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In the Jeju shamanic religion, chickens have been sacrificed for aekmagi, a ritual to prevent aek, a looming misfortune that may cause death. Whereas ordinary participants are thought to be at risk of harm when possessing or eating chickens or other offerings made to prevent aek, the simbang, Jeju shamans, are thought to be immune to it. Simbang are believed to be permanently on the threshold between the human and the divine realms. They help remove aek but are not harmed by it, because it only harms humans in the human realm, not the person on the boundary. While the other participants are temporarily placed in the liminal state during aekmagi and come back to the ordinary living human realm after the ritual, simbang remain in the perpetual liminal state. Chicken sacrifice has been omitted from aekmagi since around 2010 in most places in Jeju-do. Though ritual killing is no longer practiced, adherents still think that aek is prevented by aekmagi. The Jeju people believe that gods are the main agents of preventing aek and that they can persuade the gods to do the work without receiving chickens’ lives. In addition, due to the change in people’s view on killing animals, aekmagi without chicken sacrifice has become a more efficient ritual system for nourishing social sustenance by following the new social prescription.

Submarine groundwater discharge (SGD) is a key but understudied pathway in the terrestrial-oceanic dissolved organic carbon (DOC) cycle. In this study, fresh and saline groundwater samples were collected from two sites on Jeju Island, South Korea: Hwasun and Bangdu Bay on the western and eastern coast, respectively. DOC concentrations in fresh groundwater were extremely low (5 ± 3 μM), with pre-aged radiocarbon values ranging from –469 to –407‰. In the brackish zone of Bangdu Bay, distinctive spectroscopic signals, elevated DOC concentrations, and enriched Δ14C-DOC values along the groundwater-coastal continuum indicate active recirculation of coastal water. Overall, our findings demonstrate that SGD not only delivers aged terrestrial DOC to coastal waters but is also modified by coastal processes, underscoring its potential significant yet complex role under the influence of coastal pollutions.

The origin of the late Cenozoic intraplate volcanoes in the NE Asia has sparked debate, with explanations ranging from deep mantle plume to lithospheric extension and decompression melting of mantle upwelling by distal subduction tectonics. The Jeju volcanic field (JVF), being the closest late Cenozoic intraplate volcano to the subduction zone, sheds light on whether the intraplate volcanism is primarily plume-related or linked to plate tectonics. This study determined the primary magma composition for JVF basalts, using the most primitive bulk-rock samples (MgO > 8.5 wt%), by incrementally adding olivine to melt until reaching equilibrium with olivine (Mg# = 90) in the residual mantle. The estimated temperature and pressure of mantle melting are 1,466–1,587 °C and 2.1–4.1 GPa for anhydrous primary magma and 1,347–1,512 °C and 2.0–3.6 GPa for hydrous primary magma within the acceptable range of water contents (H 2 O = 2–4 wt%) reported from the Chinese intraplate basalts. The pressure estimates suggest that the minimal depth of the lithosphere-asthenosphere boundary is approximately ∼50–55 km. The mantle potential temperature for anhydrous primary magma is estimated to be 1,460–1,580 °C, higher than 1,300–1,400 °C of the ambient upper mantle, indicating a hot thermal regime below the JVF. Despite the absence of geophysical evidence for a mantle plume beneath the JVF, this study proposes that the hot mantle wedge is likely caused by the lateral influx or edge-driven convective upwelling of thermal plume near the leading edge of the stagnant Pacific Plate slab, contributing to the big mantle wedge. Intraplate volcanism in the JVF is proposed to be driven by lithospheric extension and decompression melting of the convective upwelling of hot sub-lithospheric mantle, influenced by distal subduction tectonics in the hot subduction zone. This model is supported by the present-day tectonics observed in the hot Ryukyu subduction zone, SW Japan.

Blue economy, the sustainable and effective use of ocean resources for economic growth, is a major challenge to coastal communities. Marine macroalgae are potentially sustainable feedstock for future food, materials, chemicals, and fuels. For seaweed biorefinery, the fractionation of the biomass to co-produce multiple products is crucial in the efficient valorization of the marine biomass. In this work, we developed a protocol for co-production of six different products from the green macroalga Ulva ohnoi using green extraction methods. A total of 90.31 ± 1.94% of the initial biomass was recovered in separated products. The fraction of the recovered products from initial dry weight biomass was 45.42 ± 1.91% salts, 3.67 ± 1.38% starch, 3.81 ± 1.26% lipids, 13.88 ± 0.40% ulvan, 14.83 ± 1.06% proteins, and 8.70 ± 1.87% cellulose. A potential revenue analyses, based on these experimental data and current market prices, suggests that total the revenue fluctuates between US$1.56 and US$3.93 kg−1 of dry biomass and depends on recovered products fraction in the seaweed biomass and products market value.

One of the 84 plant species endemic to Jeju Island, South Korea, is Salix blinii H. Lév. We surveyed its habitat to obtain quantitative information on the population demographics of S. blini , and thus to re-evaluate its conservation status and recommend in situ conservation strategies. We recorded 365 individuals in three valleys, above 1,200 m, on Mt Halla, of which 34 were flowering individuals capable of sexual reproduction. Although the population size is limited, the high proportion of small individuals suggests ongoing recruitment. Vegetative reproduction is presumed to play an important role, as it does for other Salix species that grow in valleys or along intermittent streams. Salix blinii is currently categorized as Vulnerable, based on criterion D2, on the IUCN Red List, but we reassess it as Vulnerable based on criteria D1+2 based on the number of mature individuals recorded. Although Mt Halla is designated as multiple large protected areas, small-scale protected areas within these larger areas need to be designated for more effective in situ conservation of S. blinii .

The Norwegian coastline covers more than 10° in latitude and provides a range in abiotic and biotic conditions for seaweed farming. In this study, we compared the effects of cultivation depth and season on the increase in biomass (frond length and biomass yield), chemical composition (protein, tissue nitrogen, intracellular nitrate and ash content) and biofouling (total cover and species composition) of cultivated Saccharina latissima at nine locations along a latitudinal gradient from 58 to 69° N. The effects of light and temperature on frond length and biofouling were evaluated along with their relevance for selecting optimal cultivation sites. Growth was greater at 1–2 m than at 8–9 m depth and showed large differences among locations, mainly in relation to local salinity levels. Maximum frond lengths varied between 15 and 100 cm, and maximum biomass yields between 0.2 and 14 kg m−2. Timing of maximum frond length and biomass yield varied with latitude, peaking 5 and 8 weeks later in the northern location (69° N) than in the central (63° N) and southern (58° N) locations, respectively. The nitrogen-to-protein conversion factor (averaged across all locations and depths) was 3.8, while protein content varied from 22 to 109 mg g−1 DW, with seasonality and latitude having the largest effect. The onset of biofouling also followed a latitudinal pattern, with a delayed onset in northern locations and at freshwater-influenced sites. The dominant epibiont was the bryozoan Membranipora membranacea. Our results demonstrate the feasibility of S. latissima cultivation along a wide latitudinal gradient in North Atlantic waters and underscore the importance of careful site selection for seaweed aquaculture.

Temporary seismic networks on Mt. Halla and Ulleung Island volcanoes were deployed, which employ broadband and geophone arrays to monitor potential volcanic activities and to estimate high-resolution magmatic structures beneath these volcanoes. The purpose of this paper is to introduce these networks and present early results through basic seismic analyses, suggesting the potential for future comprehensive seismological studies. The array in Mt. Halla volcano consists of five broadband sensors (JH array), and it has been operational around the Baengnokdam summit crater since October 2020. There was an additional linear geophone array (HL array) installed in September 2021 for detailed shallow subsurface imaging. Ulleung Island volcano had been under observation for two years since June 2021 with a network of nine broadband sensors (UL array) along its coast and in the Nari crater basin, complemented by a 52-geophone array (UG array) deployed in May 2022 for high-resolution subsurface studies. Despite the noisy environments typical of temporary setups, power spectral density analyses confirmed the quality of data as comparable to established reference noise models in permanent stations. Our study aimed to initiate studies uncovering seismic activities and structures beneath Mt. Halla and Ulleung Island volcanoes, specifically regarding volcanic activity. This approach detected no clear sign of volcanic seismicity on both islands, suggesting a period of magmatic dormancy. Seismic velocity variation (dv/v) analyses further indicated that environmental factors, rather than volcanic processes, influenced the changes in the physical properties of the underground structures. Conversely, the receiver function analysis and ambient noise data processing hinted at the presence of complex subsurface structures, potentially indicative of volcanic features, such as partial melting. Despite the lack of direct evidence for active magmatic processes, the collected seismic data provides a crucial baseline for future monitoring and a deeper understanding of the magmatic and tectonic dynamics beneath these volcanoes, offering valuable insights for ongoing volcanic research.

This study attempts to validate an infiltration model, the Soil Conservation Service–Curve Number (SCS–CN) method, using the nonofficial intermittent occurrence data of Eongtto Falls on Jeju Island, Korea. Simply due to the limited official continuous runoff data concerning Jeju Island, the validation of a newly set SCS-CN method for Jeju Island was practically impossible. Instead, this study tries to use nonofficial data for this purpose. This study focuses on the intermittent occurrence of Eongtto Falls, which is one of the most famous tourist attractions on the island. Various records of Eongtto Falls can be collected from newspapers, personal homepages, and various social networking services. The SCS-CN method is, in this study, used to check if effective rainfall occurs or not. In fact, this approach is quite effective on Jeju Island, as most streams are fully dry during non-rain periods. Evaluation of the SCS-CN method is based on the analysis of a contingency table, which measures the consistency of the occurrence of effective rainfall events and waterfall records. Additionally, to quantify the results of the contingency table, some measures such as accuracy, hit ratio, and false alarm ratio are used. This analysis is carried out using all the rainfall events from 2011 to 2019, and the derived results confirm that the newly set SCS-CN method is far better than the conventional one used thus far.

Two specimens, a male–female pair of Favonigobius reichei (Bleeker, 1854) (32.7–41.9 mm SL) were collected from the intertidal zone based on sandy and muddy areas in Jeju-do Island, Korea. This species is distinguished from Favonigobius gymnauchen (Bleeker, 1860), the previously recognized sole representative of the genus Favonigobius in Korea, by the following characteristics: VI–I, 8 dorsal fin rays, I, 8 anal fin rays, predorsal scales 0–1, and the black spot at the base of the caudal fin undivided and rounded. We propose a new Korean common name, “Hwang-jul-nal-gae-mang-duk” for F. reichei based on the yellow stripes on the abdomen of the male.

Each year a significant proportion of global food production is lost to pests and diseases, with concerted efforts by government and industry focussed on application of effective biosecurity policies which attempt to minimise their emergence and spread. In aquaculture the volume of seaweeds produced is second only to farmed fish and red algal carrageenophytes currently represent approximately 42% of global production of all seaweeds. Despite this importance, expansion of the seaweed sector is increasingly limited by the high prevalence of recalcitrant diseases and epiphytic pests with potential to emerge and with the demonstrated propensity to spread, particularly in the absence of effective national and international biosecurity policies. Developing biosecurity policy and legislation to manage biosecurity risk in seaweed aquaculture is urgently required to limit these impacts. To understand current international biosecurity frameworks and their efficacy, existing legislative frameworks were analysed quantitatively for the content of biosecurity measures, applicability to the seaweed industry, and inclusion of risks posed by diseases, pests and non-native species. Deficiencies in existing frameworks included the following: inconsistent terminology for inclusion of cultivated seaweeds, unclear designation of implementation responsibility, insufficient evidence-based information and limited alignment of biosecurity hazards and risks. Given the global importance of the cultivation of various seaweeds in alleviating poverty in low and middle income countries, it is crucial that the relatively low-unit value of the industry (i.e. as compared with other aquatic animal sectors) should not conflate with a perceived low risk of disease or pest transfer, nor the subsequent economic and environmental impact that disease transfer may impact on receiving nations (well beyond their seaweed operations). Developing a clear basis for development of robust international biosecurity policies related to the trade in seaweeds arising from the global aquaculture industry, by first addressing the gaps highlighted in this study, will be crucial in limiting impacts of pests and diseases on this valuable industry and on natural capital in locations where seaweeds are farmed.