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1.
Inorg Chem ; 61(48): 19058-19066, 2022 Dec 05.
Article in English | MEDLINE | ID: mdl-36414026

ABSTRACT

We report the successful growth of high-quality single crystals of Sr0.94Mn0.86Te1.14O6 (SMTO) using a self-flux method. The structural, electronic, and magnetic properties of SMTO are investigated by neutron powder diffraction (NPD), single-crystal X-ray diffraction (SCXRD), thermodynamic, and nuclear magnetic resonance techniques in conjunction with density functional theory calculations. NPD unambiguously determined octahedral (trigonal antiprismatic) coordination for all cations with the chiral space group P312 (no. 149), which is further confirmed by SCXRD data. The Mn and Te elements occupy distinct Wyckoff sites, and minor anti-site defects were observed in both sites. X-ray photoelectron spectroscopy reveals the existence of mixed valence states of Mn in SMTO. The magnetic susceptibility and specific heat data evidence a weak antiferromagnetic order at TN = 6.6 K. The estimated Curie-Weiss temperature θCW = -21 K indicates antiferromagnetic interaction between Mn ions. Furthermore, both the magnetic entropy and the 125Te nuclear spin-lattice relaxation rate showcase that short-range spin correlations persist well above the Néel temperature. Our work demonstrates that Sr0.94(2)Mn0.86(3)Te1.14(3)O6 single crystals realize a noncentrosymmetric triangular antiferromagnet.

2.
Rapid Commun Mass Spectrom ; 33(16): 1344-1354, 2019 Aug 30.
Article in English | MEDLINE | ID: mdl-31046159

ABSTRACT

RATIONALE: Otolith strontium:calcium (Sr:Ca) ratios have been extensively used to study fish migration across a river, estuary and ocean at each life stage. However, otolith Sr:Ca ratios only explain partial variations in salinity and quantitative reconstruction of salinity history of fishes remains a challenge. Using a euryhaline fish Lateolabrax japonicus as an example, this study demonstrated an isotopic method of quantitatively reconstructing the salinity histories and habitat uses of the fish. METHODS: Otolith oxygen stable isotopic ratios (δ18 Ooto values) were measured using a mass spectrometer for subsamples sequentially milled from the otolith core to the edge, and otolith Sr:Ca ratios were measured by an electron probe microanalyzer for the comparison. The mean water temperature within the studied area in the time period of each milled subsample was estimated from the Copernicus database. Based on an isotopic fractionation equation, each δ18 Ooto value and water temperature pair determined the water δ18 O value, which was then converted into salinity using published linear equations or an equation that was newly generated for this study. RESULTS: Individual fish clearly revealed different preferences in habitat use. The retrospectively reconstructed salinity history indicated that most L. japonicus inhabit and can spawn in seawater as well as in brackish estuaries. Few fish lived in freshwater during the young stage based on the analysis of δ18 Ooto profiles; however, otolith Sr:Ca ratios can only reveal freshwater residence and cannot distinguish residence in brackish water or seawater. CONCLUSIONS: This study demonstrated that otolith temporal microstructure and δ18 Ooto values are well-suited approaches for quantitative reconstruction of salinity histories of the fish. This method can improve the understanding of the habitat uses of other fishes inhabiting diverse habitats among the rivers, estuaries and oceans.


Subject(s)
Ecosystem , Fishes/physiology , Otolithic Membrane/chemistry , Oxygen Isotopes/analysis , Salinity , Animals , Fresh Water , Mass Spectrometry , Otolithic Membrane/ultrastructure , Rivers , Seawater , Taiwan
3.
J Fish Biol ; 95(6): 1506-1511, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31606890

ABSTRACT

Tenualosa ilisha was found recently in the Perak River in western Peninsular Malaysia. Molecular phylogenetic and haplotype network analyses suggest that T. ilisha has two genetically distinct populations/groups: (i) Peninsular Malaysia (Malaysia population), and (ii) Peninsular Malaysia, Thailand, India and Bangladesh (Indian Ocean population). The results also suggest that the T ilisha population in Peninsular Malaysia is genetically heterogeneous with a typical anadromous migration pattern.


Subject(s)
Fishes/genetics , Genetics, Population , Otolithic Membrane/chemistry , Phylogeny , Animal Migration , Animals , Bangladesh , India , Indian Ocean , Malaysia , Thailand
4.
Microsc Microanal ; 18(4): 852-9, 2012 Aug.
Article in English | MEDLINE | ID: mdl-22846825

ABSTRACT

Determining correlated major and trace element zoning profiles is an important goal in modern microanalysis and is critical to some geospeedometric applications. We show that a precise determination of relative variations in major element compositions of simple solid solutions is possible by LA-ICPMS, and that low accuracy (analytical bias) can be corrected for through cross correlation with electron problem microanalyzer (EPMA)-characterized working standards. Further, the relative uncertainties on binary or quasibinary solid solution endmember proportions are always lower than the relative uncertainties on the ratio of the principle substituting elements by at least a factor of 2. In calcic plagioclase, for example, the relative uncertainty on X(An) is a factor of (1-X(An)) smaller than the relative uncertainty on Ca/Na. Using a well-characterized, concentrically zoned bytownite crystal as an example, we compare reproducibilities of FE-EPMA and W-EPMA analyses with 2 µm beam diameter and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) with 16 µm beam diameter. While the accuracy of LA-ICP-MS analyses is low (analytical bias), the precision of LA-ICP-MS analyses is slightly higher than that of FE-EPMA data and comparable to that of the W-EPMA data. EPMA-corrected LA-ICP-MS data can thus be used to characterize major oxide compositional variations and potential covariations with trace elements within individual crystals.

5.
PLoS One ; 17(2): e0263986, 2022.
Article in English | MEDLINE | ID: mdl-35167606

ABSTRACT

Mineral soda alumina (m-Na-Al) glass is a common glass production group found around the Indo-Pacific region. In Iron Age Taiwan, its presence dates back to the early 1st millennium AD. This research discusses m-Na-Al glass beads excavated from Iron Age sites in Taiwan. No production sites for m-Na-Al have been found, but microstructural analysis suggests m-Na-Al glass appears to originate around South Asia and is exchanged widely. SEM-EDS and EPMA were used to analyse red, orange, yellow, green and blue m-Na-Al glass. The microstructure of the glass shows the presence of plagioclase and alkali feldspar relics in the glass, suggesting a low manufacturing temperature. Copper-based colourants are identified in red, orange, blue and green glass, while lead tin oxide is used in yellow and green glass. It appears that various types of copper-containing raw materials were procured by craftspeople, and a self-reduction process for producing red and orange glass is tentatively proposed. Additionally, the microstructure of yellow glass reveals different colouring paths were used. These results increase our understanding of the selection of raw materials, and provide an impetus for further research on the cross craft interaction between glass and copper production.


Subject(s)
Aluminum Oxide/chemistry , Glass/analysis , Sodium/chemistry , Archaeology , Color , Microspheres , Taiwan
6.
Sci Rep ; 12(1): 1652, 2022 01 31.
Article in English | MEDLINE | ID: mdl-35102296

ABSTRACT

The crust of Venus is composed of the low lying volcanic planitiae and the elevated, deformed tesserae. It is thought that the tesserae may be composed of silicic igneous rocks and that it may resemble proto-continental crust. The initial development of terrestrial continental crust is likely due to melting and deformation of primitive mafic crust via mantle-plume upwelling and collisional plate processes. Unlike Earth, the lithosphere of Venus is not divided into plates and therefore evolved continental crust, if present, developed primarily by melting of pre-existing mafic crust. Here, we report the results of high pressure equilibrium partial melting experiments using a parental composition similar to the basalt measured at the Venera 14 landing site in order to determine if silicic melts can be generated. It was found that at pressures of 1.5 GPa and 2.0 GPa and temperatures of 1080 °C, 1090 °C, and 1285 °C that tonalitic and granodioritic melts can be generated. The experimental results indicate that silicic rocks may be able to form in the crust of Venus providing the thermal regime is suitable and that the lower crust is basaltic. The implication is that the older, thicker regions of Venusian crust may be partially composed of silicic igneous rocks.

7.
mBio ; 13(3): e0125522, 2022 06 28.
Article in English | MEDLINE | ID: mdl-35608299

ABSTRACT

Methane-oxidizing bacteria (methanotrophs) play an ecological role in methane and nitrogen fluxes because they are capable of nitrogen fixation and methane oxidation, as indicated by genomic and cultivation-dependent studies. However, the chemical relationships between methanotrophy and diazotrophy and aerobic and anaerobic reactions, respectively, in methanotrophs remain unclear. No study has demonstrated the cooccurrence of both bioactivities in a single methanotroph bacterium in its natural environment. Here, we demonstrate that both bioactivities in type II methanotrophs occur at the single-cell level in the root tissues of paddy rice (Oryza sativa L. cv. Nipponbare). We first verified that difluoromethane, an inhibitor of methane monooxygenase, affected methane oxidation in rice roots. The results indicated that methane assimilation in the roots mostly occurred due to oxygen-dependent processes. Moreover, the results indicated that methane oxidation-dependent and methane oxidation-independent nitrogen fixation concurrently occurred in bulk root tissues. Subsequently, we performed fluorescence in situ hybridization and NanoSIMS analyses, which revealed that single cells of type II methanotrophs (involving six amplicon sequence variants) in paddy rice roots simultaneously and logarithmically fixed stable isotope gases 15N2 and 13CH4 during incubation periods of 0, 23, and 42 h, providing in vivo functional evidence of nitrogen fixation in methanotrophic cells. Furthermore, 15N enrichment in type II methanotrophs at 42 h varied among cells with an increase in 13C accumulation, suggesting that either the release of fixed nitrogen into root systems or methanotroph metabolic specialization is dependent on different microenvironmental niches in the root. IMPORTANCE Atmospheric methane concentrations have been continually increasing, causing methane to become a considerable environmental concern. Methanotrophy may be the key to regulating methane fluxes. Although research suggests that type II methanotrophs are involved in methane oxidation aerobically and nitrogen fixation anaerobically, direct evidence of simultaneous aerobic and anaerobic bioreactions of methanotrophs in situ is still lacking. In this study, a single-cell isotope analysis was performed to demonstrate these in vivo parallel functions of type II methanotrophs in the root tissues of paddy rice (Oryza sativa L. cv. Nipponbare). The results of this study indicated that methanotrophs might provide fixed nitrogen to root systems or depend on cells present in the spatially localized niche of the root tissue. Furthermore, our results suggested that single type II methanotrophic cells performed simultaneous methane oxidation and nitrogen fixation in vivo. Under natural conditions, however, nitrogen accumulation varied at the single-cell level.


Subject(s)
Oryza , In Situ Hybridization, Fluorescence , Isotopes , Methane/metabolism , Nitrogen/metabolism , Oryza/microbiology , Oxidation-Reduction , Soil Microbiology
8.
Sci Rep ; 11(1): 1174, 2021 01 21.
Article in English | MEDLINE | ID: mdl-33479265

ABSTRACT

The feeding behavior of the giant ambush-predator "Bobbit worm" (Eunice aphroditois) is spectacular. They hide in their burrows until they explode upwards grabbing unsuspecting prey with a snap of their powerful jaws. The still living prey are then pulled into the sediment for consumption. Although predatory polychaetes have existed since the early Paleozoic, their bodies comprise mainly soft tissue, resulting in a very incomplete fossil record, and virtually nothing is known about their burrows and behavior beneath the seafloor. Here we use morphological, sedimentological, and geochemical data from Miocene strata in northeast Taiwan to erect a new ichnogenus, Pennichnus. This trace fossil consists of an up to 2 m long, 2-3 cm in diameter, L-shaped burrow with distinct feather-like structures around the upper shaft. A comparison of Pennichnus to biological analogs strongly suggests that this new ichnogenus is associated with ambush-predatory worms that lived about 20 million years ago.


Subject(s)
Fossils , Polychaeta/anatomy & histology , Animals , Taiwan
9.
Proc Natl Acad Sci U S A ; 104(50): 19745-50, 2007 Dec 11.
Article in English | MEDLINE | ID: mdl-18048347

ABSTRACT

We have used electron probe microanalysis to examine Southeast Asian nephrite (jade) artifacts, many archeologically excavated, dating from 3000 B.C. through the first millennium A.D. The research has revealed the existence of one of the most extensive sea-based trade networks of a single geological material in the prehistoric world. Green nephrite from a source in eastern Taiwan was used to make two very specific forms of ear pendant that were distributed, between 500 B.C. and 500 A.D., through the Philippines, East Malaysia, southern Vietnam, and peninsular Thailand, forming a 3,000-km-diameter halo around the southern and eastern coastlines of the South China Sea. Other Taiwan nephrite artifacts, especially beads and bracelets, were distributed earlier during Neolithic times throughout Taiwan and from Taiwan into the Philippines.


Subject(s)
Commerce/history , Archaeology , Asia, Southeastern , History, Ancient , Humans , Time Factors
10.
Sci Rep ; 10(1): 16890, 2020 10 09.
Article in English | MEDLINE | ID: mdl-33037236

ABSTRACT

Anguillid eels of the genus Anguilla, which have a unique catadromous life history, are widely distributed across many parts of the world. However, little research has been conducted on the behavioural mechanisms of habitat segregation between sympatric species in tropical anguillid eels. To understand the ecological and behavioural mechanisms involved in the life history and migration of tropical anguillid eels, strontium (Sr):calcium (Ca) ratios were examined in otoliths of A. bengalensis bengalensis (41 specimens) and A. bicolor bicolor (130 specimens) collected from ten rivers in northwestern Peninsular Malaysia. The otolith Sr:Ca ratios revealed different habitat use between the two species. The broad range of otolith Sr:Ca ratios and habitat shift found in A. bicolor bicolor suggested that its habitat utilization was opportunistic in environments of varying salinity. A. bicolor bicolor prefers to live in the midstream to downstream areas with tidal influences. A. bengalensis bengalensis, however, was found to only reside in freshwater environments throughout their continental growth. A. bengalensis bengalensis tends to live in upstream area with no tidal influence. Their habitat use, migratory history, and habitat distribution indicate that habitat segregation occurs between the two species, leading to the different habitat preferences in tropical river systems.


Subject(s)
Anguilla/physiology , Animal Migration , Ecosystem , Rivers , Anguilla/classification , Anguilla/growth & development , Anguilla/metabolism , Animals , Calcium/metabolism , Malaysia , Otolithic Membrane/chemistry , Species Specificity , Strontium/metabolism
11.
Zookeys ; 951: 91-107, 2020.
Article in English | MEDLINE | ID: mdl-32774108

ABSTRACT

Rhinogobius formosanus Oshima, 1919 has long been considered an amphidromous goby. However, a landlocked population recently found in the Jingualiao Creek upstream of the Feitsui Reservoir in Taipei suggests that R. formosanus may complete its life in the river. This study aims to verify the habitat use of the landlocked population of R. formosanus collected from the Feitsui Reservoir and an amphidromous population collected in Malian Creek using otolith Sr:Ca ratio analysis. The hypothesis that early life history varies between the landlocked and migratory gobies was also tested. Genetic analyses show that the Feitsui Reservoir and Malian Creek populations are not genetically different. Rhinogobius formosanus from Malian Creek showed high-to-low otolith Sr:Ca ratios suggesting that these specimens spent a planktonic larval stage in the sea followed by a freshwater life at later stages. In contrast, R. formosanus from the Feitsui Reservoir showed constant lower otolith Sr:Ca ratios, implying a landlocked life history of fish in the creek upstream of the reservoir. In addition, the analysis of growth increments showed a longer pelagic larval duration for the fish in the Malian Creek (58.8 days) than those in the Feitsui Reservoir (38.8). Variation of pelagic larval duration in two genetically homogenous populations implies acclimatization to the reservoir by the landlocked gobies. This study shows that R. formosanus, like some other congeners, is capable of adapting to a freshwater landlocked environment in its early developmental stage and supports the hypothesis that landlocked populations may have a shorter pelagic larval duration.

12.
Sci Total Environ ; 725: 138195, 2020 Jul 10.
Article in English | MEDLINE | ID: mdl-32305642

ABSTRACT

Our study underpins the mechanism of organo-mineral interaction between black carbon (BC, biochar) and associated minerals in the historical BC-rich Amazonian Dark Earth (ADE) by using synchrotron-based microscopic (TXM), microspectroscopic (µFTIR) and spectroscopic (XAS and µ-diffraction) approaches. The BC-rich ADE contained over 100% more poorly crystalline minerals than the adjacent tropical soil. Linear combination fitting of k-spacing in the X-ray Absorption Spectra (XAS) revealed that ferrihydrite contributed to 81.1% of the Fe-minerals in BC. A small but distinct peak was observed at 5.7 Å-1 in the extended X-ray absorption fine structure k oscillation of BC, revealing the presence of FeC (including Fe-O-C) covalent bonds. No FeC path was yielded by the XAS fitting when an obvious peak downshift of the first (FeFe1) shell was observed, suggesting that the availability of inner-sphere FeC complexation was limited to the BC surface and interphase region. The main minerals for organo-mineral complexation were short-range-order (SRO) ferrihydrite on BC instead of corner-sharing FeO6 octahedra. Compared to ADE, the coordination number of the first (FeFe1) and second (FeFe2) shell was higher in BC, revealing a higher degree of order in coordination between the neighboring Fe mineral crystals. Black C limited the progressive aging of amorphous Fe phases and greatly enriched SRO ferrihydrite in the redox-fluctuating and high-leaching environment. The transformation of SRO ferrihydrite into the more crystalline Fe oxides was controlled by the local pH environment. A strong signal from the complexed phenolic group (aryl-OH, 1241 cm-1) and a distinct band of inner-sphere complexation (Fe-aryl C, 1380-1384 cm-1) were identified in the FTIR spectra. The enrichment of poorly crystalline minerals can have positive feedback on the long-term stabilization of BC. The scale-up application of biochar to agricultural and ecological systems may have a long-lasting impact on the enrichment and transformation of the SRO minerals in the soil.

13.
PLoS One ; 13(4): e0195544, 2018.
Article in English | MEDLINE | ID: mdl-29634730

ABSTRACT

Spawning ground of Japanese eel (Anguilla japonica) is located near the West Mariana Ridge seamount. The species travels through the North Equatorial Current (NEC) and then enters the Kuroshio Current (KC) on the migration toward East Asian growth habitats. Therefore, El Niño-Southern Oscillation (ENSO) events serve as the potentially important drivers of interannual variability across the equatorial Pacific. Because the NEC bifurcation and salinity profiles are related to ENSO events, we investigated the influence of locations of the NEC bifurcation and salinity front on the success of larval entry to the KC by numerically modeling particle transport in ocean currents from 1972 to 2013 and possible effects on the size of glass eels at continental recruitment and, via otolithometry on the duration of larval migration. Circulation and hydrography used for particle tracking were obtained from the results of the Model for Interdisciplinary Research on Climate (MIROC) high-resolution forecasting experiment. Our results demonstrated that during El Niño years, (1) the southward movement of the salinity front might cause the larvae to experience slower currents and (2) the northward movement of the NEC bifurcation might broaden the separation between their spawning ground and NEC bifurcation, thus prolonging the time needed for the larvae to enter the KC from their spawning ground, because of which the duration of entrainment in the water column and body size increase when eels reach estuarine waters. In addition, this might cause more water to flow into the Mindanao Current (MC), leading to a decline in the rate at which larvae get entrained into the KC.


Subject(s)
Anguilla , El Nino-Southern Oscillation , Larva , Animals , Models, Statistical , Water Movements
14.
Res Vet Sci ; 121: 53-58, 2018 Dec.
Article in English | MEDLINE | ID: mdl-30359811

ABSTRACT

We investigated the clinical effectiveness of subcutaneous (SC) administration of recombinant feline interferon-omega (rFeIFN-ω) at a dose of 1 M unit (MU)/kg body weight (bw) for the treatment of feline chronic gingivitis-stomatitis (FCGS) in cats infected with feline calicivirus (FCV). Among the 17 cats used in this study, there were 13 FCV-positive cats (FCVI group), which were subcutaneously injected with rFeIFN-ω. The remaining four FCV-positive cats (FCVC group) were treated with SC corticosteroid. SC injection of rFeIFN-ω was given once daily on days 1, 2, 3, 7, 8, 9, 14, and 21. Corticosteroid was subcutaneously injected at a dose of 1.0 mg/kg bw, at the same intervals as rFeIFN-ω. Clinical symptoms (salivation, pain at opening the mouth, halitosis, mandibular lymphadenopathy, and all four symptoms combined [defined as "total clinical symptoms"]) and stomatitis (the degree and extent of inflammation, bleeding from the lesion, and all three items combined [defined as "total stomatitis"]) were scored on days 0, 7, 14, 21, and 28. FCV RNAs was quantified by real-time polymerase chain reaction and the percent increase in viral copy numbers was calculated using the values on days 0 and 28. In the FCVI group, significant differences were observed in the score for clinical symptom (salivation) score and in the total clinical symptom score within the group (P = 0.018 and 0.008, respectively). Significant differences within the group were also observed in the scores for the degree and extent of inflammation in stomatitis and in the total stomatitis score (P = 0.003, 0.007, and 0.003, respectively). The total score, defined as the clinical score plus the stomatitis score, was on days 7, 14, 21 and 28 than on day 0 (p = 0.006, .0003, 0.002 and 0.002, respectively). In the FCVI group, significant difference was observed between on days 0 and on 21 (p = 0.023). The percentage change in the number of polymerase chain reaction cycles required to amplify the viral RNA was positive (indicating viral reduction) in the FCVI group, but was negative in the FCVC group. These results demonstrate that SC administration of rFeIFN-ω under the current protocol improves stomatitis by inhibiting FCV proliferation in FCV-positive cats with FCGS.


Subject(s)
Cat Diseases/prevention & control , Gingivitis/veterinary , Interferon Type I/therapeutic use , Stomatitis/veterinary , Animals , Caliciviridae Infections/veterinary , Caliciviridae Infections/virology , Calicivirus, Feline/physiology , Cat Diseases/immunology , Cats , Female , Gingivitis/immunology , Gingivitis/prevention & control , Inflammation/immunology , Inflammation/prevention & control , Inflammation/veterinary , Injections, Subcutaneous/veterinary , Male , Random Allocation , Stomatitis/immunology , Stomatitis/prevention & control
15.
PeerJ ; 6: e4741, 2018.
Article in English | MEDLINE | ID: mdl-29761056

ABSTRACT

The relationships between pelagic larval duration (PLD) and geographic distribution patterns or population genetic structures of fishes remain obscure and highly variable among species. To further understand the early life history of the tidepool snake moray Uropterygius micropterus and the potential relationship between PLD and population genetic structure of this species, otolith microstructure and population genetics based on concatenated mtDNA sequence (cytochrome b and cytochrome oxidase subunit I, 1,336 bp) were analyzed for 195 specimens collected from eight locations around the southern Ryukyu Islands, Taiwan, and the central Philippines. Eels with longer PLD and lower otolith growth rates were observed at relatively higher latitudes with lower water temperatures (54.6 ± 7.7 days and 1.28 ± 0.16 µm day-1 on Ishigaki Island, Japan, vs. 43.9 ± 4.9 days and 1.60 ± 0.19 µm day-1 on Badian, the Philippines), suggesting that leptocephali grew faster and had shortened pelagic periods in warmer waters. Meanwhile, the eels along the southwest coast of Taiwan had relatively longer PLD (57.9 ± 10.5 days), which might be associated with the more complex ocean current systems compared to their counterparts collected along the east coast of Taiwan (52.6 ± 8.0 days). However, the southwestern and eastern Taiwan groups had similar otolith growth rates (1.33 ± 0.19 µm day-1 vs. 1.36 ± 0.16 µm day-1). Despite the intergroup variation in PLD, genetic analysis revealed fluent gene flow among the tidepool snake morays in the study regions, implying that intraspecies PLD variation had a weak effect on genetic structure. The leptocephalus stage might have ensured the widespread gene flow among the study areas and leptocephalus growth was likely influenced by regional water temperature.

16.
Zool Stud ; 55: e36, 2016.
Article in English | MEDLINE | ID: mdl-31966181

ABSTRACT

Yu-San Han, Chau-Ron Wu, and Yoshiyuki Iizuka (2016) The larval stage of Anguilla japonica includes a long dispersal time over a long distance. In theory, the larvae should be distributed evenly throughout their transportation route when using both the NEC and Kuroshio, but the hypothesized new moon spawning of mature eels should lead to recruited glass eels exhibiting batch-like arrival waves, with a one-month-long cycle. However, environmental disturbances could mask the expected batch-like waves of glass eel recruitment. Thus, this phenomenon is best observed in glass eels collected from offshore waters, which are closer to the spawning site and less disturbed by these environmental factors. The offshore area of Yilan, Taiwan, is a suitable place to observe the arrival dynamics of the A. japonica glass eel. In this area, batch-like waves of glass eel arrival of A. japonica were observed, with peaks occurring between the last quarter and first quarter lunar periods, with a near one-month periodicity. No arrival peaks were found during the full moon period, suggesting that the glass eels exhibit light-avoidance behavior. Furthermore, all of the batches of arrivals were in the early pigmentation stage and similar in age (around 150-160 days), suggesting that they are likely a new arrival cohort. The tracer simulation showed that the mean tracer drift time, from the presumed spawning site to Yilan, was 155 ± 19.8 days. The observed batch-like arrival waves of glass eels in the offshore waters of Taiwan support the "New Moon Hypothesis," which suggests that there is synchronized spawning behavior of the eels during the new moon period.

17.
Zool Stud ; 55: e3, 2016.
Article in English | MEDLINE | ID: mdl-31966148

ABSTRACT

Jen-Chieh Shiao, Chien-Yu Chen, Jie Zhang, and Yoshiyuki Iizuka (2016) Salangid icefish (Salangidae) are commercially important species and are widely distributed in lakes, rivers, estuaries, and coastal area of Asia. This study examined their habitat use and migratory patterns by analyzing otolith microstructure and Sr/ Ca ratios. Neosalanx tangkahkeii and Protosalanx chinesis collected in the isolated freshwater Taihu Lake in China showed consistently low otolith Sr/Ca ratios (< 5.0 × 10-3, mean + 2 SD), which were used to represent the freshwater residence. Another batch of P. chinesis collected from the Yangtze River estuary of China also showed low otolith Sr/Ca ratios (< 5.5 × 10-3, mean + 2 SD) throughout the life history, suggesting that these fish only use freshwater environments. A group of N. tangkahkeii collected in the Pearl River estuary of China showed otolith Sr/Ca ratios between 10.0 × 10-3 and 30.0 × 10-3, indicating habitat shifts between brackish and marine environments. Salanx ariakenesis collected in the Yangtze River estuary showed variable and higher otolith Sr/Ca ratios between 1.6 × 10-3 and 36.5 × 10-3, exhibiting the diverse migratory patterns between the river and the sea with the habitat shifts occurring at the juvenile, young, and adult stages. Neosalanx anderssoni collected in the Bohai Sea, China only used marine habitats based on their consistently high otolith Sr/Ca ratios with the mean values of each fish varying between 20.7 × 10-3 and 24.6 × 10-3. The habitat use by the icefish may differ within and among species. Different migratory patterns can coexist in the same species e.g., S. ariakenesis. The euryhaline icefish, even those living in the estuary or coastal water, do not necessarily migrate between the sea and rivers, suggesting their high plasticity of habitat use and facultative anadromous behaviors.

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