Local and ecoregion effects on fish assemblage structure in tributaries of the Rio Paraíba do Sul, Brazil

Abstract

1. We examined the effects of physical and chemical habitat variables and ecoregions on species occurrence and fish assemblage structure in streams of the Paraíba do Sul basin, in southeast Brazil. 2. Fish and environmental data were collected from 42 sites on 26 first to fourth order streams (1 : 50 000 map scale) in three ecoregions. The sites occurred in one valley and two plateau ecoregions at altitudes of 40-1080 m and distances of 0.1-188 km from the main channel of the Rio Paraíba do Sul. Physical habitat (substratum, riparian cover, habitat types) and water quality (dissolved oxygen, pH, temperature and conductivity) variables were measured at each sampling site. 3. A total of 2684 individuals in 16 families and 59 species were recorded. 4. Ecoregion was a better predictor of the fish assemblage than the other environmental variables, according to the differences between the mean within-class and mean betweenclass similarities in assemblage data. 5. Differing landscape characteristics were associated with differing local variables and thereby with differing fish assemblage structures. Riffles, shrub, grass, dissolved oxygen, conductivity and temperature were closely related to fish assemblage structure. 6. Fish assemblages in sites far from the main river and at higher altitudes also differed from those near the Paraíba do Sul main channel, presumably as a result of differences in connectivity, covarying environmental factors and anthropogenic influence. 7. These results reinforce the importance of understanding how stream communities are influenced by processes and patterns operating at local and regional scales, which will aid water resource managers to target those factors in their management and rehabilitation efforts.

Defining quantitative stream disturbance gradients and the additive role of habitat variation to explain macroinvertebrate taxa richness

“…8A). A second conclusion is that the effort to control broad-scale drivers of biological assemblages through use of ecoregions and stream typologies does not eliminate the necessity to account for local habitat variability when comparing sites (Hughes et al, 1986;Waite et al, 2000;Pinto et al, 2009). Although we aimed to standardize the stream sizes, a size metric (mean width × mean depth) still explained significant differences in EPT richness.…”

Hydrologic connectivity driven natural stream fish assemblages in mountain streams in the Yangtze River basin: implications for stream fish conservation in monsoonal East Asia

“…However, the relative influence of the downstream spatial factors and other environmental variables on fish assemblages may depend on regional and variable settings, that is, the conditions of climate and environments, nature of fish communities and variables of survey. For example, the fish assemblage structure was not affected by the distance from the main river in Meridional Amazonian streams (Fernandes et al, 2013), while which was influenced by distance from the main channel in streams of the Paraíba do Sul basin in southeast Brazil (Pinto et al, 2009). Osborne & Wiley (1992) found a significant relationship between D-link and fish species richness in a central Illinois watershed.…”

“…Similar results were found in the North Taoxi River, in a mountain stream in the lower Yangtze River . Altitude is one of the most widely reported environmental factors determining habitat suitability and responsible for structuring the stream fish assemblages (Rahel & Hubert, 1991;Quist et al, 2006;Ferreira et al, 2007;Kadye et al, 2008;Pinto et al, 2009;Lorion et al, 2011;Li et al, 2012;MercadoSilva et al, 2012). The observed pattern is generally marked by a decrease in species diversity as altitude increases (Jaramillo-Villa et al, 2010).…”

“…The influences of downstream spatial factors on fish assemblages were illustrated in other river systems. In general, fish species richness declines with increasing distance to larger stream confluences of tributaries (Hitt & Angermeier, 2008), distance to stream mouth (Mullen et al, 2011) or a mainstem river (Pinto et al, 2009;Thornbrugh & Gido, 2010), and distance to ocean (Mercado-Silva et al, 2012), forward selection procedure were selected. The first and second axes accounted for 30.1 and 9.3% for the variation of species data, respectively.…”

Comparing the performance of different stream classification systems using aquatic macroinvertebrates

“…Padial et al (2012) observed that a posteriori classifications based on aquatic organisms of different taxonomic groups presented higher CS values than classifications based on a priori sample period of marginal lakes and connectivity in a flood plain in southern Brazil. Moreover, Pinto et al (2009) observed that the ecoregions of Paraíba do Sul river in southeastern Brazil presented higher CS values for fish communities than other classification systems used.…”