Effect of land-use types on the ecomorphological structure of fish assemblage in distinct mesohabitats of neotropical streams

Abstract

The use and occupation of land by human population substantially influence environmental variables and fish assemblage in streams. However, there is little knowledge on how these changes affect the ecomorphological structure of fish assemblage in mesohabitats. Therefore, we aim to assess whether the land-use types affect the ecomorphological structure of fish assemblage in distinct mesohabitats. Environmental and ichthyofaunistic data were collected in three mesohabitats (rifles, runs, and pools) of five rural and five urban streams. Twenty-one ecomorphological indices were obtained from the mean of linear morphological measurements and areas of the fishes. Subsequently, the Euclidean distance was calculated, based on the ecomorphological indices, between each pair of species, to measure the ecomorphological distances for the mesohabitats of the rural and urban streams. The results show that the urban environment is more harmful to streams than the rural one, due to changes in the environmental variables and decrease in species richness. The main environmental changes found in urban streams were the decrease in canopy cover by riparian vegetation and dissolved oxygen, and the increase in electrical conductivity and bed silting. Also, there was a significant decrease in the morphological similarity between fish species in the mesohabitats of urban streams compared to rural ones. Therefore, we can conclude that the urban environment leads to the loss of morphologically similar fish species in the mesohabitats, with only a few functionally distinct species remaining.

Taxonomic and functional diversity patterns of stream fish assemblages from Brazilian Atlantic Rain Forest

“…Stream fish studies of functional diversity have ranged in scale from ecoregions (Carvalho & Tejerina‐Garro, 2015; Teresa & Casatti, 2017) to mesohabitats (Pessoa et al, 2021; Teresa & Casatti, 2012). Furthermore, catchment (Nakamura et al, 2018; Pease et al, 2012) and stream (Pereira et al, 2021) scales are adopted.…”

Linking fish ecomorphotypes to food categories and local‐scale habitat uses along a Brazilian coastal stream

“…The first EM studies of fishes were published in the late 1970s (Gatz, 1979) and, since then, have investigated several communities, producing a large conceptual and methodological framework (Casatti & Castro, 2006; Franssen et al, 2015; Oikonomou et al, 2018; Oliveira et al, 2010; Pessoa et al, 2021; Pouilly et al, 2003; Watson & Balon, 1984; Winemiller, 1991). Statistical correlations between morphological and ecological variations, such as body shape and diet/environment variables (Pouilly et al, 2003; Willis et al, 2005), have been the basis for understanding the EM associations.…”

“…In turn, these weaknesses could be partly explained by changes in the habitat structure of streams, which are highly dynamic systems (Allan & Castillo, 2007). Therefore, natural causes, along with current anthropic modifications in riverscapes (Allan, 2004; Leitão et al, 2018), have shown substantial importance in the morphology–habitat relationships since altered habitats may force fish to use other habitats that are not predicted by their morphologies (Bhat, 2005; Dala‐Corte et al, 2016; Pessoa et al, 2021).…”