Brazilian Basins Research Articles

Dynamics of eddying abyssal mixing layers over sloping rough topography

Abstract ABSTRACT: The abyssal overturning circulation is thought to be primarily driven by small-scale turbulent mixing. Diagnosed watermass transformations are dominated by rough topography “hotspots”, where the bottom-enhancement of mixing causes the diffusive buoyancy flux to diverge, driving widespread downwelling in the interior—only to be overwhelmed by an even stronger up-welling in a thin Bottom Boundary Layer (BBL). These watermass transformations are significantly underestimated by one-dimensional (1D) sloping boundary layer solutions, suggesting the importance of three-dimensional physics. Here, we use a hierarchy of models to generalize this 1D boundary layer approach to three-dimensional eddying flows over realistically rough topography. When applied to the Mid-Atlantic Ridge in the Brazil Basin, the idealized simulation results are roughly consistent with available observations. Integral buoyancy budgets isolate the physical processes that contribute to realistically strong BBL upwelling. The downwards diffusion of buoyancy is primarily balanced by upwelling along the sloping canyon sidewalls and the surrounding abyssal hills. These flows are strengthened by the restratifying effects of submesoscale baroclinic eddies and by the blocking of along-ridge thermal wind within the canyon. Major topographic sills block along-thalweg flows from restratifying the canyon trough, resulting in the continual erosion of the trough’s stratification. We propose simple modifications to the 1D boundary layer model which approximate each of these three-dimensional effects. These results provide local dynamical insights into mixing-driven abyssal overturning, but a complete theory will also require the non-local coupling to the basin-scale circulation.

Geochemical Characteristics and Distribution of the Subsalt Source Rocks in the Santos Basin, Brazil.

The Santos Basin in Brazil is a hot area of oil and gas exploration in recent years, and its subsalt lacustrine mudstones are the main source rock of the basin. However, there is a lack of studies on the source rocks of the subsalt Picarras and Itapema formations, which is not conducive to the accurate evaluation of the source rock characteristics. Based on logging data of 51 wells and geochemical data of 16 wells, this paper makes detailed evaluations of the organic matter abundance, type, maturity, and distribution characteristics of source rocks of the subsalt Picarras Formation and Itapema Formation in the Santos Basin. The results show that the characteristics of source rocks of the Itapema and Picarras formations are similar, both of which have a high abundance of organic matter. The types of organic matter are mainly type I and II1, and the maturities are in the low-maturity to the high-maturity stage, which meets the standard of good source rocks. The total organic carbon content of the source rocks of the Picarras Formation ranges from 0.4 to 4.0%, much lower than that of the source rocks of the Itapema Formation, 0.8–5.6%. In addition, the hydrogen index average value of the source rocks of the Itapema Formation is 712.8 mg/g TOC, higher than that of the Picarras Formation, 697.5 mg/g TOC, both revealing a great hydrocarbon potential. The quality of source rocks of the Itapema Formation is better than that of the Picarras Formation. The two sets of source rocks have great hydrocarbon generation potential and are mainly developed in the eastern and western sags of the central depression. Therefore, the surrounding uplift areas will be the target for further oil and gas exploration.

Hydrological Retrospective and Historical Drought Analysis in a Brazilian Savanna Basin

Analyzing historical droughts is essential to improve the assessment of future hydrological risks and to understand the effects of climate variability on streamflow. However, prolonged and consistent hydrological time series are scarce in the Brazilian savanna region. This study aimed to analyze the performance of climate reanalysis products in precipitation estimation, hydrological modeling, and historical drought analysis in a Brazilian savanna basin. For this purpose, precipitation data from the twentieth-century atmospheric model ensemble (ERA-20CM) and the land component of the fifth generation of European ReAnalysis (ERA5-Land) with bias correction were used. The weather variables were obtained from the Climatic Research Unit (CRU) and the hydrological modeling was performed using the Soil and Water Assessment Tool (SWAT). The Standardized Streamflow Index (SSI) was used to calculate hydrological drought in the basin. Overall, ERA5-Land performed satisfactorily in precipitation estimation, mainly on the monthly time scale, hydrological modeling, and drought prediction. Since ERA-20CM showed unsatisfactory values for the performance statistics in all analyses, the hydrologic drought (1950 to 2018) was performed with ERA5-Land. The results showed both an increase in the number of dry months and a decrease in wet months in recent decades.

Empowering small stakeholders groups in selecting a long-term water management plan

Abstract Strategic water management on a river basin scale requires the inclusion of stakeholders from different sectors and the use of methodologies based on scientifically sound models and techniques, keeping in mind that the power of smaller and larger subgroups of stakeholders should be equal. In this paper, we present an approach to tackle this problem based on two Social Choice Theory (SCT) methods: preferential Borda Count and no-preferential Approval voting method. Two different scenarios of grouping members of the water committee of the San Francisco River Basin in Brazil are simulated, by interested sectors and by interested delegates from the states where the river passes through, five long-term management plans are evaluated and voted in either scenario. Results indicated that if members of the committee demonstrate reasonable competency and consistency while setting their judgments on management plans, the final group decision is the same or similar, regardless the method used. One of the conclusions is also that the voting of small subgroups may have the same power as the voting of a large subgroup in the social choice-based decision-making processes. SCT methods can thus be recommended as an equity framework to empower small groups in selecting long-term water management plans.

A New Species of Chaetostoma (Siluriformes: Loricariidae) Expands the Distribution of Rubbernose Plecos Eastward into the Lower Amazon Basin of Brazil

Uma nova espécie de Chaetostoma é descrita dos rios Maicuru, um afluente norte do baixo rio Amazonas, e Seiko, um afluente do baixo rio Xingu, ambos no estado do Pará, Brasil. A nova espécie é diagnosticada de todos os seus congêneres, exceto membros do grupo Chaetostoma anale, por apresentar o segundo raio não ramificado da nadadeira anal aumentado e com abas dérmicas posteriores. Além disso, a nova espécie se distingue dos únicos outros congêneres atualmente reconhecidos do Escudo das Guianas (C. jegui e C. vasquezi) por ter o opérculo menor e a protuberância supraoccipital não desenvolvida, composta por uma área de pele simples em juvenis e ausente em adultos. Uma filogenia multilocus revisada para as espécies de Chaetostoma é apresentada e o grupo Chaetostoma anale é discutido e reorganizado.

New deep-sea Atlantic and Antarctic species of Abyssorchomene De Broyer, 1984 (Amphipoda, Lysianassoidea, Uristidae) with a redescription of A. abyssorum (Stebbing, 1888)

During the Census of Marine Life Polarstern ANDEEP I-III and Meteor M79/1 DIVA-3 expeditions, autonomous baited trap systems were employed to sample the mobile, necrophagous amphipods from abyssal depths. Within DIVA-3 (July 10–August 26 2009), a free-fall baited trap was used successfully at three stations in the southwest Atlantic, once in the Argentine Basin and twice in the Brazilian Basin. A total of twenty-one stations were sampled by baited traps during the ANDEEP I-III (2002, 2005) cruises in the Southern Ocean. Trap sets recovered large numbers of scavenging lysianassoid and alicelloid amphipods, including specimens of the widespread and commonly considered cosmopolitan uristid species Abyssorchomene abyssorum (Stebbing, 1888). During examinations of these and other North Atlantic collections of A. abyssorum, two similar new species A. patriciae sp. nov. and A. shannonae sp. nov. were discovered. Important morphological characters which differentiate the two new species from their congeners are found in the shape of the head lobe, coxa 1, gnathopod 2, coxa 5, pereopod 7 basis and uropod 3 rami length. The new species are fully figured and an identification key is provided. Abyssorchomene abyssorum is redescribed and for the first time, the female is fully described and illustrated from new material. The Southern Ocean endemic A. scotianensis (Andres, 1983) is also described and illustrated from new collections to complement the original description.

Impacts of sugarcane expansion on water availability in a river basin in southeastern Brazil

The availability of land, favorable edaphoclimatic conditions, and water have consolidated the role of Brazil as a global player in the agricultural commodities market, which has driven intensive land use conversion in recent decades. In this context, the extensive use of biofuels to mitigate fossil fuel CO2 emissions has facilitated their replacement as pasture by sugarcane monoculture, particularly in São Paulo State that is responsible for more than 52% of the country’s sugarcane production. This expansion has occurred without evaluating its impact on water availability for other uses. Therefore, this study investigates the effects of the sugarcane expansion on the hydrological cycle of the Aguapeí River basin in São Paulo State, during 1985–2017. To achieve this goal, we first validated the hydrological model simulation by comparing the time trajectories within the Budyko framework for the sub-basin with the longest observation records. We then assessed the impact of the expansion of the area under sugarcane by comparing the streamflow over the study period against a baseline scenario, which assumed that no land use changes occurred after 1985 in six sub-basins of the Aguapeí River basin. The results revealed a reduction in streamflow with sugarcane expansion. Although these changes corresponded to only 2–5% of the mean streamflow of the baseline scenario, these can increase to 13–27% when the effect of sugarcane expansion is isolated. Our results suggested that the impacts of sugarcane on streamflow are gradually diluted at larger scales. We also estimated that the extra water consumption due to the sugarcane expansion in São Paulo State was 2150 hm3 yr−1 in 2017 compared to 1985.

Environmental Fragility Zoning Using GIS and AHP Modeling: Perspectives for the Conservation of Natural Ecosystems in Brazil

The degradation of natural ecosystems triggers global environmental, economic, and social problems. To prevent this, it is necessary to identify the aptitude of priority areas for conservation or use by considering land fragility from multiple environmental and spatial perspectives. We applied the concept of environmental fragility to a hydrographic basin in southeastern Brazil that establishes (i) potential fragility levels according to slope, soil classes, geological domains, drainage hierarchy, and rainfall information using an algebraic map, and (ii) emerging fragility levels via the addition of the land-use parameters. The methodological approach involved the integration of the analytic hierarchy process (AHP) and weighted linear combination (WLC) into a geographic information system (GIS). The medium and slightly low fragility classes predominated in terms of potential (~60%), and emerging (~70%) environmental fragility models used to model the basin. The model indicated that high and extremely high potential fragilities were concentrated in the upper basin, a region that is considered a global biodiversity hotspot. The areas with high/extremely high classes of emerging fragility in the upper basin decreased, indicating that the natural cover classes and land-use types are not in danger. We also introduce acceptable conservation practices for land management and use according to the environmental fragility categories established in the present work. The methodology applied in this study can be replicated in other global ecoregions. It provides low-cost territorial and environmental zoning and flexible replication and can be adjusted by administrators who are interested in land-use planning.

A new species of Microlepidogaster (Loricariidae: Hypoptopomatinae) from rio Pardo, a coastal drainage in eastern Brazil.

A new species of Microlepidogaster is described from rio Pardo drainage, a coastal basin in eastern Brazil. This species can be differentiated from its congeners by having the following unique features: 1) anterior portion of snout with a large odontode-free band extending laterally from the anterior tip of snout to the postrostral plate 2; 2) transverse process of second dorsal-fin pterygiophore exposed and bearing odontodes; and 3) exposed area of pectoral girdle extended to the mesial symphysis, with odontodes mainly distributed in the coracoid ventral expansion. The new species is further distinguished by several other morphological non-exclusive features. Recently, some Microlepidogaster species were reallocated to Rhinolekos. The taxonomic changes involving these genera is herein discussed.

Modeling of bottom currents for estimating their erosional-depositional potential in the Southwest Atlantic

Contourites are sediments deposited or substantially reworked by the persistent action of bottom currents which are capable of forming a wide range of erosional and depositional features on the seafloor. The study of contourites is a multidisciplinary topic linking physical oceanography and marine geology. While near-bottom circulation is an important subject itself due to different dynamic aspects and climatic estimates of abyssal water transports, it becomes especially important for studies of lateral sedimentation. The precise direct data on bottom currents on the South American continental rise and adjacent abyssal plains remain extremely rare. Numerical modeling can appear helpful for filling the gaps in our knowledge on bottom circulation in the region. This work describes an approach for mapping erosion- and deposition-dominated areas based on the modeled circulation in the bottom layers. The model domain covers the regions with different seabed topography and velocities of bottom currents: the Vema Channel, the Santa Catarina Plateau, the Rio Grande Rise, and parts of the Argentine and Brazil basins. The high vertical resolution used in the model allowed us to study the near-bottom circulation in the deep ocean, while high horizontal resolution enabled modeling currents in narrow underwater passages such as the Vema Channel. The equations that encompass the bottom current velocities and data on surface sediment grain-size are well-known; in this study, we estimate the erosional-depositional potential of bottom currents using these equations. This approach allowed identification of the regions of dominant erosion (to the northeast of the northern exit from the Vema Channel), deposition (northern part of the Santa Catarina Plateau), and non-deposition under the influence of bottom currents. The results were validated by the analysis of echo-facies distribution in the study area and variations in the surface sediment grain-size. This study embraces the transition zone between the Argentine and Brazil basins, which is crucial for understanding the deep and bottom circulation in the western South Atlantic under modern conditions and in the geological past. The presented technique can improve our knowledge on how bottom currents shape the seafloor and control sediment distribution in the Southwest Atlantic.

Early to middle eocene radiolarian biostratigraphy for the low-latitude South Atlantic Ocean (Brazil Basin, DSDP Leg 39, Site 355)

The analyses of radiolarian assemblages were carried out from low-latitude DSDP Site 355 (Leg 39), drilled in the Brazil Basin, South Atlantic Ocean. A total of 98 early to middle Eocene radiolarian events were identified in this site. The standard low-latitude radiolarian zonation was adopted for the Site 355 cores, and it allowed the identification of seven radiolarian zones: Podocyrtis mitra (RP14), Podocyrtis ampla (RP13), Thyrsocyrtis triacantha (RP12), Dictyoprora mongolfieri (RP11), Theocotyle cryptocephala (RP10), Phormocyrtis striata striata (RP9), and Buryella clinata (RP8). The radiolarian events at Site 355 were compared with previous studies from low and mid-latitudes, showing a good correlation with the low-latitude regions. On the other hand, 11 radiolarian events were clearly diachronous between low and mid-latitudes.

Testing palaeodrainage hypotheses in south-eastern Brazil: phylogeography of the sinistral livebearer fish of the genus Phalloceros (Cyprinodontiformes: Poeciliidae)

Abstract The ‘sinistral Phalloceros group’ consists of three species, P. aspilos, P. leptokeras and P. tupinamba, that belong to Phalloceros, a genus of freshwater fish endemic to South America. They inhabit the Paraíba do Sul Basin and coastal drainages in south-eastern Brazil. This group is diagnosed by large hooks in the medial portion of the gonopodial appendices in males and the sinistral direction of the urogenital papilla in females. We conducted a phylogeographic analysis of mitochondrial (COI and Cytb) and nuclear (RAG1) haplotypes of 36 individuals sampled from 11 localities to test the hypothesis that the biogeographic history of sinistral Phalloceros was mediated by connections of coastal basins caused by lowered sea-levels during the Quaternary. We evaluated the taxonomic status of these nominal taxa by integrating molecular species delimitation methods and morphological data. Our results suggest that the three nominal taxa are synonyms, and P. leptokeras is designated as the valid species name. The geographic expansion of the P. leptokeras lineage began in the coastal region (~2.3 Mya). The phylogeographic relationships among populations partially corroborate the palaeodrainage model, but also suggest that P. leptokeras colonized the inland Paraíba do Sul drainage, overcoming the Serra do Mar mountains.

An attractor domain model of seasonal and inter‐annual β diversity of stream macroinvertebrate communities

Abstract Ecological communities are dynamic systems that vary within and across years. In streams, disturbance by spates and the emergence of adult insects during the rainy summer contrast with more stable conditions in the dry winter and can potentially generate distinct and repeatable community states across years. However, demographic stochasticity and the legacies of previous spates may hamper the full attainment of characteristic community states associated with seasons. We developed an attractor domain model encapsulating these factors and hypothesised: (1) partially distinct rainy (summer) and dry (winter) communities. High benthic dynamism during the rainy period should cause higher inter‐annual variability, leading to (2) higher temporal β diversity among rainy periods than among dry periods. Historical effects (e.g., demographic stochasticity and disturbance by spates) should accumulate over the years and lead to (3) increased variation in community structures sampled further apart in time; furthermore, (4) this increase in variation should be higher among rainy than among dry communities. We used data of stream macroinvertebrates (mostly insects) in a subtropical basin in Brazil to evaluate inter‐annual variation using rank‐concordance statistics of the most common species and dissimilarity using all species. For each stream site, samples obtained in the two seasons tended to show distinct community structure using relative abundance data but were much less distinct using species composition (presence–absence). Temporal β diversity was higher among rainy than among dry seasons. The β diversity of both seasons increased with time, although this increase was 2–3 times greater during the rainy season. Our results support a model in which rainy (summer) communities are disrupted by the high dynamism caused by spates and the emergence of adult insects. The low intensity of these two factors during dry (winter) periods allows local environmental conditions to drive community structures toward a less variable, recurrent attractor state. However, the increase in β diversity with time indicates that the legacy effects of previous disturbances and demographic stochasticity preclude the full attainment of a definite stable state and that only a domain of states is approached.

Early Cretaceous non-marine ostracods from the Recôncavo Basin, Northeast of Brazil

The Early Cretaceous chronostratigraphic positioning of the northeast Brazilian basins is mainly based on ostracod distribution, including a biozoning proposal of local stages. The ostracod species were recovered from shales and siltstones samples along Gameleira, Manguinhos and Praia da Falha outcrops of the Maracangalha Formation (Recôncavo Basin). In the analyzed samples, six genera were recognized, out of a total of 1036 specimens. The non-marine ostracod fauna consists of the species Cypridea lunula Krömmelbein, 1962, Cypridea ellipsoidea Krömmelbein and Weber, 1971, Cypridea aff. C. vulgaris Krömmelbein, 1962, Cypridea sp. 1, Cypridea sp. 2, Cypridea sp. 3, Cypridea spp., Reconcavona? polita Viana, 1966, Reconcavona sp., Ilhasina amphotera Krömmelbein, 1963, Ilhasina sp. aff. I. remanei cuneiformis Krömmelbein, 1963, Ilhasina sp., Candona? condensa Krömmelbein, 1962, Brasacypris sp. and Alicenula sp. The biochronostratigraphic position of the Manguinhos outcrop in the Rio da Serra Stage (Berriasian–Valanginian) was possible through the identification of the guide species Reconcavona? polita, index in subzone RT-004.2. In the Praia da Falha outcrop the faunal association suggests an age range between the late Rio da Serra to Aratu Stage (Valanginian-Hauterivian), through the recording of the species Ilhasina amphotera and Cypridea lunula.

Evaluation of InVEST’s Water Ecosystem Service Models in a Brazilian Subtropical Basin

The biophysical modeling of water ecosystem services is crucial to understanding their availability, vulnerabilities, and fluxes. Among the most popular models, the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) models stand out. While many studies have used them, few have assessed their performance. This study evaluates the performance of InVEST’s Seasonal Water Yield, Nutrient Delivery Ratio, and Sediment Delivery Ratio models in a subtropical basin in southeastern Brazil on temporal and spatial scales, using 39 years of streamflow data, 29 for total phosphorus and total nitrogen, and 19 for total suspended solids. Statistical indicators R2, PBIAS, and NSE, were also calculated. The performance of the models varied according to the type of simulated WES and analysis scales used, with the Seasonal Water Yield model demonstrating the best performance and effectively representing the spatial and temporal variability of the average annual streamflow. All models performed well in simulating long-term mean values when compared to observed data. While one should bear in mind the study’s limitations, the results indicate that the models perform well in terms of relative magnitude, although their application in studies involving water-resource management and decision making is limited.

Using detrital zircon and rutile to constrain sedimentary provenance of Early Paleozoic fluvial systems of the Araripe Basin, Western Gondwana

The Early Paleozoic of the NE Brazilian sedimentary basins are key to understanding the primeval depositional environments and paleogeography of Western Gondwana after its final assembly. In this context, determining the sedimentary provenance of the Early Paleozoic Cariri Formation (basal unit of the Araripe Basin) may improve paleogeographic reconstructions and stratigraphic correlations. Despite the Araripe Basin being one of the best-studied interior basins of northeastern Brazil, the Cariri Formation lacks detailed geochronological and sedimentary provenance analyses, which hamper precise definitions of its depositional age, sedimentary source areas and paleogeography. Considering this scenario, we performed a combined multiproxy approach, including sedimentologic and stratigraphic analysis, detrital zircon U–Pb dating and provenance studies based on trace elements in detrital rutile. The maximum depositional age for the Cariri Formation suggests that its sedimentation started after the Late Cambrian. Detrital zircon ages and detrital rutile provenance indicate that the primary source areas for the Cariri Formation fluvial system were the orogenic terranes related to the Brasiliano Orogeny, located at the SE of the Borborema Province (e.g., Sergipano Belt), with secondary, but also important, the contribution of Cambrian sources. Records of this event are also found in northern Africa, where units related to the Neoproterozoic East African-Antarctic and Pan African orogens provided sediments for basin-scale fluvial systems.

Optimization of water allocation networks in highly engineered basins: The case of Guandu River basin, Rio de Janeiro State, Brazil

During the last decades, metropolitan areas with a large population and economic size have mushroomed, modifying the urban geography and natural environment. Along with the rising of megacities, highly engineered basins have been created, providing resource security regarding water and energy. The coastal Guandu River basin in Brazil represents an artificial basin that has been heavily intervened for decades. The basin receives almost ∼80% of the water by transfers from the Paraiba do Sul River Basin System and has an associated hydroelectric complex that generates power for the national network. It is the primary source of water and energy for the Rio de Janeiro Metropolitan Area, home to ∼13 million people. Recently, water availability for this region has been jeopardized by drought conditions due to changing rainfall patterns and competition for water resources with other users such as Sao Paolo Metropolitan Area. This study focuses on the development of an optimization framework (WANAB model) for water resources management at the macroscopic level in the Guandu Basin to guarantee economic viability and water resources sustainability. The model incorporates parameters and equations for hydrological, and engineered water and hydropower processes to determine the optimal water allocation network. Also, a multi-criteria analysis is proposed to evaluate the water availability considering different scenarios. The results show that through optimization, it is possible to have a water availability of up to ∼24 m3/s in the Guandu River basin by integrating elements such as water storage systems, grey and blackwater treatment plants with capacities up to ∼39 m3/s and ∼9 m3/s, respectively. The results show that it is possible to reach a water availability of 21 m3/s in the scenario, considering the reduction of water transfers from outside the basin due to climate change. However, the major impact is observed in the hydropower generation, decreasing from ∼2270 GWh/y to ∼1950 GWh/y. The WANAB model represents a decision-making and policy tool for optimizing water allocation networks and may be adapted for other highly engineered basins.

Flood analysis in the Canoas, Sertão, and Mampituba rivers in the South of Brazil through hydrological and hydrodynamic modeling

Floods that occur in hydrographic basins with high slopes are more susceptible to natural hazards due to the occurrence of high intensity hydrological events and the type of sloping relief. These two associated factors contribute to an increase in the destructive potential of these regions, causing economic damage and loss of life for people and animals. This study sought to assess the floodplain areas in the Canoas, Sertão, and Mampituba Rivers that contribute to the Mampituba River basin in southern Brazil, to support emergency procedures for dealing with floods and contribute to the territorial management of these spaces. From the hydrological data of the Mampituba River basin, a hydrological model was used, which generated flows that were inserted as input to a hydrodynamic model, resulting in flood patches in the plains of the modeled rivers. The calibration and integration studies of the models were carried out on a computational platform that employs the hydrometeorological knowledge represented by the models of the basin under study. The hydrodynamic modeling represented in the maps indicated that the flooding patches occur within the river channels and in the plains occupied by agriculture, with a predominance of irrigated rice paddies, pasture fields, forestry, urbanized areas, and native vegetation. In the urban region along the floodplains of the Praia Grande and Mampituba Cities, there are inns, restaurants, and residences which can suffer structural damage and expose people to the danger of a flood event of this magnitude. The results achieved allow us to infer that the integrated modeling system proved to be capable of performing efficient hydrological and hydrodynamic simulations. The methods used can be replicated in other basins and the results can support public managers for greater assertiveness in decision-making when facing the dangers of extreme weather events.

Cretaceous (Maastrichtian) chelonian burrows preserved in floodplain deposits in the Bauru Basin of Brazil: Evidence for the fossorial origin of turtle shells

Burrowing behavior is an important adaptation of animals that live in arid and semi-arid conditions. In this paper, we describe examples of vertebrate burrows from the Upper Cretaceous (Maastrichtian) Adamantina Formation of the Bauru Basin, Brazil, most likely produced by turtles. The Adamantina Formation preserves abundant and diverse turtle body fossils such as Bauruemys elegans (Testudines: Pleurodira); however turtle burrows have not been previously documented. The newly reported burrows are preserved in fluvial sandstone facies and exposed in sections that partially preserve their three-dimensional geometry. Burrows are simple J-shaped tunnels with a cross-sectional shape that is semicircular (half-dome) with a flattened floor. Such burrows show a partially preserved entrance with an inclined ramp angle (22°), and grooves and ridges up to 1 cm in width preserved along the burrows walls and floor. The architecture and sedimentary facies of the host sandstone body, together with the occurrence of Taenidium barretti and the absence of rhizoliths, suggest that the burrow was excavated by scratch digging into an exposed point bar of a meandering river channel. Based on burrow morphology, dimensions, as well as ridges,and grooves in the walls and floor, we propose that burrows were formed by a chelonian (such as a freshwater turtle) during aestivation. We highlight that these are first examples of turtle burrows reported from the Cretaceous, and their occurrence reinforces the hypothesis that the original function of turtle shells was as an adaptation to fossorial behavior.

Can Malaria Be Eradicated by 2030?

According to the 2020 World Health Organization (WHO) Malaria Report, there were 229 million malaria cases worldwide with a death toll of 409,000 in 2019. This information did not include asymptomatic malarial infections which can also have a significant impact on the health of infected individuals. Part of this may be due to the mosquitoes becoming resistant to the pyrethroid insecticide used in treated bed nets, especially if the bed nets are damaged with large holes, allowing mosquitoes to still transmit malaria. The overall reduction has tended to reach a plateau or declined in certain areas, such as the Amazon basin in Brazil where the transmission of Plasmodium vivax and Plasmodium falciparum increased more than 20% in 2016–17. Increased implementation of chemical control programs has led to the emergence and spread of insecticide resistance in Anopheles sp. and Aedes sp. populations, indicating a need to examine whether entomopathogenic fungi can be used for controlling mosquito vectors. Deforestation and increased agricultural activities have probably resulted in greater exposure to outdoor biting by the female mosquitoes. Similarly In other areas, changes in human behaviour have increased socialising outdoors and shopping after sunset when it is cooler. Apart from some attention to larval source management, so far there has been no recommendation for space treatments to reduce outdoor biting. This is despite the extensive use of space treatments in the USA by the mosquito control organisations, using cold foggers on vehicles or applying a space spray from aircraft. There has also been consideration of using an autonomous unmanned aerial spray system (UASS), a drone to apply space sprays.