Influence of environmental parameters on fish assemblage of a neotropical river with a flood pulse regime, Central Brazil

Abstract

This study aims to determine which of twelve environmental parameters (five physicochemical and seven hydromorphological) influence on the fish assemblage structure of the lower Mortes River basin located in the Bananal floodplain of the Araguaia River basin, Central Brazil. Sampling was conducted in six stretches of 1000 m each during the high and low waters. Fish were captured using gill nets and environmental parameters were measured by portable equipment or determined visually. The coinertia analysis indicated that two physicochemical (dissolved oxygen and water transparency), and four hydromorphological (channel width and depth, riparian vegetation cover and type of the riverside substrate) parameters structure the fish assemblages, both driven by the regional hydrological patterns (flood pulse). These results are explained by fish-environmental parameters relationship characteristic of the aquatic Neotropical systems.Este estudo determinou quais entre doze parâmetros ambientais (cinco físico-químicos e sete hidromorfológicos) influenciam na estrutura da assembleia de peixes do baixo rio das Mortes localizado na planície de inundação do Bananal, bacia do rio Araguaia, Brasil Central. As coletas foram realizadas em seis trechos de 1000 m cada durante os períodos de chuva e estiagem, nos quais 1036 peixes foram coletados utilizando-se redes de malhar e medidos os parâmetros ambientais utilizando equipamentos portáteis ou determinados visualmente. A análise de coinércia indicou que dois parâmetros físicos e químicos (oxigênio dissolvido e a transparência da água) e quatro hidromorfológicos (largura e profundidade da calha principal, cobertura da mata ripária e tipo de substrato da margem) estruturam a assembleia de peixes, ambos influenciados pelo regime hidrológico regional (pulso de inundação). Estes resultados são discutidos considerando a interação entre peixes e os parâmetros ambientais característicos dos sistemas aquáticos Neotropicais.

<b>Co-occurrence patterns of fish communities in littorals of three floodplain lakes of the Orinoco River, Venezuela</b>

“…Co-occurrence patterns of the fish communities in the floodplains of the Orinoco River The significant spatial variation in the composition of fish communities both among and within lakes indicates that the studied communities were structured at least partially by environmental conditions, supporting an environmental filtering process (Southwood 1977;Poff 1997;Lima & Melo 2009). The spatial separation of Mamo from the other lakes might have contributed to its differing fish population composition, although other factors such as its greater surface area could also have contributed to its greater species richness, while the acidity in Aricagua and Paramuto might explain their lower richness (Jackson et al 2001).…”

“…Recent models have assumed that communities are randomly assembled (Hubbell 2001); however, evidence from freshwater fish communities in tropical floodplains highlights the importance in their organization of factors such as biotic interactions (Winemiller 1996;de Mérona & de Mérona 2004;Barili et al 2011), species-habitat associations (Peres-Neto 2004;Rodrigues et al 2013) and environmental filtering (Rondón Suárez et al 2004;de Melo et al 2009). …”

Predicting Factors That Influence Fish Guild Composition in Four Coastal Rivers (Southeast Ivory Coast) Using Artificial Neural Networks

“…Total dissolved solids (tds), width, distance from source (ds) and canopy were the most important variables which influenced the piscivores. Changes in the river channel morphology (depth and width) are related to oscillations of the hydrological cycle due to regional seasonality (Thomaz et al, 2007;de Melo et al, 2009). Piscivores inhabit the main river channel where they can prey on fish that enter or leave the flooded region (Petry et al, 2003;de Melo et al, 2009).…”

“…Changes in the river channel morphology (depth and width) are related to oscillations of the hydrological cycle due to regional seasonality (Thomaz et al, 2007;de Melo et al, 2009). Piscivores inhabit the main river channel where they can prey on fish that enter or leave the flooded region (Petry et al, 2003;de Melo et al, 2009). In addition, water temperature appears as an important, indicator of watershed vitality because of its affecting metabolism, development, activity and assemblage composition of aquatic organisms (Naiman et al, 1992;Lasne et al, 2007).…”

“…Riparian vegetation helps determine what, how much and when materials from upland areas enter the hydrosystem. These conditions could favor the presence of refuges (tree branch and trunk, and roots) in the flooded vegetation and food prey (invertebrates, algae fixed to the substrate, arthropods and fruits) falling from the flooded vegetation (Casatti et al, 2003;de Melo et al, 2009;Edia et al, 2010). Leaves incorporated into the channel substrate help the establishment of a varied fauna that can be used as food by fish (Uieda and Uieda, 2001).…”