• The Korean Journal of Malacology
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• v.29 no.4
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• pp.273-281
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• 2013

In order to evaluate how the effects of aquacultural environment, such as temperature, salinity, DO, SS, Chlorophyll-a, COD and nutritive salts on Cupped oysters, an investigational study was conducted between September to December of 2011. During the study, different intermediate cage farms on the surface of the sea were used to culture and compare the growth and survival rate of the Cupped oysters in different fishing environments. The different intermediate cage farms used were Wonsando-ri, Chang-ri, and Pado-ri. In January of 2012, these oysters were transplanted to a horizontal net farm in a mudflat until July of that year. The adaptation rates of the Cupped oysters were tested at differential exposure times at varying intertidal periods. Wonsando-ri showed the highest water temperature and Chlorophyll-a levels, while the salinity was found to be within range of stable conditions among all three intermediate cage farms. Once the Cupped oysters were at the horizontal net farm, the growth was measured at distinct tidal exposure time of 1, 3, and 5 hours, whereby the growth rate was highest at 3, 1, and 5 hours, respectively. In addition, the oysters cultivated in intermediate cage farms had longer shell lengths compared to shell heights, while oysters cultured in the horizontal net farm had larger shell heights than shell lengths.

• 한국해양학회지
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• v.25 no.1
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• pp.8-20
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• 1990

A series of pore water data were obtained during the different time over one year period between October 1987 and October 1988, from a site on a muddy intertidal flat, located in the Kyeong-gi Bay, west coast of Korea, The results have revealed that the tidal flat is an environment of active nutrient the subface supplied by the overlying seawater is almost completely removed from the pore water at depth of about 10 cm below the sediment surface. The nutrients such as ammonium and phosphate are produced through this process and subsequently accumulated in the pore water forming steep gradients near the sediment surface. Below the main sulfate redirection zone, a secondary peak of dissolved sulfate was often observed. Greal seasonal variation of the pore water nutrient profiles was observed, which was particularly clear in their maximum concentration as well as in their concentration gradient. The rate constants of sulfate reduction and nutrient regeneration, estimated by using a diagenetic model (Berner, 1980), differ by an order of magnitude between the summer and winter seasons. The difference in sediment temperature may account for most of the calculated variation. The C:N:P ratio, calculated from the pore water nutrient gradients also exhibits a slight seasonal difference. The organic matter being decomposed by sulfate reduction appears to be depleted in depleted in nitrogen, compared to the average marine organic matter.

• Korean Journal of Ecology and Environment
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• v.49 no.2
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• pp.80-88
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• 2016

In order to reconstruct a benthic foodweb structure and assess the role of benthic microalgaes as a diet source for benthos, we analyzed the carbon and nitrogen stable isotopes of diverse benthos (bivalves, crustaceans, gastropods and fishes) and potential diets (particulate organic matter, sedimentary organic matter, benthic microalgae, seagrass, and macroalgaes) in the intertidal mudflat surrounding Yeongheung Island. The ${\delta}^{13}C$ values of the diets indicated wide ranges (- 26.5‰ to - 8.4‰) while benthos showed a small range of ${\delta}^{13}C$ values (-12.1‰ to - 17.8‰), although they were in the same range. Except for green algaes among the macroalgaes as well as sedimentary organic matter, ${\delta}^{15}N$ values of the diet candidates ($5.7{\pm}1.0$‰) were lighter in comparison to those of the benthos ($11.8{\pm}1.9$‰). Based on the ${\delta}^{13}C$ and ${\delta}^{15}N$ data, the benthos were classified into 3 groups, indicating a different diet and trophic position. But benthic microalgae is the most important diet source for all three benthos groups based on their stable isotope ratios, suggesting benthic microalgae should be a main diet to the intertidal ecosystem. Hence this study highlights that the biomass of benthic microalgae as biological resource should be evaluated for the management of the intertidal ecosystem of Yeongheung Island.

• Korean Journal of Poultry Science
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• v.42 no.4
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• pp.291-297
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• 2015

We investigated the effects of dietary pearlzyme (mudflat-bacteria origin protease) on growth performance and development of digestive organs in broilers. Two hundred forty, 4 day-old female Ross broiler chicks were divided into 2 groups (control vs. pearlzyme) which were randomly housed in 8 pens with 15 chicks/pen. They were fed one of two diets containing pearlzyme at 0 or 0.1% for 4 weeks. Dietary pearlzyme resulted in significant increase in body weight during the first week of the experiment (p<0.05). With age, weight gain and feed efficiency continued to decrease reaching significant level during the last week. Mortality was 3.3% in control but not in pearlzyme during the entire period of the experiment. Dietary pearlzyme resulted in increased weight (p<0.05) in the ceca and rectum, and increased length in the ceca (p<0.05). However, there were tendencies to increase the weight of the gizzard (p<0.071) but to decrease the length of the small intestine (p<0.068). The results of the current study show that dietary pearlzyme affects weight gain and the development of digestive organs.

• Journal of the Korea Institute of Building Construction
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• v.17 no.3
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• pp.227-234
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• 2017

This research analyzes the properties of mortar following the rise in water-cement ratio and applicability as an eco-friendly construction supply by using the mudflats of a dredged arena as a substitute for aggregate. The results of a experiment of the flow showed that the flow value decreases as the amount of mudflats increases. A test for chloride content showed that the chloride content increases with the amount of mudflats. In the compression of specimen mixed with mudflat and the testing of tensile strength, the strength weakened as the addition ratio of mudflats rose. However, with 14-day strength as the standard, most specimen showed more strength than the plain, and 14-day strength was higher than 28-day strength. It appears to be experimental error in the mixing process from the viscosity and cohesion of mudflats, and it is considered that there will be a need for an experiment on mixing methods of mudflats in the future. The compressive strength of this research was the strongest with 70% in water-cement ratio, and the tensile strength was strongest with 80% in water-cement ratio. In the evaluation of surface analysis, 70% water-cement ratio, which is finest in strength, mixing, and compactness, was selected to analyze the roughness of the surface, and the results showed that the surface became smoother as the addition ratio of mudflats increases. In conclusion, it appears that 70% water-cement ratio is the optimal mixing ratio for mortar and 10 to 30% addition ratio of mudflats the optimal ratio. It also appears that the application of interior finishing material like bricks and tiles and interior plastering material using the mudflats are possible.

• The Journal of Engineering Geology
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• v.24 no.1
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• pp.9-21
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• 2014

We examined high-resolution seismic data, side scan sonar data, surface sediments, and vibrocore samples from a sand ridge off the western part of Dukjuk-Do in Gyeonggi Bay, with the aim of interpretation of seismic stratigraphy and sedimentary environment. Based on the seismic data, the deposited sands are divided into three sedimentary units. 14C age data indicate that the top sequence (sequence I) formed at 5000-6000 yr BP, when a transgression resulted in strong shifting tides. Analyses of the vibrocore samples indicate that sequence II is a paleo-mudflat layer of intertidal sediments dominated by mud. Sequence III consists of terrestrial sediments that are presumed to have been deposited at the end of the Pleistocene, unconformably overlying the acoustic bedrock and Mesozoic granite. The side scan sonar data indicate that sand waves were formed on the seabed on top of the sand ridge. Generally, this is the direction of $N20^{\circ}E$, which coincides with the direction of tidal flow. Sand ripples occur away from the top of the sand ridge and are distributed homogeneously across a sandy slope. Vibrocore analyses indicate that the surface sediments and core sediments (samples VC-1, -2, and -3) are homogeneous, without any internal structures, and are characterized by a mixture of medium and fine sand (1-$2{\phi}$), respectively.

• Economic and Environmental Geology
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• v.37 no.3
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• pp.335-345
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• 2004

Total and extractable contents of heavy metals were measured in sediment and seafood from Bukhang and Boggil-ri tidal flats along the Mokpo coastal area, south-western part of Korean peninsular in order to assess the degree of metal pollution, metal bioavailability and metal hioaccumulation. The metal concentrations, except Pb were found to be greater than the background concentrations of sediments indicating the progress of cumulative contamination by anthropogenic origin of metals. The order of extractable metal concentrations in sediments were Mn(32-53 mg/kg)＞Zn(14-42 mg/tg)＞Cu(2.5-17.0 mg/kg)＞Pb(2.4-6.8 mg/kg)＞Cd(0.5-0.7 mg/kg). However, the amount of metals associated with extractable fraction of sediments were significantly high in Bukhang relative to Boggil-ri. Significant bioaccumulation of all metals, except Pb were observed in seaweed and benthos. The order of bioaccumulation of metals were: in concentration; all biota commonly, Mn(129-374 mg/kg)＞Zn(19-106 mg/kg)＞Cu(6-87 mg/kg)＞Cd(4.6-7.6 mg/kg)＞Pb(0.2-3.7 mg/kg), in BCF; Enteromorpha, Cd＞Mn＞Cu＞Zn＞Pb, Ilyoplax deschampsi, Cu＞Cd＞Mn＞Zn＞Pb, Urechis unicinctus, Cd＞Zn＞Mn＞Cu＞Pb. Some metal concentrations of Enteromorpha, especially Cu, Zn, weakly Pb in bukhang, Mn, Cd in boggili-ri, were correlate well with concentrations in sediment, indicating relatively more contaminated by the anthropogenic origin of metals in each tidal flat. The results clearly indicate that the seafood of bukhang, even of Boggili-ri known as clean area, are contaminated with metals.

• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.4
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• pp.76-88
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• 2014

The purpose of this study is to derive landscape characteristic elements of agricultural and fishery heritage and to classify landscape characteristic elements of Cheongsando designated as Korean agricultural and fishery heritage No.1 as well as a Globally Important Agricultural Heritage System (GIAHS). Additionally, this study was conducted to suggest priority for conservation and management of Cheongsando by grasping differences between factors which visitors deem as important and satisfying. To implement this study, the literature review was written, an on-site survey to derive landscape characteristic elements of Cheongsando and a survey on importance and satisfaction of landscape characteristic elements of Cheongsando were conducted, and reliability analysis, descriptive statistical analysis and IPA analysis were performed using SPSS 20.0. The results are as follows: The analysis showed the factors requiring persistent efforts in the first quadrant are the rape flower garden, the sea, green barley field, flat stone paddy field, breakwater and lighthouse, abalone farms, stone houses, thatched houses, a coastal road, the slow road, Stonewall Walkway of Seongseo Village, and residents' agricultural behaviors. The analysis showed the factors needing intensive management strategies in the second quadrant are the surrounding mountain area, dock, Docheong Harbor, vessels, fish market, Doksari stone wall, garish-roofed farm villages, excursion school to a slow island, pension and cafe, bus stop, shade trees, Raw Fish Street, the beach and the filming site. Analysis indicated that the factors needing management control in the third quadrant are the pine grove, the beach, tidal mudflat, the garlic fields, vinyl greenhouses, grain drying yard, sea mustard drying yard, heritage center, Choboon, Dangri exorcism, the market place, residents' fishery behaviors, residents' industrial behaviors, residents' ordinary behaviors, visitors' behaviors that visiting the dock, visitors' behaviors that walking the slow road, visitors' behaviors that eating and shopping for specialties, visitors' behaviors that experiencing agriculture and fishery. Excessive effort factors in the fourth quadrant were not derived.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.8-18
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• 2005

We studied seasonal distribution of the microphytobenthos and their primary production with $C^{14}$ method and carried out pigment analysis with HPLC in an estuarine mudflat of the Ganghwa Island, Korea from May 2002 to April 2004. The abundances of microphytobenthos were higher at the middle than upper part and lower part of intertidal flat. Abundances of microphytobenthos ranged from $2.3{\times}10^5\;cells\;cm^{-2}$ to $140.9{\times}10^5\;cells cm^{-2}$. The bloom of microphytobenthos was observed in the early spring and then it decreased from spring to summer and autumn. The pennate diatom was a predominated group among the microphytobenthos in this area. The dominant species were Paralia sulcata, Cylindrotheca closterium and Nitzschia sp.. Nitzschia sp. and Cylindrotheca closterium were predominant in February. The results of pigment analysis suggest the presence of diatoms, euglenophytes, chlorophytes, cyanobacteria, cryptophytes, chrysophytes, prymnesiophytes, dinoflagellates and prasinophytes. The biomass of microphytobenthos ranged from 1.18 to 34.25 mg chl-a $m^{-2}$, with a mean of 7.60 mg chl-a $m^{-2}$. The mean ratio of Fuco/Chl a was 0.7 which indicates that most of biomasses of microphytobenthos were due to diatoms. The ratios of Chl b/Chl a ranged from 0 to 0.82(with a mean of 0.17), implying that euglenophytes and chlorophytes lived together in special period seasonally. Temporal variation of primary production ranged from 4.2 to 113.0 $mgC{\cdot}m^{-2}{\cdot}hr^{-1}$(mean value was 33.9 $mgC{\cdot}m^{-2}{\cdot}hr^{-1}$ and initial slope$({\alpha})$ was measured from 0.002-0.005$(mgC\;mgchl-a^{-1}\;hr^{-1}){\cdot}({\mu}E\;m^{-2}\;s^{-1})^{-1}$. Assimilation number$(P_m)$ was in the range of 0.50-1.32 $mgC{\cdot}mgChl-a{\cdot}hr^{-1}$ and daily primary production ranged from 20.9 to 678.1 $mgC{\cdot}m^{-2}{\cdot}d^{-1}$(mean value was 206.72 $mgC{\cdot}m^{-2}{\cdot}^{-1}$).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.2
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• pp.117-126
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• 1999

Hampyong Bay is a semienclosed and macrotidal bay which opens to the eastern Yellow Sea through a narrow inlet in the southwestern coast of Korea. In order to understand the tidal-flat sedimentation in the semienclosed setting, morphology, sediments, accumulation rate and sea cliff erosion were investigated in the tidal flat of Hampyong Bay. The tidal flat of Hampyong Bay lacks intertidal drainage systems, and generally shows the concave-upward profile whose relief is designated by marked morphological features such as high-tide beaches, intertidal sand shoals and tidal creeks. Surfacial sediments of the tidal flat mainly consist of mud, sandy mud, gravelly mud, gravelly sand and muddy gravel, thus showing the textural characteristics of multimodal grain-size distribution, poorly sorting and positive skewness. The sediments generally coarsen landward due to the increase in coarse fraction content. Sedimentary structures are deeply bioturbated, but parallel lamination and lenticular bedding are locally found in the mudflat near mean low water line. Annual accumulation rates across the tidal flat (along Line SM) average -5.2 cm/yr with a range of -45.8~+4.2 cm/yr, indicating that the tidal flat is erosional. In general, erosion rates of upper and lower tidal flat are higher than those of middle tidal flat. Seasonally, the erosion rates are much higher during spring and winter when dominant wind direction corresponds to the long axis of Hampyong Bay. Sea cliffs are eroded at a rate of 1.4 m/yr. The biggest sea cliff erosion generally occurs 1~2 months later after tidal flats were extensively eroded. Such erosions of tidal Oats and sea cliffs in the semienclosed bay setting are interpreted to be due to wind waves coupled with local sea-level rise.