Navegando por Assunto "Habitat (Ecologia)"

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Acesso aberto (Open Access)
Composition of functional ecological guilds of the fish fauna of the internal sector of the Amazon Estuary, Pará, Brazil
(2014-12) MOURÃO, Keila Renata Moreira; FERREIRA, Valdimere; FRÉDOU, Flávia Lucena
The present study describes the spatial and temporal structure of the estuarine fish community in the internal sector of the Amazon Estuary. Samples were obtained in the main channels and tidal creeks of Guajará and Marajó Bays and Guamá River. A total of 41,516 fish specimens were collected, representing 136 taxa, 38 families and 12 orders. In the dry season, the mean salinity of the main channel increased along a limnicmarine gradient, between the Guamá River and the Marajó Bay. Species richness was lowest in the mouth of the Guamá River and in the right margin of the Guajará Bay. Fish species composition and environmental guilds differed markedly among areas: Migrants and Freshwater Stragglers were dominant in the Guamá River and the Guajará Bay, while Estuarine, Marine Stragglers and Migrants predominated in the Marajó Bay. However, the trophic guilds were still relatively well balanced, in functional terms. Piscivores and Zoobenthivores were the dominant feeding functional groups in all the studied areas. In this study, the assessment of the community and the use of the guild approach were efficient to describe the structure and functioning of the assemblages of estuarine fish also helping to assess the anthropogenic pressures in the area.
Acesso aberto (Open Access)
Efeito da monocultura de dendezeiro (Elaeis guineensis JACQ.) na integridade física e nas assembleias de peixes de igarapés da Amazônia Oriental
(Universidade Federal do Pará, 2014-02-25) FERREIRA, Márcio Cunha; JUEN, Leandro; http://lattes.cnpq.br/1369357248133029; MONTAG, Luciano Fogaça de Assis; http://lattes.cnpq.br/4936237097107099
The aim of the present study is to evaluate the effect of palm oil farming Elaeis guineenses JACQ. in the integrity of physical habitat and in the assemblages of fishes in upland streams of Eastern Amazonia. The sampling sites were established in sections (150 m) of 23 streams in the Acará-Mirim basin, northeastern of Pará state. According to the results of the index of physical integrity, all streams (n = 8) that drain forest areas were classified as preserved (IPI = 5.00 to 4.00), whereas the 15 streams that drain oil palm plantations have been classified as changed (IIF = 3.67 to 2.67). 9,734 specimens of fish belonging to six orders, 24 families, over 64 species were collected. The most abundant species during the study were Microcharacidium weitzmani, Apistogramma gr. regain, Trichomycterus hasemani, Hyphessobrycon heterorhabdus and Copella arnoldi. The richness observed in streams that drain plantations was higher (S = 61) than found in the streams in forest fragments (S = 42). The results of PERMANOVA show that exist differences between sites (GL = 22; pseud – F = 2.44; P = 0.01), however the ordering produced by NMDS shows that this difference is subtle (stress = 0.19). a similar result was obtained using functional trophic groups abundance (stress = 0.18). the results of TITAN indicates that some species are adapted to persist in certain environmental conditions, such as Aequidens tetramerus, Apistogramma agassizii and Microcharacidium weitzmani are associated with lower physical habitat integrity (P < 0.05; purity > 0.95; reliability > 0.95), while the species Hyphessobrycon heterorhabdus and Helogenes marmoratus shown to be indicative of more intact habitats (P < 0.05; purity > 0.95; reliability > 0.95). There was no correlation between the species richness and the index of physical integrity, while the only functional trophic groups that correlated with the index were the diggers and collectors browsers. These groups are composed by Cichlid fishes that have tolerant and generalist behaviors that may have explained his great contribution in the fish assemblage even in places where sedimentation was high compared to places with the nearest natural setting. This shows that even species richness was higher in altered streams there are strong evidences of loss of environmental quality in streams draining plantations generated by the cultivation of oil palm.
Acesso aberto (Open Access)
Efeitos de perturbações antrópicas sobre os fatores ambientais e espaciais na estruturação de metacomunidades de insetos aquáticos na Amazônia Oriental
(Universidade Federal do Pará, 2022-07) OLIVEIRA, Stéfany Vitória Santos; FARIA, Ana Paula Justino de; http://lattes.cnpq.br/6041546003155327; https://orcid.org/0000-0003-2729-5358; SANTOS, Raphael Ligeiro Barroso; http://lattes.cnpq.br/7227882802366966; https://orcid.org/0000-0001-9717-5461
Anthropogenic pressures resulting from changes in land use have great potential to impact the dynamics of aquatic insect metacommunities, once they alter the environmental quality of streams, and may impose barriers to dispersal. The objective of this study is to evaluate the structuring of aquatic insect assemblages (Ephemeroptera, Plecoptera and Trichoptera orders - EPT) in Amazonian streams under natural conditions (control streams) and under disturbance by human activities (altered streams) is influenced by characteristics of fluvial habitats and by the spatial structure. Our hypotheses is that in control streams, habitat characteristics are the main structuring factor of EPT assemblages, and that in altered streams, habitat characteristics related to human disturbances and spatial structure are the main assemblage structuring factors. A total of 74 streams were sampled in the Capim River basin, Pará, Brazil, wich 38 are control streams and 36 are altered streams. In each of them, environmental variables associated with water chemistry, channel hydromorphology, sediment types, riparian vegetation and insect shelter were measured, in addition to the proportion of land uses and EPT assemblages. Our results showed that several environmental characteristics of the streams were affected by human activities. Environmental factors had a greater influence on the structuring of EPT assemblages than the other factors evaluated, both in the control and altered streams. The influence of the spatial factor was weak. The assemblages of altered streams were structured both by environmental variables affected by disturbances and by variables subject to natural variation, demonstrating that the assemblages in these environments are not governed only by environmental changes. Our study demonstrates the importance of the species sorting process in metacommunities of Amazonian streams, and the role of disturbance in this process.
Acesso aberto (Open Access)
Padrões ecológicos de tubarões (Superordem: Selachimorpha) fósseis e recentes obtidos a partir de isótopos estáveis e suas considerações para manejo e conservação
(Universidade Federal do Pará, 2016-02-12) LUZ, Zoneibe Augusto Silva; TOLEDO, Peter Mann de; http://lattes.cnpq.br/3990234183124986
Sharks populations are declining drastically in many parts of the world, demanding new complementary approaches for the comprehension of biological characteristics. Amplifying the temporal range of investigation to the Miocene past (23 Ma), this research had as objective interpret ecological features from extant and fossil sharks by the way of stable isotopes measurements of carbon and oxygen, looking to generate intellectual basis for management and conservation plans. In total, 46 teeth of several localities were utilized, most are from the coastal region of eastern Amazonia, but also from proto-Caribbean fossiliferous deposits. Isotopic analysis were employed in the distinct bioapatites structures: carbonate and phosphate, where the enameloid was preferentially uptaken in the samples to reduce possibilities of collect unoriginal chemical signatures. A tooth file analyzed from extant specimens exhibited strong correlations among the involved variables (carbon and oxygen), potentially signaling an isotopic fractionation effect in the carbonate structure varying in accordance with tooth development. Oxygen in phosphate results ranged between 18,9‰ to 21.4 ‰, indicating paleotemperatures where these animals lived around 21,6°C to 30,6°C. Statistical tests were performed in the observed values, allowing the discrimination of three groups: Pirabas group (fossil sharks of Pirabas Formation) Recent group (extant sharks of the Amazon coastal region) and non-Pirabas group (fossil sharks of proto-Caribbean deposits). Global, regional and biological environmental considerations about these individuals were revised to understand their distinct chemical signatures. Oceanographic influences and changes in planetary patterns seem to justify some peculiarities of the measures found in non-Pirabas group. On the other hand, the ecological stability verified comparing the paleotemperatures of the Pirabas group with the Recent group suggests resilience on the part of these sharks, by maintaining similar ecological niches during geological time in the Amazon region. However, it also implies a biological preference for swimming in specific conditions for a better physiological performance. The ecological pattern of activity proposed for the sharks of the northern Brazil (23°C-30°C), in addition to paleointerferences about the group here realized should be incorporated in future plans of management and conservation of elasmobranchs, as they reinforce the existing scientific knowledge concerning this táxon.
Acesso aberto (Open Access)
Use of intertidal areas by shrimps (Decapoda) in a brazilian Amazon estuary
(2014-03) SAMPAIO, Herbet Aranha; MARTINELLI-LEMOS, Jussara Moretto
The present work investigated the occupation and the correlation of the shrimp abundance in relation to environmental variables in different habitats (mangroves, salt marshes and rocky outcrops) in an Amazon estuary. The collections were made in August and November 2009, at low syzygy tide on Areuá Beach, situated in the Extractive Reserve of Mãe Grande de Curuçá, Pará, Brazil totaling 20 pools. In each environment, we recorded the physical-chemical factors (pH, salinity, and temperature) and measured the area (m²) and volume (m³) of every pool through bathymetry. The average pH, salinity, temperature, area and volume of tide pools were 8.75 (± 0.8 standard deviation), 35.45 (± 3), 29.49 °C (± 2.32), 27.41 m² (± 41.18), and 5.19 m³ (± 8.01), respectively. We caught a total of 4,871 shrimps, distributed in three families and four species: Farfantepenaeus subtilis (98.36%) (marine) followed by Alpheus pontederiae (0.76%) (estuarine), Macrobrachium surinamicum (0.45%) and Macrobrachium amazonicum (0.43%) predominantly freshwater. The species F. subtilis and A. pontederiae occurred in the three habitats, whereas M. surinamicum occurred in salt marsh and rocky outcrop and M. amazonicum only in marisma. Temperature and pH were the most important environmental descriptors that significantly affected the density and biomass of shrimps.