대조차 환경의 서해 만리포 해안에서 수심의 계절별 변화와 경년적 주기성을 규명하기 위해, 2023년 10월부터 2024년 10월까지 해빈과 연안역에서 총 5회에 걸쳐 수심측량하였다. 또한 동일 조사지역의 78개 등격자 정점에서 계절별로 표층퇴적물을 입도분석하였고, 그 결과를 바탕으로 표사경향 벡터를 계산하였다. 2023년 가을, 2024년 여름 및 2024년 가을에는 외해역과 연안역에서 대체로 퇴적경향을 나타내는 수심변화가 관찰되었으며, 이 시기에는 외해와 연안에서 육지 쪽으로 향하는 강한 표사경향 벡터가 나타나 퇴적경향이 일치하였 다. 반면, 2024년 겨울과 봄에는 해안선이 북서방향으로 열려 있어 북서계절풍과 파랑의 영향을 크게 받아 침식경향이 나타났고, 표사경향 도 외해로 빠져나가는 벡터가 주로 나타나는 등 침식과 상관된 패턴을 보였다. 2023년 가을과 2024년 가을을 비교하면, 외해와 연안에서 유입되는 강한 벡터와 해빈에서 육지쪽으로 향하는 벡터가 유사한 특징을 보였다. 따라서 만리포 해안은 계절적으로 침식과 퇴적이 반복 되는 패턴을 나타내며, 겨울과 봄에는 침식되고 여름과 가을에는 퇴적되는 경향을 가지는 것으로 특징지을 수 있다.

The annual reproductive cycle of two species, Upogebia major (de Haan 1841) and Austinogebia wuhsienweni (Yu 1931), of the female mud shrimp from the west coast of Korea was investigated using histology. The collected samples were divided into adult and juvenile groups to understand the mature period of age class based on the carapace length (CL). Juvenile Upogebia (CL<25 mm) were mostly inactive gonad with early (62%-100%) and late (10%-38%) development stages during the year, whereas the adult shrimp showed a seasonal pattern of gonad maturation (CL≥25 mm). The early and late developmental stages of oocytes were observed in adult Upogebia from November to March and mature eggs appeared from April to October. In adult Ausitnogebia (CL≥15 mm), fully grown oocytes were consistently observed during the study period, in which the ripe stage was found between January and June. On the other hand, most juvenile Austinogebia (CL<15 mm) maintained an immature state in the gonad. Both species of the mud shrimp reproduced from ovigerous females in the adult population and their egg-bearing period was distinguished from January to April for U. major and from July to September for A. wuhsienweni.

A survey was conducted to analyze seasonal dynamics of the phytoplankton community at 22 stations on the surface and bottom layers in the Anma Islands of Yeonggwang (AIY) in the southern West Sea, Korea from the spring of 2020 to the winter of 2021, using a marine survey vessel Ed Ocean. Based on the survey results, there were 87 phytoplankton species in 52 genera, diatoms accounted for 67.8%, dinoflagellates 26.5%, silicoflagellates 3.5%, and cryptomonads and euglenoids accounted for 1.1% each. By season, it was simple in spring and relatively varied in winter. The phytoplankton standing crop on the surface was low (28.8±30.1 cells mL-1) in summer and high (87.0±65.1 cells mL-1) in spring. In the phytoplankton community, diatoms showed a high share (over 80%) throughout the year, and Skeletonema costatum-ls was the dominant species with a dominance of more than 60% in spring and winter, and 34.6% and 24.2% in summer and autumn, respectively. The diversity expressing the characteristics of the community structure was high (2.79±0.45) in autumn and low (1.82±0.18) in spring, unlike the phytoplankton standing crop. However, the dominance was high at (0.86±0.08) in spring and low (0.44±0.13) in autumn. Based on the results of principal component analysis (PCA) using environmental and phytoplankton-related factors, it was estimated that the biological oceanographic environmental characteristics seen through the phytoplankton community in the AIY were dominated by nutrients supplied from open seawater and surface sediments by seawater mixing, such as tidal mixing.

본 연구는 서해안 갯벌의 퇴적물 환경 및 대형저서동물 군집의 특성과 건강도를 파악하기 위해 수행되었다. 조사는 강화도부터 전남 목포까지 2017년 4월(춘계)과 8월(하계), 2018년 4월(춘계)에 실시하였다. 충남 권역의 퇴적물 입도는 조립하였으며, 경기·인천 권역, 전북 권역, 전남 권역의 퇴적물은 세립하였다. 대형저서동물은 총 140종으로, 대형저서동물 군집유사도를 분석한 결과, 대형저서동물 군집은 4개의 그룹으로 나뉘었다. Group2는 바지락 어장 정점이 포함되었으며, 바지락(Ruditapes phillipinarum)과 남방백금갯지렁이(Nephtys polybranchia)와 짧은다리송곳갯지렁이(Lumbrineris nipponica)가 우점했다. Group4에는 퇴적상이 세립한 정점이 포함되었으며, 작은부채발갯 지렁이(Eteone longa)와 유형동물(Nemertea unid.)이 높은 빈도로 출현하였다. 서해안 갯벌의 건강도 분석 결과, ISEP, BHI지수에서 대체로 ‘High (가장 양호)’상태를 나타냈으며, AMBI지수는 ‘Good (양호)’상태인 것으로 확인되었다. 따라서 서해안 갯벌의 건강도는 양호한 것으로 판단된다. 하지만 일부 지역에 오염지시종인 아기반투명조개(Theora lata), 등가시버들갯지렁이(Capitella capitata) 등이 출현하므로 갯벌 환경이 악화되지 않도록 주기적인 관리가 필요하다.

동서독은 분단 25년만인 1970년부터 독일통일을 이룬 1990년까지 총 7차례의 공식 정상회담을 개최하였다. 6차례 비공식 정상접촉도 있었다. 동서독은 지난 1990년 차가운 이성과 따뜻한 감성이 융합된 지속적인 대화와 교류협력을 바탕으로 평화적인 통일을 이룩해냈다. 통일과정에서 동서독 정상회담이 보여준 ①장기적 안목에 기초한 지속적인 대화의 추진, ②서로 양보하는 대화의 정신, ③실현불가능하고 민감한 문제를 뒤로 미루고 실현 가능한 문제를 우산시하는 현명함, ④서두르지 않고 차근차근 풀어가는 자세, ⑤서독의 동독포용 및 통일역량의 강화노력 등은 통독 30주년이 된 지금에 있어서도 남북한정상회담과 관련해서 많은 교훈 과 시사점을 주고 있다. 우리도 독일통일을 교훈삼아 ①지속적인 남북대 화와 교류협력, ②한반도 통일이해관계국에 대한 평화통일외교의 전개 및 국제사회와의 신뢰구축 강화, ③한국의 평화통일 역량강화를 모색·추진해 나가야 할 것이다.

우리나라 서남해 연안역에서 해수유동을 재현하기 위해 모든 분조를 포함하고 절점변조진폭, 위상보정인자 및 천문인수를 적용한 완전한 형태의 실조석(Real Tide)을 도입하였다. 실조석으로 해수유동을 재현한 결과, 조석의 관측치와 계산치의 상관계수는 1.0으로 진폭 및 위상의 정확도가 매우 우수하였고, U성분 및 V성분으로 구분하여 나타낸 조류는 각각 평균 0.883과 0.936의 높은 상관도를 보여 실조석으로 재현하는 것이 타당한 것으로 보였다. 그리고 잔차류의 관측치와 계산치의 차는 평균 0.006 m/s로 유의미하지 않았고, 그 진 행방향은 서로 매우 유사하였다. 그리고 본 연구의 계산결과에서 관측치와 계산치 간에 나타난 유속성분 오차는 주로 고파랑이나 폭풍을 비롯한 남풍계열의 강한 바람과 같은 기상적 요인에 의한 것이 원인으로 분석되었다. 향후 해수유동 수치모형 실험에서 하나의 변수로 작용하는 기상적 요인을 고려하고 본 연구의 실조석을 재현한다면 계산결과는 더욱 향상될 것으로 기대된다.

Species composition and seasonal variations of fish in the Five West Sea Islands in Korea, were investigated by using otter trawls and bongo nets from 2014 to 2015. During the surveyed period using an otter trawl, a total of 53 species, 147,253 ind./km2 and 2,721,296 g/km2 of fish were collected by otter trawls. The individual dominant species were Chaeturichthys stigmatias (30.3%), Coilia nasus (18.2%), Engraulis japonicus (12.3%), and Setipinna tenuifilis (12.2%). Moreover, the biomass dominant species in biomass were Liparis tanakae (21.3%), Beringraja pulchra (18.5%), Engraulis japonicus (8.3%) and Okamejei kenojei (8.1%). Eggs by bongo nets included 1,748 ind./1,000 m3 of Engraulis japonicus and 64,691 ind./1,000 m3 of unidentified species. A total of 15 species and 2,015 ind./1,000 m3 of fish larvae were collected, and the dominant species were Johnius belengerii and Pholis fangi.

We conducted a seasonal field survey to analyze the distribution patterns of a phytoplankton community and biological oceanographic characteristics in the Geum river estuary in 2018. The results showed that the phytoplankton community consisted of 58 genera and 116 species, showing a relatively simple distribution. It was controlled by diatoms at 70.2%, a low number of species in winter and spring, and a high number in summer and autumn. The phytoplankton cell density ranged from 10.0 to 2,904.0 cells mL-1, with an average layer of 577.2 cells mL-1, which was low in autumn and high in winter. The seasonal succession of phytoplankton dominant species was mainly centric diatoms from winter to summer, including Thalassiosira nordenskioeldii, Cerataulina bergonii, and Skeletonema costatum-ls in winter, S. costatum-ls and C. bergonii in spring, and Eucampia zodiacus and Th. nordenskioeldii in summer. However, the autumn species depended upon the regions, with the inner bay dominated by the centric diatom, Aulacoseira cf. granulata, the mixed areas by S. costatum-ls, and the open sea by the dinoflagellate, Lingulodinium polyedra. According to principal component analysis (PCA), the phytoplankton community was greatly affected by the inflow and expansion of freshwater, including high nutrients, which are introduced annually through the rivermouth weir in Geum river estuary. However, the estuary, which is strongly affected by annual freshwater, was limited to areas near Geumran Island, which is adjacent to the river-mouth weir.

The feeding habits of the bighead croaker Collichthys niveatus were studied using 745 specimens collected by bottom trawl net in the West Sea, Korea, in April and October of 2016, 2017 and 2018. The size of C. niveatus ranged from 4.8 to 16.0 cm in total length. The stomach contents analysis indicated that C. niveatus consumed mainly euphausiids and copepods. C. niveatus consumed mainly euphausiids and copepods in all size classes. The dietary compositions of C. niveatus was not significantly different among size classes (One-way ANOVA, P > 0.05). As body size of C. niveatus increased, the mean weight of prey per stomach (mW/ST) tended to increase.

In order to understand the tidal current and mean flow at the west channel of Yeoja Bay in the South Sea of Korea, numerical model experiments and vorticity analysis were carried out. The currents flow north at flood and south at ebb respectively and have the reversing form in the west channel. Topographical eddies are found in the surroundings of Dunbyong Island in the east of the channel. The flood currents flow from the waters near Naro Islands through the west channel and the coastal waters near Geumo Islands through the east channel. The ebb currents from the Yeoja Bay flow out along the west and the east channels separately. The south of Nang Island have weak flows because the island is located in the rear of main tidal stream. Currents are converged at ebb and diverged at flood in the northwest of Jeokgum Island. Tidal current ellipses show reversing form in the west channel but a kind of rotational form in the east channel. As the results of tide induced mean flows, cyclonic and anticyclonic topographical eddies at the northern tip but eddies with opposite spin at the southern tip are found in the west channel of Yeoja Bay. The topographical eddies around the islands and narrow channels are created from the vorticity formed at the land shore by the friction between tidal currents and the west channel.

The ichthyoplanktons were sampled by Bongo net to study the distribution of the eggs and larvae in the West coastal waters of Korea during the study period (February, May, August and October of 2017). Collected fish eggs were divided into Engraulis japonicus and unidentified species. The most dominant species, Engraulis japonicus accounted for 79.52% of the total fish egg, which was followed by unidentified species (20.48%). The total of 36 taxa in fish larvae were identified based on morphological and molecular characteristics. Fish larvae were dominant by Gobiidae species. 48.30% of the total catch in abundance, which was followed by Engraulis japonicus (31.86%). These two taxa composed 80.16% of the total collected fish larvae. The seasonal diversity index of species from the collected fish larvae in the West coastal waters in 2017 was 0.625-1.883 and the evenness index was 0.380-0.865. In addition, dominance index was 0.618-0.920 and richness was 0.573-3.189.

This study is aimed to compare stock assessment models depending on how the models fit to observed data. Process-error model, Observation-error model, and Bayesian state-space model for the Korean Western coast fisheries were applied for comparison. Analytical results show that there is the least error between the estimated CPUE and the observed CPUE with the Bayesian state-space model; consequently, results of the Bayesian state-space model are the most reliable. According to the Bayesian State-space model, potential yield of fishery resources in the West Sea of Korea is estimated to be 231,949 tons per year. However, the results show that the fishery resources of West Sea have been decreasing since 1967. In addition, the amounts of stock in 2013 are assessed to be only 36% of the stock biomass at MSY level. Therefore, policy efforts are needed to recover the fishery resources of West Sea of Korea.