• The Korean Journal of Malacology
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• v.27 no.3
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• pp.167-173
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• 2011

This study was performed to describe the effect of water temperature, salinity and density on the eggs development of the hard clam, Meretrix petechialis. Eggs of Meretrix petechialis were turned out to be demersal isolated eggs of $82.3-86.1{\mu}m$ in an average diameter after spawning. The hatching rate of D-shaped larvae by elapsed time after spawning was the highest in fertilization immediately after spawning and distinguished decrease from 1 hour of spawning. The optimum water temperature for development of D-shaped larvae from fertilization was ranged between $25^{\circ}C$ to $27^{\circ}C$. However, D-shaped larvae was not developed at $33^{\circ}C$ of water temperature. The required time from fertilization to D-shaped larvae were 37.3 hours in $20^{\circ}C$, 20.8 hours in $25^{\circ}C$, and 15.3 hours in $30^{\circ}C$. Biological minimum temperature for the egg development was estimated to be $12.4^{\circ}C$ in average. The range of salinity for the development of eggs were 20.0-37.5 psu, optimum range was estimated to be 27.5-32.5 psu.

• Journal of Aquaculture
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• v.21 no.2
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• pp.63-69
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• 2008

We isolated complementary DNA(cDNA) encoding prolactin receptor(PRLR) from gill of black porgy Acanthopagrus schlegeli. Its PRLR cDNA consists of 1,611 base pairs and encodes the protein of 536 amino acids. To investigate the osmoregulatory abilities of black porgy in different salinities(35, 10 and 0 psu), we examined the expression of PRLR mRNA in osmoregulatory organs(gill, kidney and intestine) using reverse transcription(RT)-PCR. In gill and intestine, PRLR mRNA levels were high in 10 psu, and then decreased in 0 psu, but there is no changes in kidney. Also, plasma osmolality, $Na^+\;and\;Cl^-$ levels decreased during the experimental period. These results suggest that PRLR plays an important role in hormonal regulation in osmoregulatory organs during freshwater acclimation, thereby improving the hyper-osmoregulatory ability of black porgy in hypoosmotic environments.

• Korean Journal of Environmental Biology
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• v.37 no.2
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• pp.119-128
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• 2019

The morphological characteristics of the bloom-forming dinoflagellate Akashiwo sanguinea isolated from Jangmok Harbour, Geoje in Korea was examined using light and scanning electron microscope (SEM), and its large subunit (LSU) rDNA was sequenced. Additionally, investigation was done on the effects of temperature and salinity on the growth of A. sanguinea. The cells were dorso-ventrally compressed up to 54.7-70.3 ㎛ long and 31.5-48.5 ㎛ wide. The epicone was conical while the hypocone was separated into two lobes. The nucleus was positioned at the center of the cell. The yellow-brown chloroplasts radiated close to the cell center. SEM observation indicated that A. sanguinea has an e-shaped apical groove. Molecular phylogeny based on LSU rDNA gene sequences revealed that the A. sanguinea strains isolated from Jangmok Harbor were classified in the clade of ribotype A. The maximum growth rate (0.50 day^-1) was observed at 20℃ and 20 psu, while the maximum cell density (1,372 cells mL^-1) was observed at 25℃ and 30 psu. This indicates that the blooms of A. sanguinea ribotype A in Korean coastal area are affected by water temperature, rather than the salinity.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.2
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• pp.113-123
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• 2005

Samples were collected to investigate the effect of salinity change on biological interaction between primary producers and herbivores in water column of the Youngsan estuary (Mokpo Harbor) at 8 stations from October 2003 to September 2004. The highest river freshwater inputs were introduced into the estuary from the Youngsan dike during summer (June and July 2004). Ranges of salinity were between 6 and 28.9 psu when the gates of dike were open whereas the ranges were between 24.4 and 30.3 psu when the gates were closed. Algal bloom occurred in February and July when the gates were not open at the upper region of the Youngsan estuary and the bloom was dominated $(70\%)$ by large cells of phytoplankton $(micro-sized;>20{\mu}m).\;Nano-sized (2-20{\mu}m)$ and pico-sized phytoplankton $(<2{\mu}m)$ were dominant in October, November 2003, June, August and September 2004 when the gates were open suggesting that size structure was affected by river discharge from the dike. Micro-and meso-zooplankton (herbivores) displayed the similar pattern to that of phytoplankton. The biomass of zooplankton was higher when the gates were closed than when the gates open and also the biomass was higher at the upper region of the harbor system. This results suggest that freshwater inputs affect size structure and biomass of phytoplankton by changing salinity, nutrient inputs, turbidity or light level In water column resulting in the change of the interaction between primary producters and herbivores in the Youngsan estuary.

• Journal of Environmental Impact Assessment
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• v.27 no.1
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• pp.17-32
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• 2018

The need for seawater desalination is increasing in terms of securing various water resources, but few studies are available as for the environmental impact of hypersaline concentrated water (brine) discharged from desalination plants. Domestic studies are concentrated mainly on toxicity evaluation that phytoplankton, zooplankton larvae and green algae (Ulva pertusa) are negatively affected by concentrated water. The mortality of Paralichthys olivaceus showed a linear relationship with increasing salinity, and Oryzias latipes died 100% at concentrations above 60 psu. Foreign studies included monitoring cases as well as toxicity evaluations. The number of species decreased around the area where the concentrated water discharged. The hypersaline concentrated water affects the pelagic and benthic organisms. However, the fishes escaped when exposed to salinity, and the pelagic and benthic organisms resistant to salinity survived the hypersaline environment. The salinity limit and distance from the outlet was presented as the regulatory standard for bine discharge. There were differences in regulatory standards among country and seawater desalination plants, and these regulatory standards have been strengthened recently. In particular, California Water Boards were revised to ensure that the maximum daily salinity concentration does not exceed 2 psu above the ambient salinity level within 100 m of the outlet.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.3
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• pp.122-130
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• 2013

To examine floc characteristics of cohesive bed sediment of the Yeongsan River estuary, a floc camera system has been developed and utilized to observe flocs under varying conditions. In order to validate the floc camera system, sand particles were passed through 88-125 and $63-88{\mu}m$ sieves and observed within the laboratory. Mean grain size and settling velocities were found to be 102 and $56.2{\mu}m$ and 6.7 and 5.9 mm/s, respectively. Artifacts of particles estimated outside of the sieve range are attributed to being imaged out of the depth of focus. However, as mean grain size and settling velocity of each size class were within the confidence interval, the floc camera system was confidently used to examine cohesive bed sediments of Yeongsan River estuary. The bed sediment sample was prepared with a concentration of 0.1 g/L in 0 psu deionized water. The mean grain size, settling velocity and fractal dimension of flocs were $40.6{\pm}0.66{\mu}m$, 14 mm/s, and 2.86, respectively. Experiments were also conducted using different salinities (10 and 34 psu) and sediment concentrations (0.1 and 0.3 g/L). Despite changing these parameters, the mean observed grain size and settling velocities were found to be the same within the error range of the system. The relatively higher values of settling velocity and fractal dimension are considered a result of the sediment containing relatively small concentrations of organic matter. Moreover, consistent floc size over various grain sizes and concentrations may be the result of insufficient turbulence to aggregate flocs.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.1
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• pp.1-10
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• 2014

The effects of temperature, salinity and irradiance on the growth of the dinoflagellate Akashiwo sanguinea isolated from Jaran Bay were examined in the laboratory. Maximum specific growth rate($0.28day^{-1}$) was observed with combination of $25^{\circ}C$ and 30 psu. Optimal growth (${\geq}80%$ of maximum specific growth rate) was obtained at $25^{\circ}C$ with salinities of 15~35 psu. This results indicated that A. sanguinea is a stenothermal of the high water temperature and euryhaline species. The irradiance-growth curve was described as ${\mu}=0.31(I-16.87)/(I+51.19)$. The compensation photon flux density ($I_0$) and half-saturation photon flux density ($K_I$) were $16.87{\mu}mol\;m^{-2}s^{-1}$ and $84.93{\mu}mol\;m^{-2}s^{-1}$, respectively. In conclustion, A. sanguinea has advantage physiological characteristics for the species succession at the coastal areas in summer with sufficient irradiance, high water temperature and large salinity gradient.

• Ocean and Polar Research
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• v.38 no.1
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• pp.47-57
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• 2016

Effects of environmental factors on the zoospore release and germling growth of Chaetomorpha linum were examined. Zoospore release and germling growth experiments were carried out under a combination of temperatures ${\times}$ irradiances, and a single factor of irradiances, salinities, daylength and nutrients (nitrogen, phosphorus). Zoospore release was maximal under condition of $20^{\circ}C{\times}100{\mu}mol\;photons\;m^{-2}s^{-1}$ in a factorial experiment (temperatures ${\times}$ irradiances), at $100{\mu}mol\;photons\;m^{-2}s^{-1}$ in irradiance experiment and at 34 psu in salinity conditions. After 24 days in culture, germling growth was maximal at $25^{\circ}C{\times}100{\mu}mol\;photons\;m^{-2}s^{-1}$ in temperatures ${\times}$ irradiances and at normal seawater (34 psu) in salinity. Germling growth is faster at higher irradiance under same temperature condition and it increased with increasing daylengths (8-16 h). Chaetomorpha linum grew in wide range of N and P concentrations. The growth of germling was maximal at $50{\mu}M\;{PO_4}^{3-}$ and $40{\mu}M\;{NH_4}^+$. Germling growth was more effective under nitrogen addition than phosphorus addition in culture. In conclusion, optimal environmental conditions for zoospore release were $20^{\circ}C$, $100{\mu}mol\;photons\;m^{-2}s^{-1}$, and 34 psu. In addition, the optimal germling growth was observed at $25^{\circ}C$, $100{\mu}mol\;photons\;m^{-2}s^{-1}$, 34 psu, 16 h, $50{\mu}M\;({PO_4}^{3-})$ and $40{\mu}M\;{(NH_4}^+)$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.3
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• pp.199-206
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• 2001

Behavior of nutrients along the salinity gradients in the Seomjin River estuary was investigated in March July, September and November, 1999. Sampling sites were set based on the surface salinity during each cruise rather than geographic locations. The results suggest that source of nitrate and silicate was the Seomjin River discharge, while that of nitrite and phosphate was waste disposal from the Gwangynng Bay near the mouth of Seomjin River estuary. Ammonia was supplied inside the estuary at the region about $6\~8$ km far from Nancho Island. Strong removal behavior of some nutrient such as ammonia, phosphate and silicate was observed at $5\~15$ psu salinity area in November, where high concentrations of $chlorophyll\;a\;(>8{\mu}g/L$) occurred. High N : P ratios and entirely removal of phosphate at chlorophyll a peak region suggest that phosphate is the limiting factor for phytoplankton growth. Relatively high ratios of Rb to Ra (Rb: Fluorescence before acidification, Ra: Fluorescence after acidification) at $5\~15$ psu salinity region in November indicate that phytoplankton were in good physiological condition.

• Korean Journal of Environmental Biology
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• v.37 no.1
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• pp.31-41
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• 2019

The toxic dinoflagellate Gymnodinium catenatum isolated from the southern coast of Korea was described under light and scanning electron microscopy, and its large subunit (LSU) rDNA was sequenced. In addition, the effects of temperature and salinity on its growth were investigated. The cells of G. catenatum, as viewed under the electronic microscope, were green-brown color, $38.1-77.4{\mu}m$ in length and $26.1-40.8{\mu}m$ in width. The epicone was conical, while the hypocone was trapezoidal. The nucleus was located at the central part of the cell. The apical groove was horseshoe-shaped and small pores were irregularly distributed on the cell surface. Molecular phylogeny based on LSU rDNA gene sequences showed that the Korean G. catenatum and previously reported species formed a monophyletic clade within Gymnodinium sensu stricto clade. The maximum growth rate of $0.37day^{-1}$, was obtained at $25^{\circ}C$ and 35 psu, and the maximum cell density of $1,073cells\;mL^{-1}$, was observed at $20^{\circ}C$ and 25 psu. However, G. catenatum did not grow at temperature < $15^{\circ}C$ and < $30^{\circ}C$. These results suggest that environmental conditions of summer and autumn in the southern coast of Korea may be favorable for the growth of G. catenatum.