• Journal of Environmental Science International
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• v.26 no.6
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• pp.691-710
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• 2017

This study was performed to investigate the geochemical and benthic environment of three shellfish farms in Suncheon Bay during the period of September 2014 ~ April 2015. Three sampling stations were selected; St.1 is the shellfish farm of razor clam near Jangsan area. St.2 is the shellfish farm of small ark shell near Hwapo area and St.3 is the shellfish farm of razor clam near Yongdu area. Razor clam was the dominant species at St.1, small ark shell and granulated ark shell were dominant at St.2 and St.3, respectively. Granulated ark shell inhabited St.3, although it is not cultured at that station. This station's exposure to air during the ebb tide and sediment composition likely provides the appropriate habitat for granulated ark shell species. Analysis of the number of different species showed that 8 benthos species were found to be distributed at St.1, 18 species at St.2, and 13 species at St.3. Among three stations, the highest Ignition Loss (IL), Chemical Oxygen Demand (COD) and Acid Volatile Sulfide (AVS) values were obtained from the sediment at St.2. The analysis of pore water from St.2 also showed the highest values of Total Organic Carbon (TOC), ammonia ($NH_4^+$), Dissolved Inorganic Nitrogen (DIN) and phosphate ($PO_4^{3-}$). These results are related to the fact that species dominance and richness is the highest in St.2.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.6
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• pp.457-465
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• 2014

This paper introduces a test bed for communication protocol schemes of underwater acoustic sensor network, and also shows experimental results obtained from the test bed. As a testing protocol, carrier sense multiple access/collision avoidance (CSMA/CA) is evaluated on underwater acoustic channel. A sensor node is equipped with a DSP control board of ATmega2560 and a commercial underwater modem produced by Benthos. The control board not only manipulates a GPS signal to acquire the information of location and time, but also controls the underwater modem to operate according to the procedure designed for a given testing protocol. Whenever any event takes place such as exchanging control/data packets between underwater modems and acquiring location and timing information, each sensor node reports them through radio frequency (RF) air interface to a central station located on the ground. The four kinds of packets for CSMA/CA, RTS(Request To Send), CTS(Clear to Send), DATA, ACK(Acknowledgement) are designed according to the underwater communication environment and are analyzed through the lake experiment from the point of feasibility of CSMA/CA in underwater acoustic communications.

• 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.

• Ocean Science Journal
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• v.41 no.4
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• pp.211-219
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• 2006

A comparison was made of population of the economically important cockle Anadara (=Scapharca) broughtoni (Bivalvia, Arcidae) inhabiting different areas of the Razdolnaya River estuary at the head of Amurskii Bay (Peter the Great Gulf, East Sea). Also, changes in cockle population density and structure, as well as in cockle growth rates during the last 20 years were studied. In all years of investigation, the morphometrical parameters and growth rates of cockles were smaller at the sites located close to the River mouth than farther down-estuary. The differences can be attributed to higher concentration of suspended particulate matter, decreased salinity and water temperature, as well as a longer exposure to these unfavorable environmental factors at sites located close to the River mouth, compared to farther sites. For two decades, cockle population density had decreased by almost 30 times at some sites in the River estuary. The main reason for this population decline is commercial over-fishing of the cockle. Besides, for the last 20 years, linear parameters of the cockles in the population decreased approximately by 30% and weight parameters, almost two times. Cockle growth rates also decreased for this period. Evidently, these facts are due to the damaging effect of dredging.

• Ocean and Polar Research
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• v.26 no.2
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• pp.361-365
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• 2004

Deep-sea Resources Research Center (DRRC) has been using a free-fall grab (FFG) for the resource evaluation of polymetallic nodules in the KODOS (Korea Deep Ocean Study) area, NE Pacific, since 1992. A FFG model (Model 4200, Benthos) adapting one glass buoy system (diameter 17 inch, net buoyance 25.4 kg) has been used until 1993. Since then, DRRC has carried out a study to increase the recovery rate of FFG and it was found that a revised system adapting an additional buoy (diameter 10 inch, net buoyance 4.5 kg) gives improved results. The nodule sampling tests were performed using two different models for the same study area and the resulting recovery rates were compared. The result shows no distinct difference in recovery time between two models, but average recovery rate of the revised model was increased to 99.44% from 96.06% of the original model.

• Ocean and Polar Research
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• v.22 no.1
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• pp.25-36
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• 2000

The polychaeta fauna of the benthos and fouling of the northwestern part of the East Sea was studied during the period of 1971-1998. Three introduced species of polychaetes: Hydorides elegans (Haswell), Polydora limicola Annenkova, and Pseudopotamilla occelata Moore were found. H. elegans was discovered only on the artificial surfaces in Golden Horn Inlet (port Vladivostok), where this species may occur because of hermal pollution due to the discharge of warm waters of the water cooling system of Thermal-Electric Power Station-2 (TEPS-2) in Vladivostok which has been in function since 1971. The abundant population of H. elegans exists in the bay throughout the year and is capable of reproduction. The biomass of H. elegans may reach several $kg/m^2$ in August-September. P. limicola was found at the same time in the fouling of hydrotechnical structures of Vladivostok, Nakhodka, Holmsk and Uglegorsk ports with a biomass of $1-3kg/m^2$. Slow introduction of P. limicola occurs by coastal sail ships at present. The invasion of P. occelata into Peter the Great Bay may be an example of introduction and subsequent naturalization, which produced considerable changes in the structure of benthic communities. The three species of polychaetous sessile organisms and their invasion occurred by ocean and coasters sea-going ships (unintentional transport vectors). H. elegans and P. occelata were most probably transported to the northwestern part of the East Sea from Japan, and P.

• Journal of Environmental Science International
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• v.19 no.9
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• pp.1083-1092
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• 2010

The spatial variability in the food chain structure of an estuary environment (Nanakita estuary, Japan) was investigated using fatty acid. Potential organic matter sources (terrestiral plants, macroalgae, benthic microalgae, dinflagellates and bacteria), sedimentary organic matters and benthic invertebrates (Nuttallia olivacea and Nereidae) were sampled in four locations with different tidal flat type. The main objective of the present study was to determine the origin of sediment and the food sources of N. olivacea and Nereidae along with small-scale spatial variability. The origin of sedimentary organic matters were mainly the fatty acid of bacteria and benthic microalgae. Especially, The organic matter of terrestrial plant origin was found the highest in station C. The diets of N. olivacea and Nereidae were found to be dominated by diatoms and terrestrial plants. Whereas, macroalgae and dinoflagellates showed little influence to benthic invertebrates. Moreover, according to principal component analysis, it is showed that benthic invertebrates in the same region are using the same food without relation with species. On the other hand, the N. olivacea and Nereidae of station D clearly contrasts with station B in terms of main food sources. From these results, it is suggested that food competition of benthic invertebrates revealed high a connection between small-scale spatial variability and food source in estuary.

• Ocean and Polar Research
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• v.23 no.2
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• pp.63-75
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• 2001

Species composition and community structure of the fouling found on the hulls of 28 ships traveling through 6 main shipping routes (SR)in the Far East Sea Basin were analyzed using statistical methods. Samples obtained during 1976-1990 expeditions of the Institute of Marine Biology were used for the analyses. These samples were taken from the ships anchored in the harbor by SCUBA diving and in dry-docks of the Vladivostok ship-repairing yard. Similar composition of the fouling communities occurred on the ships travelling the same SR. In five cases, fouling was dominated by different Cirripedia communities. And, in one case, a community of the mussel Mytilus trossulus was found. In most cases the results of the factor analyses showed extremely low level of the relationships among different animals and algal species in fouling communities. Each ocean-going ship had an original structure of the fouling. Spatially disconnected animal associations of tropical and boreal origin may simultaneously coexist at the same ship. This paper testified to the originality of the zone of anthropogenic substrata as a benthos concentrator in the pelagic regions of the world ocean. The fouling from different zones showed that each zone possesses peculiar features and regularities of the composition and relationships between organisms dwelling here.

• Journal of Wetlands Research
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• v.14 no.2
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• pp.303-315
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• 2012

This study developed a wetland inventory describing the characteristics and change of Nakdong estuary wetland ecosystem. The data which are used to develop the inventory are Landsat TM(April 1, 1986; June 23, 1987; June 18, 1997), Kompsat(Jan. 12, 2008) and LiDAR(March 1, 2009) images and published monitoring data of Busan metropolitan city. The developed inventory was utilized for the classification of wetland cover, the spatiotemporal analysis of wetland and landscape pattern, the distribution of benthos species etc. Furthermore, the developed 3 dimensional wetland map showed a better way to delineate wetland boundary and understand wetland dynamics. Considering these results, it's concluded that it is possible to use the similar techniques for the development of wetland inventory in Korea.

• ALGAE
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• v.33 no.4
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• pp.359-366
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• 2018

Mesocosm experiments conducted for ecological purposes have become increasingly popular because they can provide a holistic understanding of the biological complexities associated with natural systems. This paper describes a new outdoor mesocosm designed for $CO_2$ perturbation experiments of benthos. Manipulated the carbonate chemistry in a continuous flow-through system can be parallelized with diurnal changes, while irradiance, temperature, and nutrients can vary according to the local environment. A target hydrogen ion activity (pH) of seawater was sufficiently stabilized and maintained within 4 h after dilution, which was initiated by the ratio of $CO_2$-saturated seawater to ambient seawater. Specifically, pH and $CO_2$ partial pressure ($pCO_2$) levels gradually varied from 8.05-7.28 and $375-2,691{\mu}atm$, respectively, over a range of dilution ratios. This mesocosm can successfully manipulate the pH and $pCO_2$ of seawater, and it demonstrates suitability for ocean acidification experiments on benthic communities.