• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.5
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• pp.521-531
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• 2010

This study examined the community structure and temporal variation of the macro-crustaceans on Jangbong tidal flat, Incheon, Korea. Macro-crustaceans on this tidal flat were collected using a modified otter trawl from November 1999 to January 2001. The macro-crustaceans comprised 32 species, 7,741 individuals, and 29,211.3 gWWt during the study period. The Jangbong tidal flat was dominated numerically by three shrimp (Palaemon carinicauda, Crangon affinis, and Metapenaeus joyneri) and two portunid crabs (Charybdis japonica and Portunus trituberculatus). The macro-crustacean assemblages were divided into two different season and species groups based on the q-mode and r-mode clustering methods. In terms of q-mode, they consisted of a winter species group from December through April and a summer species group from May through November. The r-mode analysis showed that the species group visiting the tidal flat in winter was dominated numerically by palaemonid and crangonid shrimps, while a species group characterized by an abundance of portunid crabs and penaeid shrimps was more frequent in spring, summer, and autumn. In conclusion, our study revealed distinct temporal variation in the tidal flat use by macro-crustaceans around Jangbong Island, Incheon, Korea.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.3
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• pp.181-188
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• 2009

The macro tidal flat of the Gochanggun Myongsasipri, located on the southwestern coast of Korea, is studied in terms of seasonal variations of surface sediment and sedimentary environment. Surface sediments of 45 sites in the winter (February) and the summer (August) are sampled across three survey lines (15 sites in each survey line), respectively. The tidal flat of open-coast Myongsasipri is mainly composed of fine to medium sand, the distribution of which shows a coast-parallel trend. Grain-size distribution has a bi-modal trend, and grain size in the winter is coarser than that in the summer. During the winter, the upper tidal flat is dominated by medium sand, while the lower tidal flat is dominated by find sand. Such a feature is attributed to wave-dominated sedimentation in the winter. The finer grains of the summer rather than that of the winter and relationship between texture parameters suggest that tidal energy plays an important role in tidal-flat sedimentation during the summer. This study represents an environmental change from wave-dominated conditions in the winter to tide-dominated conditions in the summer as a result of the seasonal variation in the intensity of onshore-directed winds and waves in the Myongsasipri tidal flat.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.262-272
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• 2007

Diurnal and tidal variation in the abundance of the macro- and megabenthic assemblages were studied in the macrotidal flat, Incheon, Korea. The samples were collected by modified otter trawl during 8-9, June 2000. The macro- and megabenthic assemblages comprised a total of 60 species, including 6,309 individuals and 67,835.5 gWWt. As a result, the abundance pattern showed two different categories relating to diel and tidal cycles. First, the diel pattern of these assemblages was subdivided into 3 groups. 1) Diurnal species such as Hexagrammos otakii, Thryssa baelama, Loligo beka, Metapenaeus joyneri. 2) Nocturnal species such as Cynoglossus joyneri, Sebastes schlegeli, Charybdis japonica, Crangon affinis, Trachysalambria curvirostris, Metapenaeopsis dalei. 3)Other species showing no obvious pattern with Johnius grypotus, Platycephalus indicus, Repomucenus richardsonii. However, based on the result of Mann-Whitney U-test, diel patterns of macro- and megabenthos did not reveal any significant differences. Second, tidal variation in the macro- and megabenthic assemblages was significant between ebb and flood tides. Total macro- and megafaunal species number, abundance and biomass were higher in ebb tide$(13^h30',\;16^h30',\;1^h30',\;4^h30')$ than in flood tide$(19^h30',\;21^h30',\;10^h30',\;13^h00')$. As a consequence, the macro- and megabenthic assemblages were clearly influenced by tides but their diel variations were not significantly different.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.28 no.4
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• pp.143-157
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• 2023

This study confirmed the characteristics of macrobenthic community due to anthropogenic environmental changes in the Boryeong Jugyo tidal flat, where the habitat of manila clam (Ruditapes philippinarum) and mud shrimp (Upogebia major) is separated. The total number of occurring species was 55 during the study period with an average habitat density of 338 ind./m² and a biomass of 212.2 gWWt/m². The number of occuring species increased from 27 species at the upper flat to 37 species at the lower flat, and the dominant species differed by tide levels (Upper: Leonnates persica, Middle: Heteromastus filiformis, Lower: R. philippinarum). The macro-benthic community sturctures of the top 10 species using cluster analysis and nMDS were divided into two groups, focusing on Manila clam culture farm of lower flats and middle flats with high habitat density, reflecting the influence of specific species. The sediment composition of the U. major habitat space fluctuated highly, but it was maintained annually, and the sorting coefficient was 2.1 𝜑, and the proportion of the same particle size was increased. In particular, because the middle flat has a dense anthropogenic impact, a dominant species, H. filiformis dominated and revealed a relationship with the density of burrow holes of U. major, which is considered to be a biological interaction between these two macrofauna in this tidal flat.

• Journal of the Korean earth science society
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• v.40 no.2
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• pp.149-162
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• 2019

In the macro-tide open coast of the Korean western coast, typhoon effects were investigated in terms of variations on topography, surface sediment, and sedimentary environment, which appeared before and after the typhoon Kompasu of 2010. The Kompasu of small size and strong intensity landed on the southwestern coast of the Korean Peninsula and passed across the inland between September 1st and 2nd in 2010. Topography and surface sediments before and after the typhoon were measured and sampled along the survey line of 22 sites in the Gochang Donghori intertidal flat. The intertidal area was divided into high tidal zone, middle tidal zone, and lower tidal zone on the basis of mean high water level, mean sea level, and mean low water level. Topographic variation before and after the typhoon represented deposition of average 0.03 m in high tidal zone, erosion of average -0.15 m in middle tidal zone, and erosion of average -0.39 m in lower tidal zone, respectively. Surface sediments of the intertidal flat consisted mainly of fine to medium sands, and the ratio of fine sand was the largest both before and after the typhoon. Surface sediments after the typhoon became finer in mean grain size showing well sorting rather than those before the typhoon.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.spc1
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• pp.165-179
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• 2006

Food habits of the gavelin goby Acanthogobius hasta and the fine spot goby Chaeturichtys stigmatias populations were investigated in the Jangbong tidal flat near Incheon, Korea. Samples were taken monthly from November 1999 to January 2001. The gut contents of 248 gavelin gobies and 139 fine spot gobies were analyzed. The diet of the gavelin goby was dominated by the gammaridean amphipod Chitinomandibulum emargicoxa, the crabs Macrophthalmus japonicus and Ilyoplax pingi, the shrimp Exopalaemon carinicauda, the bivalve Raetellops pulchella and the macro-algae Porphyra tenera. On the other hand, the fine spot goby mainly feed on the shrimps Crangon affinis, Latreutes mucronatus, E. carinicauda and Alpheus japonicus, the gammaridean amphipods C. emargicoxa and Synchelidium miraculum, and the bivalve R. pulchella. A comparison between frequencies of occurrence and abundance of food items in the gut showed that crustaceans (gammaridean amphipods, crabs and shrimps) and bivalves were important foods for the two gobies. However, the main components of the gut contents were different between two species, though this was probably due to differences in spatial distribution patterns of gobies and their prey items. In conclusion, both the gavelin goby and the fine spot goby, despite being the related species and co-inhabiting the similar part of the tidal flat, had quite distinct food habits and low dietary overlap (Schoener's index: 0.4). These indicated that the two gobies are or were partitioning resources in space and time for maximum uitilization of available food.

• Journal of the Korean earth science society
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• v.37 no.2
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• pp.89-106
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• 2016

The Gochang open-coast intertidal flat is located in the southwestern coast of Korea (the eastern part of the Yellow Sea), characterized by macro-tidal range, an open-coast type, and sand substrates. This study has investigated seasonal variation in sedimentary facies of surface sediments in the Gochang intertidal flat. In the four seasons of February, May, August, and November, 2014, surface sediments of 252 sites in total were sampled and analyzed along three survey lines. The surface sediments of the Gochang intertidal flat in 2014 consisted mainly of fine-grained sand sediments showing a trend in grain size to be coarser in winter and finer in summer. Based on seasonal wave and tidal level data recorded near the study area, it was interpreted that the seasonal effects of wave were stronger than those of tide as a factor controlling surface sedimentation. High waves in winter resulted in the coarsening trend of grain size in surface sediments, whereas, during summer time, the sediments became finer by relatively low waves. Spatial sedimentary facies of the Gochang intertidal flat in 2014 represented that seasonal deviation of the upper tidal zone was larger than that of the lower tidal zone, hence sediments getting coarser in grain size and poorly sorted in the upper tidal zone. From upper to lower tidal zone, the grain size became finer and sediments were better-sorted, showing smaller seasonal deviations.

• Journal of the Korean earth science society
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• v.30 no.2
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• pp.247-256
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• 2009

Characteristics of hydrography and tidal currents were investigated in Hampyung Bay through in situ CTD data, tidal currents and elevations. According to the seasonal weather variability, hydrography showed the lower density with high temperature and low salinity in summer and the higher density with low temperature and high salinity in winter. In particular, the thermal structure like a tidal front was formed along the central channel at the neap tide of summer. The critical value of the parameter $SH(=log_{10}(H/U^3)$ where H is depth and U is $M_2$ tidal current amplitude) representing the formation position of tidal front was estimated from 2.4 to 3.5. In addition, the potential energy anomaly $({\phi})$ was ranged between 0.985 and 6.998 Joule/$m^3$, which gradually increased from the mouth into the inner bay. This front may be caused by the unique topography with wide tidal flat and the local difference of tidal current strength. The observed tidal currents at the mouth of bay showed that the ebb time was shorter than the flood time with the increase of depth. This asymmetric ebb-tide dominance is interpreted as a result of tidal distortion by the development of a shallow-water-constituent in Hampyung Bay with a wide macro-tidal flat.

• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.975-987
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• 2021

Potential habitat mapping of Meretrix lyrata which is found in large parts of South East Asian tidal flat was carried out to find out causes of collective death. Frequency Ratio (FR) method, one of geospatialstatistical method, was employed with some benthic environmental factors; Digital elevation model (DEM) made from Landsat imagery, slope, tidal channel distance, tidal channel density, sedimentary facesfrom WorldView-02 image. Field survey was carried out to measure elevation of each station and to collect surface sediment and benthos samples. Potential habitat maps of the all clams and the juvenile clams were made and accuracy of each map showed a good performance, 76.82 % and 69.51 %. Both adult and juvenile clams prefer sand dominant tidal flat. But suitable elevation of adult clams is ranged from -0.2 to 0.2 m, and that of juvenile clams is ranged from 0 to 0.3 m. Tidal channel didn't affect the habitat of juvenile clams, but it affected the adult clams. In the furtherstudy, comparison with case of Korean tidal flat will be carried out to improve a performance of the potential habitat map. Change in the benthic echo-system caused by climate change will be predictable through potential habitat mapping of macro benthos.

• Journal of the Korean earth science society
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• v.23 no.7
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• pp.565-574
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• 2002

Based on previous investigations of aerial photographs and topographical surveys, this study focuses on the sedimentologic features of the Daebudo area including sedimentation processes, sedimentary facies and hydrologic conditions of the erosional coast. A total of 137 surface sediments and one core (by hand auger) sediment were obtained to interpret the depositional environment of the erosional coast in the macro-tidal coast. Surface sediments are distributed from sandy gravel (sG) to silt (Z). Textural parameters are characterized not only by coarse, poorly sorted, positive skewed and multi-modal distribution in the supra-tidal flat, but also finer, relatively well-sorted, symmetric distribution in the intertidal flat. According to the C/M diagram, sediment transport modes of study area are characterized by the mixed mode of suspension and bedload in the upper-, middle-tidal flat and by uniform suspension in the lower-tidal flat due to tidal effect. Vertical sediment distribution of the core, collected near shoreline, shows coarsening-upward, poorly sorted pattern by the input of detritus resulting from coastal erosion. Considering the sedimentological features of the study area, it appears to be composed of a coastal zone changed by not only artificial reclamation, but also by natural processes such as strong wave action due to typhoons and storms during high water level and long/short-term sea level rising. As a result, tide-dominated erosional coasts show that the shore is affected by local, temporal and hydrological conditions near high tide level and that the intertidal flat is represented by a general tide-dominated sedimentary environment.