Relationships between fish assemblages, macrophytes and environmental gradients in the Amazon River floodplain

Abstract

During the flood season of 1992–1993, 139 species of fishes were collected from a floodplain lake system in the central Amazon Basin. Fish species distribution was examined relative to abiotic variables in seven vegetation strata on Marchantaria Island, Solimões River. Both environmental variables and species distributions were influenced by a river channel to floodplain‐interior gradient. Species diversity was significantly higher in vegetated areas than in unvegetated areas, with deeper water Paspalum repens stands harbouring the highest diversity. As a result, species richness and catches were positively related to habitat complexity, while catch was also negatively related to dissolved oxygen (DO) and water depth. Low DO and shallow waters appeared to act as a refuge from predation. Fish assemblages were related to water chemistry, but species richness was not. Canonical correspondence analysis provided evidence that floodplain fish assemblages formed by the 76 most common species were influenced by physical variables, macrophyte coverage and habitat complexity, which jointly accounted for 67% of the variance of fish species assemblages. Omnivores showed no pattern relative to the river channel to floodplain‐interior gradient while detritivores were more likely to be found at interior floodplain sites and piscivores closer to the river. Piscivores could be further separated into three groups, one with seven species associated with free‐floating macrophytes in deep water, a second with five species found in shallow waters with rooted grasses and a third with six open water orientated species. The results suggest that fish assemblages in the Amazon floodplain are not random associations of species.

Predicting fish species richness and assemblages with climatic, geographic and morphometric factors: A broad-scale study in Chinese lakes

“…Our findings were in accordance with the previous macroecology studies of fish in European lakes (Brucet et al, 2013) and Chinese water bodies (Kang et al, 2013). Some other studies, with a regional scale focus, argued that fish species richness was highly related with water depth (Cheng et al, 2012), habitat (Petry et al, 2003) and other organisms (Xie et al, 2001) in lakes.…”

“…PDM is also considered as having a large impact on niche shifts of freshwater species (Lauzeral et al, 2011), and thereby affecting fish distribution. Indeed, PDM can modify the hydrological conditions of lakes directly, such as water content, water depth, transparency and nutrient supplements (Wetzel, 2001), which in turn will affect fish populations and distributions (Brazner and Beals, 1997;Petry et al, 2003;Mello et al, 2009;Cheng et al, 2012;Kang et al, 2013).…”

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

“…This relation is common for macrophytes play a key role in nutrient dynamics, contributing to the increase in structural heterogeneity of habitats, and influencing the biological diversity, interspecific relationships, and system productivity Pelicice et al, 2005). Macrophytes are also one of the primary determinants of the structure of fish communities in lentic environments (Súarez et al, 2001 and2004;Petry et al, 2003).…”

“…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.…”

Use of the flooded forest by fish assemblages in lakes of the National Park of Anavilhanas (Amazonas, Brazil)

“…Recently, Freitas et al (2010) reviewed the factors that may explain fish diversity in Amazonian floodplain lakes, including those that are in black-water systems. The hypothesis that species diversity is mediated by spatial heterogeneity has been evaluated for floodplain lakes of the rivers Araguaia (Tejerina-Garro et al 1998) and Solimões-Amazonas (Petry et al 2003;Siqueira-Souza and Freitas 2004) but not for lakes in Amazonian black-water rivers.…”