The Brumadinho tailings dam failure in 2019 has had a profound impact on the way tailings engineers analyse and interpret stability, with the focus of assessments moving away from conventional drained behaviour to consideration of undrained and post-liquefaction resistance. One of the contributing reasons is that the Expert Panel investigation of the failure concluded that, despite the drained factor of safety being adequate, the failure took place in an undrained manner. This paper examines the Brumadinho failure from a conventional drained perspective using two-dimensional limit equilibrium and finite difference modelling. Collectively, these analyses show that the failure can also be explained by a drained triggering mechanism and therefore suggest that several additional lessons may be learnt from the failure.

Abstract Critical discussions about the Anthropocene point to the necessity of a radical recasting of politics and law. We propose that potential paths for this recasting can be found in the practices through which the Munduruku defend their territory and way of life, particularly in the self-demarcation of the Daje Kapap Eypi territory, initiated in 2014 in response to the Brazilian government's halt on the land demarcation process and the advancement of the São Luiz do Tapajós Hydroelectric Dam licensing. Through an analysis of conflicts surrounding this territory, we investigate the clash between two antagonistic legal logics: on one side, a law of the Anthropocene, which reinforces the separation between nature and society, rejects modes of existence that transcend this duality, and deepens predatory extractivism; and on the other, a cosmopolitical law of the Munduruku, in which rights and obligations are constituted by networks of human and more-than-human entities, autonomous decision-making practices, and the situated experience of territory. We argue that the cosmopolitical legal practice of the Munduruku has established territories capable of halting the advance of extractivism and ecological destruction and should be understood as a legal practice that sustains and repairs the conditions of life on a damaged planet. selfdemarcation self 201 governments government s licensing logics side society duality other morethanhuman more than entities decisionmaking decision making planet 20 2

Resumo Discussões críticas sobre a tese do Antropoceno apontam para a necessidade de uma reconfiguração radical da política e do direito. Propomos que possíveis caminhos para essa reconfiguração estão presentes nas práticas de defesa do território e modo de vida do povo Munduruku, especialmente no processo de autodemarcação do território Daje Kapap Eypi, no médio curso do rio Tapajós, iniciado em resposta à paralisação da demarcação da terra pelo governo brasileiro e ao avanço do licenciamento da Usina Hidrelétrica São Luiz do Tapajós. A partir de uma análise dos conflitos em torno deste território, investigamos o embate entre duas lógicas jurídicas antagônicas: de um lado, um direito do Antropoceno, que reforça a separação entre natureza e sociedade, rejeita modos existência que fogem a essa dualidade, e aprofunda o extrativismo predatório; e, de outro, um direito cosmopolítico dos Munduruku, no qual direitos e obrigações são constituídos por redes de entidades humanas e mais-que-humanas, por práticas autônomas de tomada de decisão e pela experiência situada e viva do território. Argumentamos que o direito cosmopolítico dos Munduruku tem constituído territórios capazes de frear o avanço do extrativismo e da destruição ecológica, e deve ser entendido como uma prática jurídica que sustenta e repara as condições de vida num planeta ferido. Eypi Tapajós antagônicas lado sociedade dualidade predatório outro maisquehumanas, maisquehumanas mais humanas, mais-que-humanas ecológica ferido

Globally, the demand for mineral products is ever increasing. Extraction of these mineral resources results in the continuous production of a huge volume of waste material, including tailing dumps. The mass of tailings usually exceeds the actual resource and often contains hazardous contaminants. This study investigated the effects of tailings disposal on soil, water, and air quality in the Nampundwe area. Water, soil, and dust samples were collected from different locations in the surrounding communities. The constituents analysed in the samples included copper, cobalt, iron, sulfate, and silica. According to the results obtained, some seepages occurred from the tailings impoundment to the shallow aquifer in the area. However, the general water quality meets the Zambia Environmental Management Agency (ZEMA) statutory limits. Recorded concentrations of sulfate (1500 mg/l), copper (1.5 mg/l), cobalt (1.0 mg/l), iron (2.0 mg/l), and silica were between 0.003 mg/l and 705 mg/l, which is far below ZEMA's statutory limit. Silica concentration was also evident in the air. The highest concentration recorded was 260 ppcc (particle per cubic centimeter) recorded in July 2019 from the northern direction of the tailings dam. The concentration was below the statutory limit of 350 ppcc. The topsoil from the northern part of the tailings recorded a silica dust concentration of 39.9 ppcc. Iron was evident in the underground soil with a concentration of 8.01 ppcc, cobalt 0.005 ppcc, copper 0.051 ppcc, while sulfate was recorded as 0.41 ppcc.

Reservoirs often experience significant evaporation, causing a reduction in productive water use and prompting calls to curtail the loss. While efforts to reduce evaporation have predominantly focused on improving efficiencies, there has been a comparatively limited exploration of the associated costs per unit of additional water yield. To address this, a unit reference value (URV) calculation approach was employed in a case study to compare the unit costs of this additional yield through various evaporation suppression methods. The evaluated techniques included chemical monolayers, shade cloth, and both hard and soft floating covers. The URV calculation factored in capital, operating, and maintenance costs over a 20-year term, specified water-saving efficiencies for each technology, and various environmentally driven evaporation and social discount rates. The resulting URVs were compared with those for raising the Clanwilliam Dam, a large-scale groundwater scheme and the URVs for desalination. Notably, monolayers emerged with the lowest URV, but their yield efficiency is severely compromised by their short lifespan and high susceptibility to wind. The URVs of shade cloth proved competitive with those of desalination but are practical only for relatively small areas. In contrast, floating hard and soft covers demonstrated higher per-unit water delivery costs than desalination due to more frequent capital equipment replacements caused by their faster wear and weathering. The findings suggest that current evaporation suppression technologies may be economically unfeasible for agricultural and even domestic water supplies. The URV calculation serves as a valuable tool for comparing the cost-effectiveness of diverse yield-additive strategies.

INTRODUCTION: The choice of baseplate material for a trial complete maxillary denture is a critical decision in prosthodontic practice. One significant factor to consider is the depth of the palatal vault, which can influence the suitability of the baseplate material. Close adaptation of the denture base is essential in preventing lateral denture movement and enhancing denture retention and support. AIMS AND OBJECTIVES: This study was undertaken to evaluate and determine the most suitable baseplate material to use on casts of various palatal vault depths. METHODS: A total of 120 casts with varying palatal vault depths categorized as shallow, moderate, and deep were fabricated (40 per group). Denture bases, all designed to a uniform 2-mm thickness, were created using four different commonly used materials: pink baseplate wax, self-cured acrylic resin, light-cured acrylic resin, and 3D-printed photo-polymerized resin. Both the casts and the fabricated denture bases were sectioned down the midline. Measurements of adaptation were taken from the left halves. Readings were taken of the gap between the denture bases and the casts at three predefined positions (I - incisive papilla, II - mid-palatal area and III - posterior palatal seal area. RESULTS: For shallow palates the best material (i.e., most closely adapted) in position I was light-cured acrylic, in position II was self-cured acrylic and in position III was light-cured acrylic. For moderate depth palates the best material in position I was light-cured acrylic, in position II was self-cured acrylic and in position III was light-cured acrylic. For deep palates the best material in position I was self-cured acrylic, in position II was self-cured acrylic and in position III was light-cured acrylic. CONCLUSIONS: For all three palatal depths, the material with the closest adaptation in position II (mid-palate) was the self-cured acrylic resin and in position III (the post-dam area) was the light-cured acrylic. In position I (incisive papilla) the light-cured resin performed slightly better in shallow and moderate palates and the self-cured resin in deep palates. It would thus seem that based on this study technicians and clinicians should consider using firstly light-cured acrylic resin or self-cured acrylic resin as opposed to the more commonly used pink baseplate wax for trial denture base plates.

Abstract: The study was conducted at the Jalpan de Serra dam, Querétaro, Mexico. In a mountain watershed with a history of artisanal mining activity in the upper part, runoff feeds the reservoir, transporting mining tailings. The Jalpan dam has been used for drinking water supply, agricultural irrigation activities and recreational purposes as a Ramsar site. The reason for the study has been the relevance and social impact of the reservoir sediments as a source of diffuse pollution. The objective was to determine the concentration of arsenic, cadmium and lead in the sediment and to evaluate the level of risk to human health and the environment. The methodology consists of the analysis by atomic absorption carried out in three sites sampled in the superficial layer of 10 cm depth, samples obtained with a PVC tube of 7 cm diameter, identified, preserved for transfer and digested with nitric acid. The results show mean arsenic concentrations of 4.278 mg/kg, cadmium 0.323 mg/kg and lead 4.873 mg/kg. In conclusion, the sediment analyzed does not represent a risk to human health or the environment of the reservoir according to NOM-147-SEMARNAT/SSA1-2004. This investigation demonstrates the lack of a policy or standard that establishes permissible limits for heavy metals in sediment.

Resumen: El estudio ha sido realizado en la presa Jalpan de Serra, Querétaro, México. En una cuenca de montaña con antecedentes de actividad minera artesanal en la parte alta, la escorrentía alimenta el embalse, transportando relaves mineros. La presa Jalpan se ha empleado para abastecimiento de agua de consumo humano, actividades de riego agrícola y fines recreativos como sitio Ramsar. El motivo de estudio ha sido la relevancia e impacto social que tienen los sedimentos del embalse como fuente de contaminación difusa. El objetivo ha sido conocer la concentración de arsénico, cadmio y plomo en el sedimento y evaluar el nivel de riesgo para la salud humana y del ambiente. La metodología consiste en el análisis por absorción atómica realizada en tres sitios muestreados en la capa superficial de 10 cm de profundidad, muestras obtenidas con un tubo de PVC de 7 cm de diámetro, identificadas, conservadas para su traslado y digeridas con ácido nítrico. Los resultados muestran concentraciones medias en arsénico de 4.278 mg/kg, cadmio 0.323 mg/kg y plomo 4.873 mg/kg. En conclusión, el sedimento analizado no representa riesgo para la salud humana o entorno del embalse según la norma NOM-147-SEMARNAT/SSA1-2004. Esta investigación evidencia la falta de una política o norma que establezca los límites permisibles de metales pesados en sedimentos.

Abstract In this paper, I present the results of ethnographic research that analyzes the social effects on peasant communities (dedicated to working the land and fishing in the river) due to the delivery of compensation and the carrying out of works for the installation of the hydroelectric dam “El Quimbo”, located in the inter-Andean valleys of the Upper Magdalena River basin, in Huila, Colombia. Those lands were flooded in 2015, and affected people received different treatments that changed their relationships with the land, the river and their communities. Thus, the theoretical contribution of the article lies in the dialogue between ecological economics and economic anthropology, hence I describe the effects of restricting to a value paid in cash or measured in productivity regarding the social value of the elements present in the territory (land, river, forest) and community relations. Methodologically, six standard-situations were constructed inductively based on interviews and conversations collected in fieldwork that covered various moments between 2010 and 2021. The six standard-situations evince the effects on the social positions of affected groups: some partially reproduced their relations with the land; some began a situation of new subordination; and others were expropriated from the reproduction of their previous social relations. I complemented the article with secondary sources based on a review of archives, newspapers, and public documents of the company and the social movement.

Resumo No artigo, apresento os resultados de uma pesquisa etnográfica que analisa os efeitos sociais sobre as comunidades camponesas (dedicadas ao trabalho da terra e a pescaria no rio) pela entrega das compensações e a realização das obras na instalação do projeto hidrelétrico “El Quimbo”, localizado nos vales interandinos do Alto Magdalena, em Huila, Colômbia. Aquelas terras foram inundadas em 2015, e os atingidos receberam diferentes tratamentos que modificaram suas relações com a terra, o rio e suas comunidades. Assim, a contribuição teórica do artigo está no diálogo entre a economia ecológica e a antropologia econômica a partir da qual descrevo os efeitos de restringir o valor social dos elementos presentes no território (terra, rio, floresta) e das relações comunitárias por um valor a ser pago em dinheiro ou medido em produtividade. Metodologicamente, foram construídas de forma indutiva seis “situações-tipo” baseadas em entrevistas e conversas coletadas durante trabalho de campo, que abarcou vários momentos entre 2010 e 2021 e permitiu demonstrar os efeitos nas posições sociais ocupadas pelos atingidos: camponeses que puderam reproduzir parcialmente suas relações com a terra, aqueles que ficaram em uma situação de nova subordinação, e os que foram expropriados da reprodução de suas relações sociais anteriores. As informações foram complementadas com fontes secundárias baseadas em revisão de arquivos, jornais e documentos públicos da empresa e do movimento social.

ABSTRACT: The research allowed to use of hydrological models for the calculation of the ecological flow of the “Jequetepeque” river, upstream of the “Gallito Ciego” dam, Peru. Information on average monthly flows was used, which was divided into two periods (1943-1987) and (1988-2019). To calculate ecological flow, seven hydrological methods were used. For the period 1943-1987, the ecological flow was calculated with the percentage establishment method (0.47 m3s-1), followed by the Tennant method (0.57 m3s-1).The period of 1988-2019, the ecological flow was calculated with the percentage establishment method (0.36 m3s-1), followed of the Tennant method (0.59 m3s-1).The analysis of variance of one factor, significant differences were compared and verified between the ecological flow calculated of the indicated methods and the minimum low-water flow taken as a baseline for comparison. With the Tukey test, it was verified that the ecological flow estimated of the hydrological method of establishing percentages for the period (1943-1987) and (1988-2019), it did not present significant differences with respect to the minimum low-water flow. It concluded that the ecological flow of the “Jequeteque” river upstream of the “Gallito Ciego” dam is 0.36 m3s-1, it obtained through the percentage establishment method.

RESUMEN: La investigación permitió usar modelos hidrológicos para el cálculo del caudal ecológico del río “Jequetepeque”, aguas arriba de la presa “Gallito Ciego”, Perú. Se usó información de caudales medios mensuales, la cual se dividió en dos períodos (1943-1987) y (1988-2019). Para el cálculo de caudal ecológico, se usó de siete métodos hidrológicos. Para el período 1943-1987, el caudal ecológico se calculó mediante el método de establecimiento de porcentajes (0,47 m3s-1), seguido del método de Tennant (0,57 m3s-1). Para el período 1988-2019, el caudal ecológico se calculó mediante el método de establecimiento de porcentajes (0,36 m3s-1), seguido del método de Tennant (0,59 m3s-1). Con el análisis de varianza de un factor se comparó y verificó diferencias significativas entre el caudal ecológico calculado por los métodos indicados y el caudal mínimo de estiaje tomado como línea base de comparación. Con la prueba de Tukey, se verificó que el caudal ecológico estimado por el método hidrológico de establecimiento de porcentajes del período (1943-1987) y (1988-2019) no presentó diferencias significativas con respecto al caudal mínimo de estiaje. Se concluye que, el caudal ecológico de río “Jequeteque” aguas arriba de la presa “Gallito Ciego” es de 0,36 m3s-1, obtenido mediante el método establecimiento de porcentajes.

Abstract Recent events involving iron ore tailings dam collapses have emphasized the need for developing alternative ways of depositing tailings. This study aims to evaluate the effects of using three hydroxamates and a sulfosuccinamate as collectors in the direct flotation of iron ore tailings, using a bench flotation. The best result obtained on bench flotation was tested in a pneumatic cell. The sample used in this study (10.8% of Fe) consists of quartz and hematite. The Aero® 6494 Promoter hydroxamate showed the highest selectivity among the analyzed reagents, reaching 64.31% of Fe in the final product of the test with the < 150 µm sample. The possibility of using these reagents as constituents of a mixed collector with dodecylamine was also investigated. In this case, the Aero® 845 Promoter sulfosuccinamate yielded the best results, with 62.84% of Fe and 59.01% of metallurgical recovery of Fe. The synergistic effect between the two reagents might be explained by the stability of the monolayer formed by the intercalation of the ions from the dodecylamine and the Aero® 845 Promoter, which reduces the electrostatic repulsion between ions of the same species This mixed collector was tested in a pneumatic cell. However, it had a lower performance in terms of Fe metallurgical recovery than in a bench-scale cell test, mainly for the finest particles, due to the greater control of the process’s variables in the bench cell. 10.8% 108 10 8 (10.8 hematite Aero 649 6431 64 31 64.31 15 investigated case 84 results 6284 62 62.84 5901 59 01 59.01 However benchscale scale particles processs process s 10.8 1 (10. 643 6 3 64.3 628 62.8 590 5 0 59.0 10. (10 64. 62. 59. (1 (

ABSTRACT The collapse of the Fundão Dam in Mariana, MG, in 2015 introduced the challenge of using Technosol, a soil type formed by deposition of iron mining waste along the Doce River banks, for agricultural purposes. This study aimed to determine the optimal water depth for enhancing production of tropical forage, Megathyrsus maximus cv. Mombasa, when grown on iron ore tailings. Additionally, it sought to establish a crop coefficient applicable to the edaphoclimatic conditions of Viçosa, MG, Brazil. The experiment was conducted throughout the summer, fall, and winter of 2022, employing 21 drainage lysimeters. A completely randomized experimental design was adopted, featuring six treatment groups (plants in Technosol receiving water depths ranging from 20 to 120% of the crop’s evapotranspiration, as derived from the control treatment), along with a control group (plants in Latosol with a depth of 100%), each with three repetitions. Our findings showed that irrigation must replace 40% of the crop evapotranspiration. Moreover, cultivating in Technosol resulted in a reduction of productive capacity by 37.39% during the summer/fall and fall seasons. For Mombasa grass grown in Oxisol, crop coefficients of 1.2 during the summer and 1.5 during the fall and winter are advised. Mariana MG 201 banks purposes forage cv tailings Additionally Viçosa Brazil 2022 2 lysimeters adopted plants 120 crops s evapotranspiration treatment, , treatment) 100%, 100 100% 100%) repetitions 40 Moreover 3739 37 39 37.39 summerfall seasons Oxisol 12 1 1. 15 5 advised 202 10 4 373 3 37.3 37.

RESUMO O rompimento da Barragem do Fundão em Mariana, MG, ocorrida em 2015, trouxe o desafio de usar o Tecnossolo (tipo de solo) formado pela deposição do rejeito de mineração de ferro nas margens do Rio Doce para agricultura. O objetivo desta pesquisa foi obter a lâmina de água para otimizar a produção da forragem tropical Megathyrsus maximum cv. Mombaça, cultivada em rejeito de mineração de ferro e determinar seu coeficiente de cultura para as condições edafoclimáticas de Viçosa, MG. O experimento foi realizado durante as estações de verão, outono e inverno do ano de 2022, com a utilização de 21 lisímetros de drenagem. O experimento foi distribuído em delineamento inteiramente casualizado com 6 tratamentos (plantas em Tecnossolo com lâminas variando de 20 a 120% da evapotranspiração da cultura, obtida do tratamento-testemunha) e adição de uma testemunha (plantas em Latossolo com lâmina de 100%) com três repetições. Recomenda-se irrigação com reposição de 40% da evapotranspiração da cultura. O cultivo em Tecnossolo diminuiu a capacidade produtiva em 37,39% nos ciclos das estações do verão/outono e outono. Recomenda-se os coeficientes de cultura de 1,2 no verão e 1,5 no outono e no inverno, para o capim-Mombaça cultivado em um Latossolo. Mariana MG 2015 tipo solo agricultura cv Mombaça Viçosa 2022 2 drenagem plantas 120 tratamentotestemunha tratamento tratamento-testemunha 100% 100 repetições Recomendase Recomenda se 40 3739 37 39 37,39 verãooutono 12 1 1, 15 5 capimMombaça capim 201 202 10 4 373 3 37,3 37,

ABSTRACT Infections of alpacas at very early ages suggest that the dams may act as asymptomatic carriers of some Eimeria species. The aim of this study was to determine the dynamics of Eimeria spp oocyst excretion in alpaca dams during the calving season at the «La Raya» Research and Production Centre, Puno, Peru. Faecal samples were taken from 50 clinically healthy alpacas of the Huacaya breed naturally infected with Eimeria spp in the two weeks prepartum, week of delivery and four weeks postpartum (period December 2018 -March 2019). Dams were categorized into three age groups [A: 3-4 (n=19), B: 5-8 (n=26) and C: 9-12 years (n=5)]. Sample analysis was carried out using Sheather solution flotation and McMaster techniques. The pregnant dams entered the calving season excreting E. punoensis [49/50 (98%)], E. alpacae [43/50 (86%)], E. lamae [5/50 (10%), and E. macusaniensis [3/50 (6%)] but not E. ivitaensis. The percentage of dams shedding oocysts of E. alpacae and E. punoensis increased after the second week postpartum, while it was found a minimal excretion load of E. macusaniensis and E. lamae before and after the calving season. There was a significant difference in opg between A and B, and between the two weeks prepartum and four weeks postpartum, in addition to a very low negative correlation (-0.0538) between the number of opg and age (p=0.0468). Animals infected with E. punoensis presented 6.5 times the prevalence of those parasitized with E. alpacae (p<0.001; 95%CI 2.33-18.13).

RESUMEN Las infecciones de las crías de alpacas a edades muy tempranas sugieren que las madres pueden actuar como portadoras asintomáticas de algunas especies de eimerias. El objetivo del estudio fue determinar la dinámica de excreción de ooquistes de Eimeria spp en alpacas madres durante la temporada de parición en el Centro de Investigación y Producción «La Raya», Puno, Perú. Se tomaron muestras fecales de 50 alpacas madres clínicamente sanas de raza Huacaya infectadas naturalmente con Eimeria spp en las dos semanas preparto, semana del parto y cuatro semanas posparto (periodo diciembre 2018 -marzo 2019). Las madres fueron categorizadas en tres grupos etarios [A: 3-4 (n=19), B: 58 (n=26) y C: 9-12 años (n=5)]. El análisis coproparasitológico se desarrolló mediante las técnicas de flotación con solución Sheather y McMaster. Las madres gestantes ingresaron al parto eliminando E. punoensis [49/50 (98%)], E. alpacae [43/50 (86%)], E. lamae [5/ 50 (10%), y E. macusaniensis [3/50 (6%)] sin excretar E. ivitaensis. El porcentaje de madres excretando ooquistes de E. alpacae y E. punoensis se incrementó desde la segunda semana posparto, eliminando cargas mínimas de E. macusaniensis y E. lamae antes y después del parto. Hubo diferencia significativa en opg entre los grupos A y B, y entre las dos semanas preparto y las cuatro de posparto, además de una correlación negativa muy baja (-0.0538) entre el número de opg y la edad (p=0.0468). Los animales con E. punoensis presentaron 6.5 veces la prevalencia de aquellos parasitados con E. alpacae (p<0.001; IC95% 2.33-18.13).

This study quantified transfer losses over the 2021/2022 water year for irrigation releases from Darlington Dam into the Sundays River, which are diverted at the Korhaans Drift Weir. A one-dimensional (1D) hydrodynamic model was set up and calibrated to simulate the transfer losses which were assumed to consist primarily of evaporation and evapotranspiration (ET). Flow measurements were undertaken with an acoustic doppler current profiler (ADCP) to verify the calibrations of the Parshall flumes at Darlington Dam and at Korhaans Drift Weir. The ADCP results showed that the Department of Water and Sanitation's (DWS's) existing discharge tables underestimated lower flows by 13% and higher flows by 16%. The hydrodynamic model results also estimated transfer losses between Darlington Dam and Korhaans Drift to range between 2.0% and 5.3%. It was determined that the transfer losses were seasonal and were lower than those determined by similar studies for other South African rivers.

Since more than one-third of dam failures have been attributed to uncontrolled seepage, it is of great mportance to investigate the behaviour of this phenomenon in order to achieve the maximum degree of safety for such dams. The present work investigated the influence of the permeability coefficient of the different materials used in zoned earth dams on different seepage parameters. For the modelling and analysis processes, the Seep/w and Seep2D software were employed. The numerical results prove that the optimum relative hydraulic conductivity between the inner and transition shells is about 0.001, and it is Detter to use filling materials with less hydraulic conductivity in the upstream transition and outer shells than η the downstream ones. A good agreement was noted between the obtained results from Seep/wand those Tom Seep2D. Reducing the hydraulic conductivity of both the upstream and the downstream shells, or of the downstream shells only, causes the pore water pressure in the dam body to increase significantly, and causes a remarkable reduction in the seeped water quantity and velocity. A moderate reduction in the different seepage parameters is achieved by reducing the hydraulic conductivity of the upstream transition shell, and a small reduction is noticed by reducing the hydraulic conductivity of the upstream outer shell.

Abstract 23. The study of fish diets allows us to understand how they influence other organisms in the ecosystem through trophic interactions. The aim of this study was to expand our knowledge of the trophic habits of Acestrorhynchus pantaneiro in the alluvial valley of the Paraná River, Corrientes (Argentina). This study involved the collection and evaluation of 140 individuals of A. pantaneiro between May 2016 and February 2018 in four areas of the Paraná River, downstream of the Yacyretá dam. The stomach contents were analyzed at the taxonomic level to calculate the following indicators: frequency of occurrence index, volumetric method, and dietary index. Of the 140 specimens evaluated, 58% had some type of food item in their stomach, whereas 42% were found empty. The analysis of stomach contents allowed us to differentiate several species consumed belonging to the orders Perciformes, Characiformes and Siluriformes; however, the genus Crenicichla presented the highest percentage values of the indicators. The results of this study suggest that A. pantaneiro, in addition to having piscivorous trophic habits, demonstrated preferences for consuming species of the genus Crenicichla.

Resumen 19. El estudio de la dieta de los peces permite entender cómo éstos influyen en los demás organismos del ecosistema a través de las interacciones tróficas. El objetivo del estudio fue ampliar el conocimiento que se tiene del hábito trófico de Acestrorhynchus pantaneiro en el valle aluvial del río Paraná. Se evaluaron contenidos estomacales de 140 individuos de A. pantaneiro recolectados con pesca eléctrica en cuatro zonas del río Paraná, aguas abajo de la represa de Yacyretá, entre mayo de 2016 y febrero de 2018. Se evaluó la presencia/ausencia de contenido estomacal y para cada ítem se analizó a nivel taxonómico procediendo al cálculo de los siguientes indicadores: índice de frecuencia de ocurrencia, método volumétrico e índice alimentario. El 58% de las muestras presentaron algún tipo de ítem alimentario en el contenido estomacal, mientras que el 42% se encontraron vacíos. Los ítems más frecuentes hallados en los estómagos fueron especies de los órdenes Perciformes, Characiformes y Siluriformes, estimándose los mayores valores porcentuales para el género Crenicichla. Los resultados de este estudio sugieren que A. pantaneiro, además de tener hábitos tróficos piscívoros, demostró preferencias por el consumo de especies del género Crenicichla.

Abstract Benthic macroinvertebrates are integral parts of inland waters, inhabiting a diversity of aquatic ecosystems where communities are spatially structured. Macroinvertebrates of some Mediterranean regions such as North Africa are still not well studied. Due this reason we proposed study the community structure in water bodies located in Northeastern Algeria. For this objective, we sampled 12 different kind of water bodies, two dams, three rivers, and seven streams during the period from October 2020 to September 2021. To biotic and abiotic data, a redundancy analysis (RDA) was applied with the aim of determine the role of both kind of variables for grouping the sites. Also, two types of Null models were considered: species co-occurrence and niche sharing for study the potential associations between species reported. Redundancy analysis showed that water velocity and conductivity were the main drivers of community structure of macroinvertebrates. The species co-occurrence results reveal that species associations are ramdom, except for two sites: El fadjoudj and Ain ben baida corresponding to Seybouse river. At the same time, there is no niche sharing and in consequence, there is no interspecific competition except in the two sites: Salah Salah Salah stream and Bouhamdane dam. The results revealed similarities with other similar studies for Algerian rivers and dams, and with other similar water bodies with Mediterranean climate. waters structured studied Algeria objective 1 dams 202 2021 data RDA (RDA sites Also considered cooccurrence co occurrence reported ramdom river time consequence dam climate 20 2

Resumo Os macroinvertebrados bentônicos são partes integrantes das águas interiores, habitando uma diversidade de ecossistemas aquáticos onde as comunidades estão espacialmente estruturadas. Os macroinvertebrados de algumas regiões mediterrânicas, como o Norte de África, ainda não são bem estudados. Por esta razão propusemos estudar a estrutura comunitária em massas de água localizadas no Nordeste da Argélia. Para tanto, foram amostrados 12 corpos d’água diferentes, duas barragens, três rios e sete córregos durante o período de outubro de 2020 a setembro de 2021. Aos dados bióticos e abióticos foi aplicada uma análise de redundância (RDA) com o objetivo de determinar o papel de ambos os tipos de variáveis para agrupar os sites. Além disso, foram considerados dois tipos de modelos nulos: co-ocorrência de espécies e compartilhamento de nicho para estudar as potenciais associações entre as espécies relatadas. A análise de redundância mostrou que a velocidade e a condutividade da água foram os principais impulsionadores da estrutura da comunidade de macroinvertebrados. Os resultados da co-ocorrência de espécies revelam que as associações de espécies são aleatórias, excepto em dois locais: El fadjoudj e Ain ben baida correspondentes ao rio Seybouse. Ao mesmo tempo, não há partilha de nicho e, consequentemente, não há competição interespecífica, excepto nos dois locais: riacho Salah Salah Salah e barragem de Bouhamdane. Os resultados revelaram semelhanças com outros estudos semelhantes para rios e barragens argelinos, e com outras massas de água semelhantes com clima mediterrânico. interiores estruturadas mediterrânicas África estudados Argélia tanto 1 dágua d diferentes 202 2021 RDA (RDA sites disso nulos coocorrência co ocorrência relatadas aleatórias locais Seybouse tempo consequentemente interespecífica Bouhamdane argelinos mediterrânico 20 2