The ichthyofauna of the Potiritá River basin: assessing the conservation status in a mining area in the Eastern Amazon

Abstract Aim Considering the importance of knowing the organisms that make up the environments impacted by human activities, we aimed to create an inventory of the ichthyofauna of a bauxite mining area in the Eastern Amazon in this work. Methods Specimens were collected with sieves, trawls, and gill nets at 37 points in rivers and streams during two expeditions (July 2017 and September and October 2017). After euthanasia and laboratory processes, we identified each individual to the lowest possible taxonomic level, and samples were deposited in scientific collections. We analyzed the conservation status of the species on state, national, and international lists. Results A total of 109 species were identified, belonging to 28 families and six orders, emphasizing the Characiformes order (57 species) and the Characidae family (22 species). We identified two new species, and none are threatened with extinction. Conclusions The high species richness recorded in the Potiritá River basin is noteworthy, considering its relatively small area. This diversity should be considered in future environmental impact studies and in monitoring the ichthyofauna in areas affected by human activities

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Aspectos ecológicos do bacu-pedra Lithodoras dorsalis (Valenciennes, 1840) (Siluriformes: Doradidae) na foz amazônica, Brasil

The aim of this study was investigate the ecological aspects related to the rock-bacu Lithodoras dorsalis (Siluriformes: Doradidae) from streams next to the city of Abaetetuba, Pará, Brazil. The aspects investigated were: feeding ecology and dispersal of plant diaspores (seeds). The study of feeding ecology and seed dispersal are important because they provide essential information for understanding the relationship between ichthyofauna and environment, allowing the taking of effective measures in the conservation of species and ecosystems. The samplings were carried out monthly from July 2010 to June 2011. In this period, 371 specimens of L. dorsalis were collected and through analysis of the gonads was found that all were immature. The average standard length was equal to 15.40 cm (SD ± 4.87 cm) and average total mass equal to 94 g (SD ± 149.45). The diet of the species was composed by 28 food items (16 allochthonous origin and 12 autochthonous origin) and Lithodoras dorsalis was classified as herbivore with a strong tendency to frugivory due to the high importance of fruits and seeds in your diet. With regard to the intensity of obtaining food by the rock-bacu, there were differences between the pluviometric periods, where the end of the transitional period wet-drought and early drought periods represented the lowest and highest feeding activity, respectively. However, there were no significant difference to the importance of the items consumed between the pluviometric periods, the diet of species was similar throughout the sampling period. About the dispersal of seeds, 268 (74.93%) of 371s pecimens of Lithodoras dorsalis showed fruit and vegetable seeds in their stomachs, the main being the assai Euterpe oleracea Mart., the aninga Montrichardia linifera (Arruda) Schott and the buriti Mauritia flexuosa Mart. For analysis we used the assai seeds Euterpe oleracea Mart. and aninga Montrichardia linifera (Arruda) Schott for reaching enough samples. From the analysis of the digestive tract of the rock-bacu was found that all plant diaspores of Euterpe oleracea Mart. were found intact, with an increase in performance of this plant germination, but this did not occur to aninga Montrichardia linifera (Arruda) Schott, because the digestion process destroyed some seeds. Thus it was concluded that Lithodoras dorsalis is a potential disperser of assai Euterpe oleracea Mart. in the Amazonian mouth, because in addition to increasing the performance of the seeds germination, there is an increase in the amount of fruits and seeds consumed by the individuals with the increasing of their body size. Finally, given the high consumption of material of allochthonous origin for Lithodoras dorsalis, we highlight the importance of riparian vegetation by providing items such as fruit and seeds, essential in the diet of Neotropical fishes and we emphasize the importance of ictiocoria for plants since many have sessile habit of life and cannot move from one location to another without the aid of dispersers.O objetivo deste estudo foi investigar aspectos alimentares do bacu-pedra Lithodoras dorsalis (Siluriformes: Doradidae) na região da foz Amazônica e seu possível papel como dispersor de sementes. As coletas dos espécimes de L. dorsalis foram realizadas mensalmente de julho de 2010 a junho de 2011, totalizando 371 espécimes capturados. Por meio da análise das gônadas constatou-se que todos os espécimes coletados encontravam-se imaturos, caracterizando-os como jovens. O comprimento padrão médio foi igual a 15,40cm (DP ± 4,87cm) e a massa total média igual a 94g (DP ± 149,45g). A dieta da espécie foi composta por 28 itens alimentares, dos quais 16 foram de origem alóctone e 12 de origem autóctone, o que define a espécie como herbívora, com forte tendência à frugivoria devido aos altos valores de importância de frutos e sementes presente em sua dieta. Houve diferença entre os períodos pluviométricos com relação a sazonalidade alimentar, sendo o final do período de transição entre chuva estiagem e o início da estiagem os períodos de menor e maior atividade alimentar, respectivamente. Porém, a importância dos itens consumidos entre os períodos pluviométricos não apresentou diferença, sendo que a dieta da espécie foi similar durante todo o período de coleta. Quanto à ictiocoria, dos 371 espécimes de Lithodoras dorsalis coligidos, 268 (74,93%) apresentaram frutos e sementes em seus estômagos (principalmente açaí Euterpe oleracea Mart., aninga Montrichardia linifera (Arruda) Schott e buriti Mauritia flexuosa Mart). Para as análises de germinação foram utilizadas sementes do açaí Euterpe oleracea Mart. e da aninga Montrichardia linifera (Arruda) Schott por atingirem quantidade suficiente de amostras. A partir da análise do trato digestivo do bacu-pedra constatou-se que todas as sementes de Euterpe oleracea Mart. apresentavam-se intactas, havendo um aumento no desempenho germinativo, porém o mesmo não ocorreu para as estruturas germinativas de aninga Montrichardia linifera (Arruda) Schott, algumas das quais apresentaram-se destruídas devido ao processo digestivo. Concluiu-se que Lithodoras dorsalis é um potencial dispersor do açaí Euterpe oleracea Mart. na Foz Amazônica, uma vez que há um aumento do desempenho germinativo das sementes. Foi constatado um acréscimo na quantidade de frutos e sementes consumidos à medida que os indivíduos aumentam o tamanho corporal. Por fim, tendo em vista o alto consumo de material de origem alóctone por Lithodoras dorsalis, destaca-se a importância da vegetação ripária por fornecer itens como frutos essenciais na dieta desta e de outras espécies de peixes neotropicais. Além disso, Lithodoras dorsalis parece fazer parte do mecanismo de algumas espécies de plantas para a colonização de novas áreas (ictiocoria), como no caso do açaí Euterpe oleracea Mart

The role of Lithodoras dorsalis (Siluriformes: Doradidae) as seed disperser in Eastern Amazon

Ichthyochory is an important process responsible for the high diversity of plant species in tropical flooded forests. Thus, this study aimed to investigate the role of a catfish species, Lithodoras dorsalis, as seed disperser in the flooded forests at the Amazon River mouth, Brazil. Analyzing the stomach contents of 371 individuals of Lithodoras dorsalis, the Germination Potential (GP%) and Germination Speed Index (GSI) of seeds that were removed intact were investigated. This allowed us to evaluate the germination performance of two important species of plants in Amazonia, Euterpe oleracea (Açaí) and Montrichardia linifera (Aninga), after passage through the digestive tract of this catfish species. Given that digestion by L. dorsalis reduced the germination viability of M. linifera and that seeds were often destroyed during consumption, we suggest that L. dorsalis may have a limited role as seed disperser of M. linifera and instead mostly act as seed predator. However, for the species E. oleracea, L. dorsalis was a potential disperser, since the performance of germination of these seeds was improved after digestion. In addition, the number of seeds consumed was directly proportional to the catfish’s body size, reinforcing the role of doradids as potential seed dispersers in tropical forests.CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorCNPq - Conselho Nacional de Desenvolvimento Científico e TecnológicoA ictiocoria é um importante processo responsável pela alta diversidade de espécies vegetais nas florestas tropicais alagadas. Dessa forma, este trabalho teve como objetivo investigar o papel de Lithodoras dorsalis como dispersor de sementes na Foz Amazônica, Brasil. Analisando o conteúdo estomacal de 371 espécimes de Lithodoras dorsalis, o Potencial de Germinação (PG%) e o Índice de Velocidade de Germinação (IGS) de sementes removidas intactas foram investigados. Isto permitiu-nos avaliar o desempenho germinativo de duas importantes espécies de plantas na Amazônia, Euterpe oleracea (Açaí) e Montrichardia linifera (Aninga), após passagem pelo trato digestivo desta espécie de bagre. Dado que a digestão por L. dorsalis reduziu a viabilidade de germinação de M. linifera e que as sementes foram frequentemente destruídas durante o consumo, sugerimos que L. dorsalis tem um papel limitado como dispersor de sementes de M. linifera e, em vez disso, age como predador de sementes. No entanto, para a espécie E. oleracea, L. dorsalis foi um potencial dispersor, uma vez que o desempenho germinativo das sementes foi melhorado após a digestão. Além disso, o número de sementes consumidas foi diretamente proporcional ao tamanho corporal do bagre, reforçando o papel de doradídeos como potenciais dispersores de sementes em florestas tropicais.UFPA - Universidade Federal do Par

Feeding ecology of immature Lithodoras dorsalis (Valenciennes, 1840) (Siluriformes: Doradidae) in a tidal environment, estuary of the rio Amazonas

Studies of feeding ecology are important for the evaluation of interactive processes in fish communities. This study evaluated the feeding ecology of Lithodoras dorsalis (Doradidae) from streams within the Amazon estuary delta (Brazil), a macro-tidal area, on different pluviometric periods. A total of 371 young specimens was collected during 12 months of sampling (July 2010 to June 2011). The species diet was composed of 28 food items analyzed by Repletion Index, Alimentary Index and Niche Breadth. Young L. dorsalis was classified as herbivore with a frugivory tendency due to the high importance of fruit and seeds in its diet. Food intake varied among sampled months, with the lowest intake being recorded during the rainy-dry season transition period, and the highest at the beginning of the dry season. The importance of food items and the composition of the diet were different throughout the year, probably due to the daily tides that allow fish to access new environments and the pluviometric periods. These results provide important data on the feeding ecology of Amazonian doradids. The study also emphasized the importance of allochthonous resources, derived from the riparian forest, which reinforces the importance of this habitat for the conservation of Neotropical freshwater fishes

Feeding ecology of immature Lithodoras dorsalis (Valenciennes, 1840) (Siluriformes: Doradidae) in a tidal environment, estuary of the rio Amazonas

Studies of feeding ecology are important for the evaluation of interactive processes in fish communities. This study evaluated the feeding ecology of Lithodoras dorsalis (Doradidae) from streams within the Amazon estuary delta (Brazil), a macro-tidal area, on different pluviometric periods. A total of 371 young specimens was collected during 12 months of sampling (July 2010 to June 2011). The species diet was composed of 28 food items analyzed by Repletion Index, Alimentary Index and Niche Breadth. Young L. dorsalis was classified as herbivore with a frugivory tendency due to the high importance of fruit and seeds in its diet. Food intake varied among sampled months, with the lowest intake being recorded during the rainy-dry season transition period, and the highest at the beginning of the dry season. The importance of food items and the composition of the diet were different throughout the year, probably due to the daily tides that allow fish to access new environments and the pluviometric periods. These results provide important data on the feeding ecology of Amazonian doradids. The study also emphasized the importance of allochthonous resources, derived from the riparian forest, which reinforces the importance of this habitat for the conservation of Neotropical freshwater fishes.CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorCNPq - Conselho Nacional de Desenvolvimento Científico e TecnológicoO estudo da ecologia alimentar de peixes é uma abordagem consistente na avaliação dos processos interativos dentro das comunidades. Dessa forma, este trabalho teve como objetivo investigar a ecologia alimentar do bacu-pedra Lithodoras dorsalis em furos próximos no delta do estuário Amazônico (Brasil), uma área sobre influência de macro-marés, em diferentes períodos pluviométricos. Durante 12 meses de coletas (julho de 2010 a junho de 2011), foram coligidos 371 espécimes jovens, sendo que a dieta da espécie foi composta por 28 itens alimentares analisados pelos seguintes índices: Índice de Repleção Estomacal, Índice de Importância Alimentar e Amplitude de Nicho. Lithodoras dorsalis quando jovem foi classificada como herbívora com tendência à frugivoria, devido aos altos valores de importância de frutos e sementes em sua dieta. A intensidade de obtenção de alimento por L. dorsalis diferiu entre os meses de coleta, onde o final do período de transição chuva-estiagem e o início da estiagem foram os períodos de menor e maior atividade alimentar, respectivamente. Também houve diferença na importância alimentar dos itens entre os períodos pluviométricos. Estes resultados fornecem informações importantes sobre a ecologia alimentar de doradídeos na Amazônia. Além disso, percebeu-se o alto consumo de material alóctone pelo bacu-pedra, sendo estes itens alimentares provenientes da floresta ripária, o que reforça a importância deste ambiente para a conservação da ictiofauna neotropical.BARBOSA, T. A. P; MONTAG, L. F. A. Universidade Federal do Par