Fish assemblage dynamics in a Neotropical floodplain relative to aquatic macrophytes and the homogenizing effect of a flood pulse

Abstract

The presence of aquatic macrophytes is a key factor in the selection of habitats by fish in floodplain lakes because these plants enhance the physical and biological complexities of aquatic habitats. The seasonal flood pulse may influence this interaction, but there is no information in the literature about the effects that flood events may have on macrophytes assemblages and its associated effects on fish assemblages. Thus, this article aimed to investigate whether species richness, evenness and similarities in fish assemblage composition differed between littoral areas vegetated with macrophytes and unvegetated areas, before and after a flood. We sampled three lakes in the floodplain of the upper Paraná River basin. Sampling was conducted before (December 2004 and January 2005) and after (early March, late March and May 2005) a flood event. Overall, species richness and evenness were higher in macrophytes-covered areas. Before the flood, the composition of fish assemblages was distinct when comparing vegetated and unvegetated areas. After the flood, the similarity in fish assemblage composition was higher, indicating a homogenization effect of floods for fish inhabiting littoral areas of floodplain lakes. After the flood, opportunistic species dominated the fish assemblages in aquatic macrophytes, apparently restructuring assemblages in the littoral, restarting a succession process. Thus, the observed homogenization effect of the flood could minimize biological interactions and could induce fish assemblages to begin a new process of structurization.

Ecomorphology and use of food resources: inter- and intraspecific relationships of fish fauna associated with macrophyte stands

“…Considering a method adopted by Casatti et al (2003), Ferrareze & Nogueira (2011) and Gomes et al (2012), fish were collected with a 1.0 m x 1.5 m sieve, 0.05 mm mesh, which was passed three times across each macrophyte stand from the bottom to the surface. Thus, different sizes of fishes were captured (CP of 5.45 mm to 36.06 mm).…”

Effects of historic flooding on fishes and aquatic habitats in a Missouri River delta

“…Our first objective was to assess how the flood impacted fish species richness, evenness, and diversity. We hypothesized that the flood would increase evenness and diversity without affecting richness (Freitas et al 2010;Gomes et al 2012;Steffensen et al 2014). Our second objective was to evaluate how the flood affected relative abundance of fishes as categorized by age class (i.e., juvenile, adult), morphology (i.e., smallbodied, large-bodied), introduction history (i.e., introduced, native), and recreational importance (i.e., sport fish, non-recreational species).…”

Metazoan endoparasites diversity of Pseudoplatystoma corruscans (Siluriformes: Pimelodidae) as an indicator of environmental alterations on a tropical aquatic system

“…As the host community composition influences the parasite community (Holmes 1979(Holmes , 1983Moore and Lasswell 1986), and as the ichthyofauna has been altered after the impoundment of Porto Primavera (Gomes et al 2012), the absence of some host species was probably the cause of the disappearance of the nematode and cestodes species cited above.…”