Conservation and trade of the endangered Hypancistrus zebra (Siluriformes, Loricariidae), one of the most trafficked Brazilian fish

Abstract Hypancistrus zebra, also known as the zebra pleco, is a small sucker-mouth catfish endemic to the Xingu River in Brazil where its survival in the wild is threatened by habitat modification and overfishing for the ornamental fish industry. It is a highly sought-after freshwater ornamental species and one of the most commonly trafficked from Brazil. To date, little is known about its global legal and illicit supply chains within the ornamental fish trade. Through a mixed methods approach (i.e., online survey, key informant interviews and web scraping), we examined the trade and trafficking of this species as well as the awareness of the international aquarist community and local and international stakeholders regarding its conservation. We also establish the historical timeline of zebra pleco keeping and breeding in captivity and assess whether commercial captive breeding can play an important role in the conservation of this species. The retail price of the zebra pleco increased worldwide after an export ban in 2004 but have since decreased to an average of $US 155 (+/-$US 23 based on geographical location) per fish. Fishermen have been consistently paid relatively little ($US 7–60) for each specimen compared to the average wholesale price of$US 100 (+/- $US 94 over time). We conservatively estimate ~100,000 specimens are trafficked out of Brazil annually, of which half or more die in transport, and only a small fraction is seized by law enforcement in Brazil or internationally. The fishes are primarily smuggled from Brazil to Peru and Colombia and then exported internationally with the majority sent to China. The majority of aquarists surveyed (representing 35 countries) were aware the zebra pleco is both endangered and highly endemic. There was less awareness that buying wild caught specimens shipped from Peru, Colombia or elsewhere implies supporting wildlife trafficking. Nevertheless, nearly three quarters of respondents preferred aquarium bred specimens, if available. The zebra pleco is being bred in captivity in high numbers in several countries, yet in Brazil it remains illegal to keep in private aquaria or to commercially breed them. Given the large success of hobby and commercial breeders around the world, H. zebra is well suited for indoor breeding facilities. We argue that implementing regulated local breeding facilities in Brazil to increase the already large numbers reproduced in captivity worldwide, could decrease the demand for trafficked specimens, one of the primary factors threatening its survival. Given its iconic status among freshwater fishes it should be recognized as a flagship species of the Xingu River's conservation

Effects of Vanadium Doping on the Optical Response and Electronic Structure of WS2_{2} Monolayers

Two-dimensional dilute magnetic semiconductors has been recently reported in semiconducting transition metal dichalcogenides by the introduction of spin-polarized transition metal atoms as dopants. This is the case of vanadium-doped WS$_2$ and WSe$_2$ monolayers, which exhibits a ferromagnetic ordering even above room temperature. However, a broadband characterization of their electronic band structure and its dependence on vanadium concentration is still lacking. Therefore, here we perform power-dependent photoluminescence, resonant four-wave mixing, and differential reflectance spectroscopy to study the optical transitions close to the A exciton energy of vanadium-doped WS$_2$ monolayers with distinct concentrations. Instead of a single A exciton peak, vanadium-doped samples exhibit two photoluminescence peaks associated with transitions to occupied and unoccupied bands. Moreover, resonant Raman spectroscopy and resonant second-harmonic generation measurements revealed a blueshift in the B exciton but no energy change in the C exciton as vanadium is introduced in the monolayers. Density functional theory calculations showed that the band structure is sensitive to the Hubbard $U$ correction for vanadium and several scenarios are proposed to explain the two photoluminescence peaks around the A exciton energy region. Our work provides the first broadband optical characterization of these two-dimensional dilute magnetic semiconductors, shedding light on the novel electronic features of WS$_{2}$ monolayers which are tunable by the vanadium concentration

Redescription and geographical distribution of the endangered fish ossubtus xinguense Jégu 1992 (Characiformes, Serrasalmidae) with comments on conservation of the rheophilic fauna of the Xingu River

The monotypic species Ossubtus xinguense was originally described based on scarce material putatively divided into juveniles and adults. Ossubtus xinguense has a restricted distribution and was previously known only from a few rapids downstream of the city of Altamira, in the Volta Grande stretch of the Middle Xingu River. Until recently, the species was rare in museums because its habitat (large rapids) is difficult to sample. Large-scale collecting efforts targeting rapids throughout the Xingu River basin have yielded an abundance of new material. Based on an analysis of the type series and freshly preserved specimens, we redescribe O. xinguense and provide detailed osteological descriptions along with comments about its relationships within Serrasalmidae. Furthermore, we expand the geographical distribution of the species and discuss its conservation status. © 2016 Andrade et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Radiocarbon geochronology of the sediments of the São Paulo Bight (southern Brazilian upper margin)

The aim of this work was to generate an inventory of the data on radiocarbon datings obtained from sediments of the São Paulo Bight (southern Brazilian upper margin) and to analyze the data in terms of Late Quaternary sedimentary processes and sedimentation rates. A total of 238 radiocarbon datings from materials collected using differents ampling procedures was considered for this work. The sedimentation rates varied from less than 2 to 68 cm.kyr-1. The highest sedimentation rate values were found in a low-energy (ría type) coastal system as well as in the upwelling zones of Santa Catarina and Cabo Frio. The lowest rates were found on the outer shelf and upper slopes. Our results confirm the strong dependency of the shelf currents, with an emphasis to the terrigenous input from the Río de La Plata outflow which is transported via the Brazilian Coastal Current, as well as of the coupled Brazil Current - Intermediate Western Boundary Current (BC-IWBC) dynamics on the sedimentary processes. At least three indicators ofthe paleo sea level were found at 12200 yr BP (conventional radiocarbon age) (103 meters below sea level - mbsl),8300-8800 cal yr BP (13 mbsl) and 7700-8100 cal yr BP (6 mbsl).O objetivo deste trabalho foi a geração de um inventário dos dados de datação de radiocarbono obtidos de sedimentos do Embaiamento de São Paulo (Margem Continental Superior do Sul do Brasil) e analisar os dados em termos de processos sedimentares quaternários e taxas de sedimentação. Um total de238 datações ao radiocarbono de materiais coletados com autilização de procedimentos amostrais diferentes foi considerado neste trabalho. As taxas de sedimentação variaram de menor que 2 a 68 cm.kyr-1. As taxas de sedimentação mais altas foram encontradas em um sistema costeiro de baixa energia (tipo ría), bem como nas zonas de ressurgência de Santa Catarina e Cabo Frio. As taxas mais baixas foram encontradas na plataforma externa e talude superior. Nossos resultados confirmam a forte dependência do sistema de correntes de plataforma, com ênfase no aporte terrígeno oriundo do Rio daPrata, transportado através da Corrente Costeira do Brasil, e da dinâmica da Corrente do Brasil - Corrente de Contorno Intermediária (CB-CCI) nos processos sedimentares. Pelo menostrês indicadores de paleo-níveis marinhos foram encontrados a 12200 anos AP (idade radiocarbônica convencional) (103 metros abaixo do nível do mar atual - manm), 8300-8800 cal anos AP (13 manm) e 7700-8100 cal anos BP (6 manm).Fundação de Amparo à Pesquisado Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Cytogenetic analysis of baryancistrus xanthellus (Siluriformes: Loricariidae: Ancistrini), an ornamental fish endemic to the Xingu river, Brazil

Baryancistrus xanthellus is a species from the Ancistrini tribe known commonly as “amarelinho” or “golden nugget pleco”. It is one of the most popular and valued ornamental fishes due to its color pattern. Also, it is an endemic species from the Xingu River occurring from Volta Grande do Xingu, region where the Belo Monte Hydropower Dam is being built, to São Félix do Xingu. The current study aimed to cytogenetically characterize B. xanthellus. Results point to the maintenance of 2n=52, which is considered the most common condition for the tribe, and a single nucleolus organizer region (NOR). Mapping of the 18S rDNA confirmed the NOR sites, and the 5S rDNA was mapped in the interstitial position of a single chromosome pair. The 18S and 5S rDNA located in different pairs constitute an apomorphy in Loricariidae. Large blocks of heterochromatin are present in pairs 1 and 10 and in the regions equivalent to NOR and the 5S rDNA. Data obtained in this study corroborated with the currently accepted phylogenetic hypothesis for the Ancistrini and demonstrate evidence that the genus Baryancistrus occupies a basal position in the tribe. © 2016, Sociedade Brasileira de Ictiologia. All rights reserved

Strong magneto-optical responses of an ensemble of defect-bound excitons in aged WS2_{2} and WSe2_{2} monolayers

Transition metal dichalcogenide (TMD) monolayers present a singular coupling in their spin and valley degrees of freedom. Moreover, by applying an external magnetic field it is possible to break the energy degeneracy between their K and $-$K valleys. Thus, this analogous valley Zeeman effect opens the possibility of controlling and distinguishing the spin and valley of charge carriers in TMDs by their optical transition energies, making these materials promising for the next generation of spintronic and photonic devices. However, the free excitons of pristine TMD monolayer samples present a moderate valley Zeeman splitting, which is measured by their g-factor values that are approximately $-4$. Therefore, for application purposes it is mandatory alternative excitonic states with higher magnetic responses. Here we investigate the valley Zeeman effect in aged WS$_{2}$ and WSe$_{2}$ grown monolayers by magneto-photoluminescence measurements at cryogenic temperatures. These samples present a lower energy defect-bound exciton emission related to defects adsorbed during the aging process. While the free excitons of these samples exhibit g-factors between $-3$ and $-4$, their defect-bound excitons present giant effective g-factor values of $-(25.0 \pm 0.2)$ and $-(19.1 \pm 0.2)$ for WS$_{2}$ and WSe$_{2}$ aged monolayers, respectively. In addition, we observe a significant spin polarization of charge carriers in the defective mid gap states induced by the external magnetic fields. We explain this spin polarized population in terms of a spin-flip transition mechanism, which is also responsible for the magnetic dependent light emission of the defect-bound exciton states. Our work sheds light in the potential of aged TMDs as candidates for spintronic based devices

Salivary molecular spectroscopy : a sustainable, rapid and non-invasive monitoring tool for diabetes mellitus during insulin treatment

Monitoring of blood glucose is an invasive, painful and costly practice in diabetes. Consequently, the search for a more cost-effective (reagent-free), non-invasive and specific diabetes monitoring method is of great interest. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy has been used in diagnosis of several diseases, however, applications in the monitoring of diabetic treatment are just beginning to emerge. Here, we used ATR-FTIR spectroscopy to evaluate saliva of non-diabetic (ND), diabetic (D) and insulin-treated diabetic (D+I) rats to identify potential salivary biomarkers related to glucose monitoring. The spectrum of saliva of ND, D and D+I rats displayed several unique vibrational modes and from these, two vibrational modes were pre-validated as potential diagnostic biomarkers by ROC curve analysis with significant correlation with glycemia. Compared to the ND and D+I rats, classification of D rats was achieved with a sensitivity of 100%, and an average specificity of 93.33% and 100% using bands 1452 cm-1 and 836 cm-1, respectively. Moreover, 1452 cm-1 and 836 cm-1 spectral bands proved to be robust spectral biomarkers and highly correlated with glycemia (R2 of 0.801 and 0.788, P < 0.01, respectively). Both PCA-LDA and HCA classifications achieved an accuracy of 95.2%. Spectral salivary biomarkers discovered using univariate and multivariate analysis may provide a novel robust alternative for diabetes monitoring using a non-invasive and green technology