Navegando por Assunto "Peixes de água doce"

Agora exibindo 1 - 4 de 4

Acesso aberto (Open Access)
Análise e caracterização do genoma mitocondrial: um estudo de caso de Cyprinodon sp. e Arapaima gigas
(Universidade Federal do Pará, 2025-05) MACEDO, Daralyns Borges; RAMOS, Rommel Thiago Juca; http://lattes.cnpq.br/1274395392752454; https://orcid.org/0000-0002-8032-1474
The advancement of next-generation sequencing technologies has enabled large-scale characterization of mitochondrial genomes across various species. However, even among fish — the group with the highest number of sequenced mitochondrial genomes — only 9.7% of valid species are represented in genetic databases. This gap limits conservation programs, which rely on genetic data to guide management strategies. The genus Cyprinodon, composed of several threatened species restricted to isolated habitats, is particularly vulnerable to habitat loss and interspecific hybridization. In this context, the present study aimed to sequence and characterize the mitochondrial genome of Cyprinodon sp., in order to clarify phylogenetic relationships and evolutionary aspects of the Cyprinodontidae family. The sample was sequenced using the Illumina HiSeq platform, assembled with Megahit software, and analyzed using tools such as MitoZ, Circos, ClustalW, MrBayes, and Figtree. The complete mitogenome comprises 16,500 bp and contains 37 genes. Concurrently, Arapaima gigas, an iconic Amazonian species historically important to fisheries, is currently threatened with extinction and classified as “Data Deficient” by the IUCN. In the Tocantins River, heavily impacted by human activities, fishers from 25 communities reported the near disappearance of the species, with only one recent sighting on Jaracuera Island. The disappearance of A. gigas has severe economic consequences for local communities. Without collaboration between fishery managers and local populations, the species faces an imminent risk of regional extinction, further exacerbated by the lack of data on its fishing dynamics in northern Brazil.
Acesso aberto (Open Access)
A heterogeneidade de bancos de macrófitas aquáticas e a diversidade de peixes em uma ria fluvial amazônica
(Universidade Federal do Pará, 2019-03) NONATO, Flávia Alessandra da Silva; MONTAG, Luciano Fogaça de Assis; http://lattes.cnpq.br/4936237097107099; https://orcid.org/0000-0001-9370-6747; MICHELAN, Thaísa Sala; http://lattes.cnpq.br/4609629132683283; https://orcid.org/0000-0001-9416-0758
In freshwater ecosystems, macrophyte species can provide habitat heterogeneity with different structural forms, ranging from free submerged species to rooted species, which serve as a substrate for spawning, food and refuge against predation to fish and other organism. In the 49 present work we tested the effect of the heterogeneity of aquatic macrophyte banks on the richness and abundance and functional traits of the fish in flooded rivers of the Amazon. To investigate the relationship between the heterogeneity of the macrophyte banks and the richness, abundance, and functional characteristics of the fish, we used them CWM analysis and simple linear regressions. We identified 16 species of aquatic macrophytes and 21 species of fish in the 34 sampling points. The macrophyte banks were dominated by the species Eichhornia azurea and. E. crassipes. The most abundant fish species were Hemigrammus ocellifer and Laimosemion strigatus. The linear regression result was only significant between the heterogeneity of the macrophyte banks on two functional attributes, both linked to the locomotion of the fish. Our results show that the association between the heterogeneity provided by the macrophyte banks is an environmental filter for fish species that have high maneuverability, since these species can swim between macrophyte structures. Thus, we can observe that the heterogeneity provided by aquatic macrophytes, although not affecting the richness and abundance of fish, is important for different species of fish, but for those that use and depend on these banks as a refuge.
Acesso aberto (Open Access)
Influência dos fatores ambientais sobre a estrutura de comunidade de peixes em diferentes ambientes aquáticos na Amazônia
(Universidade Federal do Pará, 2024-04) SILVA, Ronaldo Souza da; ORTEGA, Jean Carlo Gonçalves; http://lattes.cnpq.br/7951329810755189; HTTPS://ORCID.ORG/0000-0001-5097-9382; MONTAG, Luciano Fogaça de Assis; http://lattes.cnpq.br/4936237097107099; https://orcid.org/0000-0001-9370-6747
Species diversity varies over time and space as a reflection of resource availability, suitable conditions, and biotic interactions that can locally exclude species from the regional pool. Understanding the causes of species variations remains challenging for ecologists. Still, it is already known that both biotic (interactions) and local environmental conditions (abiotic variables) are important factors in determining fish richness and abundance. Environmental conditions act differently in various aquatic ecosystems, structuring fish assemblages differently. In this context, the central objective of this thesis was to evaluate how local and regional environmental factors influence fish assemblage structure in different aquatic ecosystems in the southwest Amazon. Firstly, we assessed how the environment affects fish assemblages in river beaches. Next, we evaluated how local and regional environments influence the fish assemblage structure associated with aquatic macrophyte banks in lake environments. Finally, we examined how stream fish assemblage structure responds answered to local and regional environmental factors. In beach habitats, we found that temperature, dissolved oxygen, and depth were important in determining variation in fish species composition, while the temperature was the only variable influencing species richness. For fish in macrophyte banks habitats, the results indicated that both local and regional environmental variables (space and hydrological period) influenced fish assemblage structure. The variables depth of macrophyte bank, bank size, and space were significant for species richness. For species composition, environmental factors such as macrophyte composition, bank size, macrophyte richness, and regional variables such as space and hydrological period were influential, with the hydrological period being the strongest predictor of this variation, showing that flood pulses are a strong determinant in the structure of fish assemblages associated with macrophyte banks in Amazonian floodplains. Finally, we evaluated the influence of local, regional (landscape), and spatial factors on fish assemblage structure in upland streams in western Amazonia. The percentage of forest and spatial component (identity of Conservation Units) influenced species richness. Meanwhile, physical habitat and spatial variables influenced species composition, indicating that the fish assemblage in Amazonian streams answered to intact environments and habitat characteristics capable of supporting the persistence of these assemblages within and between watersheds.
Acesso aberto (Open Access)
New species of Pyrrhulina (Teleostei: Characiformes: Lebiasinidae) from the eastern Amazon, Pará, Brazil
(Universidade Federal do Pará, 2019-07) FERREIRA NETTO, André Luiz; VIEIRA, Lorena Silva
A new species of Pyrrhulina is described based on 60 specimens from tributaries of the rio Amazonas: rio Anapu, rio Capim, rio Guamá and rio Xingu, and coastal drainages in the state of Pará, Brazil. The new species differs from all congeners by having the primary stripe (the horizontal stripe of dark pigmentation extending posteriorly from the snout) terminating at the distal edge of the opercle. In all other species of Pyrrhulina, the primary stripe is either restricted to the snout or continues beyond the head (i.e. at least the anteriormost four scales of the lateral line series).