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ISSN : 1225-3480
Recently, for the purpose of constructing artificial ecosystem, the public aquarium and experimental mesocosm systems are receiving attention. To design and establish an aquarium and mesocosm system, there is need of several materials for simulating the environment, such as sediments, rocks, and plants. Expecially for sessile mollusks, there must be proper materials to which sessile invertebrates can adhere. Nowadays, many aquariums and mesocosm systems are using dead coral skeletons for sessile mollusks. This study was proceeded to have data on the effect of dead coral skeletons on water qualities with the experiment on the environmental factors. For this purpose, I made glass tank for experiment, chose two types of dead coral skeletons imported from the Indonesia and observed the change of water qualities and decomposition efficiency of TAN (total ammonia-nitrogen), nitrite (<TEX>$NO_2{^-}$</TEX>) and nitrate (<TEX>$NO_3{^-}$</TEX>). As a result, the lager the surface area was, the more TAN, nitrite and nitrate decomposition rate increased. In addition, coral skeletons covered with crustose algae and bacteria in the tank showed faster TAN, nitrite and nitrate removal rate and stabilization. Accordingly, this experiment suggested that dead coral skeletons could be used as a sub filter for the closed system as well as an adhering plate.
This study was performed to know the community structure of macrobenthos and environmental factors at each 16 stations in the subtidal sandy bottoms of the southern coastal water of Jeju Island from July to November, 2011. Mean temperature and mean salinity were <TEX>$20.2-22.7^{\circ}C$</TEX>, 33.7-34.9 psu which shows stable water messes. Chlorophyll a concentrations of phytoplankton ranged from 0.71 to 1.71 mg/L (1.11 mg/L), showing higher July than September and November with a blooming in summer. The mean concentration values (the ranges in parentheses) of nitrate, phosphate, and silicate are 0.029-0.206 mg/L (0.101 mg/L), 0.001-0.027 mg/L (0.007 mg/L), 0.024-0.682 mg/L (0.454 mg/L), respectively. However, the values higher coastal zone due to influxes from the land. A total of 37 species was identified. of these mollusca comprised 29 secies (78.4%); Echinodermata 5 (13.5%); Arthropoda 3 (8.1%). density and biomass were estimated to be 550 ind./<TEX>$m^2$</TEX> and 20,951.8 gwwt/<TEX>$m^2$</TEX>, respectively. Mollusca were the most dominant faunal group in terms of abundance (481 ind./<TEX>$m^2$</TEX>) and number of species as well, whereas bivalves were predominant in biomass (16,647.6 gwwt/<TEX>$m^2$</TEX>). The dominant species were Vasticardium burchardi, Oblimopa japonica, Mactar achatina, Bornatemishistrioiw akawai, Paphia vernicosa, Amusium japonicum, Glycymeris albolineata, Astriclypeus manni in 15-30 m. The seasonal variation appeared as distinct, Mollusca of individual and biomass. When summer was make a slow increase, after the highest decrease in autumn. The abundance of macrobenthic invertebrates showed significant correlation with environmental factors (Chlorophyll a, DIN, <TEX>$SiO_2$</TEX>, Fine sand, Very fine sand) in almost all sampling depths. The biodiversity, evenness richness index were appeared 1.56-2.50 (H'), 0.49-0.80 (E'), 4.12-4.67 (R) in each stations. The dominace index were appeared Highest in November and lowest in September.
The ecophysiological characteristics of the oyster Crassostrea gigas in Taean area, west coast of Korea, were investigated after main spawning season from September 2011 to January 2012 to confirm the recovery process of condition. The cupped oysters, from 4 different off-bottom culture areas were compared the gonad indices, histological analysis combined with measurement of RNA/DNA contents and ratios in gonad of each sex were undertaken. To evaluate the health condition of oyster after spawning, the RNA/DNA ratio in adductor muscle, fatness and condition index (CI) were used. The results showed that cupped oysters cultured in Uihang coastal area were different physiological aspects than other experiment areas, namely continuously decreasing RNA/DNA content and ratio in adductor muscle, lowest CI and fatness. Oysters cultured in Iwon Station 1 and 2 showed fast recovery in RNA/DNA, increase in fatness and CI during post-spawning stage until October rapidly and there after it decreased. Oysters in Shinduri showed rapidly decrease in fatness and CI until October. On the contrary to this factors, RNA/DNA ratio in adductor muscle increased as like protein until October. Partially spawning season could be observed until December in Shinduri and Iwon Station 1.
In order to evaluate the relationship of between the contents of inorganic elements in shellfish and surface sediments, we measured the concentration of inorganic elements (As, Ca, Cd, Cr, Fe, Hg, Li, Mn, Ni, P, Pb, Zn) in various shellfish and surface sediments of research area. The enrichment factor (EF) and the index of accumulation rate (Igeo) of the metals showed that the research areas can be classified as moderately polluted, or unpolluted. And also we measured the geochemical characteristics of surface sediments(grain size, chemical oxygen demand (COD), ignition loss (IL) and acid volatile sulfide (AVS). The grain sizes for research areas of surface sediment were similar the ratio of silt and clay in comparison with other sites. The COD and IL in surface sediment ranged from 5.41 to 14.06 mg/g. d.w. (mean <TEX>$8.78{\pm}3.16$</TEX> mg/g d.w.) and from 0.92 to 3.17% (mean <TEX>$2.08{\pm}0.86%$</TEX>), respectively. Siginificant differences in metal concentrations also were determinated in the shellfish tissue among the different sites. However, except for metals(Mn, Zn), which showed some elevation of concentrations, the variations in the shellfish tissue were not related to variations in the sediment.
Goseong bay, located in southeast sea of Korea with an area of 2,100 ha, is a semi-enclosed bay well-known for oyster farming cultured in an extended range of 148 ha. The objective of this study is to provide the fundamental data in order to manage the effective sea area. A total 26 of surface sediment were collected from Goseong bay to evaluate their sedimentary environment and heavy metals. The loss on Ignition (LOI), C/N ratio, acid volatile sulfide (AVS) and heavy metals were analyzed. loss on ignition (LOI) of surface sediment range from 1.00% to 3.03% (average 2.00%). The carbonate content ranges from 0.52% to 4.29% (average 2.37%). C/N ratio of organic matter showed that most part of organic matter comes from neighboring continent. Acid volatile sulfide (AVS) value of surface sediment from 0.02 mg/g to 1.43 mg/g (average 0.24 mg/g). A ten element of surface sediments (Al, As, Cd, Cr, Cu, Hg, Ni, Pb, V, Zn) were calculated by enrichment factor (Ef) and the results show that some areas are highly polluted with respect Cu and Hg. The correlation matrix displays the existence of remarkable levels of correlation with both positive and negative values among different variable pairs. LOI and AVS showed both positive values. LOI and AVS values falls under 2% and 1%. Therefore, Goseong bay showed good in quality of sediment.
This project analyzes distinct qualities of pearl cultured in Tongyeong by physical, chemical and optical test. The result is to provide scientific data for the value of pearl from Korean seawater. It divides one year pearl, which is used as a sample in the project, into white, natural blue and yellow gold colors, and then it has been divided into A, B and C based on the quality of the last results. A chemical experiment demonstrates that the higher quality has lower protein content of less than 10%. In another test called heavy metal content test, there is no big difference among classes. In the characterization of spectroscopy, it shows 280 nm peak indicated the conchiolin. It is clear that 407 nm, 430 nm and 460 nm peak are White group that are not in processed condition.
Forty four specimens (22.5-34.2 cm ML) of Heterololigo bleekeri were collected around Dokdo, East Sea on March 1, 2012. It was identified as H. bleekeri based on the following combination of morphological character: mantle very elongate; fin large, thick, length two-thirds of mantle length; arms very short and small in relation to body size, are formula III>II>IV>I.
Due to the oil spill incident in December 2007, every facility of oyster culture was removed in western coast especially in Taean and Seosan. To restore oyster resources in Taean and Seosan, we brought oyster seeds from southern area and monitored their growth. In addition we monitored the culture environment throughout the year, and observed the number of oyster larvae and attached spats on collectors during summer. The factors of water environment were appropriate for oyster culture in both study area. The growth of shell height was larger in Uihang-ri, Taean than Jungwang-ri, Seosan. Spawning was more intensive in a short time in Jungwang-ri, Seosan than Uihang-ri, Taean. The number of oyster larvae and spats of collectors were much more in Jungwang-ri, Seosan than Uihang-ri, Taean. This study showed that transplantation of healthy oyster seeds from southern area can be a way of restoration of oyster resources in western coast. In addition, systematic approaches are necessary by building a better understanding of regional characteristics to restore and enlarge the oyster culture farms in western coast. In summary Uihang-ri, Taean will be appropriate for cultivation farms and Jungwang-ri, Seosan for seedling grounds to increase oyster culture productivity.
The genetic variation of Ark Shell, Scapharca broughtonii black was estimated using six polymorphic microsatellite (MS) loci in 443 individuals collected from five populations in Korea. The mean numbers of alleles per locus in five populations were 10-28. The mean number of alleles per locus in Jinhae Hatchery (JHH) population showed the least value as 15.5, but that in Gangjin (GJ) population showed the most value as 20.3. The mean expected heterozygosity in Saryangdo (SR) population showed the least value as 0.817, but that in Gangjin (GJ) population showed the most value as 0.831. In Jinhae hatchery(JHH) population, the mean expected heterozygosity was 0.822, there was no significant difference from those of wild population. The <TEX>$F_{ST}$</TEX> values in Gangjin (GJ) population showed significant difference from those of the other populations, which revealed Gangjin (GJ) population is genetically different from the other populations. The <TEX>$F_{ST}$</TEX> values among Jinhae Hatchery (JHH) population, Jinhae (JH) population and Saryangdo (SR) population showed lower values than the others, which implies there was a gene flow among these three populations. The <TEX>$F_{ST}$</TEX> value and genetic distance between Jinhae (JH) population and Saryangdo (SR) population showed the least value as 0.0001 and 0.0386, indicating that these two populations were genetically the same.
The specimens of triphorid snail, Bouchetriphora consfera were collected from Jeju-do, Korea and diagnostic characters were analysed. As a result, the genus Bouchetriphora is reported for the first time in Korean malacol fauna and the family Triphoridae in Korea turned out to be 15 species of 10 genera.
Aquaculture is challenged by a number of constraints with future efforts towards sustainable production. Global climate change has a potential damage to the sustainability by changing environmental surroundings unfavorably. The damaging parameters identified are water temperature, sea level, surface physical energy, precipitation, solar radiation, ocean acidification, and so on. Of them, temperature, mostly temperature elevation, occupies significant concern among marine ecologists and aquaculturists. Ocean acidification particularly draws shellfish aquaculturists' attention as it alters the marine chemistry, shifting the equilibrium towards more dissolved CO2 and hydrogen ions (<TEX>$H^+$</TEX>) and thus influencing signaling pathways on shell formation, immune system, and other biological processes. Temperature elevation by climate change is of double-sidedness: it can be an opportunistic parameter besides being a generally known damaging parameter in aquaculture. It can provide better environments for faster and longer growth for aquaculture species. It is also somehow advantageous for alleviation of aquaculture expansion pressure in a given location by opening a gate for new species and aquaculture zone expansion northward in the northern hemisphere, otherwise unavailable due to temperature limit. But in the science of climate change, the ways of influence on aquaculture are complex and ambiguous, and hence are still hard to identify and quantify. At the same time considerable parts of our knowledge on climate change effects on aquaculture are from the estimates from data of fisheries and agriculture. The consequences may be different from what they really are, particularly in the temperature region. In reality, bivalves and tunicates hung or caged in the longline system are often exposed to temperatures higher than those they encounter in nature, locally driving the farmed shellfish into an upper tolerable temperature extreme. We review recent climate change and following environment changes which can be factors or potential factors affecting shellfish aquaculture production in the temperate region.
