• Korean Journal of Environmental Biology
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• v.32 no.4
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• pp.306-310
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• 2014

The brown seaweed Sargassum fusiforme is an edible and highly valued in Korea. During the summer season, phytal organisms graze heavily on young algal blades and holdfastsof the species and substantially reduce harvestable biomass. Here, in this study, we investigated the effects of pH (range: 2~13) and salinity (range: 0~44 psu) on the removal of two major phytal animals, Caprella scaura and Gammaropsis utinomi, associated with S. fusiforme. We also examined the optimum quantum yield (Fv/Fm) of algae in the same experimental conditions to quantify the tolerance of algae to acid and salinity treatments. It was observed that the phytal animals showed more than 80% mortality at pH lower that pH 4 and the extreams of salinity (0~10 psu and 44 psu) after a 5 min of immersion. However, the quantum yield of S. fusiforme was not significantly different from controls within the pH 3~11 range, and the 0~44 psu salinity range. Precisely, if the pH and salinity conditions outside these ranges were used in comercial Sargassum culture, the removal of the animal species would be higher, but with reduced quantum yield of algae. Taken together, our study results indicated that the pH and salinity treatments could allow multiple harvests from the same holdfast of S. fusiforme.

• Fisheries and Aquatic Sciences
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• v.9 no.4
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• pp.153-159
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• 2006

The ark shell (or 'blood clam') Scapharca broughtonii is a filter-feeding bivalve that has red blood and inhabits waters approximately 10m in depth off the southern coast of South Korea. This study was part of a larger research project investigating the causes of death and restoration of shellfish resources, which are important aquaculture products in South Korea. We examined physiological responses related to survival, respiration, excretion, and amino acid changes as a result of changes in salinity. The 9-day median lethal salinity ($LS_{50}$) was 16.5 psu with confidence limits of 14.9-18.1 psu. At $25^{\circ}C$, the oxygen consumption and ammonia-nitrogen excretion rates were increased with decreases in salinity. Although the osmolality of individuals was acclimated within 2 h at 26.4 psu and 12 h at 19.8 psu, it took more than 5 days at a salinity of 13.2 psu, whereas no individuals acclimated and all died at a salinity of 6.6 psu. Of the amino acids present in the blood, taurine and alanine increased in response to decreased salinity. Tissues of the gill and the mid-gut gland were affected by decreasing salinity. These data will provide important fundamental information for examining the causes of mass mortality of shellfish in the summer.

• Animal cells and systems
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• v.15 no.3
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• pp.219-225
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• 2011

We studied oxidative stress in cinnamon clownfish exposed to hypoosmotic (35 psu ${\rightarrow}$ 17.5 psu and 17.5 psu with prolactin (PRL)) and low temperature ($28^{\circ}C{\rightarrow}24^{\circ}C$ and $20^{\circ}C$) conditions by measuring the expression and activity of Cu/Zn-superoxide dismutase (Cu/Zn-SOD), catalase (CAT), and glutathione peroxidase (GPX). The expression and activity of the antioxidant enzymes were significantly higher after the fish were exposed to $24^{\circ}C$, $20^{\circ}C$, and 17.5 psu, and expression was repressed by PRL treatment. Furthermore, we measured $H_2O_2$ and lipid peroxidation levels and found that they were significantly higher after exposure to the hypoosmotic and low-temperature environments. Additionally, we investigated changes in plasma AST and ALT levels after exposure to low temperature and hypoosmotic stress. These levels increased upon exposure of the clownfish to $24^{\circ}C$, $20^{\circ}C$, and 17.5 psu, but the levels of these parameters decreased in the 17.5 psu with PRL treatment during a salinity change. The results indicate that hypoosmotic and low-temperature conditions induce oxidative stress in cinnamon clownfish and that the parameters tested in this study may be indices of oxidative stress in the cinnamon clownfish.

• Environmental Analysis Health and Toxicology
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• v.24 no.1
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• pp.9-16
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• 2009

Effects of salinity and standard toxic metals on fertilization and embryo development rates were investigated in the sea urchin, Hemicentrotus pulcherrimus. Spawning was induced by injecting $1{\sim}2$ mL of 0.5 M KCl into the coelomic cavity. Males released white or cream-colored sperms and females released yellow or orange-colored eggs. The fertilization rate was below 30% when salinity was 20 psu and lower, but was almost above 90% when salinity was 25 psu and higher. The embryo development rate was below 60% when salinity was 25 psu and lower, but was above 80% when salinity was between 30 and 35 psu. The fertilization and embryo development rates in the control condition(not including Cu and Cd) were greater than 90%, but decreased a high negative correlation with the increasing of Cu(r=-0.80, r=-0.78) and Cd(r=-0.90, r=-0.82) concentrations, respectively. The fertilization and embryo development rates were significantly inhibited in the addition of Cu($EC_{50}$=17.30 ppb, $EC_{50}$=10.32 ppb) and Cd($EC_{50}$=364.57 ppb, $EC_{50}$=244.04 ppb), respectively. These results suggest that salinity concentrations for successful fertilization and normal embryogenesis of H. pulcherrimus are above 25 psu and 30 psu, respectively, and the biological assays of fertilization and embryo development rates using H. pulcherrimus are useful methods for the ecological toxicity test of marine pollution elements.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.4
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• pp.426-433
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• 2021

This study aimed to determine the appropriate salinity condition for optimal cultivation of the juvenile hybrid grouper Epinephleus akaara♀×E. lanceolatus♂ in conditions of decreasing salinity. The survival, growth, metabolic rate, stress, and histological response were investigated in juvenile hybrid grouper exposed to different salinities for 30 days. At 0 psu, the survival rate of the juvenile hybrid grouper was 60% on the 2nd day of exposure and all individuals died on the 3rd day of exposure. At salinities above 3 psu, all animals survived throughout the exposure period. Growth rate for body weight of the juvenile hybrid grouper was the highest in the control and the lowest at 10 psu. Plasma osmolality of the juvenile hybrid grouper exposed to different salinities was 313-355 mg Osmol/kg at salinities above 10 psu, and then decreased to 225-264 mg Osmol/kg at salinities below 5 psu. The oxygen consumption rate tended to decrease as the salinity decreased. Stress responses of the juvenile hybrid grouper were analyzed with decreasing salinity. Therefore, it is considered that a salinity of more than 20 psu is suitable for the culture of the juvenile hybrid grouper.

• The Korean Journal of Malacology
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• v.19 no.2
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• pp.133-142
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• 2003

For the effective seedling production of flat oyster, Ostrea denselamellosa, dietary value of live food, densities, water temperature and salinity on growth and survival rate of the larvae were examined. In rearing larvae by feeding them phytoplankton diets, the optimal survival rate and growth rate of larvae were found using a mixed phytoplankton diet which was mixed with Isochrysis galbana, Chaetoceros calcitrans and Chlorella sp. The highest growth and survival rates of the larvae were 208.4% and 38.8% with the phytoplankton diet. In growth and survival rates of larvae with various rearing densities, the highest survival and growth rates were 228.1% and 29.0% at the density of 2 individuals/ml. In observing rearing experiments of the flat oyster larvae under various temperature conditions, average growth rates of the larvae in respect to shell length were 202.2%, 240.4%, 250.6% and 121.3% in natural water temperatures (18-22$^{\circ}C$), 24$^{\circ}C$, 28$^{\circ}C$ and 32 $^{\circ}C$, respectively. And average survival rates of the larvae were 16.0%, 32.0%, 13.0% and 0% in natural water temperatures (18-22$^{\circ}C$), 24$^{\circ}C$, 28$^{\circ}C$ and 32$^{\circ}C$, respectively. In rearing at various salinities, the highest growth rates of the larvae in shell length was 240.0% at 30.0 psu and the highest survival rate was 31.0% at 25 psu.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.1
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• pp.8-18
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• 2003

In order to investigate the oceanic condition of fishing ground in the adjacent sea of Naro Island, the oceanographic observation were carried out by the training vessel of Yosu National University on winter, spring, summer, and autumn in 2000. Main features in the observation are as follows; 1) the ranges of temperature, salinity, and chlorophyll-a were from 4.$3\circ_C$ to 10.$1\circ_C$, from 33.1 psu to 34.9 psu, and from 0.1 $ug$/$\Omega$ to 26.2 $ug$/$\Omega$ in winter, from 8.$1\circ_C$ to 13.$7\circ_C$, from 33.1 psu to 34.3 psu, and from 0.1 $ug$/$\Omega$ to 24.4 $ug$/$\Omega$ in spring, from 14.$5\circ_C$ to 24.$2\circ_C$, from 30.5 psu to 34.1 psu, and from 0.1 $ug$/$\Omega$ to 30.0 $ug$/$\Omega$ in summer, and from 14.$8\circ_C$ to 18.$6\circ_C$, from 30.1 psu to 34.0 psu, and from 0.1 $ug$/$\Omega$ to 19.1 $ug$/$\Omega$ in autumn, respectively, 2) the temperature in the coastal region was higher than that in the open ocean while salinity was lower, and the convection was identified between the surface and the bottom during in winter and autumn, and the thermocline were made between surface and 20m layer with vertical gradients of 4.$0\circ_C$/7m in summer, 3) the chlorophyll-a in the this region was varied in each season, being highly distributed in spring, on bottom and coastal region, and 4) an evidence of sea water intrusion toward Sori Island was observed, and of inner water intrusion from Yeoja Bay was observed.

• Ecology and Resilient Infrastructure
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• v.10 no.3
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• pp.85-96
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• 2023

The study involved the categorization of domestic lakes located in South Korea into three groups based on their salinity levels: upstream reservoirs with salinity less than 0.3 psu, estuarine reservoirs with salinity ranging from 0.3 to 2 psu, and brackish lagoons with salinity exceeding 2 psu. Subsequently, the research assessed variations in the concentrations of total nitrogen (T-N) and total phosphorus (T-P) in the sediment of these lakes using statistical analysis, specifically one-way analysis of variance (ANOVA). Additionally, a laboratory core incubation test was conducted to investigate the benthic nutrient fluxes in Songji lagoon (salinity: 11.80 psu), Ganwol reservoir (salinity: 0.73 psu), and Janggun reservoir (salinity: 0.08 psu) under both aerobic and anoxic conditions. The findings revealed statistically significant differences in the concentrations of T-N and T-P among sediments in the lakes with varying salinity levels (p<0.05). Further post-hoc analysis confirmed significant distinctions in T-N between upstream reservoirs and estuarine reservoirs (p<0.001), as well as between upstream reservoirs and brackish lagoons (p<0.01). For T-P, a significant difference was observed between upstream reservoirs and brackish lagoons (p<0.01). Regarding benthic nutrient fluxes, Ganwol Lake exhibited the highest diffusive flux of NH₄⁺-N, primarily due to its physical characteristics and the inhibition of nitrification resulting from its relatively high salinity. The flux of NO₃^--N was lower at higher salinity levels under aerobic conditions but increased under anoxic conditions, attributed to the impact of salinity on nitrification and denitrification. Additionally, the flux of PO₄^3--P was highest in Songji Lake, followed by Ganwol Lake and Janggun Reservoir, indicating that salinity promotes the diffusive flux of phosphate through anion adsorption competition. It's important to consider the influence of salinity on microbial communities, growth rates, oxidation-reduction processes, and nutrient binding forms when studying benthic diffusive nutrient fluxes from lake sediments.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.4
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• pp.211-217
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• 2001

Physical oceanographic environments in the coastal sea of Chung-Moon located in the south coast of Cheju Island, Korea, where water pollutions by growing tourism complex possibly start to influence on the ecological system, are studied with hydrographic data observed monthly during July 1997 to June 2000. Winter and summer characteristics are shown in December to April and June to October, respectively, and transitional characteristics are shown in May and November. Waters show 14{\sim}16^{\circ}C$ and 34${\sim}$34.7 psu in winter and $15{\sim}27^{\circ}C$ and 32${\sim}$34.3 psu in summer. It tells that Tsushima water distributes in the whole column in winter and in the lower layer in summer, and Yangtze coastal water appears in the surface water in summer. When the influence of Yangtze coastal water is strong, salinities below 30psu are shown. Stratification is formed in the depth of about 20 m from June to October, so that it is not shown in the near shore stations, of which the depth is about10 m. Isotherms and isohalines sometimes tend to be perpendicular to the coast line in the surface, which seems to show influences from the steam power plant near St. 1 and the sewage disposal plant near St. 3. During the observation period, temperatures in St. 1 are a little higher than those in St. 2 and St. 3 except for a couple of months in summer and salinities in St. 3 are mostly a little lower than those in St. 1 and St. 2. Their effects seem to be no more than $0.4^{\circ}C$ in a distance of 300 m and no more than 0.1 psu within a distance of 30 m.

• Korean Journal of Environmental Biology
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• v.35 no.1
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• pp.6-12
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• 2017

This study focused on the physiological change of the shrimp, Litopenaeus vannamei postlarvae 15 stages, under different acclimation methods up to the endpoint of 4 practical salinity unit (psu). Besides using sea water as the control, two acclimation methods, fast acclimation (50% salinity reduction every 8 hours) and slow acclimation (50% salinity reduction every day), were adapted. Results show that the survival rate, glucose and blood uric nitrogen of each group were not significantly different. However, the ion profile differed according to the acclimation methods. Magnesium and sodium of shrimps acclimated to low salinity in both the methods, showed lower concentration than shrimps at 32 psu sea water. Especially, $Na^+$ concentration, which directly influences the osmolality of shrimp, decreased sharply in the fast acclimated group during the first eight hours (from 32 psu to 16 psu). To reduce acclimation stress, it is recommended to take more than eight hours during the first step for reducing the salinity.