WWW.WA S .ORG • WORLD AQUACULTURE • SEP TEMBER 2022 7 expanded spore broadcasting technology to improve the density of seaweeds in six coastal areas that have been degraded due to the occurrence of calcification whitening. The techniques were developed to increase the habitat density through the natural settling mechanisms of seaweeds with the combination of various application methods: 1) induction of zygote generation through the extraction of spore solution, 2) adult fragmentation in consideration of the life cycle of seaweeds, 3) bedrock application using a highpressure pump, 4) underwater broadcasting using an underwater supply line, and 5) drop broadcasting using an aerial drone. Spore broadcasting has been implemented at six locations that are new marine forest project sites this year. Broadcasting is held in JuneJuly and October-November, considering the growth period of seaweeds. The target seaweeds are native. In the first half of the year, miyeok Undaria pinnatifida, champulgasari Gloiopeltis tenax, kosiraegi Gracilaria sp., and cheonggak Codium fragile are applied. In the second half, there will be gamtae Ecklonia cava, gompi E. stolonifera, and dolgim Pyropia sp. Establishment of Oyster Spawning Grounds with the NIFS and Oyster Coop NIFS established spawning grounds for broodstock oysters in early June with the Oyster Fisheries Cooperative and oyster farmers to secure stable oyster spawning on the southern coast. They established spawning sites in six sea areas: Pildo and Jeosan in Tongyeong, Galhwa and Bongu (new location) in Namhae-gun, Yangpo in Hadong-gun, and Gadeokdo in Busan. More than 50 oyster farmers actively participated in selecting oysters, accepting chaerong nets and unloading spawning grounds this year. In recent years, oyster farmers on the southern coast have had difficulty securing seeds due to delayed maturation of broodstock oysters or not spawning simultaneously. Accordingly, in 2019, NIFS created spawning grounds by putting healthy broodstock oysters in a chaerong net according to the characteristics of each sea area on the southern coast or broadcasting them on the bottom. Before the oyster breeding field construction, seed production was secured from several hatcheries. NIFS established the effective places and methods for seeding with the implementation of a breeding field project. In 2021, NIFS secured the annual number of seeds at one time. As a result, it was possible to reduce the seed cost. This year, NIFS is expected to create oyster spawning grounds to ensure smooth oyster seed production. Criteria for considerations when constructing spawning grounds was established by continuously investigating and analyzing changes in the fattening rate, sexual maturation, spawning volume and larval diffusion characteristics of oysters by sea area. Exploring Cell Life Extension with Cryopreservation Technology of Abalone Sperm The KIMST announced success of cryopreservation technology from the project “Development of abalone culture production technology using sperm cryopreservation method” to prevent the death of abalone sperm cells (apoptosis). Professor Kang-Hee Koh’s team from the Department of Aquaculture Biology at the Chonnam National University, the lead research institute for this study, focused on the generation of free radicals by cells due to damage to the antioxidant defense system and increased lipid oxidation, which in turn accelerates cell death. A gene increase method that suppresses sperm cell death was developed. Three types of antioxidant enzyme activities (catalase, superoxide dismutase, glutathione) were increased in frozen sperm treated with natural sugars, and expression of five significant antioxidant genes (CAT, Cu/Zn-SOD, Mn-SOD, GPx, GR) was increased. Expression of mRNA increased, and the cells were relieved. In particular, the expression of apoptosis suppressor genes (BLC-2, HSP70, HSP90) was significantly increased in frozen sperm treated with saccharides, and apoptosis promoting genes (Bax, Caspase-3) were decreased. Results of this study are expected to have an epochal impact on future cell life extension research and should help preserve the genes of marine aquatic organisms and develop cryogenic biology. Through this study, it is expected that the semipermanent preservation of abalone sperm and the resulting increase in immunity will bring a paradigm shift in the seed industry of aquaculture animals and plants. — Ik Kyo Chung, President C H A P T E R R E P O R T S
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