How does conversion from forest to pasture affect the taxonomic and functional structure of the fish assemblages in Amazonian streams?

Abstract

In recent years, increasing economic development has resulted in high rates of change in land use which have a negative impact on both terrestrial and aquatic habitats (Newbold et al., 2018). In the Amazon region, many studies have demonstrated that these changes in land use have resulted in a decrease in the basal area of the forest, changes in the physical-chemical characteristics of the water, such as its temperature and pH, the loss of riparian vegetation and impacts on the associated fauna (Luiza-Andrade et al., 2017;Mendes-Oliveira et al., 2017;Prudente et al., 2017). Nepstad et al. (2008) found that approximately 20% of the forest in the Amazon region has already been transformed

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

“…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. As for fish assemblage, the presence of anthropic disturbances has resulted in a predominance of generalist and tolerant species (Teresa & Casatti, 2012;Teresa et al, 2015;Teresa & Casatti, 2017), negatively affecting functional groups such as piscivores and benthic species in Amazonian streams (Leitão et al, 2018;Cantanhêde et al, 2020).…”

Fish assemblage shifts in an Ozark river over 80 years amidst a mosaic of forest regeneration and persistent pasture

“…For example, benthic species richness increased over time in the Current River watershed, with most of these increases occurring at lower pasture (higher forested) sites. Other studies have shown benthic species are associated with more forested streams due to increased allochthonous inputs, increased interstitial spaces and a more favourable stream benthos (Cantanhêde et al, 2020; Juen et al, 2016; Ribeiro et al, 2016; Wilkinson et al, 2018). Similarly, all fish groups except for generalist centrarchids were negatively correlated with pasture land use.…”

“…These assemblages displayed a consistent shift through species space, indicating fish assemblages in the Current River have been changing to an alternative state from past communities. Previous studies have shown that fish assemblages will shift to an alternative state in response to ecological stressors such as landscape alteration (Barbosa et al, 2020; Burgad et al, 2019; Cantanhêde et al, 2020; Gido et al, 2010; Ilha et al, 2019; Pease et al, 2015); however, they will also respond to positive ecological changes such as reforestation (De Paula et al, 2021).…”

“…Many studies have shown how fish assemblages respond both taxonomically and functionally to habitat degradation (e.g. Cantanhêde et al, 2020; Pease et al, 2012; Wilkinson et al, 2018). Our study not only provides further evidence of negative impacts of land use modification, but also highlights how fish assemblages can simultaneously respond to forest regeneration in a watershed.…”

“…Gravel aggradation has led to the shallowing of pools (Hall, 1958;Jacobson & Primm, 1997) and may be increasing the Many studies have shown how fish assemblages respond both taxonomically and functionally to habitat degradation (e.g. Cantanhêde et al, 2020;Pease et al, 2012;Wilkinson et al, 2018).…”