Coast Of Taiwan Research Articles

Participatory mapping of ecosystem services of coastal wetlands in Taiwan

AbstractThere is a lack of knowledge and understanding about what ecosystem services are and how to utilize them in a sustainable way. Ecosystem services are thus often underrecognized by the decision makers in charge of creating wetland management plans. Due to this, ecosystem services, which have been used by communities for a long time, are often left out of wetland's wise‐use plans. Inclusion of local communities and promotion of local knowledge are vital aspects of creating sustainable, equitable and resilient wetland management plans that are truly ‘wise’. In this research, we utilize participatory mapping methods to engage communities and create a database of the ecosystem services being used in Chigu Salt Pan Wetland and Chigu Lagoon, located along the coast of Southwestern Taiwan. We look at who are using the ecosystem services, to what degree they are being used and where exactly in the wetland system they are being extracted/utilized. This will pave the way for future researchers to better understand the value of Chigu Salt Pan Wetland and the ecosystem services they provide and promote the use of participatory methods in other locations.

Kuroshio path variability inferred from satellite-derived sea surface topography in the northwestern Pacific

The Kuroshio has a fundamental impact on the regional oceanography of the northwestern Pacific. But identification of the Kuroshio path (KP), an abstraction of the course along which the Kuroshio mainstream moves, has not yet been established in a systematic manner. We optimally track the KP and study its variability in the northwestern Pacific south of ~31°N, where eddy activity is rich. An automatic contour method based on maximum surface geostrophic velocity along a given satellite-derived dynamic topographic isoline is applied and its performance is evaluated. Our results are robust and can be further used to derive kinematical, statistical, and spectral properties of the flow field of the Kuroshio upstream. We improve the identification method by tracing two separate KPs in different subdomains. The existence of an alignment or mismatch of these two retrieved KPs hints at the arrival of an approaching eddy. The highly variable and distorted KP east of Luzon Strait and Taiwan is due to eddy impingement. Most of the variability along the KP stems from energy with time scales of ~30–200 days and 1 year. A more consistent KP is seen north of ~26°N, with increasing surface currents of up to ~1 m s−1 before entering through the Tokara Strait. Such regional differences result from the various impacts of impinging mesoscale eddies on the Kuroshio, mainly due to blockage by the Ryukyu Islands. Our optimally determined KP is in line with the historical shipborne subsurface velocity measurements revealing the Kuroshio velocity core and observations of strong surface currents of > ~0.5 m s−1 by shore-based high-frequency radar (HFR) from locations along the east coast of Taiwan. Supportive evidence of concurrent KP distortion shows that HFR-derived vortex-like flow patterns are related to mesoscale eddies impinging from regions east of the radar footprint. Our work has value as a supplement to the data from radar operational routines, and will help interpret and diagnose these complicated HFR observations east of Taiwan.

Unforeseen green tide of floating tubular Ulva meridionalis, a lethal threat to oyster farming, along the west coast of Taiwan: tracking its origin and ecophysiological insights

Abstract Ulva green tides have adversely affected coastal ecosystems. In June 2023 in Changhua County, Taiwan, an unprecedented floating tubular Ulva bloom spanning about 30 km of coastline caused about 30 % reduction in oyster yield as reported by local farmers. Understanding its taxonomic and ecological basis is crucial for preemptive and remedial measures. Based on molecular (rbcL and tufA) and morphological evidence, U lva meridionalis was the cause of this green tide. Haplotype network analysis (based on ITS) suggests that this green tide originated from northern China via the China Coastal Current. Historical survey data indicate that U. meridionalis arrived in Taoyuan Algal Reef (about 150 km north of the bloom area) as far back as 2018. Our ecophysiological experiments revealed that U. meridionalis exhibited a rapid daily growth rate with biomass increment up to 13–21 % when subjected to local nutrient-rich waters under lower salinity and spring-like conditions. Although historical ecological and poultry/livestock data analyses showed no noticeable change in sea surface temperature and rainfall over the past decade, a gradual rise in agricultural nitrogen and phosphorus output was observed. This taxonomic and ecological background lays the groundwork for long-term ecological monitoring. Moreover, this study exemplifies the detrimental impact of an unforeseen Ulva bloom on oyster farming.

Changes in the particulate organic carbon pump efficiency since the Last Glacial Maximum in the northwestern Philippine Sea

Changes in bottom and pore water oxygenation over glacial – interglacial cycles have influenced the ocean's capacity to store particulate organic carbon regardless of its source, either the marine primary productivity or the continent-to-ocean transfer of terrestrial organic matter. In the Philippine Sea, east off Taiwan, despite being currently oligotrophic, the enhanced East Asian Winter Monsoon during the Last Glacial Maximum and the Heinrich Stadial 1 might have altered the nutrient budget in surface waters by providing nutrients from the Eurasian loess dust and deepening the vertical mixing, bringing nutrients from the nutrient-enriched Kuroshio Current subsurface waters to the surface. During the deglaciation, previous studies also suggest an overall weakening of the marine biological pump during the Heinrich Stadial 1, and the rise in sea level is expected to have led to a global significant decline in the ability of continents to bury their particulate organic carbon in marine sediments. However, changes in the continent-ocean transfer of terrestrial organic matter and on the marine biological pump around Taiwan remain poorly constrained.In the present study, we have thus aimed to reconstruct bottom – pore water oxygenation, past marine primary productivity and continental-ocean transfer of terrestrial particulate organic carbon to the ocean since the end of the Last Glacial Maximum, in order to better constrain the ability of marine sediments to capture atmospheric carbon over the past 20,000 years. To this end, sediment core MD18-3523 has been recovered from a levee of Hoping Canyon, north-east of Taiwan, in the Ryukyu forearc basin. The reconstructions were made possible by the application of multivariate statistics and transfer functions on benthic foraminiferal assemblages, by the measurement of total organic carbon concentration and by the investigation of chemical element ratios obtained from X-ray fluorescence (XRF).We observed a transition across the Bølling–Allerød and the Younger Dryas from suboxic-dysoxic bottom – pore waters during Heinrich Stadial 1 to oxic-suboxic during the Holocene, and revealed an increase in marine primary productivity during Heinrich Stadial 1 in all probability due to intensified East Asian Winter Monsoon winds. We have also identified periods of enhanced terrestrial particulate organic carbon transfer to the ocean driven by short-lived extreme events, most likely typhoons, during the Bølling–Allerød, at the beginning of the Early Holocene and the end of the Late Holocene, when the typhoon dynamics affecting Taiwan were intensified. Overall, these findings suggest an enhanced marine biological pump during the Heinrich Stadial 1 and an efficient carbon turbidity pump during the Bølling–Allerød, the Early and Late Holocene, contrasting with the western coast of Taiwan.

Long Short-Term Memory Networks' Application on Typhoon Wave Prediction for the Western Coast of Taiwan.

Huge waves caused by typhoons often induce severe disasters along coastal areas, making the effective prediction of typhoon-induced waves a crucial research issue for researchers. In recent years, the development of the Internet of Underwater Things (IoUT) has rapidly increased the prediction of oceanic environmental disasters. Past studies have utilized meteorological data and feedforward neural networks (e.g., BPNN) with static network structures to establish short lead time (e.g., 1 h) typhoon wave prediction models for the coast of Taiwan. However, sufficient lead time for prediction remains essential for preparedness, early warning, and response to minimize the loss of lives and properties during typhoons. The aim of this research is to construct a novel long lead time typhoon-induced wave prediction model using Long Short-Term Memory (LSTM), which incorporates a dynamic network structure. LSTM can capture long-term information through its recurrent structure and selectively retain necessary signals using memory gates. Compared to earlier studies, this method extends the prediction lead time and significantly improves the learning and generalization capability, thereby enhancing prediction accuracy markedly.

Community structure of whole pelagic copepods along the Kuroshio: Increase in the abundance and size in the north frontal area of the Kuroshio axis near the Japanese archipelago

The Kuroshio ecosystem is an important nursery ground for various fish species. Because the prey biomass and composition influence the recruitment of larval and juvenile fish, we investigated the variation in the abundance, carbon biomass, and community structure of copepods, which are the main prey for larval and juvenile fish, along the Kuroshio from the eastern coast of Taiwan to the Boso Peninsula, Japan from 8–November 24, 2015, using 100 μm-meshed plankton net samples. We identified two groups of stations (A and B) by the cluster analysis based on the composition and abundance for adult copepods (Q-mode). The total copepod abundance and carbon biomass were higher in Group A than in Group B. Of the dominant species assemblages classified by cluster analysis (R-mode), the abundance of species assemblages S2b and S3, which were composed of small-sized species (e.g., Oithona and Oncaea species), did not differ between Groups A and B, indicating that they were distributed abundantly throughout the Kuroshio region. On the other hand, the species assemblages (S1 and S2a) including the medium-sized calanoid copepods of coastal species and subtropical species (e.g., Paracalanus aculeatus and Clausocalanus furcatus) contributed to the high abundance and biomass of Group A. Group A occurred in the north-frontal area of the Kuroshio axis near the Japanese archipelago where chlorophyll a was high. This indicates that the community was changed by the bottom-up processes driven by nutrient supply from the subsurface layer in the north-frontal area. These results show that although the small-sized copepods were usually dominant in numerical abundance in the Kuroshio region as well as other oligotrophic oceans, the medium-sized copepods were an important component in the copepod community in water with high primary production. We concluded that the ecosystem in the north-frontal area downstream of the Kuroshio might provide optimal prey environments for diverse fish larvae and juveniles.

A marine accident analysis based on data-driven Bayesian network considering weather conditions and its application to Taiwanese waters

Few marine accident studies contemplate the weather effects on the places where and dates when shipping casualties occur. This study conducts a marine accident analysis based on Bayesian Network (BN) considering the weather characteristics of the accident spots and occurrence dates. The weather element is adopted as a node in the BN that comprises a group of five clusters illustrating the states of current speed, wave height and wind speed. A total of 431 accidents occurring in the western coast of Taiwan during the period from 2014 to 2022 are analyzed. Wave with height greater than slight sea has a certain effect on the accident frequency and severity. Mishaps are likely to suffer severe consequences if encountering the weather conditions featured by strong current, moderate/fresh breeze and slight/moderate sea. In addition, Accident Type is the most influential node of Accident Severity among the parameters, followed by Ship Type, Gross Tonnage (GT), Weather Cluster, Location and Ship Age. Finally, the three most crucial parameters leading to Very Serious Marine Casualty are Accident Type, Ship Type and GT.

Fast-track development of an automated solar photovoltaic module detecting framework utilizing open-access multispectral satellite imagery

The southwest coast of Taiwan is an important habitat for migratory waterbirds. However, the use of fossil fuels has led to climate crises. As society's awareness of environmental issues increases, renewable energy including solar power has become an irreplaceable choice. Monitoring the spread of solar photovoltaic (PV) to mitigate its ecological impact has become an important task. Yet, acquiring information related to the geographic information of this renewable energy is often challenging. Remote sensing techniques for identifying the distribution of solar PV modules have been extensively discussed and published in recent years. However, the use of high-resolution imagery, powerful computational hardware, or high-precision but technically challenging frameworks, particularly in terms of computational costs, hinders the rapid updating and dissemination of information on solar PV distribution. The aim of this study is to rapidly develop a PVs detecting framework. To do so, by utilizing the spectral reflectance characteristics of PV modules, along with open-access Sentinel-2 satellite datasets, we selected false color images derived from Bands 8 (842 nm), 11 (1,610 nm), and 12 (2,190 nm). With the foundation of ArcGIS and the U-Net deep learning architecture, we developed a framework with low training costs, simple data processing, and short training time. Through syntheses of false color with different combinations of spectral bands, we achieved a PVs detecting framework with 94.5% accuracy, 0.94 F1 score, and 0.89 Kappa in aquaculture landscape. In our application in the southwest coast region, the overall accuracy reached 96%, with a 0.92 F1 score and 0.9 Kappa performance. This framework will facilitate the rapid monitoring of the spatial and temporal distribution of PV in Taiwan, accelerate social communication, and alleviate ecological impacts.

Utilizing deep ocean water in yeast fermentation for enhanced mineral-rich biomass production and fermentative regulation by proteomics modulation

Deep Ocean Water (DOW) is rich in minerals and serves as a natural source of nutrients. However, due to the inorganic nature of these minerals, cultivating yeast in DOW could aid in the fermentation process, and simultaneously, the yeast can assimilate the minerals from DOW, resulting in a mineral-enriched yeast biomass. Focusing on three DOW sources off the eastern coast of Taiwan (TT-1, HL-1, HL-2), we fermented various yeast strains of Saccharomyces cerevisiae. Therefore, this study investigates the effects of DOW on yeast growth, alcohol dehydrogenase activity, and the biological absorption of mineral ions by the yeast. Additionally, this research employs two-dimensional electrophoresis techniques to examine how the absorbed minerals influence the regulation of yeast proteins, thereby affecting biomass and metabolism. In the result, S. cerevisiae BCRC 21689 demonstrated a remarkable ability to bio-absorb minerals such as magnesium, calcium, potassium, and zinc from DOW, enhancing its growth and fermentation performance. Proteomic analysis revealed significant shifts in the expression of 21 proteins related to glycolytic and energy metabolism, alcohol metabolism, and growth regulation, all influenced by DOW's mineral-rich environment. This indicates that DOW's mineral content is a key factor in upregulating essential enzymes in glycolytic metabolism and alcohol dehydrogenase. An increase in proteins involved in synthesis and folding processes was also observed, leading to a substantial increase in yeast biomass. This study underscores the potential of DOW as a natural enhancer in yeast fermentation processes, enriching the yeast with diverse minerals and modulating proteomic expression to optimize yeast growth and fermentation.

Beta diversity partitioning reveals homogenization in bird community composition within the forest-agriculture landscape of the northern Taiwan coast

ContextThis study examined how human-induced landscape changes affected bird diversity in mountain villages with mixed forests and cultivated fields.ObjectivesWe focused on the bird species composition (beta diversity) to determine whether species homogenization varied with forest cover differences. This study developed it as a novel metric potentially quantifying homogenization level comparison in species functional groups.MethodsBird surveys were conducted at 27 sites with forest cover scattered from 0 to 100%. Bird species were divided into forest birds and nonforest birds. Beta diversity was partitioned into turnover and nestedness-resultant components, and their contribution ratio to Sørensen beta was used to examine the effect of forest cover and pairwise cover difference.ResultsOur results indicated that forest birds exhibited low turnover and low nestedness, whereas nonforest birds exhibited nestedness distribution characteristics. The nestedness-resultant contribution ratio of nonforest birds was higher, driven by forest cover difference (slope = 0.0080, Pseudo R2 = 0.35**) than that of forest birds (slope = 0.0018, Pseudo R2 = 0.02**). Thus, we quantify the result of forest cover decreased lead to the dominated by nestedness species in nonforest birds.ConclusionsThese findings highlight the distinct effects of environmental changes on these two bird functional groups. Although the Sørensen beta diversity increases with forest cover decrease, most are contributed by nestedness-resultant nonforest birds and lead to homogenization. Thus, it is recommended that conservation plans should separately address forest and nonforest bird species to avoid the risk of underestimating species homogenization due to anthropogenic land-use and habitat degradation.

Methanooceanicella nereidis gen. nov., sp. nov., the first oceanic Methanocellaceae methanogen, isolated from potential methane hydrate bearing area offshore southwestern Taiwan.

A novel mesophilic, hydrogenotrophic methanogen, strain CWC-04T, was obtained from a sediment sample extracted from a gravity core retrieved at station 22 within the KP-9 area off the southwestern coast of Taiwan during the ORIII-1368 cruise in 2009. Cells of strain CWC-04T were rod-shaped, 1.4-2.9 µm long by 0.5-0.6 µm wide, and occurred singly. Strain CWC-04Tutilized formate, H2/CO2, 2-propanol/CO2 or 2-butanol/CO2 as catabolic substrates. The optimal growth conditions were 42 °C, 0.17 M NaCl and pH 5.35. The genomic DNA G+C content calculated from the genome sequence of strain CWC-04T was 46.19 mol%. Phylogenetic analysis of 16S rRNA gene revealed that strain CWC-04T is affiliated with the genus Methanocella. The 16S rRNA gene sequences similarities within strains Methanocella arvoryzae MRE50T, Methanocella paludicola SANAET and Methanocella conradii HZ254T were 93.7, 93.0 and 91.3 %, respectively. In addition, the optical density of CWC-04T culture dropped abruptly upon entering the late-log growth phase, with virus-like particles (150 nm in diameter) being observed on and around the cells. This observation suggests that strain CWC-04T harbours a lytic virus. Based on these phenotypic, phylogenetic and genomic results, we propose that strain CWC-04T represents a novel species of a novel genus in the family Methanocellaceae, for which the name Methanooceanicella nereidis gen. nov., sp. nov. is proposed. The type strain is CWC-04T (=BCRC AR10050T=NBRC 113165T).

Population growth, habitat use, and conservation strategies of the Black-faced Spoonbill (Platalea minor) in the southwest coast of Taiwan

Population growth, habitat use, and conservation strategies of the Black-faced Spoonbill (Platalea minor) in the southwest coast of Taiwan

Assessing the inundation risk of cultural heritages along the southwestern coast of Taiwan: present and future

Assessing the inundation risk of cultural heritages along the southwestern coast of Taiwan: present and future

Coral mariculture using abandoned abalone farming ponds in northeastern Taiwan

Stony corals are ecologically and economically important marine organisms. Coral aquaculture is essential to provide live coral materials for the marine ornamental trade, reef restoration programs, and environmental education. This study sought to establish coral farms in Taiwan. To culture corals, we adopted an abandoned abalone farming pond built along the northeastern coast of Taiwan, and investigated whether it is possible to propagate corals in this artificial environment. Stainless steel underwater tables were anchored to the pond floor, and fragments of Acropora tumida, Pocillopora damicornis, Stylophora pistillata, Favites pentagona, and Porites lobata were cultured on the tables for one year. Environmental factors in the pond were also monitored. The mean surface temperature was 23.07 °C, ranging from >30 °C in summer to 18 °C in winter. The mean salinity and pH were about 35 ppt and 8.14, respectively. Survivorship of these five species after one year ranged from 100% to 67%, with a 1.37–1.51-fold increase in weight and a 3.22–3.38-fold increase in area, demonstrating that although environmental factors fluctuate depending on the season and weather, long-term and stable asexual propagation of corals is feasible in the pond. For further optimization of culture conditions, the effects of initial fragment size for culture on subsequent survival and growth were investigated. Fragments of 3 sizes (1.5, 3.0, and 4.5 cm) were prepared from parental colonies of A. tumida, P. damicornis, and S. pistillata and cultured for 6 months by hanging them under the table. There were no significant differences in survivorship among these sizes. Differences were observed in biomass (weight) increase. In A. tumida, 3-cm fragments showed significantly more weight gain than other lengths, while 1.5-cm fragments showed a significant weight increase in P. damicornis. In S. pistillata, no significant difference in weight increase was observed among size groups, suggesting the necessity to optimize the initial fragment size for culture for each species before mass culture. Histological analysis showed that mature gametes were formed in some cultured corals, suggesting that sexual propagation may also be possible in the future. The established coral farm, which is culturing >4000 coral fragments now, will be able to support not only basic and applied coral research, but also sustainable reef development and marine ornamental trade.

Oceanimonas pelagia sp. nov., a novel biosurfactant-producing and plastic-degrading potential bacterium isolated from marine coastal sediment.

A marine bacterial strain, named NTOU-MSR1T, was isolated from marine sediment of northern coast of Taiwan. This bacterium was Gram-stain-negative, aerobic, and motile, with a single flagellum. Its rod-shaped cells measured approximately 0.5-0.6µm in width and 1.8-2.0μm in length. NTOU-MSR1T grew at temperatures ranging from 10 to 45°C, optimally at 30°C. The pH range for growth was 7.0-10.0, with optimal growth at pH 7.0-8.0. It tolerated NaCl concentrations up to 12%. The cell membrane predominantly contained fatty acids such C16:1ω7c, C18:1ω7c, and C16:0. The overall genome relatedness indices indicated that strain NTOU-MSR1T had an average nucleotide identity (ANI) of 87.88% and a digital DNA-DNA hybridization (dDDH) value of 35.40% compared to its closest related species, O. marisflavi 102-Na3T. These values fell below the 95% and 70% threshold for species delineation, respectively. These findings suggested that the strain NTOU-MSR1T was a new member of the Oceanimonas genus. Its genomic DNA had a G + C content of 61.0mol%. Genomic analysis revealed genes associated with the catechol branch of β- ketoadipate pathway for degrading polycyclic aromatic hydrocarbons, resistance to heavy metal, biosynthesis of polyhydroxybutyrate and the production of glycoside hydrolases (GH19, GH23, and GH103) for chitin and glycan digestion. Additionally, NTOU-MSR1T was capable of synthesizing biosurfactants and potentially degrading plastic. The proposed name for this new species is Oceanimonas pelagia, with the type strain designated as NTOU-MSR1T (= BCRC 81403T = JCM 36023T).

Investigation of organic contaminants in the blubber of a blue whale (Balaenoptera musculus) first stranded on the coast of Taiwan.

This study presents a comprehensive assessment of persistent organic pollutants (POPs) in the blubber of a stranded blue whale found on the coast of Taiwan. The analysis included polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), Hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). The whale exhibited evident signs of emaciation, including low body weight, reduced blubber fat content, and thin blubber thickness. The dominant fatty acid type detected in the blubber was short-chain monounsaturated fatty acids (SC-MUFA), known to aid in thermoregulation. Stable isotope ratios indicated that the blue whale occupied a lower trophic position compared to a fin whale, suggesting its proximity to krill habitats in the Southern Ocean for feeding. The average concentrations of DDTs (1089.2 ± 4.7ng/g lw; ΣDDT) and PCBs (1057.1 ± 49.8ng/g lw) in the blubber were almost one order of magnitude higher than PAHs (41.7 ± 10.0ng/g lw), HCB (70.6 ± 2. ng/g lw), and PBDEs (7.2 ± 1.2ng/g lw). Pollutant concentrations in this individual blue whale were comparable to levels found in Norway, higher than those found in Chile, and notably lower than those found in Canada and Mexico. Calculating the biomagnification factor (BMF) for the POPs from krill (Euphausia superba) to the blue whale revealed significant bioaccumulation of pollutants in this particular whale. Additional research is imperative to achieve a thorough comprehension of bioaccumulation of POPs and their potential toxicological impacts on whale health.

An Observational Study on the Rapid Intensification of Typhoon Chanthu (2021) near the Complex Terrain of Taiwan

Abstract Intensification of Typhoon Chanthu (2021) along the eastern coast of Taiwan was accompanied by pronounced asymmetry in eyewall convection dominated by wavenumber-1 features, as observed by a dense radar network in Taiwan. The maximum wind speed at 3-km altitude, retrieved from radar observations, exhibited a rapid increase of approximately 18 m s−1 within an 11-h period during the intensification stage, followed by a significant decrease of approximately 19 m s−1 within 8 h during the weakening stage. Namely, Chanthu underwent both rapid intensification (RI) and rapid weakening (RW) within the 24-h analyzed period, posing challenges for intensity forecasts. During the intensifying stages, the region of maximum eyewall convection asymmetry underwent a sudden cyclonic rotation from the eastern to the northern semicircle immediately after the initiation of terrain-induced boundary inflow from the south of the typhoon, as observed by surface station data. This abrupt rotation of eyewall asymmetry exhibited better agreement with radar-derived vertical wind shear (VWS) than that derived from global reanalysis data. This finding suggests that the meso-β-scale VWS is more representative for tropical cyclones than meso-α-scale VWS when the terrain-induced forcing predominates in the environmental conditions. Further examination of the radar-derived VWS indicated that the VWS profile pattern provided a more favorable environment for typhoon intensification. In summary, Chanthu’s RI was influenced by the three factors: 1) terrain-induced boundary inflow from the south of the typhoon, observed by surface station data; 2) low-level flow pointing toward the upshear-left direction; and 3) weak upper-level VWS. Significance Statement Tropical cyclone intensity change has been an important issue for both real-time operation and research, but the influence of terrain on intensity change has not been fully understood. Typhoon Chanthu (2021) underwent a significant intensity change near the complex terrain of Taiwan that was observed by a dense radar network. This study analyzes 24 h of radar and weather station data to investigate Chanthu’s evolution. The analyses indicate that the complex terrain affected the low-level flow near the TC. Such a change in flow pattern provided additional boundary inflow and a relatively favorable vertical wind shear pattern for TC intensification.

A Case Study on Wind Speed Oscillations Offshore the West Coast of Central Taiwan

Abstract This paper investigates a wind speed oscillation event that occurred near the coastline of central Taiwan in the afternoon of 17 February 2018, using data from observations and numerical simulations. The observed wind speeds at 100-m altitude displayed a fast-oscillating pattern of about 6 cycles between strong winds of approximately 21 m s−1 and weak winds of around 2 m s−1, with periods of about 10 min. The pressure anomalies fluctuated in antiphase with the wind speed anomalies. The synoptic analysis revealed the influence of a continental high pressure system, resulting in a cold-air outbreak over Taiwan. The cold north-northeasterly winds split into two branches upon encountering Taiwan’s topography, with ridging off the east coast and a lee trough off the west coast of Taiwan. Wind oscillations were detected in the low-level cold air offshore the west coast of Taiwan, depicted by wavelike structures in wind speeds, sea level pressure, and potential temperature. The perturbations were identified as Kelvin-Helmholtz billows characterized by regions of strong wind speeds, warm and dry air, sinking motions, and low pressure collocated with each other, while regions of weaker wind speeds, cooler and moister air, ascending motions, and high pressure were associated with each other. With terrain contributing to favorable conditions, the large vertical and horizontal wind shears resulted from the southward acceleration of low-level cold air and the northward movement of the lee trough played an important role in initiating the wind oscillations.

A 16-year meteotsunami climatology in the coastal areas of southern Asia-Pacific Ocean

This study presents the meteotsunami behavior in response to different storm types in the coasts of southern Asia-Pacific Ocean from 16 years water level records. Through the size- frequency analysis, the dangerous meteotsunami, wave height exceeding 0.3 m, can occur up to 44 events per year. Notably, during the extreme waves of the 2007 event, wave heights reached approximately 0.9-1.5 m in the Taiwan Strait and the western coastal areas of Taiwan. We have classified storms into six types by radar reflectivity images and satellite-derived precipitation. Findings indicate that predicted wave heights caused by bows and typhoons could reach hazardous magnitude of exceeding 2 m in a 100-yr interval. Spatial and temporal analysis reveals that meteotsunami occurrences are most frequent in the western regions during the winter to early spring months (December to April). Of all meteotsunami occurrences, cluster storms are identified as the most prevalent atmospheric forcing, accounting for 60% of meteostunamis. Typhoons have a 20% association with meteotsunamis along the east coasts of Taiwan during late summer to autumn. On the east coasts, typhoon type-induced events may be attributed to the combination effect of meteotsunamis and infra-gravity waves. Overall, this study provides the first comprehensive examination of meteotsunami-storm characteristics and their associated hazard risks in the coastal areas of the southern Asia-Pacific Ocean.

Sponges and their prokaryotic communities sampled from a remote karst ecosystem

Marine karst ecosystems exist at the land-sea interface and are characterised by underwater formations sculpted over time by the action of seawater. Submerged caves and crevices of these ecosystems host a rich array of marine life of which sponges are among the most abundant and diverse components. In the present study, we describe elements of the sponge fauna sampled from a unique karst ecosystem at a remote island, Orchid Island, off the southeastern coast of Taiwan. The present study includes several understudied sponge taxa, including sclerosponges (Acanthochaetetes wellsi, and Astrosclera willeyana) and several lithistid species from dark, shallow-water caves. Prokaryotic communities were obtained from a total of 22 demosponge species, of which 11 are potentially new to science. The tetracladinid, lithistids harboured prokaryotic communities, which clustered separately from all other sponge species, contrasting with the non-tetracladinid, lithistid Vetulina incrustans. The tetracladinid, lithistids, furthermore, formed two distinct clusters with species of the Spirophorina suborder clustering apart from those of the Astrophorina suborder. The sclerosponge A. wellsi also harboured a distinct prokaryotic community in terms of composition including five unique, abundant OTUs with relatively low sequence similarities to organisms in GenBank. All cave sponges were enriched with SAR202 members, a group of bacteria known for their role in the degradation of recalcitrant compounds. The highest relative abundance of SAR202 was found in A. wellsi. We propose that the cave sponges of Orchid Island may play an as-yet uncharted role in nutrient dynamics at the land-sea interface.