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거북등윤충(Keratella) 피갑 형태의 연도 및 계절별 변화
라긍환 ( Geung Hwan La ),최지민 ( Ji Min Choe ),김현우 ( Hyun Woo Kim ) 한국하천호수학회(구 한국육수학회) 2009 생태와 환경 Vol.42 No.2
낙동강 물금 지역에서 채집된 동물플랑크톤 중 윤충류인 Keratella 속을 대상으로 10년 전후(1995, 1997, 2005 그리고 2007)의 종조성 변화를 분석하고, 피갑형태에 다양한 변화를 보이는 K. cochlearis의 피갑 크기, 후돌기의 발현 여부 및 길이 그리고 후두돌기 길이의 연도와 계절에 따른 변화를 측정하였다. Keratella 속의 밀도는 봄에 높고 겨울에 낮은 뚜렷한 계절성을 보였다. 군집 내에서 K. cochlearis가 우점종이었으며 상대풍부도는 1995년과 1997년보다 2005년과 2007년에서 높게 나타났다. 연도별 K. cochlearis의 피갑 폭은 유사하였으나, 피갑 길이의 경우 여름에 감소하고 겨울에 증가하는 특징을 보였다. 모든 연도에서 후돌기를 발현하는 개체의 비율이 낮았고 특히 여름과 가을에 출현빈도가 낮았다. 후돌기의 평균 길이는 여름에 짧고 겨울에 길었으며 후두돌기 평균 길이는 겨울에 가장 짧은 것으로 나타났다. We investigated annual and seasonal changes of Keratella spp. among rotifer community in the lower part of the Nakdong River (Mulgum) for four years (1995, 1997, 2005, 2007). As well, the annual and seasonal variations of lorica morphologies including sizes, posterior and anterior spines lengths in K. cochlearis were analyzed. The density of Keratella spp. showed distinct seasonality such as spring peak and winter scarcity. K. cochlearis was the most dominant species within Keratella spp. and the relative abundances of 2005 and 2007 were higher than 1995 and 1997. The lorica length and width of K. cochlearis did not show the annual changes between four years however, there was an obvious width decrease in summer and increase in winter. The proportion of individuals that has the posterior spine was relatively low throughout four years, especially at summer and autumn. K. cochlearis displayed short posterior spine in summer and long posterior spine in winter contrary to the anterior median and intermediate spines.
최종윤,조현빈,김성기,라긍환,주기재 한국환경생태학회 2015 한국환경생태학회지 Vol.29 No.3
얕은 습지에서 환경 요인에 대한 어류의 분포와 종 조성을 평가하기 위해, 2012년 봄철(5~6월)에 경상남도에 위치한 24개의 습지에서 이화학적 요인, 수생식물, 어류 등을 조사하였다. 조사 기간 동안 20종의 어류가 동정되었으며, 잉어과 어류가 가장 우점하는 것으로 나타났다. 이화학적 요인 및 수생식물 생물량은 조사 지점에 따라 상이하였으며, 특히 수생식물 생물량은 어류 풍부도와 매우 밀접하게 관련되었다(df=1, F=32.00, P=0.001). 조사 지점간에 군집분석을 수행한 결과, 조사 지점들은 3개의 집단으로 구분되었으며, 이 또한 수생식물 생물량에 대한 영향으로 분석되었다. 첫 번째 집단의 습지에서는 검정우럭과 어류인 블루길에 의해서 우점되었으며, 그 외 어류 군집은 거의 출현하지 않았다. 두 번째 집단은 주로 잉어과 어류인 붕어가 우점한다는 점에서 첫 번째 집단과 차이를 보였다. 세 번째 집단에 속한 습지에서는 첫 번째 집단과 비슷하게, 블루길이 우점하였으나, 다른 어류 종 또한 다양하게 출현하였다. 결론적으로 얕은 습지에서 어류 군집의 분포와 종 다양성은 수생식물의 생물량에 의해 강하게 영향 받는 것으로 평가되었으며, 수생식물의 높은 생물량은 어류의 높은 풍부도 유지에 크게 기여하였다. 이러한 관점에서 습지를 복원하거나 새롭게 조성할 때 수생식물의 적절한 식재는 어류의 종 다양성에 영향을 줄 것으로 보이며, 어류가 수생태 먹이망 내에서 최상위포식자로서의 역할을 한다는 점을 감안할 때 먹이망의 건강성 유지에도 필수적일 것으로 사료된다. In order to investigate the distribution and species composition of fish in shallow wetlands that might be affected by environmental factors, we investigated the physicochemical parameters, macrophytes biomass, and fish assemblage in 24 shallow wetlands in South Korea from May to June, 2012. In this study, a total of 20 fish species were identified, and Cypinidae were found to be the most dominant species. Physicochemical parameters and macrophyte biomass were different in the survey sites, and macrophytes biomass, in particular, showed a positive relationship with fish abundance in stepwise multiple regression (df=1, F=32.00, P=0.001). According to the result of the cluster analysis between survey sites, the survey sites were divided into three groups in accordance with species composition of fish in relation to macrophytes biomass. In the wetlands of the first group, Lepomis macrochirus which belongs to Centrarchidae was found to be dominant and other fish assemblages were hardly seen. In the second group, unlike the first group, Carassius auratus that belongs to Cypinidae was found to be dominant. In the third group, Lepomis macrochirus was found to be as dominant as the first group but various other fish species appeared. Where there was abundance of the main food sources (i. e. zooplankton) of fish in the survey sites, there were more diverse macrophyte biomass. Consequently, it is proven that macrophytes strongly affect the species composition and abundance of fish, and high biomass of macrophytes support high assemblage of fish. Based on these results, we recommend establishing diverse aquatic macrophytes communities when restoring or creating wetlands to assure high diversity of fish species that use macrophytes as their habitat.
Spatial Dynamics of Diatom Community in the Mid to Lower Part of the Nakdong River, South Korea
김명철,라긍환,정광석,김동균,주기재 한국하천호수학회 2007 생태와 환경 Vol.40 No.4
Phytoplankton community dynamics were studied from 2004 to 2006 with two and four weeks interval at mid to lower part of the Nakdong River (Waegwan: RK 194, Goryeong: RK 157, Jukpo: RK 112, Namji: RK 75 and Hanam: RK 63: RK: distance from the Estuarine Barrage), South Korea. Annual averages of water temperature was about 16� � C, and dissolved oxygen was ranged between 10.0 and 11.5 mg L-1 (percent saturation, 106.5 to 112.8%). Diatoms were dominant group with over 60% of phytoplankton abundance in all study sites (Waegwan: 64%, Goryeong: 69%, Jukpo: 73%, Namji: 79%, and Hanam: 83%). However, the occasional dominances of other groups such as green algae and blue-green algae were observed from March to October. Stephanodiscus hantzschii was dominant species and the relative abundances were high at all study sites (48-72%). The ratio of S. hantzschii/total phytoplankton abundance were showed a clear increasing tendency toward the estuarine barrage: i.e. 0.31 at Waegwan, 0.39: Goryeong, 0.50: Jukpo, 0.56: Namji, 0.60: Hanam. The results of this study provide the information that the phytoplankton community structure in a regulated river system is basically affected by the physical properties such as water velocity and retention time, resulting in single species dominance by the stagnancy of river flow.
국내 남서부지역 호수 및 저수지 생태계의 플랑크톤 동태 변화
김현우 ( Hyun Woo Kim ),라긍환 ( Geung Hwan La ),정광석 ( Kwang Seuk Jeong ),박종환 ( Jong Hwan Park ),허유정 ( Yu Jung Huh ),김상돈 ( Sang Don Kim ),나정은 ( Jeong Eun Na ),정명화 ( Myoung Hwa Jung ),이학영 ( Hak Young Lee ) 한국환경생물학회 2010 환경생물 : 환경생물학회지 Vol.28 No.2
This study compares and contrasts the dynamics of plankton in 31 temperate lakes and reservoirs, and considers particularly the biomass ratio of zooplankton to phytoplankton and ecological model application. A total of 89 species of zooplankton were identified (70 rotifers, 14 cladocerans and 5 copepods) and a total of 554 species of phytoplankton were identified (176 Bacillariophyceae, 237 Chlorophyceae, 68 Cyanophyceae, and 73 other algal taxa). The total plankton abundance and species diversity were showed distinctive spatial and seasonal variation. Annual average phytoplankton density was 7,350±15,592 cells mL-1 (n=124), and the lowest was 855±448 cells mL-1 (n=4), while the highest was 72,048±13,4631 cells mL-1 (n=4). For zooplankton, small rotifer groups dominated the study sites, and approximately 3~10 species appeared in the study sites. Statistical analysis and an ecological model application revealed that the size of reservoirs affected the structure size of plankton community, i.e. relatively large number of species were found in smaller reservoirs. From this result, we can conclude that management strategy for the reservoir environment has to be focused more on small-size reservoirs, in terms of plankton community ecology.
국내 주요 강 생태계 내 동물플랑크톤의 탄소, 질소, 인 비율 해석
김현우 ( Hyun Woo Kim ),라긍환 ( Geung Hwan La ),정광석 ( Kwang Seuk Jeong ),김동균 ( Dong Kyun Kim ),황순진 ( Soon Jin Hwang ),이재용 ( Jaeyong Lee ),김범철 ( Bom Chul Kim ) 한국하천호수학회(구 한국육수학회) 2013 생태와 환경 Vol.46 No.4
The amounts of carbon (C), nitrogen (N) and phosphorus (P) in relation to dry weight (D.W.) were measured in zooplankton from the large four rivers (Han R., Geum R., Yeongsan R. and Seomjin R.) during 2004~2008. The stoichiometry of total zooplankton in four river systems was highly variable. The ranges of average C, N and P-contents were 70~620 mgC mg-1 D.W., 7.1~85.5 μgN mg-1 D.W. and 2.5~7.4 μgP mg-1 D.W., respectively. The mean C:N: P atomic ratios reflected large spatial differences. The C: P and N: P ratios of the zooplankton community ranged from 38 to 392: 1 and from 4 to 65: 1 in all sampling sites. Self- Organizing Map (SOM) was applied to the survey data, and the study sites were clearly classified into 3 clusters. Clustering was largely affected by the distribution pattern of C, N, P-contents, which is related with characteristics of river systems on the basis of stoichiometry.
영산강, 섬진강 유역권내 29개 정수생태계의 동물플랑크톤 군집 크기 구조(2010~2011)
김현우 ( Hyun Woo Kim ),라긍환 ( Geung Hwan La ),박종환 ( Jong Hwan Park ),송효정 ( Hyo Jeong Song ),황경섭 ( Kyung Sub Hwang ),임병진 ( Byung Jin Lim ),이학영 ( Hak Young Lee ) 한국환경생물학회 2012 환경생물 : 환경생물학회지 Vol.30 No.1
Abstract - This study compares the abundance and community structure of zooplankton organisms from the littoral and pelagic regions, and considers particularly trophic levels vs. zooplankton abundances. Zooplankton samples, collected every 3 months over a year from 2010 to 2011 at 29 temperate lakes and reservoirs, which belong to two different river basins (Youngsan and Seomjin River). The spatial pattern of rotifers was similar to that of total zooplankton abundance. This reflected the fact that rotifers strongly dominated the zooplankton community. There were considerable spatial variations in total zooplankton abundance (ANOVA, p/0.01), while there were no significant differences both in littoral and pelagic regions in abundance of zooplankton (ANOVA, p=0.205). The mean abundance of zooplankton in eutrophic systems was much higher than that of mesotrophic systems, while significant difference in number of species and diversity index were not shown in both trophic systems.
비선형 시계열 하천생태모형 개발과정 중 시간지연단계와 입력변수, 모형 예측성 간 관계평가
정광석,김동균,윤주덕,라긍환,김현우,주기재,Jeong, Kwang-Seuk,Kim, Dong-Kyun,Yoon, Ju-Duk,La, Geung-Hwan,Kim, Hyun-Woo,Joo, Gea-Jae 한국하천호수학회 2010 생태와 환경 Vol.43 No.1
In this study, we implemented an experimental approach of ecological model development in order to emphasize the importance of input variable selection with respect to time-delayed arrangement between input and output variables. Time-series modeling requires relevant input variable selection for the prediction of a specific output variable (e.g. density of a species). Inadequate variable utility for input often causes increase of model construction time and low efficiency of developed model when applied to real world representation. Therefore, for future prediction, researchers have to decide number of time-delay (e.g. months, weeks or days; t-n) to predict a certain phenomenon at current time t. We prepared a total of 3,900 equation models produced by Time-Series Optimized Genetic Programming (TSOGP) algorithm, for the prediction of monthly averaged density of a potamic phytoplankton species Stephanodiscus hantzschii, considering future prediction from 0- (no future prediction) to 12-months ahead (interval by 1 month; 300 equations per each month-delay). From the investigation of model structure, input variable selectivity was obviously affected by the time-delay arrangement, and the model predictability was related with the type of input variables. From the results, we can conclude that, although Machine Learning (ML) algorithms which have popularly been used in Ecological Informatics (EI) provide high performance in future prediction of ecological entities, the efficiency of models would be lowered unless relevant input variables are selectively used.