Fuzzy cluster analysis of water mass in the western Taiwan Strait in spring 2019

The classification of the springtime water mass has an important influence on the hydrography,regional climate change and fishery in the Taiwan Strait.Based on 58 stations of CTD profiling data collected in the western and southwestern Taiwan Strait during the spring cruise of 2019,we analyze the spatial distributions of temperature(T)and salinity(S)in the investigation area.Then by using the fuzzy cluster method combined with the T-S similarity number,we classify the investigation area into 5 water masses:the Minzhe Coastal Water(MZCW),the Taiwan Strait Mixed Water(TSMW),the South China Sea Surface Water(SCSSW),the South China Sea Subsurface Water(SCSUW)and the Kuroshio Branch Water(KBW).The MZCW appears in the near surface layer along the western coast of Taiwan Strait,showing low-salinity(<32.0)tongues near the Minjiang River Estuary and the Xiamen Bay mouth.The TSMW covers most upper layer of the investigation area.The SCSSW is mainly distributed in the upper layer of the southwestern Taiwan Strait,beneath which is the SCSUW.The KBW is a high temperature(core value of 26.36℃)and high salinity(core value of 34.62)water mass located southeast of the Taiwan Bank and partially in the central Taiwan Strait.

Studies on ecological characteristics variation and population dynamics of four lizardfishes in the southern Taiwan Straits

The ecological characteristics of four lizardfishes, Trachinocephalus myops, Saurida undosquamis, Saurida tumbil and Saurida elongata, were studied from specimens （910 T. myops, 454 S. un-dosquamis, 686 S. tumbil and 744 S. elongata） collected monthly in the southern Taiwan Straits from April 2005 to March 2006. The population dynamics of the four lizardfishes was also discussed by the comparison with the previous studies. All being composed of 7 a classes; the dominant group of T. myops and S. tumbil was 1–2 a, while S. undosquamis and S. elongate were 2–3 a. The total mortality coefficient Z and the fishing mortality F were at high as indicated by the exploitation ratio E（0.5）, and a large number of by-caught juvenile and young fishes showing that the stock of lizardfishes in this area was overexploited and the fishing gear was irrational. Compared with the previous studies, the maximum and mean fork length, body mass and age of the four lizard- fishes declined gradually, the lizardfishes populations were younger in age and smaller in size. The asymptotic fork length L ∞ decreased while increasing growth coefficient k, and age at the inflexion point of mass t r was younger compared with the previous studies. The declining of older ones has moderated the feeding competition and the younger ones grew faster. The larger mortality param-eters Z, M and F have revealed higher fishing pressure. The smaller change of the first mature fork length of female T . myops and the change from K selection pattern to r selection pattern of S. tumbil have indicated a more vulnerable fishery ecosystem in this area. The changes of ecological characteristics and population dynamics may be caused by over-exploitation of demersal fishes such as the lizardfishes, especially a large number of juvenile and young fishes by-catch by the current fishing gears and methods. Therefore, in addition to the traditional fishery management approach such as the minimum length-limit, ecosystem approach to fisheries management （EAF） should be taken to improve the practical marine ecosystem management, including increased fishing intensity of the non-economic species especially the feeding competitors of the lizardfishes and the conservation of the pelagic fishery population in the fisheries ecosystem, in order to restore the fishery population and achieve the sustainable use of the fishery stocks.

A Preliminary Analysis of Geologic & Seismologic Conditions for an Undersea Tunnel across the Taiwan Strait

The Taiwan Strait tunnel, as a great project, has been studied for a long time and met many challenges from the beginning of the feasibility study that has attracted attention among scientists and engineers on both sides of the Taiwan Strait and around the world as well. The key question is whether this undersea tunnel can be constructed with present technologies under such complex geologic and seismologic conditions. Results of current researches indicate that the sea floor of the Strait is covered with a horizontal layer composed of both the Pleistocene and the Holocene sandstone and shale with a thickness of about 200～300 m, without any large fault belt or fold.This can serve as a good bearing and impermeable layer for constructing such an undersea tunnel. The Penghu Islands and Penghu terrace, which are composed of hard basaltic rock over a wide area of 70 km (NS)×40 km (EW), might be connected each othar by a bridge instead of an undersea tunnel, and serve as a construction site. Although there are several geologic units separated by faults under the upper horizontal layer, these faults do not cut through the upper layer. Only the NE offshore fault along the Fujian coast and that along the west coast of Taiwan should be noticed, between which a suspension tunnel instead of an undersea tunnel can be constructed. Therefore it is judged that the tunnel beginning from Amoy, through the Jinmen Island and the Penghu Islands to the Peigang harbour is worth recommendation.

Study of the Relationship Between the Organizational Climate and the Campus Ethical Issues of Universities across the Taiwan Strait

The study applied the approach of empirical studies to select 176 teachers in 9 universities in Taiwan and Inland in China to deliver questionnaires. The study intended to explore the influence of organizational climate on campus ethics and its diversity between the universities across the Taiwan strait. The study explored that the organizational climate in the universities across the Strait was not ethically high. Yet, the universities in Inland emphasized more on campus restraint in teachers behavior, job performance and their sense of belonging to the school.The study result demonstrated that improving leadership of the universities could enhance teachers identification with their schools and could promote the level of campus across the Strait.

A Preliminary Analysis of the Tomography Problems in Constructing Bridge and Dike-Road across Taiwan Strait

The construction of the bridge across Taiwan Strait has been studied for a long time and the feasibility study that has attracted attention among scientists and engineers on both sides of the Taiwan Strait[1-4].The key question is whether this bridge and dike-road across Taiwan Strait can be constructed with present technology under such complex geological conditions or not.The results of current researches indicate that the sea floor of the Strait is covered with a horizontal layer composed of both the Pleistocene and the Holocene sandstone and shale with a thickness of about 200~300m.The distance from Pingtan island to China's Xinzhu seashore is 124 km,which might be connected by 4-6 section bridges and 5-7 section of dike-roads,and serve as a best program of the route in the north Strait section.The NE offshore fault along the Fujian coast and that along the west coast of Taiwan,China are the major tectonic lines separated by several NW faults under the upper horizontal layer,these fault 3D feature may be detecting by geo-tomography technique,which can help to deal with the foundation of bridge and dike-road piers.It is judged that the construction of bridge and dike-road beginning from Pingtan to the China's Xinzhu seashore is worth recommendation.In the procedure of the construction of large and high height bridges,must consider the steel structural member be detected by industrial CT technology,and might detect the pier of bridge and dike-road which built by steel tube and reinforced concrete at dike-roads two side,in order to get the hard basement and getting the depth of the pier extend below the sea-floor by the seismic tomographic detection method.

The Impact of Tourism Across the Taiwan Strait on the Taiwan Residents Identity

Nowadays, the search for identity in Taiwan has been more significant today compared to the past because political parties have been attempting to use Taiwan Residents identity to impact the political loyalty, the democratization as well as language. Based on current situation of tourism cross-straits, this paper respectively analyzes its economic value, political value as well as cultural value on Taiwan Residents identity. This paper finds that due to a series of strategies adopted by Tsai' government, tourism does not make a big difference in Taiwan's economy, hence, the interdependence of tourism does not remarkably diminish Taiwan Residents identity from the perspective of economic value. Furthermore, according to the current perceptions of Taiwan Residents to Mainland tourists, tourism across Taiwan Strait makes slight influence on Taiwan Residents identity. Consequently, the current effect of using tourism as an economic lever to encourage political unification is extremely rough and tenuous. Besides, to some extent, currently tourism is likely to produce greater social and cultural alienation among Taiwan Residents, which makes a contribution to boost Taiwan Residents identity. However, the result can be reverse with the current improvement of education and the quality of Chinese and admiration of China's remarkable development.

Numerical Study on Tides in the Taiwan Strait and its Adjacent Areas

Diurnal and semi-diurnal tides in the Taiwan Strait and its adjacent areas are calculated by using a two-dimensional finite-difference model. Compared with data of more than 20 observation stations around the Taiwan Strait, the model-produced results agree quite well with those of previous researches using observational data from coastal tidal gauge stations. According to the results, the co-tidal and co-range charts are given. Furthermore, the characteristics of 8 major tidal constituents have been uminated respectively. The result shows that： （1） The tide motion can be attributed to the interaction between the degenerative rotary tidal system in the north and the progressive tidal system in the south. （2） The southward and northward tidal waves of semi-diurnal tide converge in the middle of the Taiwan Strait while the diurnal tidal waves propagate southwestward through the Taiwan Strait and the Luzon Strait. （3） The maximum amplitude of semi-diurnal tides exists at the area between the Meizhou Bay and Xinghua Bay, and that of diurnal tides appears in the region to the east of the Leizhou Peninsula, （4） The patterns of co-tidal and co-range charts of N2, K2 and P1, Q1 tidal constituents are similar to those of M2, S2 and K1 O1 tidat constituents, respectively

A survey on Hydroidomedusae from the upwelling region of southern part of the Taiwan Strait of ChinaⅠ.On new species and records of Anthomedusae

Fhrough the examination of 377 samples of the Anthomedusae, eight new species and one new record are described.

Species composition and distribution of marine nematode community in the North Taiwan Strait

Marine free-living nematodes were investigated at 13 sampling stations divided into three transects in the northern Taiwan Strait in February 1998. One hundred species of marine nematodes belonging to 91 Genera 28 Families 3 Orders were identified and were first recorded in the northern Taiwan Strait. The dominant species were Vasostoma sp., Sabatieria sp. 1, Linhystera sp. 1, Spilophorella sp., Daptonema sp., Halalaimus sp. and Dorylaimopsis variabilis. Their main densities were all over 4 950 ind./m2. According to mean density at transects, marine nematode density decreased from coastal Weitou to off Minjiang Estuary, which was similar to polychaete distribution in northern Taiwan Strait. The selective deposit feeder (1A) was the dominant food type of marine nematodes in the northern Taiwan Strait, but non-selective deposit feeders (1B) and epigrowth feeders (2A) occupied high proportion, indicating diverse feeding types of marine nematodes in the northern Taiwan Strait. Some environmental factors such as currents are discussed.

Three-dimensional structure of a low salinity tongue in the southern Taiwan Strait observed in the summer of 2005

Cruise observations with CTD （conductivity-temperature-depth） profiler were carried out in the southern Taiwan Strait in the summer of 2005. Using the cruise data, two-dimensional maps of salinity and temperature distributions at depths of 5, 10, 15, 20, and 30 m were generated. The maps show a low salinity tongue sandwiched by low temperature and high salinity waters on the shallow water side and high temperature and high salinity waters on the deep water side. The further analysis indicates that the low salinity water has a nature of river-diluted water. A possible source of the diluted water is the Zhujiang （Pearl） Estuary. Meanwhile, the summer monsoon is judged as a possible driving force for this northeastward jet-like current. The coastal upwelling and the South China Sea Warm Current confine the low salinity water to flow along the central line of the strait. Previous investigations and a numerical model are used to verify that the upstream of the low salinity current is the Zhujiang Estuary. Thus, the low salinity tongue is produced by four major elements： Zhujinag Estuary diluted water, monsoon wind driving, coastal upwelling and South China Sea Warm Current modifications.

The spatio-temporal variation of wintertime subtidal currents in the western Taiwan Strait

A new data set of observations by six cruises of ship-mounted acoustic doppler current profiler（SADCP） and three 40 d long bottom-mounted ADCPs（BADCPs） is employed to reveal the spatiotemporal variability of tidal and subtidal currents in the western Taiwan Strait（TWS） during winter season. The results confirm the existence of intense cotidal lines for M2 tidal current, which is located north of 25°N. In this case, no existence of an amphidromic point can be identified. It is also revealed that the counter-wind current（CWC） can extend through the whole western TWS and even occupy the entire water column during winter monsoon relaxation. However,this CWC is observed to be thoroughly overwhelmed by the downwind China coastal current（CCC） during the two big monsoon bloom events in the winter of 2007, and the CCC consequently extends southward throughout the western TWS instead. Most importantly, the variation of the spatial extent for the CWC and the CCC in the western TWS is found to be well explained by the first two modes of the vector empirical orthogonal function（VEOF） analysis, that is, it is mainly controlled by a wind-driven quasi barotropic current as the first mode and slightly modulated by a relatively weak background current with a first-order baroclinic structure as the second mode.

Evolution of a coastal upwelling event during summer 2004 in the southern Taiwan Strait

A coastal upwelling event in the southern Taiwan Strait （STWS） was investigated using intensive cruise surveys （four repeated transects in a month） and satellite data in July and early August 2004. The extensive upwelling-associated surface cold water was first observed in early July （-2.0×10a km2） along the STWS coast. Then, the cold surface water reduced in size by -50% with decreased chlorophyll concentrations after 15 days, indicating the weakening of the upwelling event. At the end of July, the cold surface water disappeared. The temporal variations of the surface cold water and the 3-D hydrography around Dongshan Island are thought to be mainly attributed to the weakened upwelling-favorable southwestern wind, the asymmetric spatial structure of the wind field and the intrusion of warm water from the northern South China Sea.

Wave height measurement in the Taiwan Strait with a portable high frequency surface wave radar

As an important equipment for sea state remote sensing, high frequency surface wave radar （HFSWR） has received more and more attention. The conventional method for wave height inversion is based on the ratio of the integration of the second-order spectral continuum to that of the first-order region, where the strong external noise and the incorrect delineation of the first- and second-order Doppler spectral regions due to spectral aliasing are two major sources of errors in the wave height. To account for these factors, two more indices are introduced to the wave height estimation, i.e., the ratio of the maximum power of the second-or- der continuum to that of the Bragg spectral region （RSCB） and the ratio of the power of the second harmonic peak to that of the Bragg peak （RSHB）. Both indices also have a strong correlation with the underlying wave height. On the basis of all these indices an empirical model is proposed to estimate the wave height. This method has been used in a three-months long experiment of the ocean state measuring and analyzing ra- dar, type S （OSMAR-S）, which is a portable HFSWR with compact cross-loop/monopole receive antennas developed by Wuhan University since 2006. During the experiment in the Taiwan Strait, the significant wave height varied from 0 to 5 m. The significant wave heights estimated by the OSMAR-S correlate well with the data provided by the Oceanweather Inc. for comparison, with a correlation coefficient of 0.74 and a root mean square error （RMSE） of 0.77 m. The proposed method has made an effective improvement to the wave height estimation and thus a further step toward operational use of the OSMAR-S in the wave height extraction.

Spatial and temporal variability of colored dissolved organic matter absorption properties in the Taiwan Strait

Spatial and temporal variability of the absorption properties of colored dissolved organic matter （CDOM） in the Taiwan Strait was investigated in summer （July to August of 2006） and winter （from December 2006 to January of 2007） seasons. The CDOM absorption coefficient at 280 nm （a 280 ） showed a decreasing trend from nearshore to offshore areas while the spectral slope coefficient parameter calculated between wavelengths 275–295 nm （S 275 295 ） showed an increase, indicative of decreasing aromaticity and molecular weight of the CDOM. The average a 280 in winter （1.47 ± 0.50 m ^-1 ） was significantly higher than in summer （1.10 ± 0.41 m ^-1 ）, while the average S 275 295 in winter （26.7 ± 5.2 μm^- 1 ） was significantly lower than in summer （30.6 ± 5.5 μm^- 1 ）, demonstrating clear seasonal variation in CDOM abundance and properties in the Taiwan Strait. A three-end- member conservative mixing model showed that local terrestrial CDOM inputs from several rivers along the western coast were small （〈5%）. However, the distribution of CDOM in the Taiwan Strait is mainly controlled by water mass movement [i.e., the Zhe-min Coastal Current （ZCC） and the Kuroshio Branch Current （KBC） in winter and the South China Sea Water （SCSW） in summer]. Biological activity was also an important factor affecting the distribution of CDOM in the offshore region in summer months.

Two new species of Ectopleura from the Taiwan Strait,China (Cnidaria,Hydroidomedusae)

Two new species of genus Ectopleura, i.e., Ectopleura elongata sp. nov. and E. triangularis sp. nov. are described in the present paper based on type specimens from the Taiwan Strait. The types are deposited in the Third Institute of Oceanography, State Oceanic Administration, Xiamen, China.

Analysis on Features of Temperature and Salinity in the Northern Taiwan Straits During February-March, 1998

The distributional features of temperature and salinity in the northern Taiwan Straits have been analyzed based on the CTD data during February-March, 1998. The characteristics of temperature and salinity are summarized as follows: (1) there exists a coastal water along the western coast of the Taiwan Straits, with low temperature and low salinity at the upper layer; (2) a high temperature and high salinity water tongue extends northeastward along the eastern coast of the Taiwan Strait.

Tidal Current and Tidal Energy Changes Imposed by a Dynamic Tidal Power System in the Taiwan Strait, China

The Taiwan Strait has recently been proposed as a promising site for dynamic tidal power systems because of its shallow depth and strong tides. Dynamic tidal power is a new concept for extracting tidal potential energy in which a coast-perpendicular dike is used to create water head and generate electricity via turbines inserted in the dike. Before starting such a project, the potential power output and hydrodynamic impacts of the dike must be assessed. In this study, a two-dimensional numerical model based on the Delft3 D-FLOW module is established to simulate tides in China. A dike module is developed to account for turbine processes and estimate power output by integrating a special algorithm into the model. The domain decomposition technique is used to divide the computational zone into two subdomains with grid refinement near the dike. The hydrodynamic processes predicted by the model, both with and without the proposed construction, are examined in detail, including tidal currents and tidal energy flux. The predicted time-averaged power yields with various opening ratios are presented. The results show that time-averaged power yield peaks at an 8% opening ratio. For semidiurnal tides, the flow velocity increases in front of the head of the dike and decreases on either side. For diurnal tides, these changes are complicated by the oblique incidence of tidal currents with respect to the dike as well as by bathymetric features. The dike itself blocks the propagation of tidal energy flux.

Study on fish life history traits and variation in the Taiwan Strait and its adjacent waters

Large portions of the world＇s fishery resources are overexploited. Life history traits of fish species are important indicators to reveal different life history strategies and to indicate population responses to fishing pressures. For this study, empirical data on fishing grounds located in the coastal area between Fujian Coast and Taiwan Island were collected. These areas have experienced severe overfishing in the past 30 years, leading to changes in the structure and function of the fish communities. Fifty-one commercial fish species in this fishing ground were selected to study the life history traits. Using the life history traits, all the species were grouped into five different life history strategies by principle component analysis. More than 60% of the species were categorized in Group 5 that was similar to r-strategists. Twenty-five commercial species were selected for further analysis of changes in life history variables, and to discuss the population responses to exploitation. Results showed that most of the species appeared to become smaller size, shorter life, earlier maturation and faster growing under long-term exploitation. The exploitation rate of each species was also calculated to further discuss the impacts of fishing pressures to fish populations. Four species were found with the severest changes on life history traits indicating some of the species might be more susceptible to exploitation. This study on fish life history traits and their long-term variations under fishing pressures could provide important scientific implications for fishery management and conservation.

Distribution patterns of 210Po, 210Pb and the particle export in the Taiwan Strait during the winter

210Po and 210Pb are increasingly used to constrain particle dynamics in the open oceans,however they are less used in coastal waters.Here,distributions and partitions of 210Po and 210Pb were examined in the Taiwan Strait,as well as their application to quantify particle sinking.Activity concentrations of dissolved 210Po and 210Pb(<0.6μm)ranged from 1.21 to 7.63 dpm/(100 L)and from 1.07 to 6.33 dpm/(100 L),respectively.Activity concentrations of particulate 210Po and 210Pb varied from 1.96 to 36.74 dpm/(100 L)and from 3.11 to 38.06 dpm/(100 L).Overall,particulate 210Po and 210Pb accounted for the majority of the bulk 210Po and 210Pb.210Po either in dissolved or particulate phases showed similar spatial patterns to 210Pb,indicating similar mechanisms for controlling the distributions of 210Po and 210Pb in the Taiwan Strait.The different fractionation coefficients indicated that particles in the Zhemin Coastal Current(ZCC)inclined to absorb 210Po prior to 210Pb while they showed an opposite effect in the Taiwan Warm Current(TWC).Based on the disequilibria between 210Po and 210Pb,the sinking fluxes of total particulate matter(TPM)were estimated to range from–0.22 to 3.84 g/(m2·d),showing an overall comparable spatial distribution to previous reported sediment accumulation rates.However,our sinking fluxes were lower than the sedimentation rates,indicating a sediment resuspension in winter and horizontal transport of particulate matter from the Taiwan Strait to the East China Sea.

Spatial structure and seasonal changes of nekton assemblages in the Taiwan Strait

The Taiwan Strait is a transition zone between the East China Sea and the South China Sea with unique hydrology and a geographical environment that creates special marine community features.To analyze the spatial structure and seasonal changes of the nekton assemblages in the Taiwan Strait,seasonal experimental trawl surveys were conducted during 2006-2007.The results showed that there were two assemblages in the area with different sets of species,and the average similarity within each group varies between 39.38% and 74.20%.By using multivariate statistical analysis and analyzing the distribution of dominant species,we found that the structures of the assemblages had obvious seasonal variation.The middle region from the Putian transect to the Xiamen transect could be considered a mixing area for the two assemblages.The analysis of the relationship between species assemblages and environmental factors indicated that temperature was the most important factor affecting the community structure in cold seasons,and 22.5°C and 17°C could be considered dividing lines for spring and winter,respectively.In warm seasons,the most important factor was water depth,but the relationship with depth was not as significant,with a correlation between 0.264 and 0.399.The seasonal changes of nekton assemblages basically reflected the dynamic currents in the Taiwan Strait.The south coastal assemblage extended to nearly the entire area of the Taiwan Strait along with a strong and intense warm current that shrinks in spring and winter when the southward intrusion of the cold Zhejiang-Fujian coastal current becomes stronger.The impact of shortterm and long-term environmental changes,such as extreme weather,global warming and human activity on nekton assemblages,had been recognized but need further research.Our study on nekton assemblages could be used as a baseline for measuring future changes.