Reproductive Ecology of the Freshwater Melania Snail, Semisulcospira coreana (v. Martens) in Bukhan River (original) (raw)
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양수리 용늪의 용존 수은 및 총수은 농도 특성에 대한 연구
Journal of Korean Society of Environmental Engineers, 2012
Long-term measurement of total mercury (TM) and dissolved gaseous mercury (DGM) were performed in Yangsuri marsh. Average TM and DGM concentrations were 2.0 ± 2.0 ng/L and 15.0 ± 2.8 pg/L, respectively, indicating that only 2.6% of TM existed as the form of DGM in Yangsuri marsh. While TM did not show the seasonal variation a statistically high DGM concentration was observed in warm season, indicating that DGM was effectively produced by strong solar radiation and high water temperature. There was no relationship between TM and DGM concentrations in Yangsuri marsh, as observed in other studies. DGM in Yangsuri marsh was supersaturated for most of sampling period; therefore, one can conclude that Hg 0 in water surface can readily volatilize to the atmosphere.
Seasonal Variation of Phytoplankton Community in the Naktong River
ALGAE, 2002
A seasonal variation of phytoplankton community in the Naktong River was studied in seven sampling stations at monthly intervals from April 2000 to March 2001. Environmental factors such as conductivity, total phosphorus, total nitrogen and BOD were much higher at a lower reaches than the upper reaches. Especially, they rapidly increased at the st. 4 located near the discharge of the Kumho River. Total 239 taxa observed in the study were classified into 201 species, 22 varieties, 2 forma, 1 morphotype and 13 unidentified species belonging to 102 genera, 39 families, 17 orders and 8 classes. The phytoplankton standing crops were recorded a maximum of 33,389 cells • ml-1 at the st. 7 in June and a minimum of 139 cells • ml-1 at the st. 1 in September. The correlations between averages of the phytoplankton standing crops and some of environmental factors were investigated at each sampling station. The coefficients of correlation between average of the phytoplankton standing crops and BOD, T-N and T-P were 0.61, 0.45 and 0.47, respectively. In general the dominant species were Achnanthes minutissima Kütz, Nitzschia fonticola Grun., Navicula cryptotenella Lange-B in the upper reaches, Microcystis aeruginosa (Kütz.) Kütz. and Stephanodiscus hantzschii Grun. in the lower reaches.
강화도 남단 조간대에 도래하는 마도요류의 환경수용능력 예측
Journal of Wetlands Research, 2013
In this study we estimated the carrying capacity of the southern intertidal zone of Kanghwa Island to evaluate the habitat quality for Curlews(Far Eastern Curlew Numenius madagascariensis and Eurasian Curlew Numenius arquata). Biomass of the macroinvertebrate(Macrophthalmus japonicus) was estimated by based on the spatial distribution of the sediment grain size using GIS tools. According to our analysis the southern intertidal zone of Kanghwa Island was able to support 11,767 individuals for 153 days in the Spring 2012 and 16,275 individuals for 122 days in the Autumn 2012. The proportion of mean population to the carrying capacity in the Spring and Autumn was 9.4% and 5.9%, respectively. These values are 2.8-6.3% smaller than those of the previous study held in 1993-94. For the conservation of the study area, more research and management is needed. And in further studies, diverse characteristics of the intertidal habitat should be considered in spatial analysis to have a precise estimate of the carrying capacity.
Korean Journal of Environmental Agriculture, 2009
In 2006 and 2007, there was a big outbreak of the Ussur Brown Katydid, Paratlanticus ussurriensis in the central part of Korea attacking some orchard trees. Until 2000, the katydid had not been regarded as an agricultural pest because they were distributed widely in Korea with low population density and their habitats were confined mainly to hillsides of forested areas. The fact that katydid attacked orchard trees with a higher population density seemed to be related to a change in feeding environment. And the shift of their habitats from oak woodlands to commercial orchards was thought to be related to the nutritional contents of their feed. In an attempt to understand these relationships, we conducted an ecological study of the affected areas. When the katydids changed their habitats in early May of 2008 and 2009, they shifted their host plants from oak trees to peach trees. The habitat shift was closely related to the nitrogen (N) content of the host plant leaves. When katydid moved to the hillside adjacent to orchard farm, N content of oak tree leaves decreased dramatically from 5.3% to 2.2%. At that time N content of peach tree leaves were higher than the 2.2% of oak leaves, showing 3.5~5.0%. This range of N content of peach tree leaves has been consistent until late June. And feed preference analysis carried out in the laboratory showed that katydid prefered peach tree leaves to peach fruit to oak tree leaves.
2010
Anisakid nematodes third stage larvae were isolated from the muscles of masou salmon (Oncorhynchus masou). Fish were purchased from Jumunjin fishery market in Gangneung. Four Anisakid third stage larvae were isolated from 4 fish. Molecular identification of the isolated worms was conducted by PCR-RFLP analysis of ribosomal DNA internal transcribed spacer region and direct sequencing of mitochondrial DNA cox2 gene. As results, all the tested individual worms were identified as Anisakis simplex (sensu stricto). This is the first report of molecular detection of anisakid worms in salmonid fishes in Korea.
Some proposals for coastal management of the Nile delta coast
Ocean & Coastal Management, 1996
This study investigated the feasibility of CaSnO3 particles as an oxygen carrier in chemical looping combustion (CLC). CaSnO3 particles had a perovskite crystal structure and showed the structural stability after repeated reduction-oxidation reactions. The oxygen transfer capacity was 15.4 wt% almost the same as the calculated theoretical value from the crystal structure transformation during reduction. After 10 th cycles of reduction and oxidation, the oxygen transfer capacity and rate were still maintained constantly at an operating temperature. In conclusion, CaSnO3 particles could be a good alternative material as an oxygen carrier in CLC.
배합사료의 수침과 공급량이 넙치(Paralichthys olivaceus)의 성장, 혈액 및 조직 성상에 미치는 영향
Korean Journal of Fisheries and Aquatic Sciences, 2011
Two consecutive feeding trials investigated the effects of feeding rate and pellet expansion by water-soaking on the growth performance, blood components and histology of olive flounder Paralichthys olivaceus. The first two experiments were carried out to determine the effects of pellet expansion and feeding rate. In the first experiment, growth performance, feed utilization and survival of fish were not significantly affected by pellet expansion for six weeks. There were no significant differences in hematocrit, hemoglobin, aspartate aminotransferase, alanine aminotransferase, glucose and total protein of fish fed the expanded pellet. However, whole-body lipid content of fish in the non-expanded group was significantly higher than that in the expanded group. Histological analysis of the anterior intestine revealed that fish in the expanded group had shorter and smaller mucous folds. These results indicate that pellet expansion had no beneficial effect in terms of growth performance, feed utilization and fish health. In the second experiment, weight gain and feed efficiency were significantly increased as feeding rate increased from 0 to 2. 5% body weight per day (BW/d), but there were no significant differences in weight gain or feeding efficiency in fish fed the expanded pellet at ratios of 2.5% BW/d and satiation for three weeks. Plasma aspartate aminotransferase activity of fish fed the expanded pellet at a ratio of 2.5% was significantly lower than that of starved fish. Histological analysis of the anterior intestine revealed that fish in the 0% group had shorter mucous folds. Broken-line regression analysis suggested that the optimum juvenile olive flounder feeding rate was 3.5% BW/d during the low temperature season (16-17˚C).