Navegando por Autor "Ferreira, R. L."

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Artigo
Environmental factors structuring the assemblage of aquatic insects in an epigean and hypogean stretch of a Neotropical karst stream
(2021-02-01) Martins, V. M.; Ferreira, R. L.
The aim of the present study was to identify which variables structure the assemblage of aquatic insects in the subterranean environment, because knowledge about how subterranean communities are structured in rivers with hypogean sections is still emerging. In addition to identifying whether the hypogean assemblage is structured in the same way as the epigean assemblage, we sought to identify whether the environmental restrictions caused by the subterranean habitat resulted in reduced species richness and abundance compared with the epigean habitat. We sampled a 345-m stretch of a stream in Brazil and collected aquatic insects from both the epigean and hypogean environments. In the stream stretch investigated, there was a positive relationship between richness and the percentage of immersion, fine substrate and organic matter, and a negative relationship between richness and conductivity. We also verified differences between the epigean and hypogean environments regarding composition. The variables that best explained the overall assemblage structure included the epigean–hypogean environment and the percentage of coarse and fine substrate. Given the differences between these environments, we emphasise the need for management actions in karst regions that consider the discontinuity of these regions’ river communities to conserve all components of diversity.
Artigo
Environmental factors structuring the assemblage ofaquatic insects in an epigean and hypogean stretch of aNeotropical karst stream
(2021-02-01) Martins, V. M.; Ferreira, R. L.
The aim of the present study was to identify which variables structure the assemblage of aquatic insects in thesubterranean environment, because knowledge about how subterranean communities are structured in rivers withhypogean sections is still emerging. In addition to identifying whether the hypogean assemblage is structured in thesame way as the epigean assemblage, we sought to identify whether the environmental restrictions caused by thesubterranean habitat resulted in reduced species richness and abundance compared with the epigean habitat. We sampled a345-m stretch of a stream in Brazil and collected aquatic insects from both the epigean and hypogean environments. In thestream stretch investigated, there was a positive relationship between richness and the percentage of immersion, finesubstrate and organic matter, and a negative relationship between richness and conductivity. We also verified differencesbetween the epigean and hypogean environments regarding composition. The variables that best explained the overallassemblage structure included the epigean–hypogean environment and the percentage of coarse and fine substrate. Giventhe differences between these environments, we emphasise the need for management actions in karst regions that considerthe discontinuity of these regions’ river communities to conserve all components of diversity.
Artigo
We prefer nighttime, they prefer daytime: Biological rhythm variability in cave-dwelling whip spiders (Amblypygi: Charontidae) in the Neotropics
(2024-10-13) Souza, P. E. de; Gonçalves, B. da Silva Brandão; Souza-Silva, M.; Ferreira, R. L.
The lack of understanding regarding how endogenous and behavioral factors affect the biological rhythms of amblypygid arachnids in cave environments underscores a gap in chronobiologic knowledge for this group. This study investigates the influence of specialization on subterranean habitats and the presence of biological rhythms on the locomotor activity patterns of the troglobitic and troglophilic species of the genus Charinus. Specimens collected from carbonate caves in Brazil were subjected to experimental treatments of constant light (LL), constant darkness (DD), and light–dark cycles (LD). The results revealed variations in the distribution of main periods among species, without a uniform pattern. Although some specimens showed greater variability in activity patterns in the DD and LL treatments, no significant differences were observed between troglobites and troglophiles. The lack of a clear distinction in rhythms between the two groups suggests the dynamic nature of circadian rhythms in these populations, where individual variations in activity patterns indicate this behavioral diversity. Additionally, intraspecific competition for food resources, probably intensified by the oligotrophic conditions of the cave environments, may play an important role in shaping these patterns and differences in activity phases. The presence of infradian rhythms and weak circadian rhythms in some individuals underscores the importance of considering non-photic zeitgebers for a deeper understanding of these rhythms in cave organisms.