• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.1
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• pp.30-39
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• 2004

In order to understand the environmental impact of marine cage fish farms, we measured the vertical fluxes of particulate to the sediment, the distribution of organic carbon in core samples, sediment oxygen consumption rate (SOD), and macrobenthos with increasing distance from a fish cage in Miruk island located in Tongyong. The experiment was performed in August 2003. Measured values gradually decreased with distance, indicating that the organic matter in the sediment derived from the fish farm. The dominant macrobenthos species were Tharyx mulifilis, Lumbrineris longifolia, Sigambra tentaculata, and Capitella capitata, occupying 88% of the total population. Capirella capirata, an opportunistic polychaete species, were especially abundant between 0 to 5 m radius range. The estimated impact regions of organic matter enrichment based on sediment consilmption rates and compositions of macrobenthos were in good agreement. Most organic matter derived from the fish farm was deposited within a 10 m radius and then dispersed horizontally to nearby (at least 50 m) surface sediment. The vertical organic carbon fluxes to the sediment at the fish farm were higher by a factor of two than those outside the area. The remineralization organic carbon in the upper sediment layer was estimated to be 50% (1.07 g C m$^{-2}$ day$^{-1}$ ) at the fish farm. In contrast, outside the area, 30% (0.30 g C m$^{-2}$ day$^{-1}$ ) of organic carbon was recycled and the remaining 70% was deposited to the deep sediment layer.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.3
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• pp.190-200
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• 2001

An ecological study was performed to investigate the community structure of the benthic macrofaunal assemblage on the Cheokjeon tidal flat, Incheon, Korea. Benthic samples were collected between Sept. 1990 and July1992 at three stations to compare environmental factors with the structure of benthic community among station sand seasons. Overall, macrofauna comprised a total of 111 species, and the mean density (708.1 md./$m^2$) and biomass (214.9gWWt/$m^2$). The number of species and individuals of polychaetes, molluscs and crustaceans made up more than 80% of the total number. On the other hand, in terms of biomass, bivalves and holothuroideans indicated that they were the dominant faunal groups. Hierarchical classification using the Bray-Curtis coefficient categorized samples into 3 station and 4 faunal groups. In terms of q-mode, there consisted of upper, middle and low tidal flat stations, respectively. And four faunistic groups were established as follows: 1) Heteromastus filifomis-Mactra veneriformis-Solen strictus-Ilyoplax finggi (wide-ranging elevation specialists), 2)Nephtys chemulpoensis-Macrophthalmus gaponicus (high elevation specialists), 3) Glycera subaenea-Decorifer matusimana-Tritodynamia (middle elevation specialists) and 4) Nephtys polybranchia-Borniopsis tsurumaru-Asthenognathus inaequipes-Protankyra bidentata (low elevation Specialists).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.2
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• pp.169-176
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• 2000

This study was carried out to clarify the spatial and temporal patterns of macrobenthic assemblages on the subtidal area around Mokpo, southwest of Korea. A total of 238 species and 663 ind./$m^{2}$ were collected. Polychaetes were the most abundant faunal group that comprised 88 species and had a mean density of 389 ind./$m^{2}$. In the semi-enclosed Youngsan River estuarine bay and neighbouring Mokpo Port area were composed of fine sediments with high organic content, and revealed large seasonal variations in the salinity of surface water and bottom dissolved oxygen in contrast to little seasonal changes in those parameters in the outer area. The study area was classified into four station groups by the cluster analysis; the harbor area, the offshore area, and the inner and outer estuarine bay. Two estuarine bay areas showed different species composition; the dominant species of inner bay were Tharyx sp., Poecilochaetus johnsoni, Heteromastus filiformis and other opportunistic species whereas those in the outer bay were Ruditapes philippinarum, Corophium sinense. From the environmental data and species composition of benthic community, the inner bay was characterized to have unstable benthic faunal assemblages, especially under the seasonal disturbance and receiving large amount of organic matter input and intermittant discharge of fresh water. The coastal developments around Mokpo city also seem to have stressed the subtidal communities spatio-temporally.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.4
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• pp.213-228
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• 2009

This study was conducted to investigate spatio-temporal changes in macrobenthic community structure and benthic environmental conditions in Geoje-Hansa Bay, which is the greatest oyster producing site in Korea. Field survey for benthic environment and macrobenthos was seasonally carried out at 15 stations covering oyster farming sites and non-farming sites from February to November, 2008. The grain size of surface sediments was dominated by very fine silt with the mean phi of about $9\;{\Phi}$ and TOC was 1.9% on average. Mean dissolved oxygen content was 8.1 mg/L and lowest in August corresponding to the 2nd degree in seawater quality criteria. Total species number was 351 and mean density was $3,675\;ind./m^2$, both of which were dominated by polychaete worms. Spatio-temporal variation in above two biological variables was great with higher values seasonally in spring and spatially in channels rather than inner bay. Dominant species were Lumbrineris longifolia (21.3%), Aphelochaeta monilaris (17.8%) and Ericthonius pugnax(6.1%), all of which are typical species of organically enriched area. From the multivariate analyses, the whole macrobenthic community was distinguished into two groups of channel and inner bay group. Spatio-temporal changes of macrobenthic community in Geoje-Hansan Bay were related to those of TOC and acid volatile sulfide (AVS). Our results showed that Geoje-Hansan Bay should be intermediately affected by organic pollution, and that such organic enrichment was more remarkable at farming stations in the inner bay.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.598-611
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• 2022

The aim of this study was to investigate the range of influence of aquaculture activities in fish cage farms located on the southern coast of Korea (Farm A and B in Hadong, Farm C in Tongyoung, and Farm D in Geoje) by analyzing the distribution and characteristics of polychaete communities. Farm A and B showed remarkably high aquaculture intensity, and as a result, the polychaete communities near the farms were heavily polluted. However, there was a difference in the polychaete communities at a distance greater than 30 m from farm A and B, which may be due to topographical differences. The effect of the aquaculture activity of Farm C was only observed below the farm, however, the influence of aquaculture activities Farm D was maintained over a relatively long distance. According to the results of this study, the effect of the fish cage culture was mainly influenced by factors related to the production of fish, such as the stocking amount and the amount of food supply. Moreover, the distance at which the influence of aquaculture activity was observed was found to be closely related to the topographical characteristics and flow velocity around the farms.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.2
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• pp.102-117
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• 2009

This study was carried out to investigate the extent to which benthic environment of Ulsan Bay was disturbed by organic materials and trace metals from the megacity and industrial complex. Field survey for benthic environment and macroinvertebrate community was seasonally conducted from February to November 2006 at nine stations covering the inside and outside of the bay. TOC was on average 1.7% while four (As, Cu, Pb, Zn) out of seven trace metals measured exceeded the Effects Range Low (ERL) in most of the stations. Total number of species sampled was 199 and mean density was 4,578 ind./$m^2$, both of which were greatly dominated by the polychaetes. Dominant species were Aphelochaeta monilaris (22.6%), Ruditapes philippinarum (17.1%), Magelona japonica (12.2%), Lumbrineris longifolia (9.9%) and their distribution was ruled by the difference in the benthic environmental condition of each station. From the multivariate analyses, four stational groups were identified: northern part of the bay, middle and lower part of the bay, the intersection of Taewha River and Gosa stream and outside of the bay. As a result, the community heterogeneity of inner bay was much more greater than that of outer bay. SIMPER analysis showed that four groups were represented by R. philippinarum-Capitella capitata, A. monilaris-Balanoglossus carnosus, Sinocorophium sinensis-Cyathura higoensis and M. japonica-Ampharete arctica, respectively. Spatio-temporal changes of macroinvertebrate communities in Ulsan Bay were closely related to those of depth, mean grain size and organic content, and Zn was also a meaningful factor in that context.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.2
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• pp.175-183
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• 2010

To understand the variation of macro benthos community according to the installation of structure and topographic placement in the shellfish farm on tidal flat, the practical example of the tidal shellfish growing area at Namsung-ri Goheung was observed. The results of the research for the field observation were summarized as follows. (1) The ground gradient of the shellfish farm was very flat below about $1^{\circ}$. The shellfish farm ground took the shape of $\sqcup$ from the shoreline to the place of 150 m seawards, and the shape of $\sqcap$ from there to the low tide line. During ebb tide, the $\sqcup$ shape ground stored the sea water, and the $\sqcap$ shape ground was supposed to act as the effect factor to leak slowly or to prevent the outflow. (2) The oyster shell bag or the type of riprap wall as the boundary in the shellfish farm was classified into five types. The air exposure time and flooding time were 181 and 434 minutes, respectively. (3) In the numerical experiment, the deep-sea water wave coming in the study area had 0.5 m of maximum wave height to show the very stable conditions and the wave direction pattern of S-direction was dominant at Naro great ridge, and SE, SSW and S-direction were distributed strongly around the shellfish farm. (4) By the grain size analysis, the sediment around tidal flat consisted of gravel 0.00~5.81(average 1.70)%, sand 14.15~18.39(average 13.23)%, silt 27.59~47.15(average 30.84)% and clay 35.79~55.73(average 36.19)%, and the sediment type was divided into (g)M(lightly gravelly mud), sM(sandy mud) and gM(gravelly mud) by Folk's diagram. (5) The macro benthos community survey conducted in this site in January, 2010 showed that 1 species of Mollusca, 8 species of Polychaeta and 2 species of Crustacea appeared, and 11 species occupying over 1% of total abundance were dominant.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.1
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• pp.106-127
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• 2019

This study aims to understand spatio-temporal variations of macrozoobenthos community in Han River (HRE), Geum River (GRE), and Nakdong River estuaries (NRE) of Korea, sampled by National Survey of Marine Ecosystem. The survey was seasonally performed at a total of 20 stations for three years (2015-2017). Sediment samples were taken three times with van Veen grab of $0.1m^2$) areal size and sieved through a 1 mm pore size mesh on site. A total of 1,008 species were identified with 602 species in HRE, 612 in GRE, and 619 in NRE, showing similar number of species between estuaries. Mean density was $1,357ind./m^2$, showing the high in NRE ($1,357ind./m^2$), mid in GRE ($1,357ind./m^2$), and low in HRE ($1,127ind./m^2$). Mean biomass was $116.8g/m^2$, showing similar variations to density ($174.2g/m^2$ in NRE, $129.0g/m^2$ in GRE, $49.0g/m^2$ in HRE). Polychaeta dominated in number of species and density in three estuaries. Biomass-dominated taxon was Mollusca in HRE and GRE, and Echinodermata in NRE. Polychaetous species dominated all three estuaries over 4% of density, such as Dispio oculata, Heteromastus filiformis and Aonides oxycephala in HRE, Heteromastus filiformis and Scoletoma longifolia in GRE, and Pseudopolydora sp. and Aphelochaeta sp. in NRE, showing various density between estuaries. Community structure was determined by various environmental variables among estuaries such as mean grain size and sorting (HRE), salinity and mean grain size (GRE), and salinity, dissolved oxygen, loss on ignition and mud content (NRE). Our study demonstrates the application of different measures to manage ecosystems in three estuaries. HRE needs to alleviate sedimentary stressors such as sand mining, land-filling, dike construction. Management of GRE should be focused on fresh water control and sedimentary stressors. In NRE, monitoring of dominant benthos and process study on hypoxia occurrence in inner Masan Bay are necessary.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.2
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• pp.49-67
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• 2006

A mesocosm, an artificial tidal flat ecosystem, was constructed outdoors to simulate in situ physical and biochemical environmental conditions of natural tidal flat as much as possible. During the experiment from February to August 2004, the study was focused on the biogeochemical variations of superficial water and porewater after introduction of freshwater into the mesocosm. The mesocosm has three experimental conditions; SW-M-T: maintaining the saline water of approximately 20 psu; FW-M-T: complete exchange of freshwater ul the mesocosm with continuous mixing of water column: FW-NM-T: complete exchange of saline water to freshwater in the mesocosm without mixing of water column. Mass extinction of benthic macrofauna appeared due to drastic decrease of porewater salinity from 20 psu to less than 10 psu between the 63th and 91st day of freshwater introduction in FW-M-T and FW-NM-T. Throughout the periods, 7/8 of bivalves and 2/3 of polychaete populations have been extinguished in the sediment. In FW-NM-T, as temperature rises, both evident decrease of DO in water column and active release of DIP from sediment were observed. ${NO_3}^-$ was removed from water column into sediment throughout the periods. Therefore extremely low ${NO_3}^-$ was found during late spring and summer. Whereas ${NH_4}^+$ exhibited only $1/2{\sim}1/8$ of ${NO_3}^-$ concentration. Unexpectedly even after mass extinction of benthic macrofauna, we were not able to find high ${NH_4}^+$. This mesocosm study suggests that when fresh water introduce to natural tidal flat, its sediment activity functions as a potential source of DIP, but a sink of ${NO_3}^-$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.6
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• pp.399-412
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• 2005

This study investigated the composition and the distribution of the benthic polychaeta community in the semi-enclosed Yoja Bay on the southern coast of Korea and was designed to deduce temporal changes in the community with the comparison of the previous studies. In YoJa Bay, benthic polychaetous community structure was investigated on the base of the samples from 87 stations. The surface sediment was mainly composed of fine-grained sediment, mixed clayey silt and silty clay. The total benthic macrofaunal density was $387 indiv./m^2$, and the density was higher in the middle bay, and in the mouth of bay than in the inner bay. scapharca subcrenata (Bivalvia) and amphipods (Crustacea) were important species in the inner and the middle of the bar, respectively. Benthic polychaetes were comprised of 72 species with a mean density of $149 indiv./m^2$. Their distributions showed higher densities in the mouth of bay than in the rest of bay. The dominant species over 1.0 percentages were composed of the 20 species, and they occupied $84.5\%$ of the total density. The most dominant species was Sternaspis scutata ($13.6\%$), fallowed fly Heteromastus filiformis ($9.8\%$), Polynoidae indet. ($8.3\%$), Sigambra tentacuzata ($7.1\%$) and others. The cluster analysis revealed that the study area was divided into three station groups. At the station group YI located in the inner bay, the most dominant species was Heteromastus filiformis . At the station group YII in the middle bay, the dominant species was Sternaspis scutata. And at the station group YIII in the mouth of bay, the dominant species was Paraiacydonia paradoxa. Whereas Sternaspis scutata and Mediomastus sp. were the dominant species in the past study, Heteromastus filiformis and Tharyx sp. appeared newly to be the dominant species, even if their low densities that in the past. These facts mean that Yoja Bay be maintained yet as little polluted area compared to other bays on the coast of Korea, but needed some caution of marine environmental management.