Movimento incipiente e orientação de conchas de moluscos bivalves sob ação de correntes

Três espécies de conchas dos moluscos bivalves Anomalocardia brasiliana, Codakia orbicularis e Divaricella quadrisulcata foram experimentalmente avaliados em canais de laboratório com o intuito de determinar as condições de início de movimento e a orientação final das conchas após cessado o transporte. Um total de 150 experimentos foram realizados, nos quais conchas isoladas, dispostas em um leito fixo de textura arenosa, foram submetidas a ação de correntes. Este estudo relata que conchas posicionadas com a convexidade para cima são resistem mais a ação do escoamento quando o umbo está apontando para jusante. Nessa posição inicial, a variação de tamanho das conchas possui relação direta com a energia do escoamento necessária para pô-las em movimento. Já conchas mobilizadas com a convexidade para cima e com o umbo apontando para a montante, além de serem mais facilmente mobilizadas, são menos sensíveis a variação de tamanho. Em relação à forma da concha, esta pesquisa mostra que as espécies com maior área frontal tendem a serem mais facilmente mobilizadas. Os resultados de tensão de cisalhamento crítica obtidos nessa pesquisa foram normalizados em termos do parâmetro adimensional de Shields, e exibem valores muito abaixo da curva de previsão de início de movimento para grãos esféricos de Shields e possuem uma boa correlação com dados da literatura adquiridos sob condições semelhantes de escoamento e leito. Com relação à orientação das conchas, foi visto que as conchas que possuem valvas de geometria circular, quando transportadas com a convexidade para cima tendem a se orientar com o umbo apontando para jusante. Já as conchas de formato elíptico tendem a serem orientadas com o eixo de maior comprimento paralelo à ação do escoamento, possuindo um comportamento em que o umbo das valvas espelhadas (valvas direita e esquerda) apontam para margens opostas do escoamento. Esse comportamento também foi testado e confirmado em outro cenário experimental, no qual submeteu-se um leito inteiramente composto por valvas da espécie Anomalocardia brasiliana sob a ação de correntes. A maior parte das medições de orientação das valvas neste cenário (Média = 69%, desvio padrão = 12%) mostram que o umbo da valva direita tende a apontar para a margem direita do escoamento, já as valvas esquerdas apontam o umbo para o lado esquerdo do escoamento.Three bivalve mollusc shell species Anomalocardia brasiliana, Codakia orbicularis, and Divaricella quadrisulcata were experimentally tested in laboratory flumes in order to determine the threshold of motion condition and the final orientation of the shells. A total of 150 current flow experiments were conducted for single shells resting in a fixed sand bed. This study demonstrates that shells in the convex-up position are more resistant to the flow action when umbo is pointing to downstream rather than upstream. With regard to the shell shape, this research shows that species which have higher frontal areas tend to be entrained at lower flow magnitudes. The critical shear stress results were normalized in terms of the nondimensional Shields parameter, exhibiting values far below the Shields curve in good agreement with previous data in the literature under similar flow and bed conditions. Concerning the shell orientation, it was seen that circular shells in a convex-up position have a tendency to be orientated with the umbo pointing downstream. Elliptical-shaped shells transported in the convex-up position tend to be oriented with the long axis parallel to the flow direction, thus, presenting a bimodal pattern in which the umbo of the right valve is positioned opposite to that of the left valve. This behavior was also tested and confirmed in another scenario, in which current flow experiments were performed over a shell bed formed by Elliptical-shaped shells. Most of the valve orientation measurements (average = 69%, standard deviation = 12%) show that the right valve umbo tend to point to the right flow margin and the left valves point that to the left flume side. These results have direct application in the shells’ incipient motion predictions and in palaeocurrent field analysis

Threshold of motion and orientation of bivalve shells under current flow

Disarticulated shells of three bivalve mollusk species (Anomalocardia brasiliana, Codakia orbicularis, and Divaricella quadrisulcata) were experimentally tested in laboratory flumes to determine the threshold of motion and final orientation of the valves. A total of 150 current flow experiments were conducted on single shells resting on a fixed sand bed. This study demonstrated that shells in the convex-up position are more resistant to flow when the umbo is pointing downstream rather than upstream. Moreover, species with higher frontal areas were more likely to be entrained at lower flow velocities. Results of dimensionless shear stress exhibited values far below the threshold of grains movement for beds of uniform roughness (Shields curve). It was observed that circular shells in convex-up positions were mostly orientated with the umbo pointing downstream. Conversely, elliptical shells in convex-up position tended to align their longer axis parallel to the flow with the posterior side of the valve pointing downstream. These results are not only directly applicable in interpretations of incipient shell motions and in paleocurrent analyses from field and sample data, but also support construction of accurate geological models

Mobilização e transporte de conchas bivalves sob a ação de correntes

No registro geológico, depósitos bioclásticos constituídos por conchas de diversas espécies ocorrem, por vezes, através do transporte posterior à morte desses organismos. Em muitos casos é atribuído à ação de correntes como o mecanismo trativo que carreou este sedimento. Com intuito de aprimorar o estado da arte de como conchas bivalves se comportam frente à ação de correntes, foram executados experimentos físicos em canais de laboratório que objetivaram determinar como as conchas orientam-se quando transportadas por este fenômeno e, também, relacionar a magnitude do escoamento necessária para carrear conchas de diferentes formas e tamanhos. Foi executada uma série de experimentos, na qual diferentes indivíduos representantes das espécies bivalves Anomalocardia brasiliana, Codakia, Diplodonta punctata e Divaricella quadrisulcata foram submetidos à ação do escoamento. E uma segunda série de experimentos, onde um leito de conchas, composto, apenas, pela espécie Anomalocardia brasiliana, foi submetido à ação de igual fenômeno. Este estudo demonstrou que as conchas, quando posicionadas com a convexidade para cima e com o umbo voltado contra o sentido da corrente, são mobilizadas a menores magnitudes do que quando o umbo está direcionado a favor do escoamento. Constatou-se, também, que espécies assimétricas, com um eixo mais alongado, quando transportadas por correntes, frequentemente, apontam o umbo da valva direita para a margem direita do escoamento e o umbo da valva esquerda para a margem esquerda (observador olhando para jusante). Os resultados deste estudo buscaram colaborar com o entendimento necessário para se estimar e determinar magnitudes e sentido cinemático de paleocorrentes em ambientes deposicionais com presenças de conchas bivalves.On geologic record, bioclastic deposits made up by shells of several species occur by postmortem transportation of this organisms. In so many cases a transport mechanism appointed to be responsible for this deposits are water currents. In order to enhance the state of the art of how bivalve shells behave when they undergo the action of currents, physical experiments were performed in laboratory flumes that aimed to determine how the shells are guided when transported by this phenomenon and also to relate the magnitude of the flow required to entrainment shells of different shapes and sizes. A series of experiments was carried out in which different individuals representing the bivalve species Anomalocardia brasiliana, Codakia, Diplodonta punctata and Divaricella quadrisulcata underwent the flow action. And a second series of experiments, in which a bed of shells, composed only by the species Anomalocardia brasiliana, was tested to the same phenomenon. This study demonstrated that the shells, when are in a convex-up position and umbo facing to upstream, are entrainment at lower magnitudes than with umbo pointing to downstream. It was also observed that asymmetric species, with a more elongated axis, when moved by currents, frequently point the right valve umbo to the right margin of the flow and the left valve umbo to the left margin (observer looking to downstream). The results of this study collaborated with the necessary understanding to estimate and determine magnitudes and kinematic direction of paleocurrent in depositional environments with bivalve shells presence

Mobilização e transporte de conchas bivalves sob a ação de correntes

No registro geológico, depósitos bioclásticos constituídos por conchas de diversas espécies ocorrem, por vezes, através do transporte posterior à morte desses organismos. Em muitos casos é atribuído à ação de correntes como o mecanismo trativo que carreou este sedimento. Com intuito de aprimorar o estado da arte de como conchas bivalves se comportam frente à ação de correntes, foram executados experimentos físicos em canais de laboratório que objetivaram determinar como as conchas orientam-se quando transportadas por este fenômeno e, também, relacionar a magnitude do escoamento necessária para carrear conchas de diferentes formas e tamanhos. Foi executada uma série de experimentos, na qual diferentes indivíduos representantes das espécies bivalves Anomalocardia brasiliana, Codakia, Diplodonta punctata e Divaricella quadrisulcata foram submetidos à ação do escoamento. E uma segunda série de experimentos, onde um leito de conchas, composto, apenas, pela espécie Anomalocardia brasiliana, foi submetido à ação de igual fenômeno. Este estudo demonstrou que as conchas, quando posicionadas com a convexidade para cima e com o umbo voltado contra o sentido da corrente, são mobilizadas a menores magnitudes do que quando o umbo está direcionado a favor do escoamento. Constatou-se, também, que espécies assimétricas, com um eixo mais alongado, quando transportadas por correntes, frequentemente, apontam o umbo da valva direita para a margem direita do escoamento e o umbo da valva esquerda para a margem esquerda (observador olhando para jusante). Os resultados deste estudo buscaram colaborar com o entendimento necessário para se estimar e determinar magnitudes e sentido cinemático de paleocorrentes em ambientes deposicionais com presenças de conchas bivalves.On geologic record, bioclastic deposits made up by shells of several species occur by postmortem transportation of this organisms. In so many cases a transport mechanism appointed to be responsible for this deposits are water currents. In order to enhance the state of the art of how bivalve shells behave when they undergo the action of currents, physical experiments were performed in laboratory flumes that aimed to determine how the shells are guided when transported by this phenomenon and also to relate the magnitude of the flow required to entrainment shells of different shapes and sizes. A series of experiments was carried out in which different individuals representing the bivalve species Anomalocardia brasiliana, Codakia, Diplodonta punctata and Divaricella quadrisulcata underwent the flow action. And a second series of experiments, in which a bed of shells, composed only by the species Anomalocardia brasiliana, was tested to the same phenomenon. This study demonstrated that the shells, when are in a convex-up position and umbo facing to upstream, are entrainment at lower magnitudes than with umbo pointing to downstream. It was also observed that asymmetric species, with a more elongated axis, when moved by currents, frequently point the right valve umbo to the right margin of the flow and the left valve umbo to the left margin (observer looking to downstream). The results of this study collaborated with the necessary understanding to estimate and determine magnitudes and kinematic direction of paleocurrent in depositional environments with bivalve shells presence

Ambulatory and hospitalized patients with suspected and confirmed mpox: an observational cohort study from BrazilResearch in context

Summary: Background: By October 30, 2022, 76,871 cases of mpox were reported worldwide, with 20,614 cases in Latin America. This study reports characteristics of a case series of suspected and confirmed mpox cases at a referral infectious diseases center in Rio de Janeiro, Brazil. Methods: This was a single-center, prospective, observational cohort study that enrolled all patients with suspected mpox between June 12 and August 19, 2022. Mpox was confirmed by a PCR test. We compared characteristics of confirmed and non-confirmed cases, and among confirmed cases according to HIV status using distribution tests. Kernel estimation was used for exploratory spatial analysis. Findings: Of 342 individuals with suspected mpox, 208 (60.8%) were confirmed cases. Compared to non-confirmed cases, confirmed cases were more frequent among individuals aged 30–39 years, cisgender men (96.2% vs. 66.4%; p < 0.0001), reporting recent sexual intercourse (95.0% vs. 69.4%; p < 0.0001) and using PrEP (31.6% vs. 10.1%; p < 0.0001). HIV (53.2% vs. 20.2%; p < 0.0001), HCV (9.8% vs. 1.1%; p = 0.0046), syphilis (21.2% vs. 16.3%; p = 0.43) and other STIs (33.0% vs. 21.6%; p = 0.042) were more frequent among confirmed mpox cases. Confirmed cases presented more genital (77.3% vs. 39.8%; p < 0.0001) and anal lesions (33.1% vs. 11.5%; p < 0.0001), proctitis (37.1% vs. 13.3%; p < 0.0001) and systemic signs and symptoms (83.2% vs. 64.5%; p = 0.0003) than non-confirmed cases. Compared to confirmed mpox HIV-negative, HIV-positive individuals were older, had more HCV coinfection (15.2% vs. 3.7%; p = 0.011), anal lesions (45.7% vs. 20.5%; p < 0.001) and clinical features of proctitis (45.2% vs. 29.3%; p = 0.058). Interpretation: Mpox transmission in Rio de Janeiro, Brazil, rapidly evolved into a local epidemic, with sexual contact playing a crucial role in its dynamics and high rates of coinfections with other STI. Preventive measures must address stigma and social vulnerabilities. Funding: Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz (INI-Fiocruz)

NEOTROPICAL ALIEN MAMMALS: a data set of occurrence and abundance of alien mammals in the Neotropics

Biological invasion is one of the main threats to native biodiversity. For a species to become invasive, it must be voluntarily or involuntarily introduced by humans into a nonnative habitat. Mammals were among first taxa to be introduced worldwide for game, meat, and labor, yet the number of species introduced in the Neotropics remains unknown. In this data set, we make available occurrence and abundance data on mammal species that (1) transposed a geographical barrier and (2) were voluntarily or involuntarily introduced by humans into the Neotropics. Our data set is composed of 73,738 historical and current georeferenced records on alien mammal species of which around 96% correspond to occurrence data on 77 species belonging to eight orders and 26 families. Data cover 26 continental countries in the Neotropics, ranging from Mexico and its frontier regions (southern Florida and coastal-central Florida in the southeast United States) to Argentina, Paraguay, Chile, and Uruguay, and the 13 countries of Caribbean islands. Our data set also includes neotropical species (e.g., Callithrix sp., Myocastor coypus, Nasua nasua) considered alien in particular areas of Neotropics. The most numerous species in terms of records are from Bos sp. (n = 37,782), Sus scrofa (n = 6,730), and Canis familiaris (n = 10,084); 17 species were represented by only one record (e.g., Syncerus caffer, Cervus timorensis, Cervus unicolor, Canis latrans). Primates have the highest number of species in the data set (n = 20 species), partly because of uncertainties regarding taxonomic identification of the genera Callithrix, which includes the species Callithrix aurita, Callithrix flaviceps, Callithrix geoffroyi, Callithrix jacchus, Callithrix kuhlii, Callithrix penicillata, and their hybrids. This unique data set will be a valuable source of information on invasion risk assessments, biodiversity redistribution and conservation-related research. There are no copyright restrictions. Please cite this data paper when using the data in publications. We also request that researchers and teachers inform us on how they are using the data

NEOTROPICAL CARNIVORES: a data set on carnivore distribution in the Neotropics

Mammalian carnivores are considered a key group in maintaining ecological health and can indicate potential ecological integrity in landscapes where they occur. Carnivores also hold high conservation value and their habitat requirements can guide management and conservation plans. The order Carnivora has 84 species from 8 families in the Neotropical region: Canidae; Felidae; Mephitidae; Mustelidae; Otariidae; Phocidae; Procyonidae; and Ursidae. Herein, we include published and unpublished data on native terrestrial Neotropical carnivores (Canidae; Felidae; Mephitidae; Mustelidae; Procyonidae; and Ursidae). NEOTROPICAL CARNIVORES is a publicly available data set that includes 99,605 data entries from 35,511 unique georeferenced coordinates. Detection/non-detection and quantitative data were obtained from 1818 to 2018 by researchers, governmental agencies, non-governmental organizations, and private consultants. Data were collected using several methods including camera trapping, museum collections, roadkill, line transect, and opportunistic records. Literature (peer-reviewed and grey literature) from Portuguese, Spanish and English were incorporated in this compilation. Most of the data set consists of detection data entries (n = 79,343; 79.7%) but also includes non-detection data (n = 20,262; 20.3%). Of those, 43.3% also include count data (n = 43,151). The information available in NEOTROPICAL CARNIVORES will contribute to macroecological, ecological, and conservation questions in multiple spatio-temporal perspectives. As carnivores play key roles in trophic interactions, a better understanding of their distribution and habitat requirements are essential to establish conservation management plans and safeguard the future ecological health of Neotropical ecosystems. Our data paper, combined with other large-scale data sets, has great potential to clarify species distribution and related ecological processes within the Neotropics. There are no copyright restrictions and no restriction for using data from this data paper, as long as the data paper is cited as the source of the information used. We also request that users inform us of how they intend to use the data

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora

NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

Xenarthrans—anteaters, sloths, and armadillos—have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, 10 anteaters, and 6 sloths. Our data set includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the southern United States, Mexico, and Caribbean countries at the northern portion of the Neotropics, to the austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n = 5,941), and Cyclopes sp. have the fewest (n = 240). The armadillo species with the most data is Dasypus novemcinctus (n = 11,588), and the fewest data are recorded for Calyptophractus retusus (n = 33). With regard to sloth species, Bradypus variegatus has the most records (n = 962), and Bradypus pygmaeus has the fewest (n = 12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other data sets of Neotropical Series that will become available very soon (i.e., Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans data set. Please cite this data paper when using its data in publications. We also request that researchers and teachers inform us of how they are using these data