Comparative assessment of age, growth and food habit of the black-chinned tilapia, Sarotherodon melanotheron (Rüppell, 1852), from a closed and open lagoon, Ghana

Zuh, Cephas Kwesi,Abobi, Seth Mensah,Campion, Benjamin Betey The Korean Society of Fisheries and Aquatic Scienc 2019 Fisheries and Aquatic Sciences Vol.22 No.12

Background: The black-chinned tilapia, Sarotherodon melanotheron, is the most abundant fish species in the Nakwa (an open lagoon) and Brenu (a closed lagoon) in the Central Region of Ghana. Aspects of the life history characteristics and the ecology of the fish populations in both lagoons were studied to assess the bio-ecological status of this important resource. Methods: Fish samples were obtained from fishermen that fish on the Nakwa and Brenu lagoons using cast, drag and gill nets. The age of the fish was assessed from otoliths analysis and its growth modelled following the von Bertalanffy growth function. Morphometric characteristics of the fish populations were analysed using power regression and ANOVA for parameters comparisons, and Student's t test to determine whether species grew isometrically. The percentage occurrence method was used to analyse the stomach contents of the fish. Results: A total of 382 fish samples from both lagoons were measured, comprising 209 from Nakwa lagoon and 176 from Brenu lagoon. The size and weight of fish samples ranged between 3.9-11.5 cm total length and 1.0-27.3 g for Nakwa Lagoon and 5.6-12.8 cm total length and 3.2-29.8 g for the Brenu Lagoon. The estimated von Bertalanffy growth parameters were L∞ = 12.04 cm and K = 2.76/year for the Nakwa Lagoon samples and L∞ = 13.44 cm and K = 3.27/year for Brenu Lagoon samples. Daily otolith incremental rate ranged from 0.01-0.03 mm per day to 0.01-0.02 mm per day for Nakwa and Brenu lagoons, respectively. Stomach content analysis of the fish samples revealed that the species are planktivorous and the range of food varied between the lagoons. Green algae were the most prevalent food item in the stomachs of the fish samples from Nakwa with the frequency of 69% whilst diatoms (80.5%) were most prevalent phytoplanktonic food item for the fish in Brenu lagoon. Conclusions: The estimates of asymptotic length for the species in both lagoons are close to known values of the species length at first sexual maturity and points to intensive fishing pressure. As a consequence, a comprehensive sample-based survey is required in both lagoons to derive estimates of management reference points. The results of the stomach content analysis are beneficial to the construction of diet matrix for ecosystem models of the two systems.

Comparative assessment of age, growth and food habit of the black-chinned tilapia, Sarotherodon melanotheron (Rüppell, 1852), from a closed and open lagoon, Ghana

Cephas Kwesi Zuh,Seth Mensah Abobi,Benjamin Betey Campion 한국수산과학회 2019 Fisheries and Aquatic Sciences Vol.22 No.4

Background: The black-chinned tilapia, Sarotherodon melanotheron, is the most abundant fish species in the Nakwa (an open lagoon) and Brenu (a closed lagoon) in the Central Region of Ghana. Aspects of the life history characteristics and the ecology of the fish populations in both lagoons were studied to assess the bio-ecological status of this important resource. Methods: Fish samples were obtained from fishermen that fish on the Nakwa and Brenu lagoons using cast, drag and gill nets. The age of the fish was assessed from otoliths analysis and its growth modelled following the von Bertalanffy growth function. Morphometric characteristics of the fish populations were analysed using power regression and ANOVA for parameters comparisons, and Student’s t test to determine whether species grew isometrically. The percentage occurrence method was used to analyse the stomach contents of the fish. Results: A total of 382 fish samples from both lagoons were measured, comprising 209 from Nakwa lagoon and 176 from Brenu lagoon. The size and weight of fish samples ranged between 3.9–11.5 cm total length and 1.0–27.3 g for Nakwa Lagoon and 5.6–12.8 cm total length and 3.2–29.8 g for the Brenu Lagoon. The estimated von Bertalanffy growth parameters were L∞ = 12.04 cm and K = 2.76/year for the Nakwa Lagoon samples and L∞ = 13.44 cm and K = 3.27/year for Brenu Lagoon samples. Daily otolith incremental rate ranged from 0.01–0.03mm per day to 0.01–0.02mm per day for Nakwa and Brenu lagoons, respectively. Stomach content analysis of the fish samples revealed that the species are planktivorous and the range of food varied between the lagoons. Green algae were the most prevalent food item in the stomachs of the fish samples from Nakwa with the frequency of 69% whilst diatoms (80.5%) were most prevalent phytoplanktonic food item for the fish in Brenu lagoon. Conclusions: The estimates of asymptotic length for the species in both lagoons are close to known values of the species length at first sexual maturity and points to intensive fishing pressure. As a consequence, a comprehensive sample-based survey is required in both lagoons to derive estimates of management reference points. The results of the stomach content analysis are beneficial to the construction of diet matrix for ecosystem models of the two systems.

Offset in radiocarbon age between plant and shell pairs in Holocene sediment around the Mae-ho Lagoon on the eastern coast of Korea

Nakanishi, Toshimichi,Hong, Wan,Sung, Ki Suk,Nakashima, Rei,Nahm, Wook-Hyun,Lim, Jaesoo,Katsuki, Kota Elsevier 2017 Quaternary international Vol.447 No.-

<P><B>Abstract</B></P> <P>To detect long-term change in the reservoir effect of the eastern coast of Korea, we measured the radiocarbon ages of terrestrial plant and marine shell pairs from the same horizons from approximately 12 m of Holocene sediments under reclaimed land around the Mae-ho Lagoon. The lagoon sediment was examined for lithology, and sedimentary structures, as well as mollusk and diatom assemblages. From bottom to top the sediment comprised three units: transgressive lagoon, restricted lagoon, and delta. The offset in the radiocarbon age of nine pairs were also divided into three stages: 300 ± 90 to 410 ± 120 years (transgressive lagoon sediment in 7350–5800 cal BP), 640 ± 150 to 800 ± 150 years (restricted lagoon sediment in 4320–1600 cal BP), and 120 ± 140 to 330 ± 100 years (deltaic sediment in 1200–390 cal BP). The reservoir ages (R) in the sediments of transgressive lagoon and the restricted lagoon include the variation associated with dietary of shells, herbivorous and deposit-feeding, respectively. The R values in the deltaic lagoon sediment were the most representative of those in the Mae-ho Lagoon because they were obtained from the shells of a filter-feeding taxon, <I>Potamocorbula amurensis</I>, in the most recent sediment. These values from the deltaic lagoon sediment are also consistent with previously reported modern reservoir ages from the Korean Peninsula and Peter the Great Gulf around Vladivostok.</P>

신라의 동해안 연안항해와 하슬라

홍영호(Hong, Young-ho) 백산학회 2013 白山學報 Vol.- No.95

이 글의 목적은 강릉 경포호(鏡浦湖) 강문동 신라토성의 발견을 계기로 신라의 동해안 연안항해의 실상을 살펴보고, 하슬라(강릉)가 주요 거점으로 성장하게 되는 역사적 배경과 조건을 찾아보는 데 있다. 먼저, 사료와 고고자료를 통해 신라의 해상 활동을 검토한 결과, 신라는 왜(倭)의 침입을 물리치는 과정에서 점차 해군력이 성장하였고, 경주에서 동해안을 따라 연안항해도 하였던 것으로 추정되었다. 이후, 자연지리ㆍ지형적인 상황은 크게 변하지 않으므로 조선시대에 수군이 정박하는 강원도 연안항구의 실상을 토대로 신라시대 연안 항구의 입지에 대한 이해를 시도하였다. 그 결과 조선시대 강원도 동해안에서 수군이 정박하는 항구는 하구에 모래톱이 만들어져 배가 출입하는 데에 어려움이 있어, 작은 병선만 드나들어야 하는 문제점이 있음을 알게 되었다. 하지만, 작은 병선이 석호(潟湖)에 정박하였음을 보여주는 중요한 사료도 찾게 되었다. 이것은 석호가 항만(港灣)의 형태를 가지고 있으므로 출입부만 관리가 된다면 작은 배들이 정박하기에 매우 유리하였음을 반영하는 것이다. 나아가, 이러한 기록은 강릉 경포호 강문동 신라토성의 입지를 근거로 신라시대에도 석호가 정박처로 이용되었다고 주장할 수 있는 자료로 활용할 수 있다. 특히, 신라의 초기고분군과 석호의 분포가 서로 일치하므로 신라가 동해안의 연안항해를 위한 거점을 선정할 때 석호의 존재를 중요한 판단의 기준으로 삼았다고 생각된다. 신라가 하슬라를 주요 거점으로 선정하게 되는 역사적 배경은 나물왕 대를 전후로 하여 고구려와의 교섭을 위하여 동해안을 이용하면서 황초령(黃草嶺)을 지나 장진호(長津湖)를 거쳐 당시 고구려의 수도인 집안(集安)으로 가기 위한 교통로와 관련된 것으로 보인다. 신라는 당시 강릉 이북 지역은 안전을 보장하기 힘든 변방지대였고, 강릉은 경포호라는 석호가 있어 항구기능이 유리하므로 고구려와의 교섭을 위한 중간 거점으로 개척하였다고 생각된다. 여기에 동해안을 따라 남쪽과 북쪽에서 오는 해류가 동해 중부연안에서 교차하는 점도 고려되었을 것으로 보인다. 결국 강릉 경포호 강문동 신라토성은 신라가 동해안 연안항해를 하였고, 석호가 있는 지역을 중간기착지(항구)로 삼았음을 알 수 있게 해주며, 강릉을 최적의 지점으로 판단하였기에 동해안의 주요 거점으로 경영하였다고 평가하게 해 주는 매우 귀중한 자료라 하겠다. The purpose of this paper is to examine the Shilla’s coastal navigation of the East Coast of Korea on the occasion of the discovery of the Shilla Gangmun-dong earthen fortress at Gyeongpo lagoon, Gangneung, and find the historical background and conditions of Haslla’s (Gangneung) growth into an important foothold. First of all, the author examined the marine activities of Shilla Dynasty based on historical materials and archeological materials, and Shilla’s naval power gradually grew in the process of fighting back against the invasion of Japanese pirates (Wae), and Shilla is thought to have conducted coastal navigation from Gyeongju along the East Coast. Since the physical geography and topography did not change greatly, this paper tried to understand the location of coastal ports during the Shilla period based on the coastal ports in Gangwon-do Province where the naval ships of Joseon Dynasty were anchored. As a result, the ports where the naval forces of Joseon lay at anchor off the East Coast of Gangwon-do Province were difficult to access because there were sandbanks at the estuaries. So only small military vessels could access these ports. However, the author found important historical materials that show small military vessels anchored in lagoons. As lagoons are shaped like a port, if the entrance is managed, they were very advantageous for the anchoring of small vessels. Furthermore, such records can be used to argue that lagoons were used as anchorages during the Shilla period based on the location of the Shilla Gangmun-dong earthen fortress at Gyeongpo lagoon, Gangneung. In particular, as the distribution of the tombs of the early Shilla period corresponds to that of lagoons, Shilla is thought to have used the existence of lagoons as an important criterion for judgment when selecting the bases for coastal navigation in the East Coast. The historical background for Shilla’s selecting Haslla as an important base seems to have been related to the fact that Shilla used the East Coast as well as overland route in the East coastal region for negotiations with Goguryeo Dynasty, and Haslla was a main part of the traffic route for going past Hwangchoryeong to Jiban, the capital of Goguryeo during the reign of King Naemul. To Shilla, the area to the north of Gangneung was a border area, whose safety could not be secured, and Gangneung was advantageous as a port since it has the Gyeongpo lagoon. So Shilla is thought to have developed Gangneung as an intermediate base for negotiations with Goguryeo. The fact that the ocean currents coming from the south and the north, which moves along the East Coast, crossed each other off the mid-East Coast seems to have been taken into account. After all, the Shilla Gangmun-dong earthen fortress at Gyeongpo lagoon, Gangneung showed that Shilla conducted coastal navigation along the East Coast, and chose an area with a lagoon as a way station (port). It is a very valuable historical data that leads to the belief that Shilla chose and managed Gangneung as an important base of the East Coast because it was regarded as the best location.

수리화학적 환경 추적자를 이용한 강원도 석호지역에서의지하수-지표수 상호작용에 대한 연구

김동훈,이정윤,조수영,문희선,정윤영,박예진,오용화 한국지하수토양환경학회 2023 지하수토양환경 Vol.28 No.2

Groundwater–surface water interaction was evaluated using water quality parameters (temperature and electrical conductivity),distributions of stable water isotopes (δ2H and δ 18O), and Rn-222 in lagoon water, groundwater, and seawater at threecoastal lagoons (Songji (SJ), Youngrang (YR), and Sunpo (SP) Lagoon) in South Korea. From the results of compositionand distributions of δ2H and δ18O, it was found that groundwater fraction of lagoon water in YR Lagoon (76%) wasslightly higher than those of SJ (42%), and SP (63%) Lagoon. Based on Rn-222 mass balance model, groundwaterdischarge into SJ Lagoon in summer 2020 was estimated to be (3.2±1.1)×103 m3 day-1, which showed a similar or an orderof magnitude higher than the results of previous studies conducted in coastal lagoons. This study can provide advancedtechniques to evaluate groundwater–surface water interaction in coastal lagoons, wetlands, and lakes, and help todetermine the effects of groundwater on coastal ecosystems.

강원도 양양군 쌍호, 가평리습지, 궁개호, 염개호의 20세기 경관 변화

윤순옥 ( Soon Ock Yoon ),황상일 ( Sang Ill Hwang ),박충선 ( Chung Sun Park ),진민경 ( Min Kyoung Jin ) 한국지형학회 2010 한국지형학회지 Vol.17 No.4

Coastal lagoons(Ssangho, Gapyeongri wetland, Gunggaeho and Yeomgaeho) distribute densely around Osan-ri, Yangyang-gun. While Ssangho with the representative lagoon group in the East Coast has maintained the lagoon conditions of water surface since it was formed during the Climax of transgression, the others were formed at the swale areas of sand beach. They vary considerably in area reduction rates and position variations during the 20th century, and the causes examined can be divided into natural, human and other factors. They result in the lagoon aggradation stage by geomorphic development, reclamation due to rapid industrialization and urban development during the 20th century, and lacks of understanding on values of small coastal lagoon or errors in mapping and lags of survey techniques. Therefore, the plans for lagoon restorations should be proceeded by the individual properties of lagoons. The restorations of Ssangho are recommended preferentially and it is desirable to restore to the lagoon conditions of 1920s when the influences of human were minimum.

동해안 4개 석호의 수질과 식물플랑크톤 계절별 변화에 관한 연구

문병렬 ( Byeong Ryeol Moon ),전현진,전숙례 ( Sook Lye Jeon ),이재선 ( Jae Sun Lee ),신지은 ( Ji Eun Shin ),안지혜 ( Ji Hye Ahn ),양용운 ( Yong Woon Yang ),현문식 ( Moon Sik Hyun ),김미아 ( Mia Kim ) 한국환경과학회 2015 한국환경과학회지 Vol.24 No.9

The seasonal variation of phytoplankton communities and its standing crops in accordance with environmental factors were investigated at Yeongrang-ho, Cheongcho-ho, Mae-ho and Hyang-ho which are located in the East coast of Korea during April to October 2011. High concentrations of T-N and T-P were observed in four lagoons due to the inflowing nutrients from farmlands and residential areas near lagoons. Nutrient salts mainly composed of nitrogen and phosphate caused the eutrophication of the lakes, leading to the robust growth of phytoplankton. During the period of investigation, 64 to 107 taxa of phytoplankton were observed in four lagoons. Diatoms were the most dominant species with high density. Non-point pollution source was estimated as the main cause of water pollution of lagoons. Trophic states of lagoons evaluated using the value of TSI and TSIKO indicated that all the investigated lagoons were in the eutrophication state.

수질모델의 시스템 분석기법을 이용한 송지호의 수질관리방안 연구

이용석,김동진 한국자연보호학회 2012 한국자연보호학회지 Vol.6 No.2

Songji lagoon, one of the major lagoons located along the East coast, is considered to be worth preserving because of its good water quality. To consider ways to manage the water quality of Songji lagoon, this study was conducted by employing the analysis technique for system analysis of the water quality model. This study used WASP model which is a model with hydraulic part and water quality part combined. The model for Songji lagoon used the same value as the coefficients of water quality reaction used for Hwajinpo model. And it was revised and verified with the water quality measured in Songji lagoon. The spatial concentration of water quality of Songji lagoon and Hwajin po exhibited different distribution respectively, yet showing a similar characteristic in physical and water side structure. The major water quality items used in system analysis are BOD, limiting nutrients (N, P). The principal conditions reflected the system analysis are an increase or decrease of Allochthonous pollution load and removal of sediment. The study results show that the water quality of Songji lagoon is considerably changed more in sediment than Allochthonous pollution load. Especially, the management of Nonpoint pollution due to a temporary rainfall is more important among allochthonous pollution load.

Holocene salinity fluctuations of the East Korean lagoon related to sea level and precipitation changes

Katsuki, Kota,Nakanishi, Toshimichi,Lim, Jaesoo,Nahm, Wook‐,Hyun Blackwell Scientific 2017 The island arc Vol.26 No.6

<P><B>Abstract</B></P><P>Detailed diatom records within core sediments from Maeho Lagoon along the Eastern coast of South Korea revealed that the ecological dynamics of the lagoon during the Holocene were associated with relative sea level and regional precipitation. Accelerator mass spectrometry (AMS) <SUP>14</SUP>C dating indicates that sediment accumulation began prior to 8300 cal. year BP, and that the lagoon formed around 8000 cal. year BP. The salinity level of the lagoon increased until 5000 cal. year BP, and then decreased. Long‐term trends in salinity were dependent upon changes in sea level: periods of high salinity in the lagoon were generally coincident with periods of high sea levels along the east coasts of Korea and Japan. On the other hand, multicentennial‐scale fluctuations in diatom assemblages and magnetic susceptibility (MS) suggest that a 400 year fluctuation in salinity was regulated by changes in precipitation in the area of this lagoon. Changes in the westerly jet stream, controlled by variation in solar irradiance, had an important influence on precipitation volume in South Korea, suggesting that the patterns of the westerly jet stream fluctuate on a 400 year cycle.</P>

동해안 석호 담염수 혼합대에서 지하수와 지표수 상호작용의 수리지질학적 특성 평가

전우현,김동훈,이수형,황세호,문희선,김용철,Jeon, Woo-Hyun,Kim, Dong-Hun,Lee, Soo-Hyoung,Hwang, Seho,Moon, Hee Sun,Kim, Yongcheol 한국지하수토양환경학회 2021 지하수토양환경 Vol.26 No.6

This study examined hydrogeological characteristics of groundwater and surface water interaction in the fresh-saline water mixed zone of East Coast lagoon area, Korea, using several technical approaches including hydrological, lithological, and isotopic methods. In addition, the fresh-saline water interface was evaluated using vertical electrical conductivity (EC) data. For this purpose, three monitoring wells (SJ-P1, SJ-P2, and SJ-P3) were installed across the Songji lagoon at depths of 7.4 to 9.0 m, and water level, EC, and temperature at the wells and in the lagoon (SJ-L1) were monitored using automatic transducers from August 1 to October 21, 2021. Isotopic composition of the groundwater, lagoon water, and sea water were also monitored in the mid-September, 2013. The mixing ratios calculated from oxygen and hydrogen isotopic composition decreased with increasing depth in the monitoring wells, indicating saline water intrusion. In the study area, the interaction of groundwater-surface water-sea water was evident, and residual salinity in the sedimentary layers created in the past marine environment showed disorderly characteristics. Moreover, the horizontal flow at the lagoon's edge was more dominant than the vertical flow.