Land cover, riparian zones and instream habitat influence stream fish assemblages in the eastern Amazon

Abstract

The Amazon rainforest has experienced rapid land-use changes over the last few decades, including extensive deforestation that can affect riparian habitats and streams. The aim of this study was to assess responses of stream fish assemblages to deforestation and land cover change in the eastern Amazon. We expected that percentage of forest in the catchment is correlated with local habitat complexity, which in turn determines fish assemblage composition and structure. We sampled 71 streams in areas with different land uses and tested for relationships between stream fish assemblages and local habitat and landscape variables while controlling for the effect of inter site distance. Fish assemblage composition and structure were correlated with forest coverage, but local habitat variables explained more of the variation in both assemblage composition and structure than landscape variables.Inter site distance contributed to variance explained by local habitat and landscape variables, and the percentage of variance explained by the unique contribution of local habitat was approximately equivalent to the shared variance explained by all three factors in the model. In these streams of the eastern Amazon, fish assemblages were most strongly influenced by features of instream and riparian habitats, yet indirect effects of deforestation on fish assemblage composition and structure were observed even though intact riparian zones were present at most sites. Long-term monitoring of the hydrographic basin, instream habitat and aquatic fauna is needed to test for potential legacy effects and time lags, as well as assess species responses to continuing deforestation and land-use changes in the Amazon. Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for PROCAD/ CAPES funding (project no 88881.068425/2014-01), the graduate scholarship for TOB and senior internship scholarship for LFAM to conduct research at Texas A&M University (process 88881.119097/2016-1). The manuscript was improved during the review process by addressing the thoughtful comments from Philip Kaufmann and an anonymous reviewer.

Effects of Environmental Variables and Habitat Integrity on the Structure of the Aquatic Insect Communities of Streams in the Cerrado-Caatinga Ecotone in Northeastern Brazil

“…In addition to these seasonal shifts in habitat characteristics, such as the stream structure and physicochemical gradients, the composition and density of the organisms found in a stream may be influenced by its drag, which is determined by the peaks in its discharge (Collier & Quinn 2003, Castro et al 2013. This confirms the fluctuations observed in the composition of aquatic organisms, including the EPT (Reis et al 2017, Montag et al 2019.…”

The effect of different logging regimes on the ecomorphological structure of stream fish assemblages in the Brazilian Amazon

“…According to the habitat template hypothesis, temporal and spatial variations in the in-stream habitat can be considered an important environmental filter to ecological strategies of the resident fish fauna (Southwood, 1977;Poff, 1997). The hierarchical structure of streams (O'Neill et al, 1989;Tonn et al, 1990) makes their physical habitat and biodiversity highly vulnerable to alterations in the landscape of the drainage basin (Leal et al, 2016;Montag et al, 2019), which have often been assessed through the analysis of fish morphology (Hora, 1930;Gatz Jr, 1979;Mahon, 1984;Watson & Balon, 1984;Hammer, 2002;Casatti & Castro, 2006;Ohlberger et al, 2006). Previous research has shown that stream habitats in logged areas undergo systematic changes, that results in the loss of canopy cover, followed by the increase in water temperature, an increment of fine sediments in the stream bed, and homogenization of water flow (Dias et al, 2009;Prudente et al, 2017Prudente et al, , 2018.…”

Derived loss of signal complexity and plasticity in a genus of weakly electric fish

“…Natural history studies of these animals are sorely missing, and sadly, we could be running out of time. Due to the metabolic demands of their unique sensory systems, weakly electric fishes may be disproportionately susceptible to environmental disturbances such as those induced by climate change and the rapid changes in land use currently occurring in the Amazon (Markham et al 2016;Montag et al 2019). Crampton et al (2016b).…”