Fluctuations in abundance and species composition of the fish were investigated based on species collected by beam trawl in coastal waters off Gwangyang Bay from April to December in 2015. During the studying period, A total of 5,179 fishes were sampled and classified into 31 species, 19 families, and 7 orders. The dominant order was perciformes accounted for 48.4% of the total fishes. Among the appeared 31 species, Nuchequula nuchalis was the dominant species by 52.8%, followed by Pennahia argentata (6.2%), Callionymus valenciennei (5.2%), Thryssa kammalensis (5.1%), Konosirus punctatus (5.0%) acounted for 74.3% of the total fishes. The diversity index was the highest in station 1 (Hʹ=2.512) and lowest in station 2 (Hʹ=1.389). The evenness index was the highest in station 1 (E=0.762) and lowest in station 2 (E=0.421). Furthermore, the dominance index was the highest in station 2 (D=77.0%) and lowest in station 1 (D=41.6%).

Natural disasters are increasing due to recent climate change. Rainfall directly or indirectly affects aquaculture and agriculture. Therefore, it is important to anticipate and prepare for this. In this study, a study on the performance comparison between spatial interpolation techniques was conducted based on observed data, and predicted based on the data produced by the spatial interpolation techniques. The spatial interpolation methods compared the inverse distance weighting method, kriging and spatial random forest through MAE (Mean absolute error), RMSE (Root mean square error), correlation coefficient. The verification of predicted data was compared through MAE, CSI (Critical Success Index), FAR (False Alarm Ratio), POD (Probability of Detection) and ETS (Equitable Threat Score).

In this study, we investigated marine environmental conditions when Cochlodinium polykrikoides blooms occurred in the southern coastal waters of Korea, based on the reviews of 98 articles, HABs information of National Institute of Fisheries Science, and marine environmental information system of Korean Marine Environment Management Corporation. Most of C. polykrikoides blooms occurred in four sea regions, i.e., Goheung, Yeosu, Namhae, and Tongyeong in the summer, and in addition, they more frequently occurred at the eastern coast rather than at the western coast. The years were divided into two cases in terms of whether the blooms extensively occurred or did not occurred at all, but it was still unclear why they happened or did not happen. Surface water temperatures in August in these four sea regions ranged from 25℃ to 26℃ while bottom water temperatures showed a significant fluctuations with a higher temperature of 4℃ to 6℃ particularly in Goheung. Surface salinities in Yeosu were relatively lower and more fluctuating than those in the other regions owing to possibly Seomjin river flow. On the other hand, bottom salinities appeared to be stable overall, although Goheung and Yeosu were relatively lower compared to Namhae and Tongyeong. Concentrations of dissolved inorganic nitrogen (DIN) were most low and stable in Goheung at both of the surface and bottom layers while they were most high and fluctuating in Yeosu owing to possibly Seomjin river flow or adjacent industrial complex. Concentrations of dissolved inorganic phosphorus (DIP) were most high and fluctuating in Yeosu at both of surface and bottom layers while they were most low at the surface layer of Namhae but at the bottom layer of Goheung, respectively. However, concentrations of DIN and DIP did not seem to have a significance with the occurrence of C. polykrikoides blooms. Concentrations of chlorophyll a (Chl_a) were high in Goheung and Yeosu at both of the surface and bottom layers while they were low in Namhae and Tongyeong, and furthermore concentrations of Chl_a did appear a significance with C. polykrikoides blooms.

Seasonal varition in abundance and species composition of fishes collected by Seokgok stream in Gokseong-gun, Jeollanam-do, Korea, from March to October 2020. The dominant orders were cypriniformes including 35 species, 2 families followed by siluriformes including 5 species, 3 families and perciformes including 4 species, 3 families and beloniformes including 1 species, 1 family. Among the appeared 45 species, Zacco platypus indicus was the dominant species by 16.2%, followed by Zacco temminckii (11.1%), and Acheilognathus lanceolata intermedia (8.8%). The diversity was the highest in Spring (3.2), while the lowest in Autumn (3.0). The evenness was the highest in Spring (0.9), while the lowest in Summer (0.8). The dominance was the highest in Autumn (29.7%), while the lowest in Spring (22.8%). The richness wast the highest Spring (6.2), while the lowest in Autumn (5.6). The similarity of community structure was 85.3% between Summer and Autumn.

This study was investigated seasonal variation and species composition of fish species at Wang dol reef from November 2019 to August 2020. A total of 31 fish species was occurred, and the dominant fish species were dermesal fishes. The number of individuals of fishes was higher at August 2020, lower at March 2020. The number of species was higher than another study. Thamnaconus modestus was dominant, than Eopsetta grigorjewi, Hexagrammos otakii and Sebastiscus marmoratus were followed. Seasonal variation of dominant species that Eopsetta grigorjewi in March 2020, Hexagrammos otakii in May 2020 and Thamnaconus modestus in November 2019 and August 2020. These results indicated that difference between water temperature and diet community.

A total of 315 individuals of Octopus minor were collected in the mud flat, Korea from May to November 2016. The sex ratio (female : male) of O. minor was higher female with 0.54 : 0.46. The sexual group maturity by logistics model was F=0.0093ML0.2712 with and average fecundity occurred 95 individuals. Female individuals with higher 8.0 cm ML were full maturity. The gonadsomatic index (GSI) was the highest in May and June 2016 for female and male, respectively. These results indicated that the main spawning period of O. minor was from May to June.

This study examined the functional efficiency through hydraulic model test for wave energy transmission coefficient, wave energy reflection coefficient, wave overtopping, and stability of new-type wave dissipating block SEALOCK ADVANCE 61. The applied experiment time was about 2 h~4 h 30 min on prototype model on the basis of 1,000 waves, and the weight of the corresponding block was 20 ton (model: 741 g). The incident wave was experimented for total of 18 cases. As the result, wave energy reflection coefficient was 0.24∼0.57, and wave energy transmission coefficient was analyzed to be 0.15∼0.16 in case of wave overtopping occurrence. Also, wave dissipating block(SEALOCK ADVANCE 61) showed no destruction aspect, showing stable and excellent solidity aspects in general.

The fish (fish eggs, larval fish, and adult fish), caught by RN 80 net and gape net between coastal waters off Jeung island and Saok island, in January and April of 2016 were assessed for species composition in their abundance. Fish eggs and larval fish studied at three stations and were composed of 5 and 11 taxa, respectively. The adult fish were studied at one station and were composed of 20 species, 18 families, and 8 orders. The dominant species were Engraulis japonicus and Nuchequula nuchalis which were caught at all of the fish stages. Larval fish and adult fish were assessed for their richness, evenness, diversity, and dominance to gain a measure of the biodiversity. The richness index was the highest in April at adult fish (R=2.102), the evenness index was the highest in January at larval fish (E=0.953), the diversity index was the highest in April at adult fish (H’=2.010), and the dominance index was the highest in April at larval fish.

In this study, re-analysis wind fields of KMA, JMA, and NOAA were collected for the estimation of waves during typhoon MAYSAK (2009). The wind field data of KMA, JMA, and NOAA were used as input conditions, and the significant wave height, peak period, and representative wave direction were estimated using SWAN (Simulating Waves Nearshore, version 41.31) numerical modeling. Calculation ranges of the typhoon wave estimation range from 20° to 50°N and 117° to 147°E, and the latitude and longitude were composed of grid size at 0.05° (about 5 km resolution). Experimental conditions were 0~360° 60 division for direction division, and 40 division for frequency division 0.04~1.0 Hz, and JONSWAP spectrum was used. In order to verify the reproducibility of the typhoon wave estimation results, quality-controlled wave observation data provided by WINK in the typhoon MAYSAK best track were collected, and the reproducibility of wave estimation data using KMA, JMA, and NOAA wind fields was compared and reviewed.

In this study, an experiment was conducted to investigate the engine performance, combustion characteristics, and emission characteristics, according to the operating conditions of the engine and the mixture ratio of diesel oil and butanol in a diesel engine. Combustion pressure, fuel consumption, smoke concentration, excess air ratio, intake and exhaust temperature were measured during this experiment. Using these data, the coefficient of variation of IMEP (indicated mean effective pressure) and the indicated fuel conversion efficiency were calculated for investigating the engine performance. The cylinder pressure was analyzed for pressure increasing rate and heat release rate. The experimental results of butanol blending oil were compared with the those of diesel oil. The optimum operating condition of engine and proper range of butanol blending rate could be identified without bad effect to the engine performance and the soot emission in this study.

In Korea, coastal erosion in Korea gradually increases the intensity of typhoons and high waves such as swells on the coast due to climate changes such as sea level rises and sea water temperature rises. In addition, due to maintenance projects such as dam, dike and river embankment construction, the amount of sand that flows from river to coast is decreasing. Coastal erosion is accelerating due to imbalances in sand budget. Therefore, this study aims to analyze the current situation and outcomes of coastal erosion response. In particular, detailed current status, problems and improvement plans were reviewed for each stage of coastal maintenance project planning, design and construction, and monitoring, feedback management, and effective erosion countermeasures were suggested.

This study was carried out to understand the seawater flow characteristics of the waters near the Yulchon Industrial Complex in Gwangyang Bay as a basic data for understanding the habitat environment of marine ecosystems, plant plankton, shellfish, fish and algae. Numerical experiments were conducted using field observation and EFDC in the target area. As a result of field observation, half-day casting showed the dominant tidal phase, and the average flow rate of flood was 14.14 cm/s~16.09 cm/s, and the average flow rate of ebb was 11.67 cm/s~15.31 cm/s. At the time of flood tide, NW and NNW directions and at ebb tide SE and SSE directions were observed. And half-day casting (M2, S2) is the predominant algae form than one casting (K1, O1). As a result of the numerical experiment, the flow around the target area appeared in southwest direction at the time of flood tide, and the flow in the northeast direction at the time of ebb tide was strong. The flow rate of the survey area was up to 75 cm/s at the time of spring tide flood, and up to 54 cm/s at the time of ebb. At the time of neap tide flood, it appeared up to 26 cm/s, and at the time of ebb up to 21 cm/s. Therefore, systematic and continuous monitoring is needed to understand the marine ecosystem habitat in the area around Yulchon Industrial Complex in Gwangyang Bay. This study will be used as basic data.

Species composition of fish larvae in coastal waters off Wan island port were investigated in May and August, 2019. During the study period, the fish larvae were identified as belonging to 24 taxa, 19 families, and 9 orders. The dominant species of fish larvae were Engraulis japonicus, Nuchequula nuchalis, and Ammodytes japonicus. These three species accounted for 56.4% of the total number of individuals collected. The evenness index of the fish larvae was the highest in St. 4 (E=0.88) and the lowest in St. 1 (E=0.74). The richness index of the fish larvae was the highest in St. 2 (E=3.49) and the lowest in St. 4 (E=2.89). The diversity index of the fish larvae was the highest in St. 4 (H′=2.53) and the lowest in St. 1 (H′=2.19). The dominance index was the highest in St. 1 (D=51.12%) and the lowest in St. 4 (D=34.76%). The similarity index was the highest between St. 5 and St. 2 by 92.14%.

해양환경 특성 조사에서 수온은 13.54~24.80℃, 염분 30.23~32.00 psu, pH는 7.85~7.98, 용존산소는 7.38~8.26 mg/L의 범위로 나타났다. 갯벌 노출 시간 및 고도 조사에서 지반고는 248.85~278.88 cm의 범위로 나타났으며, 노출 시간은 5시간 5분에서 6시간의 범위로 나타났다. 본 연구에서 채집된 낙지는 총 345개체였으며, 외투장은 2.25~9.72 cm ML의 범위로 나타났으며, 평균 6.09 cm ML로 나타났다. 생체량은 7.40~293.20g의 범위로 나타났으며, 평균 82.78 g으로 나타났다. 외투장 7.00~7.99 cm의 개체군이 전체의 89개체 (24.1%)로 가장 많이 출현하였다. 낙지의 주 먹이생물은 게류로 나타났으며, 다음으로 새우류, 이매패류, 갯지렁이류로 나타났다. 낙지 인공 산란장 적지 기준은 수질환경, 퇴적환경 및 생물학적 요인으로 구분되었다. 수질환경은 수온 10.0~20.0℃ (최적 범위 10.0~16.0℃), 염분은 27.0~35.0 psu, 염분의 변화에 민감함으로 주변에 하천이 없어야 한다. 용존산소는 5.0 mg/L 이상을 유지하여야 한다. 퇴적환경은 사니질성분의 갯벌조간대가 알맞으며, 노출시간은 6시간 이내, 지반고는 280 cm 이내여야 했다. 생물학적 요인은 생물학적 최소형인 7.0 cm ML 이상의 낙지를 사용하여야 하며, 산란기인 5~6월, 10~11월이 조성적기였다. 또한 주변에 풍부한 낙지 먹이생물이 서식하여야 한다. 인공산란장 조성은 암수낙지를 3일간 어두운 환경에서 교접을 시킨 후 이를 10 m당 1개체씩 (1 ha에 100개체) 조성된 인공산란장에 방류한다. 이러한 인공산란장이 조성되면, 자율관리어업공동체를 구성하고 지자체 및 유관기관의 기술지원 및 행정지원을 통한 유기적인 연대관계를 유지하여야 할 것이다.

This study was conducted to investigated the morphology comparison of cranium, orbital bone, and jaw bone skeletons of nine species of Scorpaenidae fish; Sebastes inermis, Sebastes thompsoni, Sebastes schlegelii, Sebastes vulpes, Helicolenus hilgendorfi, Inimicus japonicus, Sebasticus marmoratus, Sebasticus tertius, and Inimicus japonicus. Samples were collected from December, 2012 to May, 2013 in fisheries market in Yeosu, Korea and were applied to analyzes such as morphology of skeleton. As a result, taxonomic characteristics of skeleton were vomer, frontal, sphenotic, parietal, the second suborbital bone, dentary, articular, and angular.

At the center of the Noryang waterway, there is the Gwangyang Bay, the Yeosu Strait is located at the west, and the Jinju Bay, the Gangjin Bay and the Sacheon Bay is located at the east. The freshwater from several rivers is coming into the study area. Especially in the event of flood, the freshwater of the Seomjingang is flowing into the Gwangyang Bay area (including the Yeosu Strait) and freshwater of the Gahwacheon (discharge of Namgang Dam) is flowing into the Jinju Bay area (including the Gangjin Bay and the Sacheon Bay) in great quantities. The Gwangyang Bay area and the Jinju Bay area are connected with the Noryang waterway. In addition, the freshwater out of the Seomjingang and the Gahwacheon also affect through the Noryang waterway. In this study, we elucidated the characteristics of seawater exchange rate and residence time seasonally, with a consideration of the freshwater out of 51 rivers, including the Seomjingang and the Gaghwacheon, using a particle tracking method. The result showed that the particles released from the Gwangyang Bay area moved to the Jinju Bay area through the Noryang waterway. However, the particles moved from Jinju Bay area to Gwangyang Bay area appeared comparatively small. Seasonal seawater exchange rate ranged from 41.2 to 51.3% for the Gwangyang Bay area and from 58.0 to 62.1% for the Jinju Bay area. In addition, seawater exchange rates in summer turned out to be larger than those in any other season. The residence time appeared to be 13.3 to 14.7 days in the Gwangyang Bay area and 9.2 to 10.1 days in the Jinju Bay area. As a result, residence time of the Jinju Bay area turned out to be a little bit smaller than those of the Gwangyang Bay area.

Species composition and community structure of fish eggs and larval fishes in coastal waters off Geoje island were investigated from November, 2018 to August, 2019. Durng the study period, the fish eggs were identified as belonging to 9 taxa. The dominant species of fish eggs were Engrauils japonicus, Nuchequula nuchalis, and Sillago japonica. These three species accounted for 73.2% of the total number of individuals collected. The collected larval fishes were identified into 16 taxa, 15 families, and 4 orders. The dominant species of larval fish were E. japonicus, N. nuchalis, and Sebastes schlegelii. These three species accounted for 61.4% of the total number of individuals collected. The diversity index of the larval fishes was the highest in summer by 1.92 and the lowest in winter by 1.30. The community similarity of each season was the highest between spring and summer by 54.6%.

For morphological and osteological studies of Plectorhinchus cinctus, samples were collected in Yeosu fisheries market and analyzed. The differences of covariance were presented in following characteristics: body color, body shape, black bands, and spots ranging from back to tail. P. cinctus had 12 dorsal fin spines, 15~16 fin rays, 16~19 pectoral fin rays, 1 ventral fin spines, 5 ventral fin rays, 3 anal spines, and 6~9 fin rays. The taxonomic characteristics of skeleton were supra-occipital bone, the basisphenoid bone in the skull, the maxillary bone, the angular bone in the jaw bone, existence and nonexistence of the supra-temporal bone in the shoulder, and the number of the branchiostegal ray bones.