Fish communities of the Pantanal wetland in Brazil: evaluating the effects of the upper Paraguay river flood pulse on baía Caiçara fish fauna

Abstract

The physicochemical variables and the ichthyofauna associated with aquatic macrophyte beds in two stretches of the baı´a Caiçara were evaluated seasonally between September 2005 and May 2007. Low depth, high water transparency, and relatively well-oxygenated waters characterized both stretches during the low water season, whereas the flooding of the upper Paraguay River correlated with drastic alterations in these variables: depth registered a fivefold increase, and turbid and anoxic waters predominated during the high water season. During the falling and low water seasons, species richness, fish abundance, biomass, and diversity were significantly higher than during periods of rising and high waters. The presence of large-sized migratory species, however, was strictly associated with the high water season. The results suggest strong relationships between the abiotic and biotic components of the system and indicate an overall high degree of dependence of the system on the hydrological seasonality of the upper Paraguay River.

To connect or not to connect? Floods, fisheries and livelihoods in the Lower Rufiji floodplain lakes, Tanzania

“…"the ease with which organisms, matter or energy transverse ecotones between adjacent ecological units" (Ward et al 1999). In riverine systems, water-mediated or hydrological connectivity is thought to be key for the persistence of aquatic biota (Jenkins and Boulton 2003), including fish, in both temperate (Fullerton et al 2010) and tropical systems (Pains da Silva et al 2010). Science-based fisheries management advice has largely failed to deliver even in biologically "simple", single-species, single-type, temperate-zone fisheries (Bayley 1988), as stocks have continued to collapse, often because the political will to fully implement the advice has been a stumbling block (Pauly et al 2002).…”

The biological, ecological and conservation significance of freshwater swamp forest in Singapore

“…For example, Leigh & Sheldon (2009) found that hydrological connectivity had a major effect on macroinvertebrate assemblages, with highly connected water bodies displaying greater macroinvertebrate diversity than isolated water bodies, which tended to have fewer diverse assemblages and were dominated by a handful of taxa. Similar effects have been noted in tropical systems where wet or monsoon season flooding has resulted in greater proportions of migratory species and changes in community assemblages (da Silva et al, 2010). On a smaller scale, changes in physical habitat caused by alterations in flow regime can increase habitat heterogeneity and thereby increase species diversity (Downes et al, 1998;Bunn & Arthington, 2002).…”

“…Junk et al (1989) stressed the importance of seasonal flood pulses through effects such as over-bank flooding, which strongly influences biological community structure through allochthonous inputs and changing of the physical habitat (Douglas et al, 2005;Davidson et al, 2012). For example, in Brazilian floodplains da Silva et al (2010) found that turbid and anoxic water conditions dominated in the high water season compared to low or falling water seasons, which had relatively well oxygenated and low turbid waters. The differences in seasonal hydrology impacted fish diversity, abundance and biomass, which were significantly higher in falling and low water seasons than during the high water season (da Silva et al, 2010).…”

“…For example, in Brazilian floodplains da Silva et al (2010) found that turbid and anoxic water conditions dominated in the high water season compared to low or falling water seasons, which had relatively well oxygenated and low turbid waters. The differences in seasonal hydrology impacted fish diversity, abundance and biomass, which were significantly higher in falling and low water seasons than during the high water season (da Silva et al, 2010). In tropical wetland forests similar changes have been documented in macroinvertebrate communities with stream physico-chemistry as well as insect assemblages, density and biomass reflecting fluctuations in seasonal rainfall (Ramirez et al, 2006).…”

Macrofaunistic Diversity in Vallisneria americana Michx. in a Tropical Wetland, Southern Gulf of Mexico

“…This however has not been experimentally tested for the BRPC. The effect of the increase in quantitative habitat complexity provided by the greater on the density of the fauna is expected to be minimised and remain similar, especially in the case of fish, as mobile fauna colonises areas with emergent rooted vegetation that are prone to flooding, in coastal plain wetlands that are regulated by flood pulses (Fernandes et al, 2009;da Silva et al, 2010).…”