• 한국수산과학회지
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• 제2권1호
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• pp.71-82
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• 1969

The present investigations were carried out with the purpose of making clear the fundamental features of the seasonal variations in chemical composition of the brown algae. Three species of samples, Ecklonia cava, Sargassum sagamianum and Hizikia fusiforme have been analyzed monthly for their contents of total ash, crude protein, alginic acid, mannitol, and laminarin over a year period. Three kinds of samples were collected from the same locality, situated on the southern coast of the Che-ju Island, from September 1966 to August 1967. In addition, the comparative analysis was made on fronds and stipes of the plant for their chemical composition. The results obtained are summarized as follows: 1, In general, the three species examined underwent a similar mode of seasonal variation, and no essential difference was detected among them. 2. The chemical composition of the plant exhibited a considerable difference between the species. The content of total ash in H. fusiforme was remarkably higher than those in the two other species respectively. The alginic acid content was relatively high in S. sagamianum and low in H. fusiforme. The contents of crude protein, mannitol and laminarin were appreciably high in E. cava and low in H. fusiforme in general. 3. The most outstanding feature in the seasonal variation was that, in general, the total ash, crude protein, and alginic acid contents were at a maximum in the winter months while laminarin and mannitol contents were at a minimum. The converse was true in summer. Total ash-Maximum values were observed from December to February and minimum from August till October. Crude Protein-All species exhibited maxima in January and February, and minima from August to October. Alginic acid-Maximum contents occured from January to March and minimum from September to November. Mannitol-The maximum content of mannitol was In May and lune and minimum in January, February and March. Leminerin-Maximum content was in September and October, and minimum in January and February. 4. The wide seasonal variation in chemical constitution occured in the fronds, but the stipes showed a slight seasonal variation. In the chemical composition, the stipe was high in alginic acid, low in mannitol and laminarin. The reverse was in the frond.

• 한국해양학회지:바다
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• 제16권4호
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• pp.246-253
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• 2011

낙동강 하구역에서 홍수기 전후에 저서동물군집 영향을 알아보기 위한 조사에서, 저서환경은 대부분 지역에서 사질 퇴적상이 우세하였으며, 일부 수로 지역에서 복잡한 퇴적상을 나타냈다. 홍수기 방류에 의한 공간에 따른 퇴적상 변화는 관찰되지 않았으며, 홍수기 이후 하구역 상부에서 유기물이 소량 증가하였다. 저서생물 종조성은 공간적으로 차이를 보였는데, 홍수기 이후에 배수갑문 근처 지역에서 종조성이 감소하였다. 군집분석 결과는 3개 군집구조가 나타났으며, 하구역 하부에 위치한 사주를 기준으로 공간적 구배를 나타냈다. 사주 상부에는 Sinocorophium sinensis, Magelona japonica, Heteromastus filiformis 등 유기오염 기회종들이 우점하였다. 기회종이 디수 출현한 것은 낙동강 하구둑 주변에 서식하는 저서동물이 방류로 인한 유기물 유입 영향에 따른 것으로 해석되며, 방류로 인한 영향은 방조제 부근에서 사주지역까지 나타났고, 사주 바깥지역은 대량방류로 인한 저서동물의 종조성 변화는 관찰되지 않았다.

• 수산해양기술연구
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• 제43권4호
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• pp.251-260
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• 2007

A species composition and population structure of fish, collected 16 times by bottom otter trawl in the coast of Geumo Island, from February 2002 to November 2005, was investigated. The fish species caught by bottom otter trawl from year 2002 to 2005 was entirely 72 species, 41 classes, and 12 orders, and the number of appearance and biomass was 5,999 individuals and 287,902.1g, respectively, being of the Perciformes(31 species and 19 classes; 43.1% in total number of species appeared) as a dominant species. 638 individuals of Leiognathus nuchalis which was 10.6% in total fish were appeared and 465 individuals of Konosirus punctatus(7.8%), 449 individuals of Engraulis japonicus(7.8%). biomass of Sebastes schlegeli was 33,258.7g as a dominant species(11.6% in total fish appeared) and 18,821.1g of Liparis agassizii(6.5%), 16,708.0g of Konosirus punctatus(5.8%). The diversity index of species per months of the collected by a small otter trawl in coastal water of Geumodo from year 2002 to 2005 was 2.860-3.639 and the evenness index was 0.825-0.887 in case of dominance index was 0.224-0.268 against the evenness index. The similarity of community structure per yearly was very high because of the relative difference(0.006), which was the least in 2004 and 2005.

• 한국수산과학회지
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• 제38권1호
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• pp.20-28
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• 2005

Species composition and seasonal variation of decapod crustacean assemblage in Hampyeong Bay, Korea were examined. Sampling was monthly made by a shrimp trawl between March 2003 to February 2004. A total of 39 species of 20 families were collected. Of these, Latreutes planirostris, Palaemon gravieri, Parapenaeopsis tenella, Exopalaemon carinicauda, Charybdis japonica, Trachysalambria curvirostris and Palaemon macrodactylus were dominant species comprising $84.3\%$ of the total number of individuals. Charybdis japonica, P. gravieri, Oratosquilla oratoria, E. carinicauda, T curvirostris, Metapenaeus joyneri and P. tenella represented $90.6\%$ of the total biomass. While total abundance (number of individuals) was high in spring, total biomass and species richness (number of species) and diversity were high in summer. Cluster analysis, based on monthly abundance data of the 14 most common species, showed that the species were separated into three different groups. Group A composed of Leptochela gracilis, Alpheus japonicus, Crangon uritai, P. macrodactylus, E. carinicauda, P. gravieri, O. oratoria, C. japonica, which were year round residents, group B M. joyneri, T. curvirostris and P. tenella, which were abundant in summer, and group C Crangon hakodatei, Latreutes anoplonyx and L. planirostris, which were abundant in winter. Principal component analysis revealed that seasonal variation in the decapod crustacean assemblage was attributed to the abundance of temporal species such as penaeid shrimps, which were abundant in summer, due to seasonal variation of water temperature and reproductive pattern.

• 수산해양기술연구
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• 제59권3호
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• pp.196-205
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• 2023

This study investigated the species composition and bycatch status of fishes by fyke net between June and November 2020 in Asanho lake and Chungjuho lake. During the survey period, the catches in Asanho lake were identified as 2,931 individuals of 16 species from a total of six families and in Chungjuho lake were identified as 1,645 individuals of 14 species from a total of eight families. The dominant species in Asanho lake was Erythroculter erythropterus which accounted for 59.6% of the the total number of individuals and 40.5% of the total biomass caught. The dominant species in Chungjuho lake was Lepomis macrochirus which accounted for 48.2% of the the total number of individuals and Erythroculter erythropterus which accounted for 60.2% of the total biomass caught. The bycatch rates of non-commercial species in Asanho lake and Chungjuho lake were 77.0% and 82.6%, respectively. As a result of analyzing the frequency distribution of the total length of Carassius auratus and Siniperca scherzeri, which were the dominant species among commercial species, the bycatch rate of small individuals was 87.1%, and 42.7%, respectively.

• Fisheries and Aquatic Sciences
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• 제26권8호
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• pp.470-481
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• 2023

Algal overgrowth in shrimp culture ponds can affect the quality of the aquatic environment, thereby adversely affecting the shrimp and causing economic losses. The objective of this study was to evaluate the variation in phytoplankton composition in intensive shrimp ponds in Bac Lieu province, Vietnam. Phytoplankton samples were collected in three black tiger shrimp (Penaeus monodon) ponds and three whiteleg shrimp (Litopenaeus vannamei) ponds. The collected data were analyzed using SPSS and canonical correlation analysis softwares. In total, 75 species of phytoplankton were recorded in black tiger shrimp ponds and 64 species in whiteleg shrimp ponds. Diatoms had the highest species diversity with 29-30 species (39%-47%), followed by green algae with 9-19 species (14%-25%); species numbers of other phyla varied from 5-12 (8%-16%). The total number of phytoplankton species throughout the study varied from 34-50 species. Algal density was relatively high and ranged from 497,091-2,229,500 ind./L and 1,301,134-2,237,758 ind./L in black tiger shrimp and whiteleg shrimp ponds, respectively. The diatom density tended to increase during the final stage of the production cycle in black tiger shrimp ponds. Blue-green algae and dinoflagellates also increased in abundance at the end of the cycle, which can affect shrimp growth. Diatoms were significantly positively correlated with pH, salinity, total ammonia nitrogen, and nitrate (NO₃^-) concentrations (p < 0.05). Blue-green algae and dinoflagellates were positively correlated with salinity, phosphate (PO₄^3-), and NO₃^-. Algal species diversity was lower in the whiteleg shrimp ponds than in the black tiger shrimp ponds. Several dominant algal genera were recorded in the shrimp ponds, including Nannochloropsis, Gyrosigma, Chaetoceros, Alexandrium, and Microcystis. The results of this study provide basic data for further investigations, and they contribute to the management of algae in brackish-water shrimp ponds.

• Journal of Ecology and Environment
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• 제48권1호
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• pp.60-73
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• 2024

Background: The available information on terrestrial pest gastropods and their impact on the environment worldwide is scarce and outdated. The present study aimed to address this gap by conducting the first comprehensive survey of pest gastropods in the Nuwara Eliya District, an important vegetable growing area in the highlands of Sri Lanka. Eighty agricultural lands were surveyed over two years by establishing ten 1 m2 sampling plots per crop type in each agricultural land. Geo-coordinates, air temperature, elevation, relative humidity, daily rainfall, soil pH, species richness and abundance were recorded for rainy and non-rainy periods. The relationship between species composition and environmental variables was analyzed using multi-regression models and distribution maps. Results: Out of the 14 species recorded in agricultural lands, nine were identified as exotic pest species. Species abundance (t = 4.69, p < 0.05) and diversity was higher in the rainy period and the dominant species during this period were Bradybaena similaris (t = 2.69, p < 0.05) and Deroceras reticulatum (t = 2. 46, p < 0.05). Eggs and estivating adults were found in soil and under decaying organic matter during the non-rainy period. The exotic species showed broader preferences for the measured environmental factors and showed a wider range in distribution compared to the native species. Variation in pest gastropod composition was significantly accounted for by elevation, relative humidity, soil pH and daily rainfall. Additionally, the species richness and abundance varied across locations due to the combined effects of elevation, crop type and stage, and field type. Conclusions: The study emphasizes the importance of understanding the biology and ecology of gastropod pests to develop effective management strategies. By considering the influence of environmental factors and implementing appropriate soil management techniques, such as targeting specific habitats and crop stages, it is possible to mitigate pest populations and minimize their impact on agricultural lands. Overall, this research contributes valuable insights into the dynamics and interactions of terrestrial gastropods in agricultural ecosystems, supporting sustainable pest management practices.

• Fisheries and Aquatic Sciences
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• 제24권9호
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• pp.297-310
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• 2021

The rockworm gut flora was identified at each growth stage to elucidate the composition of the bacterial community. The source material was Marphysa sanguinea fed regular feed and fed biofloc at the adult stage in parallel. The systematic bacterial community composition was determined based on the next-generation sequencing method, and alpha diversity and beta diversity were conducted to access the species diversity within and between the bacterial communities, respectively. The composition of the gut flora changed considerably as the rockworms developed. The shift in the gut flora was confirmed at the phylum, family, and genera level of the bacterial communities. The Vibrio species associated with high rockworm mortality occupied 7.7% of the gut flora at the larval stage; however, they disappeared in the healthy adult gut. Moreover, different gut flora was observed between adults fed regular feed and those fed biofloc. Specifically in the biofloc-fed adult gut, several immune relevant and water-purifying bacteria were detected. The biofloc-fed adult gut flora could decompose and mineralize organic sediment, and thus be effectively utilized for integrated multitrophic aquaculture. The Venn diagram revealed that only two bacterial species were shared throughout all growth stages, and the biofloc-fed adults exhibited the highest diversity within the bacterial community.

• 한국수산과학회지
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• 제54권4호
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• pp.498-507
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• 2021

Ichthyoplankton (fish eggs and larvae) were collected seasonally collected from 2017 to 2019 to clarify whether Dokdo serves as a fish spawning and/or nursery ground. Fish eggs were identified and classified into 16 species. The dominant fish egg species were Engraulis japonicus, Maurolicus japonicus, and Parajulis poecilepterus. Fish larvae were identified and classified into 15 species. The dominant fish larvae species were E. japonicus, M. japonicus, and Sebastes owstoni. A cluster analysis similarity percentages revealed two distinct groupings according to sample location (stations) with E. japonicus and M. japonicus as the main group influencers. E. japonicus was the dominant species off Dokdo. The species diversity and abundance peaked in summer. The diversity index, richness index, and evenness index fluctuated seasonally. There were no predominant species variations among the years. Sedentary species such as P. poecilepterus, Semicossyphus reticulatus, and Glyptocephalus stelleri occurred in the inshore stations. E. japonicus, M. japonicus, and Trachipterus trachypterus occurred in the offshore stations. Our results show these species use Dokdo as spawning and nursery grounds.

• The Korean Journal of Ecology
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• 제20권1호
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• pp.27-33
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• 1997

Species composition and the amount of nutrients absorbed by regenerating plants on a pine forest in the immediate postfire year were compared with those in an unburned pine forest in Kosung, Kangwon Province. Pteridium aquilinum var. latiusculum, Cyperus amuricus, Lespedeza biolor, Quercus serrata, Lysimachia clethroides were the most abundant species in burned area. In unburned area. Quercus mongolica, Rhododendron mucronulatum, Carex humilis, Rhododendron schlippenbachii, Spodiopogon sibiricus were the most abundant species. Standing biomass of understory vegetation in burned and unburned area was 170.2 g $D.W/m^2$ and 171.3g $D.W/m^2$, respectively. Nutrient concentrations of plants in burned area, especially for phosphorus and potassium, were higher than those in unburned area. The amounts of nutrients absorbed by understory plants in burned and unburned area were 37.4 and 33.6 kg/ha for N, 0.36 and 0.19 kg/ha for P, 30.6 and 18.8 kg/ha for K, 8.5 and 7.8 kg/ha Ca, 5.2 and 5.7 kg/ha for Mg, respectively. This suggests that regenerating vegetation can hold the significant amount of nutrients, although there may be considerable losses of nutrients from ecosystem after fire.