Anais da Academia Brasileira de Ciencias最新文献

Melastomataceae comprises to 5,858 plant species across 173 genera globally. Brazil hosts the highest diversity for this family, including 1,453 species, with a great number of endemics. The Brazilian Caatinga is an important domain for Seasonally Dry Tropical Forests, Shrubs and Woodlands in South America, highlighting exceptional environmental diversity and hosting endemic and rare species. While the representation of Melastomataceae in the Caatinga is limited, the colonization of xeric environments by select species has garnered attention. One of these is Pleroma caatingae, a threatened species previously thought to be endemic to the state of Bahia, and recently collected in the Ceará state. This study provides an updated morphological description and uses a predictive Species Distribution Model (SDM) to predict potential species' distribution and conservation status. The findings not only enhance knowledge of neotropical species distribution patterns, but also highlight the importance of preserving overlooked arid habitats, such as the inselbergs, which harbor intriguing biodiversity as well.

Sampling (or sample) bias is a widespread concern in scientific research, across several disciplines. The concept of sampling bias originated in statistical studies. The consequence of a biased sample is that scientists will conclude about a population different from their target. In paleontology, sampling bias is typically related to fieldwork context. Human factors, known as sullegic (e.g. collection method, historic resampling) and trephic (transport, and curatorial processes) factors can generate bias. Other factor is the ugly fossil syndrome (i.e. choosing based on completeness of the specimens, or according to the researcher interest). Thus, sampling implies information loss. Biased samples add artificial results and can be considered an additional taphonomic filter. Therefore, sampling bias and the collector role and choices are frequently linked and almost indistinguishable. Compared to the treatment of this topic in other research fields, little related discussion has been held in vertebrate paleontology, especially regarding what happens at the interface between the biosphere, lithosphere, and anthroposphere, and during the transition between the anthroposphere and the patrisphere (museums). Numerous questions still arise. As a community, we must pay attention, to minimize the loss of information, from field activities to cataloging.

Sea ice is a critical component of the cryosphere and plays a role in the heat and moisture exchange processes between the ocean and atmosphere, thus regulating the global climate. With climate change, detailed monitoring of changes occurring in sea ice is necessary. Therefore, an analysis was conducted to evaluate the potential of using the Gray Level Co-occurrence Matrix (GLCM) texture analysis combined with the backscattering coefficient (σ°) of HH polarization in Sentinel-1A Synthetic Aperture Radar (SAR) images, interferometric imaging mode, for mapping sea ice in time series. Data processing was performed using cloud computing on the Google Earth Engine platform with routines written in JavaScript. To train the Random Forest (RF) classifier, samples of regions with open water and sea ice were obtained through visual interpretation of false-color SAR images from Sentinel-1B in the extra-wide swath imaging mode. The analysis demonstrated that training samples used in the RF classifier from a specific date can be applied to images from other dates within the freezing period, achieving accuracies ≥ 90% when using 64-bit grayscale quantization in GLCM combined with σ° data. However, when using only σ° data in the RF classifier, accuracies ≥ 93% were observed.

The Hunga Tonga-Hunga/Hunga-Ha'apai eruption on January 15, 2022 sent off a plume of ash material up to the stratosphere and triggered a meteotsunami and barometric pressure pulse that rippled through the atmosphere and oceans all around the world. The nature of the volcanic event and its global impacts on the oceans, atmosphere, lithosphere and the cryosphere are a matter of debate. Here we present a first overview of the time travel of the sound atmospheric pressure wave through the Antarctic continent based on in situ measurements, which represented a unique event observed through the polar ice sheet during the instrumental meteorological era. In addition, we estimated the tsunami travel time of the Hunga-Tonga event from a first order model to infer its impact over the Antarctic Sea ice and ice shelves. One outcome from our observations and modeling is the detection of the meteotsunami in the Antarctic Peninsula and the impact of the continental relief over the atmospheric pressure wave dispersion.

The harsh Antarctic climate limits soil formation and the development of terrestrial ecosystems, with most biological activity concentrated in the short summer season in ice-free areas. There, penguins play a crucial role in nutrient transport from marine to terrestrial environments, significantly impacting soil properties through guano deposition. This study focuses on characterizing the ornithogenic soils of Half Moon Island in Maritime Antarctica, examining how lithology, vegetation, and geomorphology influence their formation and distribution. Fieldwork conducted during the 2014/2015 austral summer included excavating and sampling 21 soil profiles. Soils were analyzed for physical and chemical properties and classified. Half Moon Island's soils are predominantly Cryosols and Leptosols, characterized by little development, high gravel content (skeletic), and significant cryoturbation. High variability in soil chemical properties was observed, with principal component analysis highlighting distinct clusters based on landscape position, geology, vegetation and ornithogenic influence. The findings underscore the diverse pedoenvironments of Half Moon Island, shaped by past and present ornithogenic activity and post-glacial geomorphological processes. This research highlights the soil variability in Antarctic environments and the significant ecological importance of seabird colonies on small, isolated islands.

In this paper, we looked at the effect of mobility by students, post-doctorates and professors on science in Brazil. We analysed CAPES, CNPq, FAPESP and Incites data to examine the number of scholarships and their impact on posterior publishing. Decision trees, including the region of the country, length of stay by student and Professor, as well as institution abroad, were evaluated, along with logistic regressions. The number of incoming professionals to Brazil is still incipient. The number of undergrad students was not crucial in forming scientific ties, but the number of postgraduates (> 180 days) and professor stays (>90 days) was important. The highest impact factor of publications shows a greater probability of higher impact with more than six postgraduate students going to institutions in the global north region and professors staying for more than 90 days. Looking only at doctors and professors (Mobility after training), the country of most interest was the United States, followed by France and England, which are similar regarding professors. France had a greater emphasis on postdoctoral studies. Databases need to be improved to include factors such as gender and color/race as well as the origin of scholars from abroad.

In Brazil, the recurring environmental impacts due to insufficient inspection and inadequate management of potentially toxic mining tailings have raised significant concerns. The study concentrates on examining the mobility of elements in flotation (ft) and cyanidation (ct) tailings from gold mining operations, following successive extractions. The influence of extractants on the release of elements from both ft and ct samples, including As, Cd, Cu, Cr, Pb, Se, and Zn, was examined and compared to the ABNT NBR 10004:2004 standard. The samples were obtained from a gold mining company in Brazil. Sequential extraction tests for ft and ct samples were conducted to simulate weathering effects, using solutions of 0.1 mol L-1 citric acid, 0.1 mol L-1 acetic acid, 0.1 mol L-1 oxalic acid, 0.1 mol L-1 ammonium acetate, and distilled water at pH 5.5. The results revealed that the established limits for Pb and Cd under the ABNT NBR 10004:2004 standard were exceeded in a 1:1 tailing-to-extractor ratio. In ct samples, both elements surpassed the standard limits for all extractors, except for Cd when using water. In ft samples, Pb exceeded the limits with all acids, while Cd exceeded the limits only in the presence of acetic acid and ammonium acetate.

This study examined the taxonomic composition and ecological aspects of planktonic green algae (Chlorophyta) in four urban ponds (Parque da Lagoa, Lagoa Grande, Laguneville, and Pindoba) in Feira de Santana, Bahia State, Brazil. We analyzed 96 samples collected bimonthly in 2022 and identified 54 taxa, with the majority (42) classified as uncommon or sporadic. The most common species were Monoraphidium circinale and Lemmermannia komarekii, found in 100% and 95.8% of samples, respectively. Parque da Lagoa had the highest number of taxa (43), followed by Lagoa Grande (40), Laguneville (31), and Pindoba (30). Most taxa were found in water with high levels of oxygenation (5.8-12.3 mg L-1) and conductivity (400-1000 μS cm-1), neutral to slightly alkaline conditions (pH 7-8), and moderate water temperature (26-27 °C). Significant differences in the composition of planktonic green algae and limnological variables were observed among ponds. These studies underscore the importance of implementing actions aimed at the restoration and conservation of urban ponds in Feira de Santana to avoid biodiversity loss and eutrophication while ensuring the provision of critical ecosystem services, such as local climate regulation.

Pollen dispersal by insects determines the patterns of reproductive encounters between plants with flowers that have spatially or temporally segregated sexes. Pollinators exhibit varied responses to environmental gradients, such as those in grassland-forest ecotones. Individual-based interaction networks are useful yet underexplored tools to understand how interactions vary across these gradients. To test how a grassland-forest ecotone gradient affects these interactions, we studied pollination networks of Butia odorata individuals, a key palm tree species in a threatened South American grassland ecosystem. We assessed, through Structural Equation Models (SEMs), how network metrics (specialization and modularity) and pollinator richness and abundance (total, peripheral, core) respond to gradients of habitat and population structure in the grassland-forest ecotone. Networks with more spatially isolated palms showed greater specialization and modularity. Pollinator richness was dependent on the habitat context and pollinator role. The peripheral pollinators were negatively affected by palm density. The core pollinators were positively affected by tree cover, which, in turn, was positively associated with palm density and proximity to the forest. Our results suggest that palm population density can modulate the presence of peripheral pollinators, while increased tree cover in the grassland matrix can promote pollinator diversity by decreasing the dominance of core species.

Fish is an important food item in the diet of humans, whereas it is also a major source of exposure to toxic chemicals. Persistent organic pollutants (POPs) and mercury (Hg) are known to have hotspots of contamination across the coast of Pernambuco, Brazil. This study investigated organochlorines and Hg in muscle samples from respectively 17 and 14 individuals of the stingray Hypanus berthalutzae - a fishing resource used to prepare a traditional dish in the local cuisine. DDTs, HCHs and mirex were not detected in the samples. Mean concentrations of PCBs, CHLs and total Hg were 0.032, 0.004 and 60 ng g-1 wet weight (ww), respectively. Ecological and biological parameters are important factors in the bioaccumulation of pollutants in fish. Although the concentrations of POPs and Hg do not present a health risk to consumers in general, they may pose a health risk to certain groups such as children and people who eat H. berthalutzae daily. This paper is relevant for the conservation of an endemic stingray species widely consumed in northeastern Brazil and classified as vulnerable in terms of risk of extinction.