specimens were the most abundant fauna, and followed by nematodes (27.5%), polychaete worms (15.7%), and benthic harpactoid copepods (10.4%). A latitudinal trend was shown in the distribution of macrobenthos; the maximum density of $1,832\;ind./m^2$ appeared at station N06 and the most poverished community occurred at station N09 with the density of $248\;ind./m^2$. The density of typical macrofaunal taxa except foraminiferans and nematods was $116\;ind./m^2$. In the vertical distribution of macrobenthos, more than 70% of macrobenthos occurred in the upper 2 cm layer, and upper 4 cm layer contained about 90% of macrofauna. Polychaete worms consisted of 22 families, and cirratulid and paraonid worms were dominant polychaete species. The prominant feeding guilds of polychaete worms were SDT (surface, descretely motile, tenaculate feeding) and SMX (surface, motile, non-jawed); they comprised more than 50% of polychaete abundance. These feeding guilds of polychaete worms suggests that the deep sea benthos should be well adapted the newly settled deposits from water column, but this should be clarified by the further studies.

• Proceedings of KOSOMES biannual meeting
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• 2009.06a
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• pp.159-159
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• 2009

• Proceedings of KOSOMES biannual meeting
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• 2009.06a
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• pp.161-161
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• 2009

• 한국해양학회지
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• v.19 no.2
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• pp.153-162
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• 1984

This study was conducted to interpret the relations between the polychaete community and its environments in Kwangyang Bay during July, 1982. The type of sediments in the study area varies from sand to clay and the organic content obtained by ignition was in the ranges of 0.3% to 15.4%. The polychaetes which occurred at 25 stations comprised 70 species representing 63 genera and had an average density of 490 animals/m$\^$2/. The most abundant species were Lagis bocki (20%), Lumbrineris longifolia (10%), Chohe teres (7%), and Sternaspis scutata (5%). The polychaete populations show the highest density in muddy sand sediments and have a tendency to decrease their abundance in finer sediments such as bud and clay. The individual numbers of each feeding type show the same tendency. Kwangyang Bay consists of three distinct characteristic communities, representing different physical and biological factors: delta community, muddy flat community and channel community. Delta community has very poor organisms and seems to be determined by physical factors such as tidal current, and by sediment conditions and seems to be determined by physical factors such as tidal current, and by sediment conditions and by the food availability. Muddy flat community shows more diverse and higher abundance than delta community but seems to be impoverished by the stress of oxygen deficiency in sediments. Channel community has the highest density in the study area and comprises more various feeding types. This is probably due to the supply of allochthonous materials from the Seomjin River and offshore as food, the heterogeneous sediments and some biological interactions within habitats.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.4
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• pp.195-205
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• 2013

Excessive input of organic matters from fish cage farming has been considered as one of the major factors disturbing benthic ecosystem, especially in semi-enclosed coastal waters. Recently offshore aquaculture in the vicinity of Jeju-do has been introduced to minimize that kind of negative impact. This study was conducted to investigate the ecological impacts of offshore aquaculture on the macrobenthic polychaete communities. A total of ten sampling works were carried out for 28 months, spanning from 10 days after starting giving feed to 3 months after stopping giving feed. During the study period, mean current velocity was quite strong with the range of 50 cm/s to 70 cm/s. TOC of surface sediment was constantly low. Significant changes in polychaete community were detected just three months after starting giving feed, which were the increase of the number of species and density at all stations. Up to 18 months after the start of farming, the amount of feed provided played an important role in the fluctuation of the number of species and density, especially at 0 m and 10 m stations. After reducing the amount of feed provided, dominance of some opportunistic species within 10 m distance from fish cages still lasted to the end of aquaculture. However, opportunistic species disappeared 3 months after the end of farming, which indicated the sign of recovery from the disturbance. From these results, the amount of food input and the period of cultivation were critical factors disturbing polychaete community and ensuing changes in this offshore and oligotrophic waters as well. In addition, study on the changes of polychaete community structure before and after fish farming showed more detailed changes in benthic ecological state than geochemical approach did.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.943-953
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• 2021

The purpose of this study is to investigate sediment recovery after the relocation of fish cage farms, by examining the changes in sediments and the benthic polychaete community. A preliminary survey was carried out in October 2017, before the relocation of the farms, and monthly surveys were conducted from November 2017 to October 2018 after the farms were moved. Subsequently, it was conducted every 2-3 months until October 2020. The survey was carried out at three stations (Farm1-3) at the location of the removed fish farms and at three control stations (Con1-3) without farms. The overall organic carbon content of the farm stations was higher than the control stations, but it gradually decreased after the farm was demolished, and there was no statistically significant difference about one year after the relocation of the farms (p<0.05). In the benthic polychaete community, abiotic community appeared at the farm stations in the summer, and consequently, the community transitioned to a low-diversity region with the predominant species Capitella capitata, which is an indicator of pollution. Until the abiotic period in the summer of the next year, the species diversity increased and the proportion of indicator species decreased, showing a tendency of recovering the benthic polychaete community, and these changes were repeated every year. In this study, the abiotic community appeared every year owing to the topographical characteristics, but as the survey progressed, the period of abiotic occurrence became shorter and the process of community recovery progressed expeditiously. Biological recovery of sediments after the relocation of the fish farms is still in progress, and it is imperative to study recovery trends through continuous monitoring.