Brittle-ductile deformation effects on zircon crystal-chemistry and U-Pb ages: an example from the Finero Mafic Complex (Ivrea-Verbano Zone, western Alps)

A detailed structural, geochemical and geochronological survey was performed on zircon grains from a leucocratic dioritic dyke discordantly intruded within meta-diorites/gabbros forming the External Gabbro unit of the Finero Mafic Complex. This latter is nowadays exposed as part of a near complete crustal section spanning from mantle rocks to upper crustal metasediments (Val Cannobina, Ivrea-Verbano Zone, Italy). The leucocratic dyke consists mainly of plagioclase (An18-24Ab79-82Or0.3-0.7) with subordinate amounts of biotite, spinel, zircon and corundum. Both the leucocratic dyke and the surrounding meta-diorites show evidence of ductile deformation occurred under amphibolite-facies conditions. Zircon grains (up to 2 mm in length) occur mainly as euhedral grains surrounded by fine grained plagioclasedominated matrix and pressure shadows, typically filled by oxides. Fractures and cracks within zircon are common and can be associated with grain displacement or they can be filled by secondary minerals (oxides and chlorite). Cathodoluminescence (CL) images show that zircon grains have internal features typical of magmatic growth, but with local disturbances. However EBSD maps on two selected zircon grains revealed a profuse mosaic texture resulting in an internal misorientation of ca. 10o. The majority of the domains of the mosaic texture are related to parting and fractures, but some domains show no clear relation with brittle features. Rotation angles related to the mosaic texture are not crystallographically controlled. In addition, one of the analysed zircons shows clear evidence of plastic deformation at one of its corners due to indentation. Plastic deformation results in gradual misorientations of up to 12o, which are crystallographically controlled. Trace elements and U-Pb analyses were carried out by LA-ICP-MS directly on petrographic thin sections and designed to cover the entire exposed surface of selected grains. Such investigations revealed a strong correlation between internal zircon structures, chemistry, U-Pb isotope ratios and mylonitic fabric. U-Pb data return highly discordant and variable ages: in particular, the 206Pb/238U ages range from Carboniferous to Triassic within the same zircon grain. The youngest 206Pb/238U data derive from narrow axial stripes oriented parallel or at low angle with respect to the foliation planes. These stripes are characterized by an overall HREE, Y, U and Th enrichment possibly reflecting deformation of the grain in presence of interstitial fluid phases, likely related to a concomitant magmatic activity. Deformation related structures (cracks and fractures) within zircon grains acted as fast-diffusion pathways allowing fluids to modify the geochemistry and isotopic systems of zircon. Our results suggest that fluid-assisted brittle-ductile deformation can severely modify the trace elements and isotopic composition of zircon with unexpected patterns constrained by stress regime. In similar cases, our observations suggest that, for a more appropriate interpretation of the petrologic evolution and age variability, a direct characterization of the internal structures of zircons still placed in their microtextural site is highly recommended

Dinâmica larval do mexilhão dourado Limnoperna fortunei no reservatório de Aguas Corrientes, rio Santa Lucía, Uruguay

The golden mussel (Limnoperna fortunei) is an invasive exotic species that has several negative impacts in ecosystems worldwide. Santa Lucía River is the main drinking water source, supplying 60% of the total population of Uruguay. L. fortunei has been reported since 1996 in the basin, and nowadays is present in the three reservoirs that supply the water treatment plant. The aim of this study was to analyze the temporal dynamics of L. fortunei larvae in Aguas Corrientes reservoir (Santa Lucía River). We quantify diary L. fortunei larvae and phytoplankton, we also measure physicochemical parameters of water. L. fortunei larvae showed a seasonal dynamic and its development was promoted by temperatures up to 17°C. Temperature was the main variable controlling the presence of larvae. Once temperature was optimal for its reproduction, the reservoir level was the key variable to determine the presence of larvae. This shows the importance of flow managing in the reservoir in order to reduce golden mussel impacts during the reproductive season. We also propose two alternative regulation mechanisms of larvae, acting at two different scales: physiological and environmental.El mejillón dorado (Limnoperna fortunei) es una especie exótica invasora que causa grandes perjuicios a nivel mundial. El río Santa Lucía es la principal fuente de agua potable que abastece al 60% de la población de Uruguay. L. fortunei ha sido reportado desde 1996 en la cuenca y actualmente se encuentra en los tres embalses que abastecen a la usina potabilizadora. El objetivo de este trabajo fue caracterizar la dinámica temporal de las larvas de L. fortunei en el embalse de Aguas Corrientes (río Santa Lucía). Para esto se realizaron análisis diarios del embalse donde se midieron parámetros fisicoquímicos y cuantificaron larvas y la comunidad fitoplanctónica. Las larvas de L. fortunei presentaron una dinámica estacional y su desarrollo fue favorable a temperaturas mayores a los 17°C. La temperatura fue la principal variable moduladora de la presencia de larvas. Una vez que la temperatura fue adecuada para su reproducción, la cota del embalse resultó ser la variable clave para determinar la presencia de larvas. Esto evidencia la importancia del manejo del caudal del embalse durante la época reproductiva del mejillón para disminuir sus impactos. Se plantean dos mecanismos de regulación de las larvas que actúan a diferentes escalas: fisiológico y ambiental.O mexilhão dourado (Limnoperna fortunei) é uma espécie exótica invasora que causa grandes danos em todo o mundo. O rio Santa Lucía é a principal fonte de água potável que abastece 60% da população do Uruguai. L. fortunei é registrada desde 1996 na bacia e atualmente é encontrada nos três reservatórios principais que abastecem a estação de tratamento de água. O objetivo deste trabalho foi caracterizar a dinâmica temporal de larvas de L. fortunei no reservatório de Aguas Corrientes (rio Santa Lucía). Para isso, foram realizadas análises diárias do reservatório, onde foram medidos parâmetros físico-químicos e quantificadas as larvas e a comunidade fitoplanctônica. As larvas de L. fortunei apresentaram dinâmica sazonal e seu desenvolvimento foi favorável em temperaturas superiores a 17°C. A temperatura foi a principal variável moduladora da presença de larvas. Uma vez que a temperatura foi adequada para sua reprodução, a elevação do reservatório passou a ser a variável chave para determinar a presença de larvas. Isso mostra a importância do gerenciamento da vazão do reservatório para reduzir os impactos do mexilhão dourado. Ao mesmo tempo, dois mecanismos de regulação das larvas são propostos atuando em diferentes escalas: fisiológica e ambiental

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Delayed colorectal cancer care during covid-19 pandemic (decor-19). Global perspective from an international survey

Background The widespread nature of coronavirus disease 2019 (COVID-19) has been unprecedented. We sought to analyze its global impact with a survey on colorectal cancer (CRC) care during the pandemic. Methods The impact of COVID-19 on preoperative assessment, elective surgery, and postoperative management of CRC patients was explored by a 35-item survey, which was distributed worldwide to members of surgical societies with an interest in CRC care. Respondents were divided into two comparator groups: 1) ‘delay’ group: CRC care affected by the pandemic; 2) ‘no delay’ group: unaltered CRC practice. Results A total of 1,051 respondents from 84 countries completed the survey. No substantial differences in demographics were found between the ‘delay’ (745, 70.9%) and ‘no delay’ (306, 29.1%) groups. Suspension of multidisciplinary team meetings, staff members quarantined or relocated to COVID-19 units, units fully dedicated to COVID-19 care, personal protective equipment not readily available were factors significantly associated to delays in endoscopy, radiology, surgery, histopathology and prolonged chemoradiation therapy-to-surgery intervals. In the ‘delay’ group, 48.9% of respondents reported a change in the initial surgical plan and 26.3% reported a shift from elective to urgent operations. Recovery of CRC care was associated with the status of the outbreak. Practicing in COVID-free units, no change in operative slots and staff members not relocated to COVID-19 units were statistically associated with unaltered CRC care in the ‘no delay’ group, while the geographical distribution was not. Conclusions Global changes in diagnostic and therapeutic CRC practices were evident. Changes were associated with differences in health-care delivery systems, hospital’s preparedness, resources availability, and local COVID-19 prevalence rather than geographical factors. Strategic planning is required to optimize CRC care