• Ocean and Polar Research
• /
• v.34 no.3
• /
• pp.297-304
• /
• 2012

Pylaiella littoralis was collected in the Chuuk lagoon of the Federated States of Micronesia (FSM). The FSM has a variety of coral reef ecosystems, which provide essential materials, such as minerals, vitamins, essential amino acids, for marine organisms. In this study, the antioxidant activities of ethanol and enzymatic extracts of P. littoralis were evaluated by measuring their scavenging activities on DPPH free radical, Alkyl radical, hydroxyl radical and cell viability. The enzymatic extracts were hydrolyzed to prepare water soluble extracts by using five carbohydrate degrading enzymes (AMG, Celluclast, Termamyl, Ultraflo, and Viscozyme) and five proteases (Alcalase, Flavourzyme, Kojizyme, Neutrase, and Protamex). As a result, the enzymatic extracts prepared by Flavourzyme, Ultraflo, and Kojizyme exhibited the greatest effects in DPPH free radical, alkyl radical scavenging activity and cell viability. Also, these enzymatic extracts had a higher antioxidant effect then commercial antioxidants in DPPH free radical and Alkyl radical scavenging activity. This study suggests that P. littoralis might be a useful source of natural antioxidants for the development of dietary supplements.

• Spatial Information Research
• /
• v.23 no.2
• /
• pp.31-38
• /
• 2015

Remote sensing data is used to increasing efficiency on benthic cover type survey. Satellite and aerial imagery has variance of reflectance by water column effect even if bottom is consisted with same cover type and condition. This study tried to analyze advances of surveying extent and accuracy through water column correction of CASI-1500 hyperspectral image. Study area is coast of Gangneung city, South Korea where benthic environment is rapidly changing with bleaching of coral reef. Water column correction coefficient was estimated using regression models between water reflectance ($R_W$) and depth for sand bottom then the coefficients were applied to whole image. The results shows that expanded interpretable depth from 6-7m to 15m and decreased variation of reflectance by depth. Additionally, water column corrected reflectance image shows 13%p increased accuracy on benthic cover type classification.

• 한국해양학회지
• /
• v.30 no.2
• /
• pp.69-76
• /
• 1995

A turbidite core sediment (RN88-PC5) from 2051 m on the deep-sea floor at the southern margin of Okinawa Trough was examined. Sedimentological characteristics were quite different between sandy sediments and hemipelagic sediments and hemipelagic sediments in terms of benthic foraminiferal assemblage, grain-size and chemical composition. All turbidite sandy sediments were clearly transported from shallow area as they include typical coral reef dwelling benthic foraminifera which were not found in the background hemipelagic sediments. These layers also suggest that the sediments were transported by turbidity-related currents and implies that sedimentological mechanisms were different between sandy sediments and hemipelagic sediments. The result of the /SUP 14/ C age dating and the stable oxygen isotopic fluctuation of planktonic foraminifera show a gradual warming trend of the surface water from about 10 Ka to present. Also Termination lb as well as two fresh water input events were recognized at ca2 and 7 ka.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.54 no.2
• /
• pp.180-187
• /
• 2021

This study was conducted to investigate the reproductive characteristics of the Neon damselfish Pomacentrus coelestis in Chuuk lagoon (7°27' N, 151°53' E), Micronesia, Equatorial Pacific Ocean. The specimens used in this study were collected from August 2009 to September 2010 from around the coral reef area at a depth of 3-10 m in the northwest coast of Weno Island. Overall, 228 individuals were collected over 14 months from this area, of which 115 were females and 108 were males. Among 108 males, 30 were found to be hermaphrodites and the sex of 5 individuals could not be determined. The overall sex ratio was approximately 1.06:1 (female:male), and the ratio of sexually active individuals was 0.79:1. The gonadosomatic index (GSI) fluctuated and showed the highest value of 8.43±1.21 in December 2009 and the lowest value of 3.36±0.71 in September 2009 in sexually active females. Males showed the highest GSI value of 2.64±0.93 in June 2010 and the lowest value of 0.35±0.06 in July 2010. Based on the fluctuation of GSI, the trends in the appearance of monthly sexually active individuals, and biopsy of the gonads, P. coelestis was found to be a hermaphrodite species of protogynous type and is considered to be reproductively active throughout the year.

• Korean Journal of Remote Sensing
• /
• v.39 no.1
• /
• pp.23-45
• /
• 2023

Tuvalu is a small reef islands country in the Pacific Ocean. Its coastal regions are very much dynamic due to the profound effects of tropical cyclones and sea level rise (SLR). However, research works on coastline dynamics of Tuvalu mainly cover its capital, Funafuti. Therefore, this review summarizes the extent of long-term coastal changes in different islets of Funafuti and on overall Tuvalu. In Funafuti, highly accreting areas are Te Afualiku, Fuafatu, Motugie, and Amatuku, and highly eroding areas are Fuagea and Tefala with the fully disappeared islet of Vasafua after 2005. However, in spite of different causes and supposition of scientists on disappearing these lands the accretion is more dominant than erosion which resulted in 7.3% net increase of land areas of Tuvalu over 117 years till 2015. Severe tropical cyclones mainly caused accretion of land areas by forming coral rubble rampart formation and further reworks and erosion to small sandy islands whereas frequent low-energy cyclones mainly caused erosion. Though, till now severe erosion of coastal areas are not evident by global SLR, islets of Funafuti experienced remarkable shoreline increase as formation of 30-40 m wide rubble rampart formation along 19 km in 1971 by tropical cyclone Bebe and net increase of area of 3.45 ha by tropical cyclone Pam in 2015. In spite of such overall accretion of coastal areas several scientists suspect drowning of its areas in future because of high SLR (~5.1±0.7 mm/year) at Funafuti which supposedly will not work as a breakwater anymore. Thus, protection measures should be taken to prevent coastline erosion as well as land reclamation activities should be done following the global examples.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.26 no.1
• /
• pp.17-33
• /
• 2023

Disasters in coastal regions are a constant source of damage due to their uncertainty and complexity, leading to the proposal of green infrastructure as a nature-based solution that incorporates the concept of resilience to address the limitations of traditional grey infrastructure. This study analyzed trends in research related to coastal disasters and green infrastructure by conducting a co-occurrence keyword analysis of 2,183 articles collected from the Web of Science (WoS). The analysis resulted in the classification of the literature into four clusters. Cluster 1 is related to coastal disasters and tsunamis, as well as predictive simulation techniques, and includes keywords such as surge, wave, tide, and modeling. Cluster 2 focuses on the social system damage caused by coastal disasters and theoretical concepts, with keywords such as population, community, and green infrastructure elements like habitat, wetland, salt marsh, coral reef, and mangrove. Cluster 3 deals with coastal disaster-related sea level rise and international issues, and includes keywords such as sea level rise (or change), floodplain, and DEM. Finally, cluster 4 covers coastal erosion and vulnerability, and GIS, with the theme of 'coastal vulnerability and spatial technique'. Keywords related to green infrastructure in cluster 2 have been continuously appearing since 2016, but their focus has been on the function and effect of each element. Based on this analysis, implications for planning and management processes using green infrastructure in response to coastal disasters have been derived. This study can serve as a valuable resource for future research and policy in responding to and managing various disasters in coastal regions.

• Journal of Veterinary Science
• /
• v.24 no.5
• /
• pp.69.1-69.11
• /
• 2023

Background: Kalkitoxin (KT) is an active lipopeptide isolated from the cyanobacterium Lyngbya majuscula found in the bed of the coral reef. Although KT suppresses cell division and inflammation, KT's mechanism of action in vascular smooth muscle cells (VSMCs) is unidentified. Therefore, our main aim was to investigate the impact of KT on vascular calcification for the treatment of cardiovascular disease. Objectives: Using diverse calcification media, we studied the effect of KT on VSMC calcification and the underlying mechanism of this effect. Methods: VSMC was isolated from the 6 weeks ICR mice. Then VSMCs were treated with different concentrations of KT to check the cell viability. Alizarin red and von Kossa staining were carried out to examine the calcium deposition on VSMC. Thoracic aorta of 6 weeks mice were taken and treated with different concentrations of KT, and H and E staining was performed. Real-time polymerase chain reaction and western blot were performed to examine KT's effect on VSMC mineralization. Calcium deposition on VSMC was examined with a calcium deposition quantification kit. Results: Calcium deposition, Alizarin red, and von Kossa staining revealed that KT reduced inorganic phosphate-induced calcification phenotypes. KT also reduced Ca⁺⁺-induced calcification by inhibiting genes that regulate osteoblast differentiation, such as runtrelated transcription factor 2 (RUNX-2), SMAD family member 4, osterix, collagen 1α, and osteopontin. Also, KT repressed Ca²⁺-induced bone morphogenetic protein 2, RUNX-2, collagen 1α, osteoprotegerin, and smooth muscle actin protein expression. Likewise, Alizarin red and von Kossa staining showed that KT markedly decreased the calcification of ex vivo ring formation in the mouse thoracic aorta. Conclusions: This experiment demonstrated that KT decreases vascular calcification and may be developed as a new therapeutic treatment for vascular calcification and arteriosclerosis.

• Korean Journal of Ichthyology
• /
• v.19 no.4
• /
• pp.274-285
• /
• 2007

The subfamily Chrominae of damselfishes (Teleostei: Pomacentridae) includes the genus Chromis and Dascyllus. They are found throughout the tropical oceans and form a major component of coral reef communities. There are 5 species of the Chrominae currently recognized in Korea. This study was conducted to infer phylogenetic position of two Korean Chromis species and one Dascyllus species within general category of their each genus in worldwide level. This study also includes one species of Japanese Dascyllus. In the phylogenetic analysis, the Japanese D. aruanus grouped with D. aruanus previously reported from French Polynesia. Korean Chromis fumea grouped with Australian C. nitida and the p-distance value between the two species is relatively very low (0.047). Korean C. notatus grouped together with C. flavomaculata (New Caledonia). In the sequence analysis of some Korean and Japanese damselfishes, there was no sequence variation between D. melanurus (Jeju, Korea) and D. melanurus (Indo-Pacific), but the sequences of the two populations were different in only one nucleotide sites from that of D. melanurus in Indonesian Archipelago. The sequences of Dascyllus aruanus (Japan) were different in two nucleotide sites from it in French Polynesia. There were high difference between the sequences of two Korean species, Chromis fumea and Korean C. notatus. The variations among mitochondrial cytochrome b sequences indicate that the gene sequence could be used as DNA barcode for identification of local populations of D. aruaus and D. melanurus as well as species level.

• Proceedings of the KSRS Conference
• /
• v.2
• /
• pp.1011-1014
• /
• 2006

Coarse resolution (9 - 50 km pixels) Sea Surface Temperature satellite data are frequently considered adequate for open ocean research. However, coastal regions, including coral reef, estuarine and mesoscale upwelling regions require high-resolution (1-km pixel) SST data. The AVHRR SST data often suffer from navigation errors of several kilometres and still require manual navigation adjustments. The second serious problem is faulty and ineffective cloud-detection algorithms used operationally; many of these are based on radiance thresholds and moving window tests. With these methods, increasing sensitivity leads to masking of valid pixels. These errors lead to significant cold pixel biases and hamper image compositing, anomaly detection, and time-series analysis. Here, after manual navigation of over 40,000 AVHRR images, we implemented a new cloud filter that differs from other published methods. The filter first compares a pixel value with a climatological value built from the historical database, and then tests it against a time-based median value derived for that pixel from all satellite passes collected within ${\pm}3$ days. If the difference is larger than a predefined threshold, the pixel is flagged as cloud. We tested the method and compared to in situ SST from several shallow water buoys in the Florida Keys. Cloud statistics from all satellite sensors (AVHRR, MODIS) shows that a climatology filter with a $4^{\circ}C$ threshold and a median filter threshold of $2^{\circ}C$ are effective and accurate to filter clouds without masking good data. RMS difference between concurrent in situ and satellite SST data for the shallow waters (< 10 m bottom depth) is < $1^{\circ}C$, with only a small bias. The filter has been applied to the entire series of high-resolution SST data since1993 (including MODIS SST data since 2003), and a climatology is constructed to serve as the baseline to detect anomaly events.

• Journal of Aquaculture
• /
• v.9 no.1
• /
• pp.73-81
• /
• 1996

This study was conducted to study the reproductive cycle in female fusilier, Caesio diagramma by using the histological methods. Histological changes of the ovary were well correlated with the patterns of gonadosomatic index (GSI) and hepatosomatic index (HSI). GSI was increased in April as the value of HSI increase and reached to its maximum in May and June. Oocytes at the chromatin-nucleolus and peri-nucleolus stages were observed in the ovary throughout the year. In April, oocytes containing yolk appeared in ovaries of a few fishes. Most oocytes appearing in May and June belonged to the tertiary yolk stage. Frequency of oocytes appearance at the tertiary yolk stage in May and June was higher than that of the other months. Moreover, the empty follicles and atretic oocytes were observed in the ovaries with many vitellogenic oocytes during these two months. Thereafter, oocytes of the yolk stage disappeared in September. The spawning period of C. diagramma is from the month of April to June, and this species belongs to an asynchronous and multiple spawner.