In this study, we estimated the distribution density of giant jellyfish in coastal waters of Korea in 2023 and compared the occurrence of giant jellyfish over four years. In May, the giant jellyfish were mainly distributed in the waters of the Yangtze River outflow, and in July, they were highly distributed in the west of Jeju Island and near the south coast of Korea. In addition, when comparing the distribution densities of giant jellyfish in Korea over four years, both acoustic and sighting surveys showed that the highest density of jellyfish occurred in 2021.

In this study, the vertical distribution of giant jellyfish analyzed echo counting method and such survey methods as sighting and trawl were used to compare its density estimates. In May and July 2021, surveys were conducted in the East China Sea and the coastal waters of Korea. As a result, Nemopilema nomurai were evenly distributed in all water layers in East China Sea in May and July. When considered the correlation by each survey methods, it is possible to identify jellyfish in the surface area by sighting method and using sampling net; however, it has a low correlation with acoustic estimates due to marine environmental factor such as weather condition, wind and atmospheric pressure. Therefore, the result can be utilized by basic data when estimating jellyfish’s distribution patterns and density estimates from each survey methods hereafter.

Jellyfish envenomation is a world-wide health problem, which often seriously affect the fishery and bathing activities. To date, few individual jellyfish venoms proteins have been thoroughly characterized yet. In this work, four species of scyphozoan jellyfish (Nemopilema nomurai, Cyanea nozakii, Aurellia aurita and Rhopilema esculentum) are compared according to their, cytotoxicity, hemolytic potency, brine shrimp toxicity and protein components. Jellyfish venoms showed higher cytotoxicity in H9C2 heart myoblast than in C2C12 skeletal myoblast, with the exception of C. nozakii venom. This result suggests that the selective cytotoxic effects may be possibly related to their in vivo effects of cardiac tissue dysfunction. On the other hand, hemolytic activity could be also observed from all tested jellyfish venoms. N. nomurai jellyfish venom displaying the greatest hemolytic activity. As an alternative method of evaluating the toxicities of jellyfish venoms, the toxicity on brine shrimp was examined with the four jellyfish venoms. From this, the venom of N. nomurai showed higher toxicity against brine shrimp than the other jellyfish venoms, which is consistent with the results of cytotoxicity assay as well as hemolysis assay of the present study. SDS-PAGE analysis of four jellyfish venoms showed the similar pattern with molecular weight of around 40 kDa, and appeared to be the major protein components. These results provided that N. nomurai jellyfish venom was potently toxic than other scyphozoan jellyfish venoms and may explain to some extent the deleterious effects associated with human envenoming.

The Nemopilema nomurai is a large jellyfish attaining a weight of 200 kg and bell diameter of 2 m when fully grown. To prevent damage to this species, this study determined the acoustic characteristics of N. nomurai using frequencies 38 and 120 kHz. The CPUE of N. nomurai and the averaged SV of 38 and 120 kHz had a lower (+) correlation coefficient and relationship at 120 kHz (R=0.51) than at 38 kHz (R=0.15) was significant. In addition, the averaged SV at 120 kHz was higher than at 38 kHz. The δMVBS120-38 in section catches ≥97.8% wet mass of N. nomurai was -2.2 to 5.6 dB. The δTS120-38 in situ TS was extracted in sections catches of only N. nomurai by FMT. It was found that the averaged in situ δTS120-38 were at 0.6 and 0.1 dB. Furthermore, it results showed a close relationship between the bell diameter and TS of N. nomurai. The dominance of smaller N. nomurai (11.0~20.0 cm bell diameter in the air) corresponded to a similar proportion of low TS values (-69.0~-65.0 dB). A small number of larger N. nomurai (25.0~38.0 cm bell diameter in the air) were collected, in which TS values were the highest (-62.0~-58.0 dB).

The Nemopilema nomurai a very large jellyfish that has been found in the East China Sea and is now are migrating to Korea and Japan. To investigate the occurrence of N. nomurai based on the changing marine environment of the East China Sea, we conducted field survey in the early summer from 2006-2008. We observed the marine environment using CTD and the occurrence of N. nomurai using FMT and bottom trawling. We caught the most N. nomurai in 2007 and the fewest in 2008 and environment factors influencing its are more sensitive temperature than salinity. Large quantities of N. nomurai with a small bell diameter were caught in 2007 and large individuals with a significant bell diameter were caught in 2008. This appeared which between the catch and bell diameter of N. nomurai had (-) correlation (R=-0.988, p=0.098). Meanwhile, the spatial distribution of N. nomurai concentrations in lower salinity mixed seawater inflow in Changjiang Diluted Water.

A giant jellyfish (Nemopilema nomurai), which is presumed developing in the East China Sea, is recently one of major issues in the Northeast Asia region due to its fatal damage to the fishery. The biomass estimates have generally been conducted by trawl sampling and sighting survey methods. The biological research is also needed to clarify such environmental origin or diurnal migration patterns. While trawl sampling or sighting survey methods are effective to investigate its density estimates in its distributed community of near bottom or surface, they have a problem in investigation on the vertical distribution of jellyfishes. In this case, an echo sounding detection would have an advantage to survey it more extensively and effectively. This trial was conducted to observe the vertical distribution of giant jellyfish, where thermocline strongly formed, during mooring at each station of the East China Sea and southern coastal area using acoustical and optical methods. By the results, they were observed to exit and move at the water column under the thermocline using the optical camera and echo sounder system, and the information was analyzed to find out the acoustical sound scattering characteristics relatives to 120kHz frequency. These results can be utilized effectively to estimate the vertical distribution and biomass of Giant jellyfish with comparing results from trawl sampling and sighting survey methods, hereafter.

본 연구에서는 해파리로부터 콜라겐 추출물을 제조하였고, 이에 대한 보습 효과를 측정하였다. 보습 효과 는 caspase 14 발현, filaggrin, hyaluronan synthase-3 (HAS- 3), aquaporin-3 (AQP-3) 및 desmocollin (DSC)을 측정하였다. 그 결과, caspase 14 mRNA 발현은 비교물질인 retinoic acid (RA)와 유사한 효 과를 나타냈다. 그리고 콜라겐 추출물은 20 mg/mL의 농도에서 각각 211.7%, 139.9%, 212.5% 및 116.8%의 filaggrin, HAS-3, AQP-3 및 DSC 발현 증가를 나타냈다. 따라서, 본 연구에서 해파리 콜라겐 추출물은 보습 효과를 갖는 화장품 소재로서의 개발 가능성이 클 것으로 기대할 수 있다.

본 연구에서는 노무라입깃해파리(Nemopilema nomurai) 가수분해 추출물의 미백활성에 대하여 검색하였다. 가수분해 시료(NHE, N. nomurai Hydrolized Extract)는 노무라입깃해파리를 상업용 단백질분해효소(Protamex, Alcalase, Flavourzyme, Neutrase)를 이용하여 55℃에서 pH 5-8 조건으로 처리하는 과정을 거쳐 얻었다. 미백활성은 B16-F1 멜라노마 세포에서 멜라닌 색소 합성 저해능 평가를 통하여 확인하였다. 실험결과, Neutrase로 처리된 시료(N-NHE)에서 100μg/mL의 농도에서 멜라닌 생성이 가장 효율적으로 89.9% 감소되는 것을 관찰하였다. 이 시료는 또한 tyrosinase와 TRP-1 (tyrosinase related protein-1) 단백질의 발현을 억제하였다. 이상의 연구 결과는 노무라입깃해파리 가수분해 추출물의 화장품 미백 소재로의 개발 가능성을 보여주고 있다.