Environmental predictors of the life history of the flag tetra Hyphessobrycon heterorhabdus (Characiformes: Characidae) in streams of the Eastern Amazon

Abstract This study aimed to characterize the reproductive biology of Hyphessobrycon heterorhabdus, and its response to environmental variations in the Eastern Amazon streams. We sampled specimens every two months, between March 2019 and January 2020. The population was evaluated for sex ratio, reproductive activity, growth pattern, condition factor, size at the first sexual maturation, spawning type, and fecundity. We analyzed 180 specimens, which showed a sex ratio of 1.6 males for each female across the whole period, with 2.3 males for each female during the period of greatest reproductive activity. The peak of reproductive activity coincided with higher precipitation periods and was partially predicted by factors such as water temperature, stream discharge, dissolved oxygen, substrate complexity, and electrical conductivity. The length where 50% and 100% of population to reach sexual maturity was 18.0 and 22.0 mm for males and 19.7 and 27.0 mm for females. The oocyte diameters showed a bimodal frequency, with at least two batches of oocytes. The average fecundity of 197 oocytes. The results indicate that this species presents an opportunistic strategy, and the tactics that make up this strategy depend on variations in both the physical structure of the habitat and physicochemical aspects of the water

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

Catálogo Taxonômico da Fauna do Brasil: setting the baseline knowledge on the animal diversity in Brazil

The limited temporal completeness and taxonomic accuracy of species lists, made available in a traditional manner in scientific publications, has always represented a problem. These lists are invariably limited to a few taxonomic groups and do not represent up-to-date knowledge of all species and classifications. In this context, the Brazilian megadiverse fauna is no exception, and the Catálogo Taxonômico da Fauna do Brasil (CTFB) (http://fauna.jbrj.gov.br/), made public in 2015, represents a database on biodiversity anchored on a list of valid and expertly recognized scientific names of animals in Brazil. The CTFB is updated in near real time by a team of more than 800 specialists. By January 1, 2024, the CTFB compiled 133,691 nominal species, with 125,138 that were considered valid. Most of the valid species were arthropods (82.3%, with more than 102,000 species) and chordates (7.69%, with over 11,000 species). These taxa were followed by a cluster composed of Mollusca (3,567 species), Platyhelminthes (2,292 species), Annelida (1,833 species), and Nematoda (1,447 species). All remaining groups had less than 1,000 species reported in Brazil, with Cnidaria (831 species), Porifera (628 species), Rotifera (606 species), and Bryozoa (520 species) representing those with more than 500 species. Analysis of the CTFB database can facilitate and direct efforts towards the discovery of new species in Brazil, but it is also fundamental in providing the best available list of valid nominal species to users, including those in science, health, conservation efforts, and any initiative involving animals. The importance of the CTFB is evidenced by the elevated number of citations in the scientific literature in diverse areas of biology, law, anthropology, education, forensic science, and veterinary science, among others

Aspectos reprodutivos e alimentares da piranha Serrasalmus gouldingi fink & machado-allison, 1992 (Characiformes: Serrasalmidae) em rios afogados da Amazônia Oriental

The present work aimed to evaluate the reproductive biology, condition factor and feeding ecology of Serrasalmus gouldingi in relation to fluviometric variations of lower Anapu River, in “drowned” rivers of Caxiuanã National Forest, Eastern Amazonia, Pará, Brazil. 275 specimens were bimonthly collected during July 2010 to May 2011 and their total length, total weight, gonad and stomach weight were measured. The gonads were analysed histologically to verify the sex and maturation degree, while the stomachs were evaluated through the identification of the consumed items. The sexual proportion did not differ from 1:1considering the studied period as a whole, however the females were more frequent during the transitional periods of drawdown and filing. The species spawning was “parcelada”, showing two peeks of reproductive activity during the periods which preceded the increase in the local fluviometry. The L50 was estimated in 12.24cm for males and in 16.13cm for females. The species growth was positively alometric, showing a gain of weight in relation to length, and the condition factor, when analysed along the entire sample period, decreased mostly during the spawning. The diet of S. gouldingi was composed of 32 items, grouped in 10 categories. The composition indicated an omnivorous diet with a strong tendency to piscivory, once fish fragments were the most predominant item, followed by fruits and seeds and allochthonus arthropods. The distinct hidrological periods were significantly different in relation to diet composition, although no significant difference was detected among sex and maturation degree. Males and females showed the same variation pattern of repletion index, with a more intense feeding during the increase of the river´s level, while it was less intense during the transitional periods (drawdown and filing). The species also showed some variation in their breadth niche, with lower values during the wet period, attributed to the almost exclusive consumption of fruits and seeds.O presente trabalho teve como objetivo avaliar a biologia reprodutiva, fator de condição e ecologia alimentar da piranha Serrasalmus gouldingi em relação a variações fluviométricas de rios afogados da região do baixo Rio Anapu, Amazônia Oriental, Pará, Brasil. Foram analisados 275 exemplares coletados bimestralmente de julho 2010 a maio 2011. Após coletados, os indivíduos foram mensurados quanto ao comprimento total, massa total e eviscerados para obtenção da massa da gônada e do estômago. As gônadas foram verificadas histologicamente quanto ao sexo e estágio de maturação, e os estômagos avaliados através da identificação do conteúdo estomacal. Quanto aos aspectos reprodutivos, a proporção sexual observada não diferiu de 1:1 para o período estudado como um todo, enquanto que para os diferentes períodos amostrados, verificou-se o predomínio de fêmeas durante os períodos transicionais de enchente e vazante. A espécie apresentou uma desova do tipo parcelada com dois picos de atividade reprodutiva nos períodos que antecederam os principais aumentos na fluviometria local. O L50 foi estimado em 12,24cm para machos e 16,13cm para fêmeas. O crescimento da espécie mostrou-se do tipo alométrico positivo, com um maior incremento de peso em relação ao comprimento e um fator de condição que, quando analisado ao longo do período amostrado, apresentou um decréscimo principalmente durante o período de desova. A dieta de S. gouldingi foi composta de 32 itens, agrupados em 10 categorias alimentares. Baseado em sua composição os resultados indicaram uma dieta onívora com forte tendência à piscivoria com um predomínio no consumo da categoria fragmentos de peixe, seguida por frutos e sementes e artrópodes alóctones. Diferenças na composição da dieta foram verificadas entre diferentes períodos hidrológicos, contudo, não houve diferença entre o sexo e estágio de maturação. Para o índice de repleção, machos e fêmeas apresentaram um mesmo padrão de variação, mostrando uma alimentação mais intensa durante os períodos de aumento do nível dos rios, e uma atividade menos intensa durante os períodos transicionais de vazante e enchente. A espécie também demonstrou variação em sua especificidade alimentar com uma dieta mais especialista durante o período de cheia, atribuída ao consumo quase que exclusivo de frutos e sementes

Influência da exploração madeireira na estrutura do hábitat e diversidade das assembleias de peixes de riachos na amazônia oriental

Logging is one of the main activities responsible for the deforestation in the Amazon and is considered an important threat to biodiversity in this region. However, the international market demand for sustainable forest products has resulted in a partial substitution of the conventional exploration method (CE) with the reduced impact exploration (EIR) technique, also considered an important strategy to minimize damages to the Amazon forest and its biodiversity. However, little is known about the effect of these activities on the structure and functioning of riparian ecosystems and their biological communities. In this sense, the present study aimed to evaluate the effect of different methods of logging on the structure of the physical habitat of streams and taxonomic and functional diversity of the fish assemblages of these environments, as well as the elaboration of multimetric indices that allow a rapid and robust evaluation of the ecological integrity of these environments. A total of 47 streams were sampled in the Rio Capim basin, 13 of which were in unexplored areas, 11 in EC areas and 23 in RIL areas. The habitat structure was characterized based on 19 environmental variables, later compared between the different exploration methods. The fish assemblages were sampled using hand net, with a standardized effort, and evaluated as to the composition and different components of the functional diversity. Both methods of logging resulted in changes in the structure of the physical habitat of the streams, however only in areas of CD these changes influenced the taxonomic composition of fish species. In RIL areas only variations in the relative abundance of fish species were observed in relation to the temporal exploitation gradient. Despite the above results, the presence of logging, be it EC or EIR did not affect components of the functional diversity of fish assemblages. However, changes in the habitat of rachis associated with the presence of logging had been directly related to the functional attributes commonly associated with generalist strategies of the species, which are common associated with altered environments. According to the multimetric indexes, streams in RIL areas presented better habitat integrity when compared to streams in CD areas, but still lower than habitat integrity in unexplored streams. On average, EIR areas also presented intermediate values ​​of biotic integrity, however, this differed only in areas of CD. In the studied region, RIL showed to be an interesting strategy to minimize alterations in riach ecosystems resulting from logging. However, the present study was conducted only on a local spatial scale, and considering areas that went through a single exploration cycle. However, changes in physical habitat show that EIR also influence the structure and consequently the ecological integrity of these environments, reinforcing the need for a greater number of studies to understand the real effect of this activity in these environments.CNPq - Conselho Nacional de Desenvolvimento Científico e TecnológicoA exploração madeireira encontra-se entre as principais atividades responsáveis pelo descatamento na Amazônia, sendo considerada uma importante ameaça para biodiversidade dessa região. Contudo, a demanda do mercado internacional por produtos florestais sustentáveis resultou em uma substituição parcial do método de exploração convencional (EC) pela técnica de exploração de impacto reduzido (EIR), também condiderada uma importante estratégia para minimizar danos à floresta Amazônica e sua biodiversidade. No entanto, pouco se conhece sobre o efeito dessas atividades na estrutura e funcionamento dos ecossistemas de riachos e suas comunidades biológicas. Nesse sentido, o presente estudo objetivou avaliar o efeito dos diferentes métodos de exploração madeireira sobre a estrutura do habitat físico de riachos e diversidade taxonômica e funcional das assembleias de peixe desses ambientes, além da elaboração de índices multimétricos que permitam uma avaliação rápida e robusta da integridade ecológica desses ambientes. Foram amostrados 47 riachos na bacia do Rio Capim, sendo 13 em áreas não exploradas, 11 em áreas de EC e 23 em áreas de EIR. A estrutura do hábitat foi caracterizada com base em 19 variáveis ambientais, posteriormente comparada entre os diferentes métodos de exploração. As assembleias de peixes foram amostradas utilizando rede de mão, com um esforço padronizado, e avaliadas quanto a composição e diferentes componentes da diversidade funcional. Ambos os métodos de exploração madeireira resultaram em alterações na estrutura do habitat físico dos riachos, no entanto somente em áreas de EC essas alterações influenciaram na composição taxonômica das espécies de peixes. Em áreas de EIR, foram observadas apenas variações na abundância relativa das espécies de peixe em relação ao gradiente temporal de exploração. Apesar dos resultados acima, a presença da exploração madeireira, seja ela EC ou EIR não afetou componentes da diversidade funcional das assembleias de peixe. No entanto, alterações no habitat de raichos associados a presença da exploração madeireira estivera diretamente relacionado à atributos funcionais comumente associados a estratégias generalistas das espécies, as quais são comuns associadas a ambientes alterado. De acordo com os índices multimétricos, riachos em áreas de EIR apresentaram uma melhor integridade do habitat quando comparados a riachos em áreas de EC, mas que asinda sim foi inferior a integridade do habitat em riachos não explorados. Em média, áreas de EIR também apresentaram valores intermediários de integridade biótica, contudo, este diferiu somente em áreas de EC. Na região estudada, a EIR mostrou ser uma estratégia interessante para minimizar as alterações nos ecossistemas de riach resultante da exploração madeireira. Contudo, o presente estudo foi realizado apenas em uma escala espacial local, e considerando áreas que passaram por um único ciclo de exploração. Contudo as alterações no habitat físico demosntram que a EIR também influência na estrutura e consequentemente na integridade ecológica desses ambientes, reforçando a necessidade de um maior número de estudos para compreensão do real efeito dessa atividade nesses ambientes