• Korean Journal of Environmental Biology
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• v.41 no.2
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• pp.101-108
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• 2023

Recently, in relation to climate change, many studies have been conducted to predict the potential habitat area and distribution range of tilapia and the suitability of habitat for each species. Most tilapia are tropical fish that cannot survive at water temperatures below 10 to 12℃, although some tilapia can survive at 6 to 8℃. This study predicted habitable areas and the possibility of spreading of habitat ranges of tilapia (Oreochromis niloticus and Oreochromis aureus) known to inhabit domestic streams. Due to climate change, it was found that habitats in the Geum River, Mangyeong River, Dongjin River, Seomjin River, Taehwa River, Hyeongsan River, and the flowing in East Sea were possible by 2050. In addition, it was confirmed that tilapia could inhabit the preferred lentic ecosystem such as Tamjin Lake, Naju Lake, Juam Lake, Sangsa Lake, Jinyang Lake, Junam Reservoir, and Hoedong Reservoir. In particular, in the case of tilapia, which lives in tributaries of the Geumho River, Dalseo Stream, and the Nakdong River, its range of habitat is expected to expand to the middle and lower of the Nakdong River system. Therefore, it is judged that it is necessary to prepare physical and institutional management measures to prevent the spread of the local population where tilapia currently inhabits and to prevent introduction to new habitats.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.1-12
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• 2006

Distributions of water temperature and DO profiles were investigated in Andong Reservoir from 1992 to 2004. Thermal stratification began to form from May of every year. Increasing water temperature of epilimnion, temperature difference between epilimnion and hypolimnion increased until August. Lower oxygen layer was formed at metalimnion from June or July of every year and there were 2 layers depending on each year. The two lower oxygen layers were affected by rainfall and inflow between July and September when thermal stratification was formed. The metalimnetic oxygen minima strongly formed at 2 layers, upper and lower part, when the average rainfall and inflow were ${\geqq}$ 170 mm, ${\geqq}$ 50 $m^3\;sec^{-1}$, respectively. It formed weakly when they were > 400 mm and > 200 $m^3\;sec^{-1}$ for one month. The upper part of low oxygen layers formed on the interface of epilimnion and metalimnion showed larger decreasing rate of DO than temperature and it disappeared around November. The lower part of those farmed on interface of metalimnion and hypolimnion existed until December and disappeared in January, this layer showed larger decreasing rate of temperature than DO. DO increased between the upper and lower part of the low oxygen layers. DO on hypolimnion increased under metalimnion and dramatically decreased near the bottom of the reservoir. Temperature of the inflow during rainy season was similar to that of the reservoir's metalimnion, DO was similar or higher and BOD, COD and SS increased. Density layer caused by turbidity was formed in metalimnion, and turbidity increased under the upper part (oxygen increasing layer) of metalimnetic DO minima layers reaching the maximum at the direct upper part of the lower DO minima layer. The upper part of DO minima layers formed on the interface of epilimnion and metalimnion is related to organic activity on the surface, and the lower part of those was considered to be the result of turbid water inflow to metalimnion during rainy season.

• Korean Journal of Ichthyology
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• v.22 no.3
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• pp.147-153
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• 2010

A study was carried out to examine the effect of water temperature on daily pattern and rate of total ammonia nitrogen (TAN) excretion in juvenile Pacific cod Gadus macrocephalus (mean body weight: $36.5{\pm}0.8\;g$) under fasting and feeding conditions. Fish were acclimated over 10 days under three different water temperatures (9, 11 and $13^{\circ}C$), and transferred to TAN measuring system under each water-temperature condition. After 72 hours of starving, fasting TAN excretion was measured at each temperature. To investigate post-prandial TAN excretion, fish were hand-fed with a commercial diet containing 40.6% crude protein for 7 days, two times daily at 08:00 and 16:00 h. Water was sampled from both the inlet and outlet of the fish chamber every 2 h over a 24-h period. Both fasting and post-prandial TAN excretion increased with increased water temperatures (p<0.05). Mean fasting TAN excretion rates at 9, 11 and $13^{\circ}C$ were 9.3, 11.0 and $11.9\;mg\;TAN\;kg\;fish^{-1}\;h^{-1}$, respectively. The value of $9^{\circ}C$ was lower than those of 11 and $13^{\circ}C$ (p<0.05), but there was no significant difference between $11^{\circ}C$ and $13^{\circ}C$. Mean post-prandial TAN excretion rates at 9, 11 and $13^{\circ}C$ were 23.0, 31.6 and $45.4\;mg\;TAN\;kg\;fish^{-1}\;h^{-1}$, respectively. A peak value of post-prandial TAN excretion rate occurred after 2 h from each feeding, and the second value is always higher than the first value. Maximum post-prandial TAN excretion rate occurred after 10 h from the first feeding at $9^{\circ}C$ (mean $38.0\;mg\;TAN\;kg\;fish^{-1}\;h^{-1}$), $11^{\circ}C$ ($52.9\;mg\;TAN\;kg\;fish^{-1}\;h^{-1}$) and $13^{\circ}C$ ($77.5\;mg\;TAN\;kg\;fish^{-1}\;h^{-1}$), respectively. The TAN loss for ingested nitrogen at $9^{\circ}C$ (43.9%) was lower than those of $11^{\circ}C$ (46.4%) and $13^{\circ}C$ (48.4%). The overall results indicate that water temperature exhibits a significant effect on the nitrogen excretion of juvenile Pacific cod.

• Korean Journal of Ichthyology
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• v.21 no.1
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• pp.7-14
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• 2009

The effect of water temperature (T) and body weight (W) on oxygen consumption of fasted starry flounder Platichthys stellatus was investigated in order to assess the metabolic response of this species at given conditions. The oxygen consumption rate (OCR) was measured under six different water temperatures (4, 7, 10, 13, 16 and $19^{\circ}C$) and at two different body weights (mean weight of fry group : 1.5 g; fingerling group : 37.4 g) at an interval of 5 minutes for 24 hours using a continuous flow-through respirometer. In each treatment three replicates were set up and a total 540 fish in fry groups and 90 fish in fingerling groups were used. The OCRs increased with increase of water temperature in both groups (p<0.001). Mean OCRs at 4, 7, 10, 13, 16 and $19^{\circ}C$ were 1386.0, 1601.7, 1741.0, 1799.2, 2239.1 and $2520.3mg\;O_2\;kg\;fish^{-1}\;h^{-1}$ in fry groups, and 83.8, 111.4, 126.3, 147.1, 187.7 and $221.3mg\;O_2\;kg\;fish^{-1}\;h^{-1}$ in fingerling groups, respectively. The OCRs decreased with increasing body weights at six different water temperatures (p<0.001). The relationship between water temperature and body weight is described by the following equation : OCR=1520.91+40.85T-49.22W ($r^2=0.95$, p<0.001). The energy loss by metabolic response increased with an increase in water temperature and a decrease in body weight (p<0.001). Mean energy loss rates by oxygen consumption at 4, 7, 10, 13, 16 and $19^{\circ}C$ were 907.9, 1046.5, 1141.6, 1177.0, 1467.3 and $1650.1kJ\;kg\;fish^{-1}\;d^{-1}$ in fry groups and 54.8, 73.0, 82.9, 96.2, 122.9 and $144.6kJ\;kg\;fish^{-1}\;d^{-1}$ in fingerling groups, respectively. The $Q_{10}$ values of fingerling groups were higher than those of fry groups at given temperature ranges. The $Q_{10}$ values at $4{\sim}7^{\circ}C$, $7{\sim}10^{\circ}C$, $10{\sim}13^{\circ}C$, $13{\sim}16^{\circ}C$ and $16{\sim}19^{\circ}C$ were 1.62, 1.32, 1.12, 2.07 and 1.48 in fry groups, and 2.59, 1.52, 1.67, 2.25 and 1.73 in fingerling groups, respectively.

• Korean Journal of Remote Sensing
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• v.33 no.6_1
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• pp.901-915
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• 2017

Recently, global climate change has caused a catastrophic event in the Arctic Ocean, directly and indirectly. The air-sea interaction has caused the significant sea-ice reduction in the Arctic Ocean, and has been accelerating the Arctic warming. Many scientists are worried about the Arctic environment change, suggesting that many of anomalous events will produce direct or indirect biophysical effects on the Arctic. The aim of this study is to understand the inter-annual variability of the Arctic Ocean in wide-view using multi-satellite-derived measurements. Sea surface temperature (SST) and sea ice concentration (SIC) data were obtained from Optimum Interpolation Sea Surface Temperature (OISST) and ECMWF ERA-Interim, respectively. Chlorophyll-a concentration (CHL) was obtained from Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) and Aqua sensor from MODerate resolution Imaging Spectroradiometer (MODIS-Aqua) sensor which has continuously observed since 1998. From 1998 to 2016 summer in the Arctic Ocean which was defined as regions over $60^{\circ}N$ in this study, there were three consequences that CHL increase ($0.15mg\;m^{-3}\;decade^{-1}$), SST warming ($0.43^{\circ}C\;decade^{-1}$) and SIC decrease ($-5.37%\;decade^{-1}$). While SST and SIC highly correlated each other (r = -0.76), a relationship between CHL and SIC was very low ($r={\pm}0.1$) because of data limitations. And a relationship between CHL and SST shows meaningful results ($r={\pm}0.66$) with regional differences.

• Korean Journal of Soil Science and Fertilizer
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• v.15 no.4
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• pp.221-225
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• 1982

Soil and water temperature were measured at different distances from the irrigation inlet of a Paddy land supplied with $16^{\circ}C$ water. The rice growth and yields of Nongbaek variety (Japonica) and Milyang 23 variety (Indica${\times}$Japonica)were interrelated with average soil and water temperature from tillering to heading stage. Water temperature was asymtotically increased to $21^{\circ}C$ as cold water forwarded, while the distribution of soil temperature showed linear shape with distance overall, water temperature was 1 to $2^{\circ}C$ higher than soil temperature. Cold soil and water temperature shorterned culm length and panicle exertion and retarded heading date resulting in yield reduction, Response of rice growth and yield to water temperature was apparently different between two varieties. Nongbaek variety produced no grains below $17^{\circ}C$, but it's reproductive growth was possible from 17 to $20^{\circ}C$. A normal yield could be obtained at $21^{\circ}C$. Comparatively, no reproductive growth of Milyang 23 variety was Possible even at $19^{\circ}C$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.15-19
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• 2007

Mass mortalities of the farmed sea squirt, Halocynthia roretzi, occurred in August, 2006 along the Gyeongbuk coasts of the East Sea without any pathological symptom. Suspecting the No. 10 typhoon, Wukong, which had passed over the relevant locations in the middle of August, 2006 as a culprit of the mortalities, we compared water temperature stratifications of the affected coasts before and after the typhoon. Just prior to the typhoon, cold waters lower than $15^{\circ}C$ were stratified at depths deeper than 10m probably by a persisting upwelling of cold bottom waters. The typhoon enforced water off-coast waters into coasts for 5 days, replacing the cold waters at depths $10{\sim}20m$ which can be justified by Ekman Spiral Effect. The results were an increment of water temperature by $10^{\circ}C$ and more at depths where sea squirts were suspended. The sudden elevation of water temperature might drive the sea squirts under abnormal stress to mass mortality.

• Korean Journal of Ichthyology
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• v.11 no.2
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• pp.155-162
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• 1999

To study the distribution of larva and juvenile of the sand eel, Ammodytes personatus in the Kangwon coastal, samples were collected by the larva net (RN 80 net) and small drag net at 60 stations from January 1996 to December. Appearance season of larva and juvenile of sand eel was appeared untill the January to June in the Kangwon-do coast, and the densities of them were high in June. Appearance phase, length frequency distribution of larva and juvenile of sand eel were distributed that the average standard length 10.0~30.0mm in the temperature range of $5.0{\sim}6.0^{\circ}C$ at the January to March, and April to June occurred the average standard length 40.0~80.0 mm in the temperature range of $7.2{\sim}12.0^{\circ}C$. It was distributed in southern part of Kangwon-do coast until the February to March 1996. And association of the sand eel migrated to the northern and middle part of Kangwon-do coast at April when surface water temperature was higher than $7.2^{\circ}C$. It was considered that the migration of the abundance larva and juvenile of sand eel in this area is mainly affected by the water temperature.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.773-784
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• 2018

In this study, we examined the UA (upwelling age) using wind data of AWS/ASOS in the East Sea coast and the correlation between UA and SST (sea surface temperature) from May to August in 1995 to 2016. The data used the 6 observations of the wind data of AWS/ASOS and the SST data of the COD/RISA provided by the National Institute and Fisheries Science near the East Sea coast. The UA was calculated quantitatively low but it rose when the actual cold water mass occurred. Correlation analysis between UA and SST showed the negative (-) r (correlation coefficient) predominately. At the time of cold-water mass in June to August 2013, the r had a very high negative value of -0.65 to -0.89 in the 6 observations. It proved that as the UA increases, the SST is lower. By knowing the UA, we were able to evaluate the trend of upwelling in the cold-water mass of the East Sea coast in the long term and it will contribute to minimizing the damage to aquatic organisms according to the size and intensity of the upwelling.

• The Korean Journal of Malacology
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• v.31 no.1
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• pp.1-8
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• 2015

This study was conducted to investigate the effects of elevated water temperature (WT) on biochemical and immunological factors in the hemolymph of the abalones, Haliotis discus hannai and H. discus discus. The abalone were exposed to various WT; 20, 22, 24, 26 and $28^{\circ}C$ for 4 days. In the control and $20^{\circ}C$, total-protein (TP), glucose and calcium (Ca) in hemolymph of H. discus discus were higher than the values in H. discus hannai. The values of magnesium (Mg), alkaline phosphatase (ALP) and lysozyme in H. discus hannai were similar to the H. discus discus in the control. There were no significant alterations in TP, glucose and Mg levels of hemolymph in H. discus hannai and H. discus discus by WT increases. The values of Ca, ALP and lysozyme were increased in H. discus hannai exposed to the high temperature (26 and $28^{\circ}C$) compared to control, while the values in H. discus discus were not significant difference between the WT groups. The phenoloxidase (PO) activity was increased in hemolymph of H. discus hannai exposed to high temperature (${\geq}24^{\circ}C$) compared to the control (P < 0.05). These physiological and immunological parameters were significantly changed in H. discus hannai. However, these parameters in H. discus discus were barely altered at the high WT (P < 0.05). These results suggested that H. discus hannai is considered to be more sensitive than H. discus discus at the high WT.