• Korean Journal of Ichthyology
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• v.31 no.3
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• pp.172-177
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• 2019

Seasonal fluctuation in abundance and species composition of fish in coastal waters off Dolsan island were investigated using seasonal samples collected by an otter trawl in 2012. A total of 4,848 fishes were sampled and classified into 52 species, 29 families, and 7 orders. The dominant species was Leiognathus nuchalis (2,786 individuals, 57.5%), Amblychaeturichthys hexanema (164 individuals, 3.4%), and Ilisha elongata (141 individuals, 2.9%). The highest number of individuals was found in summer (2,174 individuals), while the lowest number of individuals was found in winter (321 individuals). The diversity index was the highest in spring (H'=3.06) and the lowest in summer and fall (H'=1.77). Temperature was the principal factor to determine the collected number of individuals (r=0.94) and the number of species (r=0.83).

• Journal of Aquaculture
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• v.19 no.4
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• pp.236-241
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• 2006

Seasonal variation of the infection by three species of symbiotic copepods in clam, Tresus keenae was investigated in south coast of Korea. The prevalence and abundance of three symbiotic copepods showed seasonal variation with a peak in winter. Reproduction of the copepods occurs from early autumn to spring as indicated by higher ratio of gravid copepods. The frequency distribution of Lichomolgus inflatus, Pseudomyicola spinosus and Anthessius progectus in their host population could be fitted with negative binominal distribution. Results from the present study suggest that seasonal fluctuation in prevalence, relative density and mean intensity is related to temperature and life history of the symbiotic copepods.

• The Korean Journal of Community Living Science
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• v.17 no.2
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• pp.49-60
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• 2006

It was measured the energy expenditure in each season, the cold tolerance in winter and the heat tolerance in summer. Farmers' adaptability to the change of environment was compared with those of city-dwellers such as indoor workers and street cleaners to determine the effect of living environment, especially living temperature, on the health of human body. It turned out that farmers had experienced wide range of temperature that was higher in summer and lower in winter than indoor workers. Farmers and street cleaners showed seasonal adaptation in energy expenditure, which was high in winter and low in summer. However, indoor workers did not show seasonal changes. Energy expenditure had an inverse correlation with the temperature in work place where subjects spend the longer time in a day except in female indoor workers in Seoul. And It was proved that farmers and street cleaners had stronger cold tolerance and heat tolerance than indoor workers.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.21 no.4
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• pp.144-157
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• 2016

The community structure of meiobenthos was investigated from seasonal surveys at four stations of Keunso Bay in Taean. Samples of meiobenthos were collected in August, October, 2013 and January, April, 2014. Triplicate faunal samples were collected by using an acryl corer with a 3.6 cm diameter at each station. The mean grain size of the study area ranged from 3.65 ø to 6.35 ø. Total 13 meiofaunal groups were found in the study area. The total density of meiobenthos at each station was be $1,521-7,849ind./10cm^2$. Nematodes were the most dominant faunal group at all stations. The subdominant group were Sarcomastigophorans and benthic harpacticoid copepods. The highest meiofaunal density was shown in spring, whereas the lowest density was recorded in summer. A total of 13 meiobenthic taxa were found, the richest taxa in October at station 2 ($13ind./10cm^2$), and the lowest in April at station 4 ($5ind./10cm^2$). There were seasonal fluctuations in the number of meiobenthic taxa decreasing from summer to spring. The density of meiobenthos gradually decreased as the depth of sediment increased. Seasonal changes in the vertical distribution of meiobenthos in the study area occurred mainly near the sediment surface.

• Journal of Ecology and Environment
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• v.43 no.2
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• pp.104-116
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• 2019

Background: The composition of wild bird populations in temperate zones greatly varies depending on phenological changes rather than other environmental factors. Particularly, wild birds appearing in wetlands fluctuate greatly due to the crossover of species arriving for breeding during the summer and for wintering. Therefore, to understand the changes to species composition related to phenology, we conducted this basic analysis of populations to further the cause of the protection of wetland-dependent wild birds. Methods: It is wrong to simply divide a wild bird population investigation into seasons. This study identifies species composition and indicator species that change along with seasons. Wetlands to be surveyed are protected by natural monuments and wetland inventory and are in a state close to nature. In order to identify as many species as possible in wetlands, a survey was conducted in both shallow and deep wetlands. The water depth varied in these areas, ranging from 0.2 to 2.0 m, allowing for both dabbling and diving ducks to inhabit the area. Surveys were conducted using line-transect and distance sampling methods and were conducted at intervals of 2 weeks. The survey was conducted under the following three categories: the eco-tone and emergent zone, the submergent zone, and the water surface. The survey was conducted along a wetland boundary by observing wild birds. A PC-ord program was used for clustering, and the SAS program was used to analyze the changes in species composition. The data strongly indicates that day length is the main factor for seasonal migration periods, despite the fact that climate change and increasing temperatures are often discussed. Results and conclusions: The indicator species for determining seasons include migrant birds such as Ardea cinerea, Alcedo atthis, Anas penelope, and Poiceps ruficollis, as well as resident birds such as Streptopelia orientalis and Emberiza elegans. Importantly, increases in local individual counts of these species may also serve as indicators. The survey results of seasonal fluctuations in temperate zones shows that spring (April to June), summer (July to September), autumn (October), and winter (November to March) are clearly distinguishable, even though spring and summer seasons tend to overlap, leading to the conclusion that additional research could more clearly identify fluctuation patterns in species composition and abundance in the study area.

• Journal of Korean Society of Forest Science
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• v.36 no.1
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• pp.33-37
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• 1977

The secular trends and seasonal variation of the prices of imported lauan sawtimber, domestic red pine logs and sawtimber have been analyzed to find out the features and origins of price fluctuation in Korea for the period of 1961~1971. The results may be summarized as follows: 1. The relative prices of red pine logs were raised by 1.23 percent per year, and those of red pine and lauan sawtimber were decreased by 0.10 and 0.93 percent, respectively through the period. As a whole, there is a tendency in the country that timber prices were gradually decreased by lowing timber demand through savings in consumption and exploitation of alternative materials, with the increased supply through continuous log import. 2. There is also a tendency that the seasonal variation reduced in the last 15 years. In the period of 1961~1968, the seasonal price indices were peaked in spring and autumn, but thereafter peaked in spring and dropped down until winter. 3. In secular and seasonal variations of timber prices, the trend of sawtimber prices was dependent upon that of log prices but the fluctuation was larger in log prices.

• Journal of Environmental Science International
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• v.23 no.9
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• pp.1563-1572
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• 2014

The autecology of the Zostera marina and Z. japonica was studied in populations growing in the same locality (Sagumi Bay, southwestern coast of Korea). Environmental factors and plant characteristics were examined monthly from August 2008 to September 2011. Along intertidal zone, Z. japonica (0.1-0.5 m above mean lower low water, MLLW) occurred above Z. marina (0.5-2.5 m MLLW). Tidal exposure at low tide during day was the highest in the spring and the lowest in the summer. Underwater Irradiance showed seasonal fluctuation that was the highest in spring and summer caused by tidal pattern. Strong seasonal patterns in water temperature appeared to control the seasonal variations in morphology, biomass and leaf growth. The seasonal pattern of Z. japonica resembled that of the Z. marina in morphological characteristics, above-and below-ground biomass, whereas it differed in shoot density and leaf elongation. Despite some similarities in seasonal growth patterns, the patterns of Z. japonica were lagged by 2 month of Z. marina. Seasonal variation in the above biomass of Z. marina was caused by changes in density and plant size, whereas that of Z. japonica was mainly caused by changes in shoot density. Zostera marina was more sensitive to high temperatures than Z. japonica, and the increasing water temperature during the summer became the factor that inhibits the growth of the Z. marina. Zostera Japonica, there is no clear change according to the amount of the light. It is because its habitat locates above that of Zostera marina so that the amount of the light that is necessary to growth is enough and in this condition, any preventing factor does not seem to work at all. Although underwater light getting into Zostera marina's habitat is very low level and there is no any hindrance to the survival of them, it prevents them from their productivity a bit.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.479-486
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• 2012

Runoff characteristics of pollutant loads of the lower Han River was studied before full implementation of Total Pollution Load Management System(TPLMS). Magnitude of macroscopic(annual) fluctuation was in the order of Namhan River > Han River > Bukhan River, gross weight TP > gross weight TN > gross weight BOD, gross weight deviation > concentration deviation. Flux variation was higher than that of concentration. Microscopic(weekly) fluctuation showed similar pattern to macroscopic scale. TP showed the highest deviation resulting in the lowest reliability. 60% of annual flux passed during summer 3months resulting in 43-46% pass of gross weight at the lower Han River. Strong correlation was found between flux and gross weight especially in gross weight TN. Gross weight pollution increased as high as 400% while passing Seoul area due to the concentration. The deviation from moving average increased during summer season in the gross weight TP and BOD. Seasonal tendency was confirmed especially in gross weight TN and TP using autocorrelation function.

• International Journal of Industrial Entomology and Biomaterials
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• v.1 no.1
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• pp.65-71
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• 2000

A study was conducted to examine the relationship between abiotic factors and the population of white-fly (Dialeuropora decempuncta) in mulberry field. The study reveals that relationship between abiotic factors and the whitefly population is very much existent like other pests in other agricultural crops. Duration and time of distinct occurrence of whitefly in mulberry is influenced by the abiotic conditions of field. Abiotic parameters of previous month are more important in influencing the intensity of the pest than the current abiotic factors. Not all the abiotic factors are equally important but factors like minimum temperature, fluctuation in temperature during the days minimum relative humidity, fluctuation in relative humidity and rainfall are the major important lactors in influencing the intensity of the pest under consideration.

• Korean Journal of Environmental Biology
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• v.30 no.3
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• pp.173-184
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• 2012

In order to investigate the fluctuation rates [FR] of phytoplankton after passage through a cooling system, the standing crops, chlorophyll a concentrations and carbon assimilation number of phytoplankton were surveyed at intake and outlet at Wolsong nuclear power plant [NPP] from July 2006 to June 2008. As a result, the total mean standing crops of phytoplankton were $1.0{\times}10^6\;cells\;L^{-1}$ and $7.3{\times}10^5\;cells\;L^{-1}$ at intake and outlet, respectively. The FR of phytoplankton by passage through the cooling system [PTCS] was 27.0%. Among them, the FR of microplankton and nanoplankton were 34.1% and 12.4%, respectively. In addition, the FR of diatoms and dinoflagellateswere 33.9% and 29.7%, respectively. These results showed the entrainment effects on microplankton and diatoms by PTCS were higher than those of nanoplankton and dinoflagellates. The FR of total chlorophyll a concentrations were 54.4%, and the FR of microplankton, nanoplankton and picoplankton were 58.9%, 38.5%, and 52.4%, respectively. So the entrainment effects on microplankton by PTCS were higher than those of nanoplankton and picoplankton. The mean FR of carbon assimilation number of phytoplankton was 57.6%, and the seasonal variations of FR of carbon assimilation number ranged from 47.5% to 76.8%. Our results indicated that the phytoplankton species responded differently to power plant operating conditions such as elevated temperature, chlorination, and mechanical impacts.