Growth Bands Research Articles

Interplay between Growth Mechanism, Materials Chemistry, and Band Gap Characteristics in Sputtered Thin Films of Chalcogenide Perovskite BaZrS3

Interplay between Growth Mechanism, Materials Chemistry, and Band Gap Characteristics in Sputtered Thin Films of Chalcogenide Perovskite BaZrS₃

Clam shrimp Nothocarapacestheria from the Lower Jurassic of the Junggar Basin, northwestern China

Abstract Nothocarapacestheria Rohn et al. , 2014 was erected based on material from the Upper Triassic–Lower Jurassic of the Paraná Basin, Brazil. Here we describe a Nothocarapacestheria species that has been discovered in the Lower Jurassic Badaowan Formation in Xinjiang, northwestern China. The described species is characterized by: (1) almost the whole carapace being ornamented with medium reticulations, 3–6 polygons per growth band, 20–60 µm mesh diameter; (2) the gradual transition to radially elongated reticulations in the distal region of the carapace, sometimes ending as radial lirae; and (3) fine puncta in the mesh of reticulations. Through this study, we are able to infer that the distribution of Nothocarapacestheria was more widespread than previously thought, and that Euestheria sp. previously reported from the Lower Jurassic Badaowan Formation are probably poorly preserved or juvenile individuals of Nothocarapacestheria .

It’s a trap!: Modern and ancient halite as Lagerstätten

ABSTRACT Chemical sediments, such as bedded halite (NaCl), are strongly influenced by environmental conditions during deposition and, if unaltered, may preserve microorganisms, microfossils, and organic compounds for hundreds of millions of years. Recent studies show that halite is an excellent repository for organic materials, as well as a variety of environmental data. Halite is a perfect trap. Due to its rapid growth, parent brine, gas, crystals of other minerals, and any organic material are encased within primary fluid inclusions or as solid inclusions along growth bands. These inclusions function as “snapshot” repositories of the hydrosphere, atmosphere, lithosphere, and biosphere. However, organic material in halite is still relatively unknown in the sedimentological and paleontological communities. Here, we present highlights of preservation in halite to showcase the diversity of life that has been documented within it. We also discuss: 1) the properties of halite that give it such excellent preservation potential, 2) the challenges to and strategies for studying organic material in halite, 3) preservation in other salt minerals such as gypsum, and 4) implications for astrobiological research. Recommendations for the future study of organic material in halite include collaboration amongst chemical sedimentologists, paleontologists, and microbiologists.

Facile synthesis of multicolor emitting sulfur quantum dots and their applications in light blocking field, anti-counterfeiting and sensing

Sulfur quantum dots (SQDs) have aroused widespread interest from researchers in a wide range of fields due to their excellent photoluminescent properties. Ethylenediamine, diaminopropane and butanediamine were used as precursor amine raw materials to interact with sublimated sulfur to synthesize SQDs with blue, cyan and green fluorescence emission, respectively. Multicolour emitting SQDs were first prepared via sulfur-amine interactions. Further characterization and calculations showed that the precursor amine substances could alter growth size and band gap energy of SQDs to allow for a wider absorption and fluorescence transfer to long wavelength emission region, resulting in tunable fluorescence emission. In terms of application, the excellent down-conversion properties of SQDs were utilized to obtain highly transparent and flexible photoblocking films by blending SQDs with polyvinyl alcohol matrixes, achieving a blocking of light in UV region of up to 99.69 %. In addition, we constructed an encoded storage microarray based on standard 8-bit ASCII character binary codes using BSQDs and GSQDs to store and encrypt important information. Finally, GSQDs-based fluorescent sensors were designed to achieve fluorescent trace detection of o-nitrophenols with limits of detection as low as 2.54 μM. The multicolor emitting SQDs prepared in this work have great potential for applications in analytical detection, optical anti-counterfeiting and light blocking.

Depositing >1.5 Mt of Tin Within <1 m.y. of Initial Granitic Intrusion in the San Rafael Tin (-Copper) Deposit, Southeastern Peru

Abstract The San Rafael Sn (-Cu) deposit, located in the Eastern Cordillera of southeast Peru, is one of the world’s largest cassiterite-bearing vein systems (>1 Mt Sn produced since 1969). The deposit consists of a quartz-cassiterite-chlorite-sulfide lode system spatially associated with an upper Oligocene (ca. 24 Ma) S-type granitic pluton. Based on a revised paragenetic sequence for the deposit, we interpret the temporal setting of both magmatic (biotite, K-feldspar) and hydrothermal (muscovite, adularia, cassiterite) minerals analyzed by 40Ar/39Ar step-heating and U-Pb laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) geochronology. The least-disturbed biotite sample from the megacrystic monzogranite yielded a 40Ar/39Ar plateau age of 24.10 ± 0.26 Ma (2σ), which constrains the time of cooling of the upper part of the pluton to below 300°C. Greisen developed on top of the granitic cupola and its immediate metamorphic aureole dated at 24.24 ± 0.24 Ma (2σ; 40Ar/39Ar muscovite average plateau age) is interpreted to be contemporaneous with the emplacement of pre-ore quartz-tourmaline veins and breccias. In situ U-Pb dating of cassiterite, including both botryoidal cassiterite (“wood tin”) and coarse-grained cassiterite in quartz-chlorite veins and breccias, constrains the timing of the main Sn ore stage to between 24.10 ± 0.37 and 23.47 ± 0.53 Ma (2σ). Botryoidal and coarse-grained cassiterite are characterized by similar trace element compositions with fluctuating metal concentrations across growth banding, suggesting significant changes of physicochemical conditions of the hydrothermal system during cassiterite precipitation, likely caused by rapid and repeated mixing between magmatic fluids and meteoric groundwaters. Polymetallic sulfide-rich veins and quartz-carbonate veins are constrained to have formed between 22.72 ± 0.11 and 22.29 ± 0.24 Ma (2σ), based on adularia 40Ar/39Ar plateau ages. The latter overlap partially reset 40Ar/39Ar age spectra for K-feldspar megacrysts in the host granite and thus reflect pervasive alteration by hydrothermal fluids. Collectively, the results show the magmatic-hydrothermal system spanned at least 2 m.y. with the main Sn ore stage representing <1 m.y. in the lifetime of the deposit. The latest polymetallic stages postdate the main Sn ore stage by ca. 1 m.y. and reflect the waning of the hydrothermal system, accompanied by additional incursion of meteoric groundwaters. This study provides further evidence that the present-day exposed level of the San Rafael granite was a passive host for the Sn mineralization and only provided the structural focusing for the mineralizing fluids derived from a deeper part of the magmatic system.

Seasonality and lake water temperature inferred from the geochemistry and sclerochronology of quaternary freshwater bivalves from the Turkana Basin, Ethiopia and Kenya

Reconstructing past environmental variability at short (annual-decadal) time scales is critical for understanding ecosystem change and ecological drivers of evolution. One promising approach to reconstructing that variability is through the use of stable isotope geochemistry and sclerochronology, the study of growth banding in organisms that undergo accretionary growth. We used a combination of sclerochronology, conventional stable isotope ratios and clumped isotope paleotemperatures to improve our understanding of past seasonality and climate variability in the Turkana Basin (Kenya, Ethiopia), which experiences a highly seasonal (tropical semi-desert) climate. In this case study, we apply these approaches to both Early Pleistocene and Holocene bivalve shells (Etheria and Pseudobovaria) to develop a model using various proxies of seasonal-interannual temporal variability in lake temperature and isotope chemistry. We leverage this model to better understand how lakes in the Turkana Basin have changed over short time-scales in the past. One modern (1979) river oyster has exclusively negative δ18O values through ∼1.5 yrs of growth and clumped isotope temperature reconstructions (30.1–31.5 °C) consistent with a river delta provenance. Late Holocene shells show a wider range of isotopic variability within each shell's growth history than the modern sample (∼2‰ for the modern sample vs. 5–7‰ for the Late Holocene samples) and near modern paleotemperatures, suggesting growth under both seasonal Omo flood pulse and lacustrine conditions. Middle Holocene shells exhibit less δ18O variability, consistent with growth in fresher Lake Turkana water at the end of the African Humid Period (12-5 ka), and with both surface water temperatures and water column temperature range similar to the Late Holocene. The Early Pleistocene shells have large seasonal δ18O cycles (4–7‰), with δ18O values comparable to modern and Holocene deltaic shells, and a large range of paleotemperatures (21.8–31.3 °C, including temperatures notably cooler than those measured in the modern lake: 25–31 °C), reflecting growth under significant seasonality in paleo-Omo River runoff. Oxygen isotope cycles suggest high degrees of seasonality of the paleo-Omo River runoff (or that of other major influents) into paleolake Lorenyang at ∼1.6 Ma, which may be similar to modern hydroclimate conditions. Comparison to prior datasets from nearby outcrops in the same basin suggests an increase in hydroclimate seasonality between 1.9 and 1.6 Ma. The combination of clumped isotope paleotemperature estimates from shallow water species such as E. elliptica with TEX86 measurements (derived here from previously published, contemporaneous sediment core studies from the south basin of Lake Turkana), which record temperatures near the oxycline, may provide a new approach to estimating past temperature variability along a vertical profile in lakes, thereby providing information on water column mixing regimes. Our approach greatly expands our toolkit for understanding coupled climate seasonality and variability in the Turkana Basin.

Investigating the Relationship between Growth Rate, Shell Morphology, and Trace Element Composition of the Pacific Littleneck Clam (Leukoma staminea): Implications for Paleoclimate Reconstructions

Due to their robust preservation and widespread nature, marine bivalve shells are increasingly used as informative, high-resolution records of past environmental conditions. Unfortunately, few studies have investigated variability amongst individuals in a genetic cohort and throughout their ontogeny. We measured several morphological properties and the element patterning of 200-day-old juvenile Leukoma staminea (Conrad, 1837) grown in identical conditions from the same reproductive cohort. We hypothesized that slower shell growth would correspond to the reduced incorporation of trace/minor elements (Sr, Mg, and S) in the aragonite lattice, as has been documented in other biomineralizing marine invertebrates. Microprobe analyses of adult shells revealed higher levels of S, Sr, and Mg in the dark, slower-growing growth lines compared to the light, faster-growing increments, particularly in the inner shell layer, thus refuting our hypothesis. Moreover, elemental count variation within single adult shells generally tracked changes in shell microstructure (i.e., higher counts in prismatic microstructures) and growth line patterns, and these differences are detectable on a micrometer scale. Juvenile shells of different sizes showed variation in S, Sr, and Mg counts as well, but it was unclear whether the variability closely tracked changes in microstructure, body size, and/or growth line patterns. In all individuals, regardless of life stage, the outermost shell layer showed higher Sr and S count values, and these elements closely mirrored each other within individual shells. The results presented herein represent the first in-depth description of the shell mineralogy, microstructure, body size variability, and geochemical properties of modern L. staminea, a common eastern Pacific, shallow, infaunal bivalve, allowing for the rigorous evaluation of L. staminea shells as recorders of past environmental and biological change. Significant intraspecific variation in the young body size, growth band patterning, and elemental composition of individuals of the same age and genetic stock complicates the use of size alone as a proxy for age in historical studies. Additionally, elemental composition shifted from high to low values (for example, Sr ranging from ~190 to 100 counts) at a very fine (micrometer) scale within single shells, as evidenced by visible correlations between microstructure and elemental composition. While young L. staminea shells are likely not useful as archives of (paleo)environmental conditions, adult L. staminea shells are likely suitable if micrometer-scale variability in shell structure and chemistry is accounted for.

Co-existing two distinct formation mechanisms of micro-scale ooid-like manganese carbonates hosted in Cryogenian organic-rich black shales in South China

Manganese-rich deposits in the lower member of the Datangpo Formation (DTP) (ca. 663–654 Ma) in South China formed in the aftermath of the Cryogenian Sturtian glaciation. The Mn in the DTP occurs dominantly as rhodochrosite and Ca-rhodochrosite. A hydrothermal origin of the Mn2+ is shown by the rare earth element distribution and significantly high Mn/Fe ratios (3–19, average = 10.1). Previous studies suggested a microbially-mediated process for controlling the DTP black-shale hosted Mn carbonate deposits. However, detailed reports on the formation mechanisms of micro-scale (<2–5 μm) ooid-like Mn carbonates in the DTP have rarely been published. Systematic petrography and geochemical analyses in this study demonstrate the coexistence of two types of micro-scale ooidal-like Mn carbonates formed through two distinct mechanisms, either dominated by microbially-mediated or physiochemically-forced pathways. The Type I Mn carbonate has relatively larger grain size of 2–5 μm and exhibits a radial-concentric microfabric that shows signs of growth banding in the form of alternating light and dark laminae, which mainly express variation in Ca and Mn concentrations. The initial precipitation phase of the Type I Mn carbonate is interpreted to be Mn oxide/hydroxide, based on positive Ce anomalies and selective enrichments of particular trace elements. Novel evidence indicates that the capture of Mn as a carbonate phase directly from the water column by primarily precipitated calcite, which is referred to as the Type II Mn carbonate, has also contributed to the DTP Mn-rich deposits. Multiple roles of organic matter in Mn carbonate formation have been established: (1) catalysed Mn-redox cycling; (2) trapping and transportation of initial mineral precipitates to sediments; (3) serving as a carbon source; (4) regulating the morphology of the Mn carbonate. As a key link for understanding Cryogenian carbon and Mn cycling, specific formation pathways for the DTP Mn-carbonates are likely to have been controlled by given atmospheric-oceanic compositions (including oxygen level, pCO2, and redox conditions) in response to major geological and biological events during the interglacial period. In turn, massive storage of inorganic carbon and phosphorous in Mn carbonate phases would have had a substantial influence on biogeochemical carbon cycling during the Cryogenian.

Growth and temperature-tuned band gap characteristics of LiGd(MoO4)2 single crystals for optoelectronic applications

LiGd(MoO4)2 has been investigated due to its optoelectronic applications, especially for development of light-emitting diodes. In the present paper, LiGd(MoO4)2 single crystals grown by Czochralski method was studied in terms of structural and temperature dependent optical properties. X-ray diffraction analysis showed that the crystal crystallizes in a single phase tetragonal structure. Raman spectrum exhibited six distinguishable peaks around 207, 319, 397, 706, 756 and 890 cm−1. These peaks correspond to vibrational modes of free rotation, symmetrical stretching, symmetric bending, antisymmetric stretching and antisymmetric bending of (MoO4)2− tetrahedron. Infrared transmittance spectrum had eight minima around 2114, 2350, 2451, 2854, 2929, 2960, 3545 and 3578 cm−1 which are due to multiphonon absorptions. Spectral change of transmittance curves at various temperature between 10 and 300 K was utilized to elucidate temperature effect on absorption characteristics. Optical band gap of the material was found using Tauc and spectral derivative methods. The band gap value was obtained as 3.09 eV at room temperature and this value increased to 3.22 eV with decreasing temperature down to 10 K. The detailed analysis on the temperature dependency of the band gap was applied by Varshni model. The band gap at 0 K and change of rate of the band gap were estimated as 3.23 eV and −1.45 × 10−3 eV/K, respectively. Room temperature photoluminescence spectrum of the crystal presented a peak around 709 nm which corresponds to red light emission. LiGd(MoO4)2 is a potential candidate for optoelectronic devices emitting red light.

Lower skeletal extension in Pleistocene Orbicella (Montastraea) corals than in their modern counterparts

IntroductionDespite warmer conditions during the Last Interglacial, coral colonies of Orbicella were abundant and reached large sizes on many Caribbean reefs, including the extinct O. nancyi.MethodsTo explore variation in growth rates, we examined the yearly mean linear extension of growth bands in two fossil Orbicella species and compared them with two modern species of the same genus from shallow waters of the wider Caribbean.We measured the linear extension of corals exposed in a fossil reef and their modern counterparts, from both in situ colonies and coral slab X-rays.ResultsFew coral colonies showed autocorrelation or a linear trend on their linear-growth time series. A Bayesian ANOVA showed lower linear-extension rates of fossils compared to modern colonies and similar or lower than other fossil corals from the Pleistocene. Growth rates and growth form contribute significantly to the amount of tissue and size of coral colonies and can be a decisive trait for inter and intra specific competition.DiscussionIt is unlikely that temperature or interspecific competition explain modern coral extension rates and the low rates of the fossils data, which seem to be controlled instead by past habitat conditions.

Re-estimation of juvenile's Isurus oxyrinchus growth in the Mexican Pacific through a multi-model inference approach and verification of growth band periodicity.

An update of the age and growth for juveniles of shortfin mako shark (Isurus oxyrinchus) from the Mexican Pacific is presented, based on the analysis of growth band counts from dorsal vertebrae of 198 individuals (110 females 74-231 cm of total length, TL, and 88 males 72-231 cm TL) caught during 2008-2018. New available information on vertebral growth band periodicity (biannual deposition in juveniles) and the convenience of using vertebrae form the dorsal region over cervical region to count growth bands, as well as a multi-model approach, were used. The von Bertalanffy growth model (VB), Gompertz, logistic and the two parameters of VB were fitted to the length-at-age. Only the ages ≤ 6 years were used for the fitting of the models and their performance was compared with the small-sample bias-corrected form of Akaike information criterion (AICc), their differences and weights . Following a multi-model inference approach, the model averaged asymptotic length , length-at-age 0 and their unconditional standard error , were estimated for each sex scenario using the 3-parameters version of each model.The precision of growth band counts was acceptable for the different methods used and by two different readers. The Centrum edge analysis (CEA) and marginal increment analysis (MIA) did not support the hypothesis of biannual band pair formation for juveniles, likewise for adults the periodicity could not be verified due to the low sample of large animals. Still, age was estimated assuming the formation of two pairs of growth bands per year during the first five years of age and one pair of bands per year afterwards considering direct validation information. The estimated ages ranged from 0-14 for females and 0-6 for males. The Kimura's likelihood ratio test showed no differences in the growth curves of juveniles by sex (P>0.05). According to the AICc, the 2-VB better fitted the length-at-age data for sex combined (Linf = 386.4 cm, k = 0.12 yr-1 , L0 = 70 cm). The model averaged and were 378.3 cm ( = 64.5) and 69.5 cm = 6.3) respectively. The growth parameters determined for juveniles of I. oxyrinchus are similar with those estimated in other regions, showing relatively fast growth rate as previously reported, medium longevity in comparison to other shark species and natural mortality close to those reported in the last stock assessment for the North Pacific Ocean. These life-history parameters should be considered to evaluate the population in the region to develop better fishery management and conservation measures.

Age and Growth Estimation of Bigeye Tuna, Thunnus obesus (Lowe, 1839) in the Eastern Indian Ocean Deduced from Otolith Microstructure

Age-based stock assessment of globally important species, like bigeye tuna Thunnus obesus (Lowe, 1839), is urgently required to develop appropriate management plans for fisheries sustainability. This study aimed to estimate age and growth parameters using annual increments count of sectioned-otoliths, which effectively employed for age determination of tunas. Samples were collected from Indonesian tuna longline catch landed in the Port of Benoa from March until December 2017. Multi-models were employed to obtain robust growth parameters, and Akaike Information Criterion (AIC) was relied for the best fit model selection among those evaluated. Growth band formation was validated using marginal analysis (MI), indicating that one ring is deposited yearly and slow growth peaked during July (Australian winter). The von Bertalanffy growth model was selected as the best model fitting growth parameters from raw age data, as expressed as Lt = 183.49 (1-e-0.134(t+2.991)). Large variances in growth were detected at the same age, with the oldest age of 15. Over 50% of fish in the Indonesian catch were &lt;5 years old, that may have implications for fisheries sustainability.

Crystal growth, characterization and electronic band structure of TiSeS

Layered semimetallic van der Waals material $\mathrm{Ti}{\mathrm{Se}}_{2}$ has attracted a lot of attention because of interplay of a charge density wave (CDW) state and superconductivity. Its sister compound ${\mathrm{TiS}}_{2}$, being isovalent to $\mathrm{Ti}{\mathrm{Se}}_{2}$ and having the same crystal structure, shows a semiconducting behavior. The natural question rises---what happens at the transition point in $\mathrm{Ti}{\mathrm{Se}}_{2\ensuremath{-}x}{\mathrm{S}}_{x}$, which is expected for x close to one. Here we report the growth and characterization of TiSeS single crystals and the study of the electronic structure using density functional theory (DFT) and angle-resolved photoemission (ARPES). We show that TiSeS single crystals have the same morphology as $\mathrm{Ti}{\mathrm{Se}}_{2}$. Transport measurements reveal a metallic state; no evidence of CDW was found. DFT calculations suggest that the electronic band structure in TiSeS is similar to that of $\mathrm{Ti}{\mathrm{Se}}_{2}$, but the electron and hole pockets in TiSeS are much smaller. The ARPES results are in good agreement with the calculations.

Using High-Resolution X-Ray Computed Tomography to Test the Preparation of Stalagmites for Paleo-Climate Reconstruction

Stalagmites being prepared for paleoclimate analysis should typically be slabbed along the central growth axis. This is an important first step because it allows for the highest resolution of sampling with minimal over- or under-sampling of the growth layers. Further, stable isotope ratios and trace element concentrations along the central growth axis most closely record climate variability. Choosing how to slab to best expose the central growth axis for geochemical sampling is challenging based on external morphology alone. High-resolution X-ray computed tomography (XRCT) can provide the ability to discern the internal growth morphology of stalagmites non-destructively, inexpensively, and rapidly. These data can inform selection of optimal slabbing plane(s) and can help identify locations for preliminary U-series dating. We develop a conceptual screening model to assess rapidly the internal morphologies of uncut stalagmites. The specifics of screening the internal morphologies through XRCT scans include investigating the internal porosity of the sample, the number and size of voids and hiatuses, and the presence and absence of growth layers and growth axes. We demonstrate that XRCT scans capture the migration of center of growth in uncut stalagmites of both simple and complex internal morphologies. XRCT scanning facilitates the investigation of stalagmites with complex internal growth banding, opening up avenues to work on such samples when stalagmites with simpler internal morphologies are not available. Further, screening stalagmites for paleoclimate reconstructions using XRCT improves the sustainability of speleothem science by helping researchers select which stalagmites should be returned to caves without destructive slabbing, thereby minimizing impact on caves.

Post-deposition hydrothermal alteration and U-Pb isotopic resetting of wolframite in the Tiantangshan deposit, Nanling Range (South China): Implications for complex isotopic ages of ore deposits

Tiantangshan deposit in the southeastern Nanling Range is a newly discovered Rb-Sn-W polymetallic deposit. In this paper, we present in-situ U-Pb isotope and major and trace element analyses of wolframite from the Tiantangshan deposit to examine the possible post-deposition hydrothermal alteration and U-Pb isotopic resetting of wolframite, with additional insight into possible genesis of variably young mineralization ages in the Nanling Range. Wolframite in the W ore body (wolframite-cassiterite quartz veins) of the Tiantangshan deposit comprises two stages, i.e., Wolf I and Wolf II. The primary Wolf I occurs as euhedral crystals with oscillatory growth bands, and is rich in Fe relative to Mn, with Mn/(Mn + Fe) ratios varying from 0.15 to 0.26. The Wolf I yielded U-Pb age of 133.7 ± 1.8 Ma (2σ; MSWD = 0.6). The Wolf II crosscuts and occurs as rims of the Wolf I with irregular boundaries, which has higher Mn and lower Fe contents than the Wolf I, with Mn/(Mn + Fe) ratios varying from 0.43 to 0.88. It shows similar REE pattern and concentrations of multiple elements (e.g., Sc, Ti, V, Zr, Hf and In) with the Wolf I, and also correlates with the Wolf I for elemental ratios of Nb vs. Ta, Zr vs. Hf, Nb + Ta vs. WO3 and Sn vs. WO3. These features suggest that the Wolf II was formed by replacing the Wolf I. The Wolf II yielded U-Pb age of 95.4 ± 1.3 Ma (2σ; MSWD = 0.8). Collectively, the U-Pb age of Wolf I (∼134 Ma) represents the W mineralization age in the Tiantangshan deposit, whereas, the age of the Wolf II (∼95 Ma) does not represent a second stage of W mineralization, but isotopic resetting during post-deposition hydrothermal alteration of the Wolf I. The fluids accounting for the Wolf II was likely sourced from granites of the Late Cretaceous episode (∼96 Ma) outcropping in adjacent areas. Our results indicate that wolframite and its U-Pb isotope system is susceptible to post-deposition hydrothermal alteration. This study also implies that later magmatism and hydrothermal fluids may result in isotopic resetting and the variably young ages in the Nanling Range. Therefore, interpretation of ages obtained from a hydrothermal ore deposit should be based on detailed macroscopic to microscopic observation and multiple isotopic ages of different minerals, and particularly, abnormal young ages need to be treated with caution.

Vertebral Chemistry Distinguishes Nursery Habitats of Juvenile Shortfin Mako in the Eastern North Pacific Ocean

AbstractShortfin Mako Isurus oxyrinchus are ecologically and economically important apex predators throughout the global oceans. The eastern North Pacific Ocean contains several coastal nurseries for this species, where juveniles can forage and grow until venturing into offshore pelagic habitats, where seasonal migration and reproduction occurs. Opportunistically sampled vertebrae from both male and female juvenile Shortfin Mako (65.5–134.4 cm total length, neonate to age 2) were sourced from two distinct nurseries in the eastern North Pacific: the Southern California Bight (n = 12), USA, and Bahía Sebastián Vizcaíno (n = 11), Mexico. Mineralized vertebral cartilage was analyzed to determine concentrations of selected elements (Li, Mg, Mn, Zn, Sr, Ba, standardized to Ca) using laser ablation inductively coupled plasma mass spectrometry, targeting growth bands at specific life stages, including postparturition at the birth band and the recent life history of the individual at the vertebral edge. The elemental variation exhibited by these individuals over ~1 month of life before capture was explored by comparing recent vertebral concentrations, with Zn:Ca, Sr:Ca, and Ba:Ca concentrations significantly different between nurseries (Southern California Bight versus Bahía Sebastián Vizcaíno). Element variability through ontogeny was detected, as Li:Ca, Mg:Ca, and Zn:Ca concentrations were significantly different between individual past and recent vertebral bands. These findings suggest that vertebral chemistry approaches may enhance understanding of nursery habitat sources of migratory sharks.

Age and growth assessment of the near-threatened fish Rita rita (Siluriformes: Bagridae) in the Ganges basin

Introduction: Rita rita is a freshwater catfish under threat of extinction, mainly from loss of breeding and nursing grounds. A reliable method for age and growth estimation is needed by fishery managers. Objective: To identify the best body structure for age and growth estimation. Methods: We assessed estimates precision based on Average Percent Error (APE), Coefficient Variation (CV), and Percent Agreement (PA) between readers separately analyzed each calcified structure. We used 390 fish samples from three rivers, Ganga, Yamuna and Ramganga, from September 2018 to August 2019. Results: The three indicators favored the use of vertebrae for age estimation; the growth band seems to be annual and formed from May to September. The growth equations were Lt = 90.19(1-e-0.145(t+0.51)) for Ganga; Lt = 91.19 (1-e-0.14(t+0.59)) for Yamuna and Lt = 89.63 (1-e-0.15(t+0.68)) for Ramganga. Conclusion: This species reaches moderate growth in these rivers, where vertebrae are the recommended age estimation structure, followed, in case of need, by sectioned otoliths, whole otoliths and opercular bones. Pectoral spines should be avoided, especially in older fish.

Antarctic Bioconstructional Bryozoans from Terra Nova Bay (Ross Sea): Morphology, Skeletal Structures and Biomineralization

Among Antarctic bryozoans, some species are able to develop calcitic bioconstructions promoting habitat complexity, but the processes leading to biomineral formation are mostly unknown. The present work investigated three Antarctic bryozoans, from morphological to skeletal features, including the organic matrix associated with the skeleton (SOM). Cellarinella nutti Rogick, 1956 and Reteporella frigida Waters, 1904 were collected in November 2018 from a shallow site (25 m) and Cellarinella njegovanae Rogick, 1956 from a deep site (110 m) at Terra Nova Bay (Ross Sea, Antarctica). Both Cellarinella species showed 5–6 “growth check lines” (gcl) on their laminae. The morphometrical characterization conducted on the growth bands (gb) and zooids, within the band across bands, revealed a variability in length with time (C. nutti: from 4099 µm for gb1 to 1449 µm for gb6; C. njegovanae: from 1974 µm for gb 3 to 7127 µm for gb2). Zooid length varied within gb, from the proximal to the distal part of the bands, but differences also occurred across bands. The shortest zooids (~625 µm) were found at the proximal part and the longest (~ 1190 µm) in the middle part of the gb in C. nutti, whereas in C. njegovanae the shortest zooids (~ 660 µm) were found in the distal part and the longest (~1190 µm) in the proximal part of the gb. Micro-CT analyses indicated the ratio of basal zooidal walls (RbwT gcl/gb) ranged from 3.0 to 4.9 in C. nutti and from 2.3 to 5.9 in C. njegovanae, whereas Reteporella frigida did not form any gcl on either side of the colony. Preliminary characterizations of the SOM for the three species evidenced a mixture of proteins and polysaccharides with properties similar to those of better-known biominerals, in terms of quantity and electrophoretic behavior. In addition, a “lectin fingerprint” has been established for the first time in bryozoans, displaying the presence of chitin or chitin-related saccharides. Understanding the complexity of the processes regulating skeleton formation is a key aspect in comprehending the adaptation of bioconstructional ecosystems and the survival of the associated biodiversity under the future ocean.

Inferring habitat use of the Pacific White Shark using vertebral chemistry

The conservation and management of highly migratory sharks relies on understanding age-related movements and nursery habitat utilization. We reconstructed the habitat use and migratory history of young White Sharks (Carcharodon carcharias), a highly protected species, by utilizing natural chemical tracers (element:Ca ratios and stable isotope analysis, SIA) in vertebral cartilage growth bands. Two nursery areas in the northeastern Pacific are known, but migration patterns of immature White Sharks within the Gulf of California (GC) and natal philopatry are poorly understood. Vertebrae from coastal Mexican artisanal fisheries off central Baja California in the Pacific (12 neonates and juveniles; 139-280 cm total length) and the GC (3 subadults; 289-355 cm TL) were analyzed to characterize (1) trophic histories from collagen δ13C and δ15N values, and (2) in utero patterns and post-birth environmental histories from element:Ca time-series. Mean δ15N values from vertebral edges of GC sharks, representing the most recent feeding, was +5‰ higher than in the Pacific, reflecting the intense denitrification that permeates the regional food web and supporting SIA as tracers of migration between regions. A subadult from the GC likely resided within the system throughout its life, and two subadults migrated into the GC. Most neonate and juvenile sharks caught in the Pacific had SIA that did not overlap with those of the GC, but a single subadult likely migrated to the GC. Element:Ca ratios displayed ontogenetic trends, with Li:Ca, Zn:Ca, and Ba:Ca significantly higher before the birth mark in sharks captured in the GC. Edge values were significantly higher in Zn:Ca and Ba:Ca in the GC compared to the Pacific, suggesting elemental ratios may serve as tracers of migration between regions. Subadult sharks collected from GC displayed elevated maternal Zn:Ca and Ba:Ca, suggesting mothers may have resided in the GC for an extensive period pre-birth. Some White Sharks may reside within the GC from birth until at least the subadult stage (ca. 3 m TL), and there may be an unidentified nursery. Chemical tracers, coupled with genomic and tagging studies, should improve understanding of the importance of the GC to White Shark populations in the northeast Pacific.

Growth mechanism study and band structure modulation of a manganese doped two-dimensional BlueP-Au network.

Two-dimensional (2D) materials are a very promising material family. The two-dimensional inorganic metal network called BlueP-Au network is rapidly attracting the attention of researchers due to its customizable architecture, adjustable chemical functions and electronic properties. Herein, manganese (Mn) was successfully doped on a BlueP-Au network for the first time, then the doping mechanism and electronic structure evolution was studied by in situ X-ray photoelectron spectroscopy (XPS) based on synchrotron radiation, X-ray absorption spectroscopy (XAS), Scanning Tunneling Microscopy (STM), Density functional theory (DFT), Low-energy electron diffraction (LEED), Angle resolved photoemission spectroscopy (ARPES), etc. Mn atoms tend to be stably adsorbed on two sites of the BlueP-Au network. It was the first observation that atoms can absorb on the two sites stably simultaneously. It is different from the previous adsorption models of BlueP-Au networks. The band structure was also successfully modulated, and overall down about 0.25 eV relative to the Fermi edge. It provided a new strategy for customizing the functional structure of the BlueP-Au network, which has provided new insights into monatomic catalysis, energy storage and nano electronic devices.