Influence of the macrophyte Eichhornia azurea on fish assemblage of the Upper Paraná River floodplain (Brazil)

Abstract

The architecture of aquatic macrophytes adds structural complexity to the littoral region. This increased habitat heterogeneity prompts greater diversity and stability of biotic communities. However, there are few studies that explore the ecological role of macrophytes in the Neotropical region. Then, the aim of this study was to determine spatial and diel influence of near-shore Eichhornia azurea stands on fish assemblage attributes and structure, in the Upper Paraná River floodplain, considering a meso-habitat scale. To achieve this objective, fish were trapped in four stands of macrophytes, in three positions (middle and border of the stand and open area) with samplings taken at different times of the day (6 h, 12 h and 18 h). A total of 537 fish of 16 species were caught. Dissolved oxygen varied significantly among positions. Fish assemblage attributes (species richness, evenness and Shannon Diversity Index) also varied among positions. Fish assemblage structure (summarized by a detrended correspondence analysis) and size structure were strongly influenced by times of the day and positions. The patterns observed can be explained by factors such as oxygen concentration, food resource availability and predation, all influenced by macrophytes. We suggest that any strategy to manage fish diversity and fish stocks has to consider aquatic macrophytes.

Caracterização da comunidade de plantas aquáticas de dezoito reservatórios pertencentes a cinco bacias hidrográficas do Estado de São Paulo

“…O entendimento da dinâmica da relação entre as diferentes espécies de uma comunidade de plantas aquáticas em um determinado ambiente depende: das espécies que compõem a comunidade; da densidade da vegetação; e das características morfológicas das plantas, além das variações das características físicas e químicas de cada ambiente (Dibble & Harrel, 1997;Agostinho et al, 2002). As assembléias de plantas aquáticas flutuantes podem estar relacionadas com a concentração de nutrientes em água e no sedimento, ao passo que locais no reservatório que permitam maior penetração da luz solar podem-se destacar como ideais para ocorrência de espécies submersas.…”

Local factors affecting the testate amoeba community (Protozoa: Arcellinida; Euglyphida) in a neotropical floodplain

“…Studies have defined the main characteristics of different communities associated with aquatic macrophytes, revealing the determinative factors of their structures. The high productivity of these plants depends on the physical, chemical, and biological characteristics of the environment, as well as and the influence of floods on the environment's local factors (Agostinho et al, 2007;Lamentowicz et al, 2007;MaiaBarbosa et al, 2008;Thomaz and Cunha, 2010;Villabona-González et al, 2011).…”

Morphometric and biotic variables as potential predictors ofLudwigia sedoides(Humb. & Bonpl.) Hara in a large Amazonian reservoir

“…However, macrophytes also play important ecological functions (Madsen et al, 2001;Engelhardt and Ritchie, 2002) as they provide habitat and resources for invertebrates, *Corresponding author: fmpelicice@gmail.com fish and other organisms (Pelicice et al, 2005;Agostinho et al, 2007a;Gualdoni et al, 2009;Thomaz and Cunha, 2010). In addition, aquatic plants show high rates of primary production (Boyd, 1971;No˜ges et al, 2010) and participate in nutrient cycling (Carpenter and Lodge, 1986;Cronin et al, 2006;Bini et al, 2010).…”