Southeastern Coast Of Taiwan Research Articles

Redescription of Malacosarcus macrostoma (Günther, 1878) from the abyssal zone off Taiwan, northwestern Pacific Ocean (Beryciformes, Stephanoberycoidei, Stephanoberycidae)

The large-mouth pricklefish, Malacosarcus macrostoma (Günther, 1878), previously known from five specimens collected from the central Pacific Ocean, is redescribed based on three specimens collected from the abyssal zone (4,412–4,813 m) off the southeastern coast of Taiwan. These specimens contribute to a more comprehensive description of M. macrostoma and represent this species’ westernmost and deepest record. This study provides a detailed description, fresh photographs, and notes on their morphological characteristics of the specimens. Lastly, the distributional records of M. macrostoma are discussed.

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.

Sequestration of P fractions in the soils of an incipient ferralisation chronosequence on a humid tropical volcanic island

BackgroundPhosphorus (P) is the limiting nutrient in many mature tropical forests. The ecological significance of declining P stocks as soils age is exacerbated by much of the remaining P being progressively sequestered. However, the details of how and where P is sequestered during the ageing in tropical forest soils remains unclear.ResultsWe examined the relationships between various forms of the Fe and Al sesquioxides and the Hedley fractions of P in soils of an incipient ferralitic chronosequence on an altitudinal series of gently sloping benches on Green Island, off the southeastern coast of Taiwan. These soils contain limited amounts of easily exchangeable P. Of the sesquioxide variables, only Fe and Al crystallinities increased significantly with bench altitude/soil age, indicating that the ferralisation trend is weak. The bulk of the soil P was in the NaOH and residual extractable fractions, and of low lability. The P fractions that correlated best with the sesquioxides were the organic components of the NaHCO3 and NaOH extracts.ConclusionsThe amorphous sesquioxides, Feo and Alo, were the forms that correlated best with the P fractions. A substantial proportion of the labile P appears to be organic and to be associated with Alo in organic-aluminium complexes. The progression of P sequestration appears to be slightly slower than the chemical and mineralogical indicators of ferralisation.

Age validation, growth estimation and cohort dynamics of the bony flying fish Hirundichthys oxycephalus off eastern Taiwan

Flying fishes (Exocoetidae) are commonly found in the epipelagic zone and play an important role in Taiwan in maintaining the stability of the marine ecosystem, local culture and coastal fisheries. However, little is known about their biology and life history, even though several species are of important commercial value in western Pacific countries. Overexploitation of one of the dominant species, the bony flying fish Hirundichthys oxycephalus, is a critical issue in the fishery management and resource assessment of this species. In the present study, H. oxycephalus eggs were harvested off northeastern Taiwan, while adult fish were collected mainly off the southeastern coast of Taiwan. We validated the daily periodicities of the growth increments in 3 otolith pairs based on the successive otolith examination of fish reared in the laboratory from fertilized eggs. The asteriscus was determined to be the most suitable otolith for age determination of the fish. Age (in days) was calculated by counting the number of growth increments on the mounted otolith and adding 11. By using a growth coefficient of 0.0075 d−1, the asymptotic length of these fish was estimated to be 253.86 mm. Back-calculated hatching dates indicated that an occurrence of the summer spawning cohort coincided with the known egg-fishing season off the northeastern coast. On the other hand, the source of the adult fishery off the southeastern coast originated from a new winter spawning cohort. The cohort dynamics of this species were found to be more complicated than previously thought. Our findings could be added to the information already known about the reproductive ecology of H. oxycephalus and used to improve the fisheries management of these fish.

Vertical and horizontal movements of sailfish ( Istiophorus platypterus) near Taiwan determined using pop-up satellite tags

Sailfish ( Istiophorus platypterus) are of substantial economic importance to Taiwan because of their seasonal abundance (April to October, with a peak from May to July) off the island's eastern coast. They are harvested by drift gill nets, set nets, harpoons, and as incidental bycatch by inshore longline fisheries. Although the biology of sailfish has been investigated in eastern Taiwan, there is a paucity of data on movement patterns. Pop-up satellite archival tags (PSATs) were used to study the vertical and horizontal movements of three sailfish in 2008. The fish were tagged near the southeastern coast of Taiwan and linear displacements ranged from 1050 to 1400 km (~ 40 km day − 1 ) from deployment to pop-up locations and all movements were confined to the East China Sea. Sailfish spent 88% of their time in the upper uniform mixed layer above 50 m, but made more extensive vertical movements during the nighttime ( x ¯ = 60.61 m ± 48.24 SD) than daytime ( x ¯ = 35.21 m ± 35.37 SD). Depths and ambient water temperatures visited ranged from 0 to 214 m and 30.0° to 17.8 °C, respectively. However in all cases, the depth distribution appeared primarily limited by an 8 °C change in water temperature. Diel diving patterns also suggested basking behavior. Sailfish behavior makes them particularly vulnerable to surface fishing gears.

Formation of the Convective Lines off the Mountainous Coast of Southeastern Taiwan: A Case Study of 3 January 2004

Abstract Convective lines frequently occurring off the mountainous coast of southeastern Taiwan under weakly synoptically forced weather conditions are one of the most well-known mesoscale phenomena in Taiwan. These lines usually develop close to the coast but frequently can also be observed well offshore. While nearshore lines are better understood, the formative processes of the offshore lines remain unclear. The main objective of this study is to use various available observations (e.g., Doppler radar, surface and sounding observations, QuikSCAT, and NCEP data) collected over southeastern Taiwan to investigate a specially chosen case on 3 January 2004, in an attempt to identify possible mechanisms leading to the formation of the offshore lines. The studied line was formed ∼50–60 km away from the southeastern coast of Taiwan and oriented south-southwest to north-northeast and approximately parallel to the coast. Detailed analyses of the event indicated that the formation of the line did not appear directly relevant to coastal land/sea breezes or offshore flow. Instead, orographic forcing was observed to play a crucial role in the initiation of the line. Particularly, an orographically forced northerly flow due to upstream blocking was evident to the west of the line. The convergence generated as the prevailing northeasterly onshore flow encountered the nearshore blocked flow was found to be an important low-level forcing conducive to the initiation of moist convection associated with the line. In addition, the persistence of the coastally blocked flow and the degree of ambient convective available potential energy (CAPE) were also shown to be closely related to the maintenance and overall intensity of the observed line’s convection. The orographically induced convective forcing identified in this study is distinctly different from the conceptual model of line formation proposed by previous studies of the nearshore lines. It is thus strongly suggested that multiple mechanisms may exist upstream of coastal mountains in southeastern Taiwan, which act to initiate the lines with diverse formative locations relative to the coastline.

High‐resolution simulation of a nocturnal narrow convective line off the southeastern coast of Taiwan in the Mei‐yu season

This study performed high‐resolution numerical simulation on a convective line that occurred roughly 10–30 km offshore of southeastern Taiwan overnight of 14–15 May 1998. Three experiments at successively higher resolution (10, 2, and 0.5 km) but smaller domain were carried out, and the narrow line is eventually reproduced. It is found that shallow (offshore) return flow along the coast appeared since daytime due to topographic blocking on the weak prevailing (onshore) south‐southeasterly wind, producing convergence at their interface near shore. During the night, mountain breeze further strengthened the offshore flow and convergence, and the line initiated. Once developed, downdrafts and outflow boundaries from old clouds triggered new clouds, and this was more active along the (eastern) boundaries against the undisturbed environmental flow. Thus, repeated new cloud formation took place throughout the night and into the next morning.

Statistical Location and Timing of the Convective Lines off the Mountainous Coast of Southeastern Taiwan from Long-Term Radar Observations

Abstract In this study, observations from the C-band Doppler radar on Green Island, which is located off the southeastern coast of Taiwan, during 1998–2004 were analyzed to investigate the statistical characteristics of the convective lines occurring off the mountainous coast of southeastern Taiwan, with emphasis on their formative location and timing. A total of 211 cases of the lines were identified during the study period. It is shown that the lines were clearly a year-round phenomenon and five cases occurred per month on average. Statistical analyses for all identified cases reveal that the formative area of the lines was extended substantially from nearshore regions to at least ∼100 km offshore, with the region of the most frequent formation primarily confined to an elongated zone located ∼30 km off the coast. Along-coast variations of line formation were also evident and were shown to be closely related to the nearshore terrain features. The lines tended to form more frequently during the nighttime hours than the daytime hours, with a formative peak between 2000 and 2200 LST. Minimum formation was found near noon between 1200 and 1400 LST; however, considerable cases still could be found during the late morning and late afternoon hours. More than 70% of the lines (∼150 cases) had a duration of less than 4 h, and the mean duration for all lines was calculated to be ∼3.5 h. In addition, this study also documented statistical differences in the formative and flow characteristics between the nearshore and offshore lines, which are distinguished by offshore distances of formative location that are less or greater than 40 km, respectively. Of particular note, the analyses presented strongly suggest that the physical mechanisms contributing to the initiation of the nearshore and offshore lines are fundamentally different.

Cavity dynamics and breeding success of the Lanyu Scops Owl (Otus elegans)

The Lanyu Scops Owl (Otus elegans) breeds in natural tree cavities on Lanyu (Orchid Island), a subtropical island off the southeastern coast of Taiwan in the western Pacific. There are no cavity-making birds or mammals on the island. This study attempted to understand the relationship between this owl’s cavity use and breeding success. In a 10-ha study site, all cavities on all trees with a diameter breast height larger than 18 cm were documented. There were 257 cavities in 119 trees, and 94 of them were used by owls at least once during the study period. The detailed location and size of these 94 cavities in 74 trees were recorded and monitored. From 1999 to 2006, more than 80% of breeding owls were color-marked and their cavity use and breeding success were tracked. Nest trees were taller than other trees, and cavities used by owls were higher above the ground, and larger than unused cavities. Unused cavities were mostly unsuitable due to flooding or decay, or were on trees already containing a nest. Regardless of how many cavities there were on a tree, a single tree never had more than one Lanyu Scops Owl nest at a given time. More than 60% of the 94 cavities were used multiple times. Cavity occupancy frequently showed gaps, usually following breeding failure. Cavity quality (the proportion of years a cavity was used during the study) and female quality (the proportion of years an owl bred out of the total number of years it competed for cavities) significantly contributed to the average fledging success of owls, but male quality did not.

Application of artificial neural networks in typhoon surge forecasting

A typhoon-surge forecasting model was developed with a back-propagation neural network (BPN) in the present paper. The typhoon's characteristics, local meteorological conditions and typhoon surges at a considered tidal station at time t−1 and t were used as input data of the model to forecast typhoon surges at the following time. For the selection of a better forecasting model, four models (Models A–D) were tested and compared under the different composition of the above-mentioned input factors. A general evaluation index that is a composition of four performance indexes was proposed to evaluate the model's overall performance. The result of typhoon-surge forecasting was classified into five grades: A (excellent), B (good), C (fair), D (poor) and E (bad), according to the value of the general evaluation index. Sixteen typhoon events and their corresponding typhoon surges and local meteorological conditions at Ken–fang Tidal Station in the coast of north-eastern Taiwan between 1993 and 2000 were collected, 12 of them were used in model's calibration while the other four were used in model's verification. The analysis of typhoon-surge forecasting results at Ken–fang tidal station show that the Model D composing 18 input factors has better performance, and that it is a suitable BPN-based model in typhoon-surge forecasting. The Model D was also applied to typhoon-surge forecasting at Cheng-kung Tidal Station in south-eastern coast of Taiwan and at Tung-shih Tidal Station in the coast of south-western Taiwan. Results show that the application of Model D in typhoon-surge forecasting at Cheng-kung Tidal Station has better performance than that at Tung-shih Tidal Station.

Ecology and Reproductive Patterns of the Agamid Lizard Japalura swinhonis on an East Asian Island, with Comments on the Small Clutch Sizes of Island Lizards

I describe the habitat use, diet, and the male and female reproductive cycles of Japalura swinhonis, an oviparous agamid lizard inhabiting Orchid Island, a tropical island off the southeastern coast of Taiwan. Ninety percent of lizards (n=126) were observed on tree trunks or at the forest edge. The diet of J. swinhonis on Orchid Island consisted mostly of hymenopterans (53.33%) and orthopterans (16.67%). The mean snout-vent length (SVL) of adult males was 74.58 (n=89) and that of females was 69.31 (n=37) mm. Females exhibited a long vitellogenic period from November to February, with parturition occurring from March to October. The onset of vitellogenesis did not correlate with the mass of the female fat bodies. Females produced two to five eggs per clutch, and clutch size was not correlated with SVL. Two clutches were recorded during a single year in some individuals. Clutch size in J. swinhonis was compared with that in other Japalura species. Clutch sizes of Japalura species are larger in mainland China than on insular Taiwan. Clutch size is also mainly affected by environmental constraints, and smaller clutch sizes are probably affected by predators on Orchid Island.

Ecology and Reproductive Patterns of the Grass Lizard, Takydromus sauteri, in a Tropical Rain Forest of an East Asian Island

Abstract I describe habitat use, diet, and male and female reproductive cycles of Takydromus sauteri, an oviparous grass lizard inhabiting Orchid Island, a tropical island off the southeastern coast of Taiwan. All T. sauteri were observed on leaves of Japanese silver-grass (Miscanthus floridulus) at the forest edge. The diet of T. sauteri consisted mostly of spiders (35.7%) and Hemipterans (14.3%). Two prey categories, spiders and gymnoceratans, numerically dominated the diet. Two lizards' stomach contained plant seeds, and two had eaten roaches. Mean snout–vent length (SVL) of adult males (N = 59) was 64.2 (range: 60.3–73.7) mm and that of females (N = 63) was 67.1 (range: 50.6–76.5) mm. Females exhibited spring and summer vitellogenesis with parturition occurring from February to August. Onset of vitellogenesis showed a negative correlation with mass of female fat bodies. Females produced one to four eggs per clutch, and clutch size was not correlated with SVL. Two clutches were recorded during a single...

Radar Observations of the Diurnally Forced Offshore Convective Lines along the Southeastern Coast of Taiwan

Abstract This study documents offshore convective lines along the southeastern coast of Taiwan, a frequent but poorly understood mesoscale phenomenon that influences coastal weather during the Taiwan mei-yu season. Doppler radar and surface observations were gathered from a specially chosen period (11–15 May 1998) when the offshore convective lines were active off the southeastern coast of Taiwan. These observations were used to show the basic character, structure, and possible formative processes of offshore convective lines. The synoptic environment accompanying these events was found to be relatively undisturbed and featured uniformly prevailing southerly/south-southeasterly winds in the boundary layer with southwesterlies/westerlies aloft. Examination of radar data during the study period indicates that the lines generally occurred ∼10–30 km offshore and were characterized by an elongated narrow zone (∼5–10 km wide) of heavy precipitation. The lines were oriented roughly parallel to the coastline and generally did not move significantly. The intensity of the radar reflectivity associated with the lines exhibited a marked diurnal variation and was closely related to the coastal offshore flow developing at night. Detailed analyses of an event on 14–15 May 1998 further show the important physical link between the offshore flow and the development of the line. The offshore line was found to be located near and immediately ahead of the seaward extent of the offshore flow. Particularly, a very narrow zone (∼2 km) of low-level heavy precipitation (40–45 dBZ) coincided with regions of strong updrafts and convergence, where the prevailing southerly onshore flow encountered the cool offshore flow nearshore. This offshore flow–induced convergence, given a stable thermodynamic condition in the lowest ∼1 km in the inflow region, was a crucial low-level forcing that provided lifting to trigger moist deep convection in this case. The line’s precipitation tilt eastward was confined primarily to the warmer inflow side rather than feeding the offshore flow to the west of the line. No consistent upshear tilt of updrafts throughout the storm layer was observed, which is consistent with the presence of a strong westerly shear in the line’s environment. Both of these observations explain a relatively strong (weak) modification of low-level onshore (offshore) flow by precipitation. Additionally, a combination of surface and Doppler radar observations indicates that the leading edge of the offshore flow moved seaward very slowly at 0.7 m s−1 and possessed a frontal character with notable discontinuities in near-surface wind and temperature (instead of pressure and dewpoint temperature).

Retrieved Thermodynamic Structure of a Subtropical, Orographically Influenced, Quasi-Stationary Convective Line

Airborne Doppler radar and flight-level measurements were used to document the three-dimensional thermodynamic structure of a convective line that developed off the southeastern coast of Taiwan on 16 June 1987 during the Taiwan Area Mesoscale Experiment. During the period of aircraft observation the convective line appeared to be quasi-stationary in a region ;90 km away from the coast. Calculations of perturbation pressure and buoyancy retrieved from the Doppler-radar-derived wind fields show that a high pressure perturbation associated with negative buoyancy existed in the region of heavy precipitation in the lowest level. In low levels, an elongated zone of low pressure was documented along the line, which was closely related to the distributions of buoyancy. These retrieved features are basically consistent with those calculated from in situ observations. In mid- to upper levels, the high (low) pressure perturbation lay around the updraft cores on the upshear (downshear) of environmental shear. The quantitative diagnosis for the perturbation pressure indicates that the positive buoyancy associated with the in-cloud latent heat release as well as evaporative cooling occurring near cloud base and subcloud regions is crucial to determine the low-level perturbation pressure distributions. However, dynamic forcing contributing to the pressure perturbation cannot be ignored in middle levels, because of updraft‐ shear interaction due to the presence of pronounced cross-line wind shear and corresponding updrafts reaching maximum values near midtroposphere. In distinct contrast to squall lines, which are rapidly moving, the near-surface temperature gradient across this quasi-stationary line was very weak, and at low levels no gust front, rear inflow, or dynamically induced high pressure was evident near the leading edge of the line. Analyses presented here suggest that the persistent, stationary convergence, in association with the deceleration of low-level southeasterly flow as it approached the nearshore blocked flow, played an important role in maintaining and organizing the deep convection in this case.

Formative Stage of a Long-Lived Mesoscale Vortex Observed by Airborne Doppler Radar

Abstract The formative stage of a long-lived mesoscale cyclonic vortex was captured by the NOAA P-3 aircraft as it investigated a developing mesoscale convective system (MCS) near the southeastern coast of Taiwan on 16 June 1987 during the Taiwan Area Mesoscale Experiment. The supporting environment of the mesovortex was characterized by an exceptionally moist atmosphere and moderate ambient vertical shear through a deep layer from the near surface to ∼6 km, with much weaker shear and winds aloft. In addition, a pronounced low-level mesoscale shear/convergence zone, which resulted from the interaction of southeasterly flow with northeasterly flow confined to the near-coast region, existed in the vicinity of the observed mesovortex. Composite three-dimensional wind fields derived via pseudo-dual-Doppler synthesis show the vortex had a horizontal diameter expanding from ∼40 km to ∼70 km in the lower to midtroposphere, respectively, and exhibited considerable tilt through this layer. Contrary to previously d...

Reproductive Biology of the Sea Snake, Laticauda semifasciata, in Taiwan

Four species of sea snakes, Laticauda semifasciata, L. laticaudata, L. colubrina and Emydo- cephalus ijimae occur near Orchid Island on the southeastern coast of Taiwan. We describe here aspects of the reproductive biology of the most abundant species, L. semifasciata, based on a sample of 243 snakes collected between April 1986 and March 1987. Eight meristic and morphometric characters were examined for sexual dimorphism. The two best indicators were caudal width and the number of subcaudal scales. Minimum snout-vent lengths at sexual maturity for male and female snakes were 70 and 80 cm, respectively. The breeding season for female snakes was prolonged and peaked between August and November. There was no seasonal fluctuation in the weight or dimensions of the testes; sperm were found within the vas deferens throughout the year. Mating took place sometime before ovulation. Three to seven eggs (mean, 4) comprise the clutch. There are indications that some females may breed more than once per year. Eggs were laid in muddy water within tidal caves where they would not be inundated by sea water; moisture levels during incubation were maintained by fresh water dripping from condensation on the cave roof. The incubation period was 4 to 5 months.

Zooplankton communities in the upwelling water off the southeastern coast of Taiwan : Huang, Che-Chung, 1983. Acta oceanogr. taiwan., 14:136–145

Zooplankton communities in the upwelling water off the southeastern coast of Taiwan : Huang, Che-Chung, 1983. Acta oceanogr. taiwan., 14:136–145

FOCAL MECHANISMS AND TECTONICS IN THE TAIWAN-PHILIPPINE REGION

Seismic activity and focal mechanisms in the vicinity of Taiwan and the Philippines are studied to elucidate the tectonics in this complex region. Epicentral distribution and vertical profiles of earthquake foci support the idea that the entire Philippines is not a part of the Eurasian plate, but another block of lithosphere and the relative motion between the Philippine Sea and the Eurasian plates is shared by the subduction along the two boundaries, west and east of the Philippines. Thrust type of mechanisms are the dominant mode of deformation along the eastern margin of the Philippines; in contrast, no thrust type of solutions are obtained along the western margin of this islands. Between Taiwan and Luzon, mode of plate consumption is most complex. Seismic activity is mostly shallow and diffuse in a 200km wide zone. Reverse faultings along the eastern margin of Taiwan, strike-slip faultings off the southeastern coast of Taiwan, and normal faultings between the Manila trench and the North-Luzon trough are the major mode of deformation. We believe that the region between Taiwan and Luzon constitutes a left-lateral shear zone due to the gradual transition of site of plate consumption from eastern margin of Taiwan to east Luzon. Subduction under the west-facing Luzon arc in this region is likely to be ending now; this might be causing the opening of the sedimentary wedge behind the Manila trench. Normal faultings in this study probably indicate the initial phase or prespreading phase of opening of the area behind the Manila trench.