• Journal of Ecology and Environment
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• 제31권2호
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• pp.125-129
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• 2008

To predict Daphnia secondary productivity along a trophic gradient indexed as total phosphorus (TP) concentration, we estimated energy transfer efficiencies from food quality for Daphnia such as eicosa-pentaenoic acid (EPA) or docosahexaenoic acid (DHA) content. Eleven flow-through Daphnia magna growth experiments were conducted with seston from 9 lakes, ponds and river waters. Primary productivities were estimated from food supply rates in the flow-through experiments, producing energy transfer efficiencies from seston to D. magna. We found DHA content was the best predictor of energy transfer efficiencies among the essential fatty acids. An asymptotic saturation model explained 79.6% of the variability In energy transfer efficiencies. Based on empirical data in this study and empirical models from literature, we predict that Daphnia productivity would peak in mesotrophic systems by decreasing food quality and Increasing food quantity along trophic gradient.

• 한국환경과학회지
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• 제23권9호
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• pp.1537-1549
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• 2014

The objectives of this study were to analyze reservoir trophic state, based on Trophic State Index (TSI), spatial variation patterns of three zones (riverine, transition, and lacustrine zone), and empirical models through 20-years long-term data analysis. Trophic variables of TP and CHL-a were highest during the summer monsoon, and decreased along the main axis from the riverine to lacustrine zone. In the mean time, TN did not show the trend. Ratios of N:P and Secchi disc transparency (SD) increased from the riverine to lacustrine zone. The analysis of trophic state index (TSI) showed that mean TSI (TP) and TSI (CHL-a) were 62 and 57, respectively, and these values were highest in the transition zone during the summer. This zone should be managed well due to highest lake water pollution. The analysis of Trophic State Index Deviation (TSID) showed that algal growth was primarily limited by light penetration, and this was most pronounced in the monsoon season. The analysis of empirical models showed that the value of $R^2$, based on CHL-SD model, was 0.30 (p < 0.0001) in the transition zone and the $R^2$, based on TP-SD model, was 0.41 (p < 0.0001) in the transition zone.

• 생태와환경
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• 제40권4호
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• pp.503-510
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• 2007

The purposes of the study were to analyze the seasonal effects on the fish fauna and compositions including trophic guilds and tolerance guilds. For the study, we collected fish samples twice in June as premonsoon period and early September 2007 as monsoon periods in five sampling sites of the Gap Stream, and then biological oxygen demand (BOD), nutrients (TN, TP) and suspended solids (SS) were compared with the guild data along the gradient of upstream-to-downstream. Chemical water quality, based on BOD, TP, and TN degraded gradually from the upstream to downstream reach and there were about 3 fold difference between S1 and S5. Water quality was worse in the premonsoon than the monsoon, and the heavy monsoon resulted in a dilution of the polluted river by rain water, especially, in the downstream reach. Total number of fish species, based on the catch per unit effort (CPUE), showed a distinct difference between the two seasons; 30 species were sampled in premonsoon, but 23 species were sampled in the monsoon, indicating a seasonal difference in the fish fauna. Tolerant species dominated the fish community (48.3%) in the stream, and the proportions prior to physical disturbance by the monsoon rain were evidently greater in the downstream reach than the upstream. This reflected the characteristics of urban stream polluted by nutrient enrichment as shown in the BOD and TP values. Sensitive species in the premonsoon decreased from the gradient of upstream-to-downstream reach. Such seasonal modifications in the trophic and tolerance guilds were evident. In the analysis of trophic guild and habitat guild, during the premonsoon the proportion of insectivore and riffle-benthic species were largely greater in the upstream reach than the downstream, whereas the proportions were opposite along the gradient of the stream in monsoon. Thus, the patterns of chemical water quality along the longitudinal gradients reflected the premonsoon conditions of insectivores and tolerant species, indicating that summer monsoon data of fish may not match with water quality due to large physical disturbance by flow regime. Seasonal monsoon in this region as well as the chemical pollution may act as a key role influencing the fish compositions of trophic and tolerance guilds and fauna. The data collected during the premonsoon rather than the monsoon, thus, may be better predictor for a diagnosis of stream health conditions.

• Journal of Microbiology and Biotechnology
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• 제23권6호
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• pp.739-749
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• 2013

The seasonal and spatial diversity of picocyanobacteria (Pcy) in lakes of the Great Mazurian Lakes (GLM) system was examined by DGGE analysis of molecular markers derived from the 16S-23S internal transcribed spacer (ITS) of the ribosomal operon and the phycocyanin operon (cpcBA-IGS). The study of nine lakes, ranging from mesotrophy to hypereutrophy, demonstrated seasonal variance of Pcy. The richness and Shannon diversity index calculated on the basis of both markers were higher in spring and lower in early and late summer. No statistically significant relationships were found between the markers and trophic status of the studied lakes or Pcy abundance. There were, however, statistically significant relationships between the diversity indices and sampling time. The analysis pointed to a different distribution of the two markers. The ITS marker exhibited more unique sequences in time and space, whereas a greater role for common and ubiquitous sequences was indicated by the cpcBA-IGS data. Examination of the Pcy community structure demonstrated that communities were grouped in highly similar clusters according to sampling season/time rather than to the trophic status of the lake. Our results suggest that time is more important than trophic status in shaping the diversity and structure of Pcy communities. The seasonal changes in picocyanobacteria and differences in diversity and community structures are discussed in the context of well-established ecological hypotheses: the PEG model, intermediate disturbance hypothesis (IDH), and horizontal gene transfer (HGT).

• 생태와환경
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• 제45권2호
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• pp.174-189
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• 2012

본 연구는 인공호의 영양 단계에 따른 피라미 개체군의 전장-체중 관계 및 비만도 지수 (K)의 차이를 알아보기 위해 2008년~2010년까지 부안호, 양양호, 진양호, 금풍지, 예당지 및 마산지 등의 6개 인공호를 대상으로 실시하였으며, 광범위한 분포 특성과 섭식 특성을 보이는 피라미(Zacco platypus)를 본 연구의 대상 어종으로 선정하였다. 총인 (TP)과 엽록소-a (Chl-a)를 이용한 영양상태지수(TSI) 분석 결과 양양호와 부안호는 빈영양(30~40), 진양호와 금풍지는 중영양 (40~50), 예당지와 마산지는 부영양 (50~70)상태로 나타났다. 6개 호수에서 총 47종 26,226개체의 어류가 채집되었으며, 빈영양호 (양양호, 부안호)에서는 민감종이 우세한 현상을 보였다. 한편, 중영양호 (진양호, 금풍지)와 부영양호 (예당지, 마산지)에서는 내성종이 우세한 것으로 분석되어 호수의 영양 상태에 따라 우세종의 내성특성에 차이를 보이는 것으로 나타났다. 전장-체중 관계 분석 결과에 따르면, 회귀계수 b값은 중 영양호(3.07~3.17)와 부영양호(3.15~3.21)에 비해 빈영양호 (2.77~2.79)에서 낮은 값을 보였다. 이러한 결과는 호수의 영양상태가 피라미 개체군의 성장도에 영향을 주는 것으로 사료된다. 전장에 따른 비만도 지수 (K) 관계 분석 결과 중영양호와 부영양호에서는 양의 기울기를 보인 반면, 빈영양호에서는 음의 기울기를 나타내 호수의 영양상태에 따라 차이를 보였다. TSI (TP), TSI (Chl-a)와 회귀계수 b값의 상관관계를 분석한 결과 b=0.012*TSI (TP)+2.395 ($R^2$=0.797, p=0.017), b=0.013*TSI (Chl-a)+2.367 ($R^2$=0.822, p=0.013)으로 나타나 높은 상관관계를 보였다. 한편, 부영양화가 진행될수록, 비정상개체의 비율이 증가하는 것으로 나타났다. 결론적으로, 전장-체중 관계와 비만도 지수 분석에 의한 피라미 개체군의 성장도는 영양염류나 식물플랑크톤의 생체량과 같은 영양상태를 반영하는 것으로 사료되며, 과도한 부영양화는 수환경의 오염을 초래하여 피라미 개체군의 성장과 건강도에 부정적인 영향을 미치는 것으로 사료된다.

• 생태와환경
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• 제43권2호
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• pp.199-211
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• 2010

The objectives for this study were to evaluate spatial and temporal characteristics of water quality, based on long-term water quality monitoring data during 1993~2008. We found that physico-chemical and ecological conditions in the Daecheong Reservoir (DR) were modified by the construction of upper dam (i.e., Yongdam Reservoir). total phosphorus (TP), Secchi depth (SD), and chlorophyll-a (CHL) in the DR showed significant longitudinal decreases along the headwater-to-the downlake, indicating a large spatial variation, and this gradient was more intensified during the high-flow season (monsoon). Nutrient-rich water containing high nitrogen and phosphorus in the monsoon season (July~August) passed through the reservoir as a density current in the metalimnetic depth, and also high suspended solids increased in the metalimnetic depth, especially during the monsoon. According to the deviation analysis of Trophic State Index (TSI), >50% of TSI (CHL)-TSI (SD) and TSI (CHL)-TSI (TP) values were negatives, so that inorganic suspended solids (non-votatile solids) influenced the underwater light regime against phytoplankton growth. Also, ratios of CHL:TP after the dam construction evidently increased, compared to the values before the upper dam constructions, indicating a greater yield of phytoplankton in the unit phosphorus. Overall data showed that ecological and functional changes in Daecheong Reservoir occurred after the construction of upper dam (Yongdam Reservoir).

• Animal cells and systems
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• 제3권2호
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• pp.153-159
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• 1999

In an artificial pH-gradient batch culture system, the effects of acidification on the species composition of a heterotrophic bacterial community were analyzed. As a result of this study, it was found that total bacteria numbers were not affected by acidification and that the population of hetero-trophic bacteria decreased as pH became lower. The heterotrophic bacteria isolated from the entire pH gradient were 12 genera and 22 species. Among them, 64% were gram negative and 36% were gram positive bacteria. As pH decreased, the distribution rate of gram negative bacteria increased while that of gram positive bacteria decreased. The diversity of genera decreased from 13 to 5 as pH decreased from 7 to 3. The G+C content of all of the 202 isolated strains varied from 22.8 to 77.0%, and increased in interspecies of same genus as pH decreased. As a result of clustering analysis, the diversity index of species ranged from 1.13 to 2.37, and it had lower indices as pH decreased. In order to evaluate the diversity of numbers of sample of different size, a rarefaction method was used to analyze the expected number of species appearance according to pH. The statistical significance of species diversity was verified by the fact that the number decreased at lower pH.

• 생태와환경
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• 제50권4호
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• pp.403-410
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• 2017

본 연구는 2008년부터 2016년까지 1차부터 7차까지 총 12,873지점을 대상으로 하천차수별 어류분포를 조사하였다. 하천차수에 따른 피라미와 참갈겨니 개체군의 분포 양상에서 차이를 보였으며, 상관관계 분석 결과 두 개체군간 잠재적인 경쟁관계 가능성을 확인하였다. 두 개체군과 다른 공서 어류의 생태특성은 하천차수의 구배에 따라 중간종, 민감종, 내성종, 육식종, 초식종, 잡식종 등 뚜렷한 구배가 나타나는 반면, 충식종의 경우 뚜렷한 구배가 나타나지 않았다. 어류의 생태특성에 따르면, 피라미의 경우 중간종이면서 잡식종, 참갈겨니의 경우 민감종이면서 충식종으로 구분이 되는데, 두 개체군은 내성도 길드의 중간종과 민감종, 섭식 특성 길드의 잡식종과 충식종에서 유사한 상관관계의 변화를 보였지만, 두 개체군은 생태특성에 따른 각 기능군과 서로 다른 상관성의 차이를 보였다. 어류평가지수는 하천차수의 증가에 따라 감소하는 경향을 보였으며, 상관관계 분석 결과 두 개체군은 하천차수별 상관성의 차이를 보였지만, 1차에서 4차까지 유사한 상관관계의 변화를 보였으며, 5차부터 7차까지 차이를 보였다.

• Journal of Ecology and Environment
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• 제45권4호
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• pp.218-227
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• 2021

Background: Artificial light at night has recently been identified as a major factor adversely affecting global insect diversity. Here, we compared the insect diversity in Gwangneung Forest Biosphere Reserve, specifically in the Korea National Arboretum (with no artificial light at night), with that of three nearby urban sites with a gradient of artificial light at night (five locations at each site). We analyzed the effects of the artificial night lighting index, mean annual temperature, and field light intensity (lux) at night on the insect community structure. Results: The urban sites generally exhibited higher species richness and abundance as well as clear indicator species compared with the control site. The size distribution of the collected insects markedly differed between the control and the three urban sites. The abundance of herbivorous and omnivorous insects increased and decreased, respectively, with the increase in light intensity. Species richness of herbivorous and omnivorous insects was likely correlated with the field light intensity at night and artificial night lighting index, respectively. Conclusions: This study demonstrates the association between nighttime environment and marked changes in insect community structure and revealed consequent transition of ecosystem services by changes in trophic group composition.

• 생태와환경
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• 제42권4호
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• pp.452-464
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• 2009

The objectives of this study were to evaluate spatial and temporal variability of water quality in 10 reservoirs and identify the key nutrients (N, P) influencing chlorophyll-a (CHL) along with analysis of empirical models and zonal patterns of total phosphorus (TP) and CHL. We analyzed total nitrogen (TN), TP, CHL, water clarity (Secchi depth, SD), and evaluated potential limiting nutrient using ambient N:P ratios and previous criteria of ambient nutrients. Water clarity and CHL varied largely depending on the seasonal monsoon and type of reservoir, but trophic state was diagnosed as eutrophy, base on mean CHL in most reservoirs. The peak of TP did not match the contents of CHL due to rapid flushing during the high run-off period. In the reservoir of DR, regression coefficient in the $P_r$ was 0.510 but was 0.159 in the $M_o$, while the TP-CHL relation in the YR increased during the monsoon compared to the premonsoon. The regression coefficient in the $P_r$ was not statistically significant but the value of $M_o$ was 0.250. TP showed similar longitudinal zonal gradients among the reservoirs of DR, YR and JR. Empirical models of TP-CHL, based on overall data, showed that CHL was determined by phosphorus($R^2=0.244$, p=0.0019). Regression analysis of CHL-SD showed a stronger linear fit ($R^2=0.638$, p<0.001) than the TP-CHL model.