How deforestation drives stream habitat changes and the functional structure of fish assemblages in different tropical regions

Abstract

Deforestation can modify stream habitat and the functional structure of fish assemblages. The aims of this study were (a) to identify whether deforestation has a similar effect on local habitats from two biogeographically distinct river basins in a tropical region; (b) to identify how fish trait–habitat relationships were influenced by deforestation; and (c) to compare functional redundancy patterns in these basins. Environmental and biological variables were obtained for 160 stream reaches, 85 located in the Alto Paraná River basin and 75 in the Machado River basin. Traits were associated with body size, habitat preference, food items and foraging period. Linear models were constructed to verify the environmental convergence of habitats across streams from the Alto Paraná and the Machado basins. An RLQ and a fourth‐corner analysis were conducted to investigate how deforestation affected habitat variables and trait–habitat relationships. The nearest relative index (NRI) was used as a functional redundancy measure. Deforestation led to a similar habitat gradient from streams with a higher proportion of coarse roots in more forested catchments to streams with streamside grasses, bare soil and unconsolidated substrate in more deforested catchments; however, a general pattern of fish trait–habitat relationships was not identified across basins. Functional redundancy was associated with a long history of habitat loss in the Alto Paraná streams, whereas functional complementarity was related to more recent and less intense habitat loss in Machado streams. We believe that differences in regional species pools and historical processes between the basins influenced the fish functional responses to deforestation. Nevertheless, the results highlighted the importance of stream habitat heterogeneity and the presence of preserved forest fragments in a region to prevent the loss of unique traits. Decision‐makers should therefore maintain large forest fragments and restore riparian forests to preserve stream habitat and the functional structure of fish assemblages.

Fishes from the Río Alvarado drainage, Upper Río Magdalena Basin, Colombia

“…The sampling campaigns of this study were carried out seven years ago and some environmental conditions along the Río Alvarado drainage could have changed since then due to continuous anthropogenic activities, as deforestation, land use, and water pollution. The effects of these human activities mainly include changes related to habitat heterogeneity (Bojsen and Barriga 2002;Cassatti et al 2012) and loss of functional and species diversity (Ferreira et al 2018;Zeni et al 2019). Accordingly, this raises interest to assess if the composition noted in this study has changed through time.…”

Avaliação ambiental da qualidade limnologica e de sedimentos em córrego do Centro Oeste do Brasil

“…Deste modo, a redução e a alteração da paisagem próximo aos corpos hídricos pode afetar a integridade ambiental, pois a vegetação ciliar tem a função regular a temperatura através do sombreamento e controlar a entrada de contaminantes e sedimentos nos corpos hídricos (Lorion;Kennedy, 2009;Gonçalves et al, 2018). Sendo que, uma das grandes consequências do desmatamento da mata densa é o desequilíbrio ambiental, o impacto imediato sobre a segurança da vida aquática (Zeni et al, 2019). A redução da cobertura vegetal nativa no entorno do córrego Curral de Arame, pode estar facilitando ao transporte de elementos químicos, corroborando os resultados de elevados valores de Fe na água deste ambiente aquático.…”

“…Research, Society andDevelopment, v. 9, n. 8, e893986288, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i8.6288 menores serão as concentrações de Fe no leito do córrego Curral de Arame. Sendo que, a vegetação ciliar tem função reguladora para manter a qualidade da água, além de, atuar como filtro natural, como uma barreira física para mitigar a entrada de sedimentos e de contaminantes no curso de rios e córregos (Zeni et al, 2019) Importante salientar, que por mais que o Fe seja considerado um elemento essencial para as funções biológicas dos organismos, por outro lado, seu excesso disponível na água do córrego Curral de Arame pode acarretar sérios danos na vida aquática, principalmente pelo seu potencial de bioacumulação (Maurya et al, 2019). Além de, poder provocar riscos da ingestão desta água com elevados valores de Fe, por animais domésticos e silvestres.…”

How modified landscapes filter rare species and modulate the regional pool of ecological traits?

“…These changes are related to species-specific traits and have a marked effect on the functional structure of communities. For example, local deforestation reduces substrate heterogeneity, streambed stability and wood volume, and thus have negative effects on species that explore the stream bottom and highly structured microhabitats, such as those with broad pectoral fins and dorsal eyes (Leitão et al, 2018;Zeni et al, 2019).…”