• Title/Summary/Keyword: BRACKISH WATER AREA

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Overview of the Fisheries and Aquaculture Resources in the Democratic Republic of Congo

  • Ekoma, Christian Ngunda;Mangala, Rapael Bukura
    • Journal of Marine Bioscience and Biotechnology
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    • v.3 no.1
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    • pp.13-17
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    • 2008
  • The Congo has a maritime coastline of 40 km, covering an area of $2,345,409km^2$. The fluvial system covers around $34,000km^2$ in a network of more than 33,000 km of rivers, principal tributaries, and streams. There are around 1,000 known species of fish, essentially freshwater and some brackish. The lakes of the Rift Valley contain the richest lacustrine fauna in the world. The family of Cichlidae alone has more than 900 species. At the same time, the lakes are profoundly different. Lake Tanganyika has 250 species of fish, of which 216 are endemic, whereas Lake Kivu contains only 32 and 16, respectively. A dense hydrographic network of water surfaces, inundated plains and lakes cover around $86,080km^2$ (3.5% of the national area) and have a considerable aquatic potential. The large peripheral lakes of the East cover around $48,000km^2$ of which 47% are under Congolese jurisdiction. The respective areas belonging to the Congo are: Lake Tanganyika, $14,800km^2$; Lake Albert, $2,420km^2$; Lake Kivu, $1,700km^2$; Lake Edward, $1,630km^2$; Lake Mo$\ddot{e}$ro, $1,950km^2$. Another two important lakes in the interior, Lake Tumba and Lake Mai-Ndombe, cover (between them) 2,300 and $7,000km^2$, depending on season (less in the dry season and more in the rainy season). There are also the lakes of the Kamalondo depression ($6,256km^2$), Lake Tshangalele ($446km^2$) and Lake N'Zilo ($280km^2$).

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Seasonal Variation in Species Composition of Fish in the Estuary of Saemangeum Waters during the Construction of a Dike in 2001-2002 (방조제 건설 중인 2001-2002년 새만금 하구역 어류 종조성의 계절 변동)

  • LEE Tae Won;MOON Hyung Tae;KIM Gwang Cheon
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.36 no.3
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    • pp.298-305
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    • 2003
  • Seasonal variation in species composition of fish in the estuary of Saemangeum water in the western coast of Korea was determined using seasonal samples collected by an otter trawl from April 2001 to February 2002. Species compositions did not differ significantly among the 4 stations (p>0.05, Wilcoxon signed-rank test). The cumulative number of species and species diversity (H') approached asymptote after four 30-min trawl hauls. Therefore 30-min trawl samples from each of the four stations were pooled to represent each season. A total of 45 species 2758 individuals and 30,346.8 g of fish were collected during the study period. Of the fish collected Leiognathus nuchalis, Synechogobius hasta, Neosalanx jordani, Konosirus punctatus and Chaeturichthys stigmatias predominated in abundance accounting for $68\%$ of the total number of individuals. Seasonal variation of fish abundance showed a similar trend to those of the other western coastal waters of Korea. The resident species were collected only in spring and autumn. Number of species and biomass were highest in summer due to the catch of many migrating species. In winter catch amount was low, and only 7 species were collected.. Brackish water fishes were more abundant in the study area, and Johnius grypotus and Cynoglossus joyneri were not premominated compared to the other coastal waters. This difference in species compositions may be related to the lower salinity in this estuarine habitat than in the other western coastal waters of Korea.

Ecological Stability of the Shihwa Lake Evaluated by Zooplankton Distribution in the Lake Shihwa and Adjacent Coastal Area (시화호와 인근 해역의 동물플랑크톤 분포로 본 시화호의 생태적 안정성)

  • Park, Chul;Huh, Sung-Hoi
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.2 no.2
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    • pp.87-91
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    • 1997
  • Ecological stability of the Lake Shihwa, artificially made by the construction of the Shihwa Dike, was evaluated by the species composition and variation in biomass of zooplankton. Species composition and seasonal variation in biomass in the seaside stations were similar to those observed in nearby bays and coastal zone. However, those in the lake sites showed very different patterns. The brackish water copepod, Sinocaianus tenellus, held the first rank in every season (with more than 66% in spring, 98% in summer and fall, and 80% in winter). The species composition was very simple and the biomass (in terms of total individuals $m^{-3}$) varied markedly with season up to the order of $10^4$ magnitude. These results imply that the lake ecosystem made by the construction of Sihwa dike is in very unstable stage probably due to the input of industrial wastes as well as unpredictable variation in salt content caused by irregular control of the watergate of the dike and resultant irregular flow direction of the water through the gate.

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Benthic Macroinvertebrates and Environmental Characteristics of Madongho Wetland (마동호습지의 저서성 대형무척추동물과 환경특성)

  • Hyeon-Woo Han;Seung-Hyeon Lee;Chun-Sik Yoon;Sung-Jin Hong;Seon-Woo Cheong
    • Journal of Environmental Science International
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    • v.33 no.2
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    • pp.139-160
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    • 2024
  • The community structure of benthic macroinvertebrates in the Madongho Wetland protected area and inflow river located in Goseong-gun, Gyeongsangnam-do, was investigated in 2022 and 2023. We collected and identified 3,582 individuals belonging to 7 classes, 23 orders, 51 families, and 78 species over the 2 years from six sites. Gnorimosphaeroma naktongense was the dominant species with a ratio of 20%, and Caridina denticulata denticulata was the subdominant species with a ratio of 13.32%. Predators and gathering collectors were the most abundant in the functional feeding group, while sprawlers were the most diverse and numerous in the habitual dwelling group. Diversity, richness, dominance, and evenness were calculated as the biological indices. In addition, various biological water quality indices were calculated. Most insects in the inflow rivers belonged to group I in evaluating relative resistance and resilience, showing high colony stability. The results of analyzing the correlation between salinity and substrate particle size with brackish water species showed that Gnorimosphaeroma naktongense and Hediste japonica had a significant positive correlation with salinity, while Assiminea lutea and Neomysis awatschensis had a significant positive correlation with substrate particle size. Additionally, Sinelobus kisui was found to be a new record of Korean Tanaididae in this study.

Ecological Motif on the Salt-Water Plants of Brackish Area in Buandam (부안댐 기수역내부의 염생식물에 관한 생태적 주제성)

  • Oh Hyun-Kyung;Beon Mu-Sup;Lee Myung-Woo;Whang Bo-Chul
    • Korean Journal of Environment and Ecology
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    • v.20 no.3
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    • pp.311-318
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    • 2006
  • In an estuary, ecological dynamic is modified for a long time and memorized in soils and landscapes. As landscape memory, ecological motif is defined with dominance and rarity of vegetation. The purpose of the study is to investigate the existing vegetation character and to propose the ecological motif of this area. The present salt-water plants, community species composition and constancy degree around the estuary in Buandam watershed Buan-gun, Jeollabuk-do were analyzed. The results are as follows. The flora of the salt-water plants was listed as 16 taxa; 6 families,13 genera,14 species and 2 varieties. 5 taxa were Gramineae, 4 taxa Chenopodiaceae, and 4 taxa Comrositae. The salt-water plant communities are a total of 10 communities as listed; Zoysia sinica-Artemisia scoparia community, Phacelurus latifolius community, Artemisia scoparia Cnidium japonicum community, Limonium tetragonum -Artemisia scoparia community, Artemisia scoparia community, Suaeda japonica community, Elymus dahuricus community, Suaeda asparagoides community, Zoysia sinica community, and Zoysia sinica-Suaeda japonica community. Analyzed by the community classification species class of constancy degree, Phacelurus latifolius, Cnidium japonicum, Limonium tetragonum, Suaeda japonica, Elymus dahuricus and Suaeda asparagoides belong to I, Zoysia sinica and Artemisia scoparia to II. Elymus dahuricus, Setaria viridis var. pachystachys, Echinochloa crusgalli var. oryzicola, Phacelurus latifolius, Atriplex gmelini, Salicornia herbacea, Calystegia soldanella and Aster tripolium belong to the accompaniment species to I: Zoysia sinica, Suaeda asparagoides, Artemisia capillaris to II; Suaeda japonica, Artemisia scoparia to III ; Cnidium japonicum to IV: Limonium tetragonum, Artemisia fukudo to V. And the ecological motif is the Phacelurus latifolius community.

Effects of Landscape Ecological Characteristics on Bird Appearance - Focused on The Nakdong River Estuary - (경관생태학적 특성이 조류출현에 미치는 영향 - 낙동강 하구를 대상으로 -)

  • Kim, Bum-soo;Yeo, Unsang;Oh, Dongha;Sung, Kijune
    • Journal of Environmental Impact Assessment
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    • v.24 no.3
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    • pp.287-299
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    • 2015
  • If the Nakdong River estuary is to be sustainable, land use management practices need to consider bird habitat requirements, especially given that the area serves as an important migratory bird sanctuary. In this study, bird habitats found in the Nakdong River estuary were classified into 11 different types including Phragmites australiss, mud flat, farmland, open surface in freshwater, sand bar, riparian forest, Scirpus planiculmis, waterway, construction, grasslands, and open surface in sea or brackish water. Taking into consideration the regional characteristics, habitat properties, and landscape indices, a total of 12 study sites were analyzed. Mud flat, construction, farmland, and P. australis account for 80% of the total land area. The high area ratio of construction and farmland to other types of habitat revealed a high amount of historical human activity and intervention in the area. Both patch numbers as well as patch density were high in West Nakdong River, Samrak Waterfront, Maekdo River, and Daejeo Floodgate, with these areas showing the greatest fragmentation as well. Total numbers of species and individuals had a positive correlation with the area and the number of habitat types. Findings suggest that protecting the habitat area, especially in S. planiculmis, is the most important factor for bird habitat management and that future development could result in habitat loss, having a profoundly adverse impact on bird populations. Therefore, it is important that the total area should be carefully protected by land use regulations in order to ensure that the Nakdong River estuary maintains its functional integrity as a migratory bird sanctuary.

Minor Siliceous Microfossil Group and Fossil Cysts from the Yeonil Group (Tertiary) in the Northern Area of the Pohang Basin, Kyeongbuk Province, Korea (경북 포항분지 북부 지역의 연일층군(제3기)에서 산출되는 포낭류 화석을 비롯한 소수 규질 미화석군에 대한 연구)

  • Koh, Yeong-Koo
    • Journal of the Korean earth science society
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    • v.27 no.1
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    • pp.95-117
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    • 2006
  • From the Tertiary Yeonil Group distributed in Songra and Cheongha areas, the northern part of the Pohang Basin, nine archaeomonad species belonging to two genera, and other three types of chryophycean cysts considered as stomatocysts, five endoskeletal dinoflagellate species belonging to three genera and eighteen ebridian species belonging to eleven genera were identified. Based on above siliceous microfossil assemblages, the Yeonil Group is corresponded to Middle Miocene age. The group is correlated with the Calvert Formation (Maryland in USA) and the Hojuji Formation (in Central Japan) by its archaeomonad cysts. And, the group is correlated with the intervals of Actiniscus elongatus to Middle Hermesinella conata zones in Southwest Pacific region and of Spongebria miocenica to Middle Hermesineila schulzii zones in $V{\o}ring$ Plateau, Norwegian Sea, based on the ebridian assemblages of the group. From the chrysophycean cyst including archaeomonad, endoskeletal dinoflagellate and ebridian assemblages in the Yeonil Group of the study area, it is inferred that cold water masses dominated during the deposition oi the group with occasional warm water. The upper part of the group might be somewhat colder than the lower one of the group in depositional condition. In addition, minute chrysopycean cysts considered as stomatocysts suggest the influence of fresh or brackish water during the deposition of the group.

Studies on Intestinal Trematodes in Korea XI. Two Cases of Human Infection by Heterphyes heterphyes nocens (한국의 간흡충에 관한 연구 XI. Heterophyes heterphyes nocens의 인체감염 2례)

  • 채종일;서병설이순형
    • Parasites, Hosts and Diseases
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    • v.22 no.1
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    • pp.37-42
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    • 1984
  • Two human cases of Heterophyes heterophyes nocens infection were proved by identifying adult worms after treatment with bithionol or praziquantel in 1983 in Korea. They are 37 (Case 1) and 24-year old (Case 2) males whose resi¬dence or native village is a southern coastal area in Kohiing-gun, Chollanam-do. The Case 1 had the gastrointestinal symptoms such as epigastric pain and indigestion, and the Case 2 heart problems such as arrhythmia and ventricular premature beat in EKG and digestive symptoms such as diarrhea and abdominal pain. After the treatments, 35 and 67 specimens of H. hetero¬phyes nocens respectively were collected from the diarrheal stools through stereomicroscopy. The Case 1 was concommitantly infected with Clonorchis sinensis and the Case 2 with 3 other kinds of heterophyid flukes and with Diphyllo¬bothrium latum. The cases said to have eaten raw brackish water fish such as mullets (Mugil cephalus), perches (Lateolabrax japonicus) and gobies (Acanthogobius flavimanus) which are the intermediate hosts of H. heterophyes nocens in Korea.

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Environmental Factors and Phragmites Distribution at Various Habitats in Eulsukdo Ecological Park (을숙도 생태공원내 서식지별 환경요인과 갈대분포 특성)

  • Chung, Yong Hyun;Sung, Kijune;Kang, Daeseok;Lee, Suk Mo;Park, Soyoung
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.11 no.3
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    • pp.50-61
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    • 2008
  • Environmental factors and phragmites growth properties at various habitats in Eulsukdo ecological park were investigated to understand major factors affecting phragmites distribution in constructed wetlands. Although phragmites is very important species in wetland ecosystem, it should be controlled to prevent excessive expansion within the restricted park area. The results showed that phragmites dominant sites have the highest LAI among other emerged plants habitats and could adversely affect for waders habitats. Phragmites were also found at the areas with wide ranges of water-depth than other plants, and showed phragmites could be favored for occupying the newly constructed wetlands like Eulsukdo ecological park. The results showed difference in soil redox potential between phragmites dominant and non-dominant sites. Because soil redox potential is affected by wetland hydrology like flooding duration, control of wetland hydrology should be considered for creation and management of constructed wetlands. The results also showed that differences in soil cation exchange capacity, soil salinity, soil organic matter content and site inclination between phragmites dominant and non-dominant sites as well as brackish and freshwater areas. Those abiotic factors can be important considerations for the sustainable wetland management especially for the phragmitest managements in the ecological park.

Prevalence and Seasonal Abundance of the Dominant Mosquito Species in a Large Marsh near Coast of Ulsan (울산 해안의 습지 주위에 서식하는 주요 모기의 발생 소장)

  • 정영석;이동규
    • Korean journal of applied entomology
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    • v.42 no.2
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    • pp.125-132
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    • 2003
  • Seasonal fluctuations in density of mosquito species were investigated at two cow sheds near to a large, reedy marsh with fairly polluted brackish water near the coast of Yongam-ri, Cheongryang-myon, Ulsan, Korea. Female mosquitoes were collected biweekly using Nozawa light traps from March to September, from 1999 to 2001. On average, 4,416.1, 5,505.9 and 6,863.8 females per trap night were collected from 10 species in 5 genera in 1999, 2000 and 2001, respectively. Among them, An. sinensis was most abundant (53.4% in species ratio), followed by Cx. tritaeniorhynchus (43.0%), Cx. inatomii (1.6%), Ochlerotatus dorsalis (1.3%) and Cx. pipiens pallens (0.5%). A malaria vector, An. sinensis and a Japanese encephalitis vector, Cx. tritaeniorhynchus were collected 3,663.3 females and 3,142.5 females per trap night from June to September for the years, respectively. According to the biweekly population changes at the area, Cx. inatomii which was dominant species in 1997, was the most abundant in the early July during 1999-2001.