The role of vegetated areas on fish assemblage of the Paraná River floodplain: effects of different hydrological conditions

Abstract

In this paper, we analyze the changes in composition and abundance of fish assemblages in seven vegetated floodplain wetlands with different connectivity across different hydrologic conditions: after a prolonged connection of the floodplain with the main channel, during receding water, and after a prolonged isolation. We also investigated the size and abundance of large-sized migratory species found in these wetlands and the food resources exploited by the dominant fish. Fishes were captured by diurnal seining (8.0 m x 1.50 m, 5 mm mesh) along macrophyte banks. Despite the high total number of species registered (100), sample species richness varied between 7 and 31, depending on the sampling site and the sampling date. Cluster analysis indicated low similarity between sites during both the isolation and the prolonged connection. Species turnover decreased from high water (β = 40.33) to low water (β = 33.83), with the minimum value of beta diversity index obtained during the isolation of the floodplain wetlands (β = 26.83). Our results indicated that different dominant populations of fish occur in different hydrological conditions, even though high water and isolation phases occur in the same season of different years. The ordination (NMDS) indicated the importance of hydrologic conditions in structuring fish assemblages in the studied floodplain. Small-sized characids, typically associated with macrophytes, dominated the fish assemblages, whereas the younger stages of large sized migratory species were found in low abundance. The maximum standard length of the fish captured was 28 cm and for large migratory fish, standard length varied between 1.6 and 25.0 cm. The dominant fish used several food resources, but littoral macrophytes-associated organisms had a high frequency of occurrence in the three hydrologic conditions. The high species richness of fish in the small, vegetated lakes was related to the high spatial heterogeneity during different hydrological conditions. Disturbances in the hydrological pulses could reduce the biodiversity by modifying the connectivity of the floodplain with the river channel. Conservation of these vegetated wetlands requires maintenance of actual width range of connectivity that provide diverse habitat along the time.Neste artigo analisamos as mudanças na composição e abundância das assembléias de peixes de sete áreas úmidas de planície de inundação com vegetação e com diferentes conectividades e em diferentes condições hidrológicas: depois de uma conexão prolongada da planície de inundação com o canal principal, durante o recuo das águas e após um isolamento prolongado. Nós também investigamos o tamanho e abundância das espécies migratórias de grande tamanho encontradas nestas áreas úmidas e os recursos alimentares explorados pelas espécies dominantes. Os peixes foram capturados com rede durante o dia (8.0 m x 1.50 m, malha de 5 mm) nos bancos de macrófitas. Apesar do alto número de espécies registradas (100), a riqueza de espécies nas amostras variou entre 7 e 31, de acordo c...

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

“…In floodplain aquatic environments, studies aiming to find spatial or temporal patterns in response to environmental variations indicated that fish assemblages are associated with macrophyte cover, habitat complexity and depth of water bodies (Mourão et al, 1988;Petry et al, 2003;Neiff et al, 2009;Maltchik et al, 2010), among other factors. Assemblages can also differ spatially because the hydrological connectivity among the different parts of the floodplain is limited by the distance between ponds and river channel (Pouilly and Rodríguez, 2003), and by the isolation time of the ponds (Súarez et al, 2001(Súarez et al, , 2004.…”

Structure of the littoral fish assemblage in an impounded tributary: the effects of macrophytes presence (subtropical region, Brazil)

“…Additionally, they provide refuge from predators to young and small adult fish (Meschiatti et al, 2000;Agostinho et al, 2003Agostinho et al, , 2007Neiff et al, 2009). Thus, the high complexity provided by the presence of macrophytes can promote higher fish diversity, abundance and species richness (Petry et al, 2003;Pelicice et al, 2005;Agostinho et al, 2007;Dibble and Pelicice, 2010), influencing the fish assemblage structure of littoral habitats.…”

Spatial and temporal variation of fish assemblage associated with aquatic macrophyte patches in the littoral zone of the Ayapel Swamp Complex, Colombia

“…These affect biodiversity and a range of processes such as fish reproduction and predation (Pusey & Arthington, 2003). At the same time, aquatic plants increase the spatial complexity of these ecosystems, favoring the presence of numerous fish species (Pelicice et al, 2005;Willis et al, 2005;Neiff et al, 2009;Thomaz & Cunha 2010). The effect of flood cycles on the structure of aquatic communities (Junk & Wantzen, 2004;Neiff et al, 2008Neiff et al, , 2009) is attenuated through the use of floating aquatic vegetation by the fish in the littoral area of the Ayapel Swamp Complex (ASC).…”

“…At the same time, aquatic plants increase the spatial complexity of these ecosystems, favoring the presence of numerous fish species (Pelicice et al, 2005;Willis et al, 2005;Neiff et al, 2009;Thomaz & Cunha 2010). The effect of flood cycles on the structure of aquatic communities (Junk & Wantzen, 2004;Neiff et al, 2008Neiff et al, , 2009) is attenuated through the use of floating aquatic vegetation by the fish in the littoral area of the Ayapel Swamp Complex (ASC). This biotope acts as a refuge, nursery and storage of resources coming from detritus, periphyton, and macro and micro invertebrates (Poi de Neiff & Neiff, 2006;Sánchez-Botero et al, 2007;Montoya-Moreno & Aguirre-Ramírez, 2009;Villabona-González et al, 2011).…”