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Satellite Remote Sensing-Based Monitoring of the Relationship Between Low-Salinity Waters and Essential Marine Variables in the East China Sea
No full text1
Sulfated steroids isolated from the marine sponge Petrosia (Strongylophora) strongylata and their antimicrobial activity
No full textThe extract of Petrosia (Strongylophora) strongylata was separated to trace sulfated terpenoids, which were expected to be present in the crude extract based on its 1H NMR spectrum. As a result, seven sulfated (1–7) sterols and one highly oxygenated steroid (8), including two unreported analogs (4 and 7), were isolated and identified. The MIC measurement of all isolated compounds against six bacterial cell lines demonstrated that compounds 1–7 efficiently inhibit the growth of Gram-positive bacteria. Compound 8, which lacks the sulfate group in the structure, displayed no activity even at a concentration of 128 µM. This study demonstrated that the sulfate groups in the structures of sterols play a critical role in the growth inhibition of Gram-positive bacteria, suggesting the potential of sulfated sterols for use as antimicrobial agents. The modes of action of these compounds and their molecular targets are currently under investigation.11Nsciescopu
Impacts of Along-Strait Winds on Sea Level, Sea Surface Temperature, and Current in the Jeju Strait During Summer 2022
No full textThe along-strait wind in the Jeju Strait (JS) significantly impacts the sea level, surface temperature, and currents on its northern and southern coasts. During the summer of 2022, the winds in the JS were characterized by strong easterly winds that occurred before the approach of several typhoons. A strong correlation of 0.61 was found between the along-strait wind and the difference in sea level anomaly between the strait’s south and north coasts. A more robust correlation of 0.71 was estimated between the along-strait wind and the difference in sea surface temperature anomaly. When the positive (eastward) wind blows along the strait, it causes upwelling along the north coast, resulting in cold anomalies there and warm anomalies along the south coast, and vice versa. In addition, a positive correlation (r = 0.39–0.50) was estimated between the along-strait wind and along-strait surface current, with a negative correlation (r = −0.68 to −0.44) for the cross-strait current in most observation stations of the JS, except near the coast of Jeju Island. The positive along-strait wind causes the sea level to fall on the north coast and strengthens the eastward surface current. In contrast, the negative (westward) along-strait wind has the opposite effect, causing the sea level to rise near Wando, then slowing down or reversing the eastward surface current. Overall, these findings show that Ekman dynamics can explain wind-induced coastal upwelling and downwelling on both coasts of the JS, providing valuable insights into the environmental conditions surrounding marine organisms in this coastal region.11Nsciescopuskc
Spatial variability of sediment oxygen consumption and benthic nutrient fluxes in the continental shelf of the Southern Yellow Sea during spring
No full textTo understand the factors controlling organic carbon (OC) and nutrient cycling in continental shelf sediments, we estimated total sediment oxygen uptake (TOU) and benthic nutrient flux (BNF) in the Southern Yellow Sea (SYS) during spring. The OC (0.28 to 1.58%), TN (0.03 to 0.22%), C/N ratio (7 to 11), and δ13C (–23.81 to –22.23‰) in the surface sediments showed spatial variation. The TOU ranged from 11.9 ± 0.02 to 20.5 ± 0.03 mmol O2 m−2 d−1, depending on the spatial distribution of OC content, with higher values in finer sediments. Sediment OC oxidation rates varied between 9.1 and 15.8 mmol C m−2 d−1, accounting for 5−87% of primary production in surface waters. The BNFs were comparable with other continental shelves, with dissolved inorganic nitrogen and dissolved inorganic phosphate fluxes contributing 1 to 33% and 2 to 14%, respectively, of the nutrients required for primary production. The findings suggest that sediment OC quantity and quality, influenced by sediment type, are major factors controlling the spatial variation of benthic OC cycles in the SYS. However, the benthic-pelagic coupling in the SYS during spring was weak, primarily because of low sediment OC oxidation and BNF rates. This study highlights the need for further research on temporal variability to fully understand the biogeochemical cycles in the Yellow Sea.11Nsciescopu
Legacy and emerging persistent organic pollutants in sea turtles from Korean waters: Levels, profiles, and interspecies differences
No full textSea turtles, as endangered species with their long lifespans, wide-ranging migration, and high trophic level, are effective bioindicators of marine pollution. Despite the importance of global monitoring of persistent organic pollutants (POPs) in sea turtles, research has been limited, especially in Asia. This study examined the accumulation of POPs in the livers of 44 sea turtles from Korean waters, including loggerhead (Caretta caretta) and green turtles (Chelonia mydas). The turtles accumulated the chemicals in the order PAHs > PCBs > DDTs > PBDEs > CHLs, HBCDs, hexachlorobenzene, HCHs > mirex, pentachlorobenzene. Loggerhead turtles had significantly higher levels of DDTs, HCHs, pentachlorobenzene, and PBDEs than green turtles (Wilcoxon rank sum test, p < 0.01), along with a higher proportion of bioaccumulative congeners and isomers, likely due to their primarily carnivorous diet compared to the predominantly herbivorous diet of green turtles. Conversely, HBCD levels were similar in both species, yet green turtles had a higher proportion of γ-HBCD—the dominant isomer in commercial HBCDs used as plastic additives, with lower bioaccumulation potential—likely reflecting their greater ingestion of plastic debris than loggerhead turtles. Notably, sea turtles had higher ratios of γ-HBCD to α-HBCD and HBCDs to PCBs than seabirds from Korean waters, implying greater exposure to plastic-derived POPs. This study highlights the widespread accumulation of legacy and emerging POPs, including plastic-associated chemicals, in Korean sea turtles. These findings underscore the need for global POP monitoring in sea turtles and further research on the environmental fate and impact of plastic-associated chemicals.11Nsciescopu
Evaluation of Coastal Debris Interpretability under Varying GSD Conditions in UAV Imagery
No full text무인항공기(unmanned aerial vehicle, UAV)를 이용한 해안 쓰레기 모니터링 수행 시 고도는 이미지데이터의 품질, 모니터링 수행 시간에 직접적인 영향을 미치는 중요 고려 요소이다. 하지만 고도를 기준으로 모니터링 체계를 마련한다면 UAV 기체가 변할 때마다 카메라 변화에 따른 공간해상도 변화가 생기게되고 영상 내 대상물 인식에 차이를 준다. 이에 사용하는 기체에 따라 변화되지 않는 공간해상도를 고려한해안 쓰레기 연구가 중요시되고 있다. 본 연구에서는 UAV 영상의 공간해상도(ground sample distance,GSD)에 따른 해안 쓰레기 인식 수준의 차이를 분석하여, 조사 목적에 따른 적정 모니터링 기준을 제안하고자 하였다. 국가 해안 쓰레기 모니터링 사업의 정점 중 하나이자 국가 지정 해수욕장인 포항 칠포해수욕장에서 100 m 범위의 구역을 지정하고UAV를 활용해 0.5 cm/pixel (18.6 m), 0.75 cm/pixel (27.9 m), 1.0 cm/pixel(37.2 m), 1.25 cm/pixel (46.5 m) 의 GSD 범위로 복잡한 형태의 해안 쓰레기 이미지를 수집하였다. 수집된이미지에서 국가 해안 쓰레기 모니터링 사업의 최근 4개년도 플라스틱 해안 쓰레기 상위 10개 항목을 대상으로 출현 항목별 총 개수와 빈도를 분석한 뒤 분리수거 기준을 적용하여 최종 9개의 분석 항목을 도출하였다. 이후 National Image Interpretability Rating Scales (NIIRS) 이미지 판독 기준을 적용하여 각 GSD 별로UAV 이미지 내 해안 쓰레기의 판독 가능성을 확인(I: Identify), 구별(B: Distinguish), 탐지(D: Detect), 불탐지(N: Not Detect)의 4등급으로 평가하였다. 그 결과 해안 쓰레기의 유무를 판단하는 UAV 실태조사에는1.25 cm/pixel의 GSD가 쓰레기의 부피나 무게를 포함한 상세 모니터링에는 0.5 cm/pixel의 GSD가 적합한것으로 나타났으며, 일반적인 범용 모니터링에는 0.75–1.0 cm/pixel의 GSD 범위가 적정한 것으로 제시되었다. 본 연구 결과는 목적과 상황에 따라 최적의 공간해상도(GSD)를 선택하여 효율적인 해안 쓰레기 모니터링 기준을 제공할 뿐만 아니라 관련 조사 및 관리 활동에서 비용과 시간 절감에 기여할 수 있을 것으로기대된다.33Nscopuskc
Seasonal diversity of bacterial communities attached to expanded polystyrene and the influence of environmental factors
No full textThe plastisphere is an ecosystem of microbial communities on plastic surfaces, where certain bacteria exhibit substrate specificity. In particular, pathogenic bacteria occur at relatively higher abundances on plastics compared to the surrounding seawater. However, studies investigating the diversity of plastic-attached bacteria in response to marine environmental changes remain limited. This study was conducted over one year from April 2022 at the Korea Institute of Ocean Science and Technology, South Sea Research Institute (Jangmok, Geoje), bacteria attached to expanded polystyrene (EPS) were analyzed using 16S rDNA metabarcoding. EPS was chosen because it is one of the most common types of plastic waste worldwide and is a significant pollutant in Korean aquaculture. The results showed that EPS harbored bacterial communities distinctly different from those in the surrounding seawater, with monthly variations, except during the low-temperature season. Gammaproteobacteria predominated, while Bacilli and Clostridia of the phylum Bacillota exhibited high prevalence during specific periods. Moreover, the genus Vibrio, known for its potential pathogenicity, appeared at about 20 times the abundance found in seawater. These findings suggest rapid, substrate-specific shifts in bacterial communities on EPS in response to environmental changes and highlight the need for further research into the colonization and risks of pathogenic bacteria due to plastic weathering.2
우리나라 남해안에서 expanded polystyrene에 부착하는 박테리아 군집의 계절적 다양성과 환경요인의 영향
No full textPlastisphere는 플라스틱 표면에 생존하는 생물 군집의 생태계로, 특정 박테리아 군집은 플라스틱에 기질 특이성을 보이는 것으로 알려져 있다. 특히 병원성 박테리아는 플라스틱에서 주변 해수에 비해 상대적으로 높게 출현하고 있다. 그러나 해양환경 변화에 따른 박테리아 및 병원성 박테리아의 부착 다양성에 대한 연구는 부족하다. 따라서 자연생태계에서 플라스틱의 박테리아 및 병원성 박테리아의 부착 다양성을 파악하고자 2022년 4월부터 1년간 한국해양과학기술원 남해연구소 연구 해역(거제 장목 소재)에서 EPS 재질 플라스틱에 부착된 박테리아를 대상으로 16S rDNA metabarcoding 기법을 이용하여 박테리아 및 잠재적 병원성 박테리아 다양서 분석을 수행하였다. 플라스틱 재질의 선정은 expanded polystyrene (EPS)로 전 세계에서 가장 많이 발생하는 플라스틱 쓰레기 중 한 종류로 보고되고 있다. 특히 우리나라에서는 이매패류의 양식 등에 부표로 사용되어 중요 환경 쓰레기 인자로 분류되고 있다. 분석 결과, EPS에 부착된 박테리아 군집은 주변 해수와 뚜렷한 차이를 보였으며, 저수온기를 제외하고 매월 출현 양상이 달랐다. 특히 Gammaproteobacteria가 최우점을 이루었고, Bacillota의 Bacilli와 Clostridia는 특정 시기에 높은 출현율을 보였다. 잠재적 병원성 박테리아 군집으로 알려진 Vibrio속은 해수보다 약 20배 높은 비율로 출현하였다. 따라서, EPS에서 환경 변화에 따른 기질 특이적인 부착 박테리아 군집의 급격한 변동과 함께 잠재적 병원성 박테리아의 선택적 기질 특이성이 관찰되었고, 향후 플라스틱 풍화에 따른 병원성 박테리아의 가입양상과 위해도의 추가 연구를 수행할 계획이다.2
DATA TRANSMISSION METHOD AND DATA TRANSMISSION APPARATUS OF A RELAY NODE USING A PLURALITY OF BUFFERS IN A DELAY TOLERANT NETWORK
No full text통신 링크가 빈번히 끊어지는 극한 (위성/수중통신 등) 환경에서 Delay tolerant network (DTN) 은 신뢰
할 수 있는 단대단(end-to-end) 통신을 위해 제안되었음. 빈번히 발생하는 링크 끊김 문제를 해결하기 위
해 DTN에서는 중간 패킷 전달자인 relay node가링크 환경이 좋지 않을 때 받은 데이터를 잠시 저장한 뒤
링크 환경이 좋아지면 최종 목적지 node에 전달하는 store-and-forward 프로토콜이 사용되고 있음. 또한,
relay 네트워크를 위해 여러 협력 통신 (cooperative communication)은 throughput을 증가시키고, 네트워
크 커버리지를 넓힐 수 있음. 제안하는 기술은 DTN 환경에서 단일버퍼/다중버퍼를 지닌 relay node들이 2
개의 안테나를 가진 destination node에게 시공간 선 부호화 (space-time line code) 기법을 활용하여 패
킷을 전송하는 방법이다
Fish sound characteristics of brown croaker (Miichthys miiuy) and redlip croaker (Larimichthys polyactis) using a passive acoustic monitoring
No full textMany fish species in aquatic environments produce biological sounds associated with feeding, spawning, social interactions, and other behaviors. Recently, passive acoustic monitoring (PAM) has been widely used in ocean soundscape research to measure underwater sounds for the management and protection of aquatic life. At least 178 fish families, the fishes communicate using sound. Among fish species, the Brown croaker (Miichthys miiuy) and Redlip croaker (Larimichthys polyactis) are important species in the Northwest Pacific Ocean. This study
recorded the vocalizations of 150 adult Brown croakers and 2,000 adult Yellow croakers, analyzing the acoustic parameters of call and chorus signals, vocalization patterns, and their relationships with ocean environmental factors.
As a result, the call sounds of the Brown croaker had a pulse duration of 119.9 ms, an inter-pulse interval of 20.9 ms, and 6.8 pulses per call. The zero-peak sound pressure level was 150.8 dB, while the peak, minimum, and maximum frequencies were 600.8 Hz, 307.9 Hz, and 905.2 Hz, respectively. The bandwidths of -3 dB and -10 dB were 199.1 Hz and 546.9 Hz, respectively. Additionally, the chorus sounds of the Brown croaker had a zero-peak sound pressure level of 161.3 dB, with a peak frequency of 509.0 Hz. In contrast, the chorus sounds of the Redlip croaker had a zero-peak sound pressure level of 126.3 dB. The peak, minimum, and maximum frequencies were 554.0 Hz, 295.7 Hz, and 889.5 Hz, respectively, with bandwidths of -3 dB and -10 dB at 89.6 Hz and 594.8 Hz, respectively. The Brown croaker produced sounds primarily in mid-September, near the night-time (17:00–23:00). In contrast, the Redlip croaker vocalized between April and June, with a concentration of sound production during the night- to early morning- times (17:00–06:00). These findings confirm the spawning
periods and temporal patterns of vocalization for each fish species. and the acoustic characteristics of croaker sounds provides valuable insights for ocean soundscape management, contributing to marine ecosystem conservation and the identification of spawning and fishing
grounds.1