Flood pulse and the dynamics of fish assemblage structure from neotropical floodplain lakes

Abstract

– The dynamics of fish assemblages from seven floodplain lakes of Salado River (Argentina) was monthly analysed during two contrasting hydrological seasons. Partial canonical correspondence analysis indicated that assemblage structure was predictably linked to environmental characteristics that varied along temporal and spatial scales. Species distributed differentially along an environmental gradient of temperature, hydrometric level, conductivity, macrophyte cover and transparency in relation to their sensory capabilities (following piscivory‐transparency‐morphometry model) and life history strategies. During high water season, assemblages were associated with temperature and hydrometric level, factors which varied mainly across temporal scales and exhibit a regional range of action. During low waters, assemblage structure correlated with macrophyte cover and transparency, factors that varied fundamentally on spatial scales and have local impact. These results indicate that the determinism of fish assemblages does not vary substantially between hydrometric periods, although the environmental variables affecting fish assemblages and their scale of action are clearly different.

Spatial distribution of fish assemblages along environmental gradients in the temporary ponds of Northern Pantanal, Brazil

“…The influence of macrophyte cover on the structure of fish assemblages was also observed by o n l y Scarabotti et al (2011), who stressed its local impact by regulating the predator-prey relationship that lead to changes in the assemblage composition. Consequently, Parauchenipterus striatulus, Eigenmannia trilineata and Psellogrammus kennedyi -strongly characterised by environments with large cover and high richness of macrophytes -may be related to a lower predation pressure and efficiency in the allocation of food resources.…”

“…Nevertheless, few studies quantified the length of spatial autocorrelation Súarez et al (2001) observed that in distant lagoons isolated for various periods, macrophyte cover and lagoon depth were the main determinants of species richness. Furthermore, during the isolation period, the internal functioning factors that drive the local abiotic processes and interactions among species lead to a differentiation in the fish assemblages between ponds through a deterministic process (Scarabotti et al, 2011). Therefore, the absence of a spatial pattern in fish species composition suggests that local deterministic processes have created a meso-scale random distribution.…”

“…These factors describe the increasing isolation of water bodies, which in turn increases fish density and reduces migration (Scarabotti et al, 2011). This may also result in assemblages with different composition, as a consequence of different probabilities of colonisation and extinction of each species (Pazin et al, 2006).…”

“…In addition, stronger biotic interactions, e.g. competition and predation Lewis 1994, 1997;Tejerina-Garro et al, 1998;Súarez et al, 2001), physiological stress (Winemiller et al, 2000), macrophyte cover and water transparency observed in permanent ponds (Scarabotti et al, 2011) may influence and regulate fish assemblages in temporary ponds. Hence, these communities may be shaped by deterministic environmental pathways (niche theory) (Lewis et al, 2000), or be structured by demographic stochasticity (neutral theory) (Hubbell, 2005), where the difference between these composition patterns is related to the dispersal ability of (McGill et al, 2006).…”

Factors affecting the distribution of fish during receding flood in lower Irtysh: effects of water level and diurnal cycle

“…Furthermore, in relatively high latitude temperate rivers (e.g., Sveden; Lepori et al, 2005), local environmental heterogeneity may not significantly structure fish assemblages. Finally, relative contribution of spatial and temporal factors may change during the flood cycle (Scarabotti et al, 2011). Highly variable environments should strongly favour generalist species (Poff and Allan, 1995) which would be relatively tolerant to spatial and temporal (including seasonal) effects, so that their abundance would not respond much to these environmental changes (Arau´jo et al, 2009).…”