Ecological Determinism on the Orinoco Floodplain

Multiple states in river and lake ecosystems

“…In general, the importance of directional flow and horizontal connections has led to an emphasis on spatial complexity rather than temporal complexity in river ecology (e.g. Fisher et al 1998;Ward 1998;Lewis et al 2000;Naiman et al 2000a). However, temporal variation in stream flow has also been identified as an essential driver of river biodiversity, production and sustainability (Poff et al 1997;Ward 1998).…”

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

“…competition and predation Lewis 1994, 1997;Tejerina-Garro et al, 1998;Súarez et al, 2001), physiological stress (Winemiller et al, 2000), macrophyte cover and water transparency observed in permanent ponds (Scarabotti et al, 2011) may influence and regulate fish assemblages in temporary ponds. Hence, these communities may be shaped by deterministic environmental pathways (niche theory) (Lewis et al, 2000), or be structured by demographic stochasticity (neutral theory) (Hubbell, 2005), where the difference between these composition patterns is related to the dispersal ability of (McGill et al, 2006). Thus, closer assemblages should be more similar to one another than more distant ones (Gaston and Chown, 2005).…”

Management Strategies for Large River Floodplain Lakes Undergoing Rapid Environmental Changes

“…The case studies on critical management issues of rapid environmental changes of the large river basins were collated from various continents including the Yangtze River System, Asia (Yang et al, 2007;Chen et al, 2011), the Mississippi River System, North America (Wren et al, 2008), the Orinco, Salado and the Paraguay River Systems, South America (Lundberg et al, 1987;Claps et al, 2009), Orange-Vaal River System, South Africa (Ashton et al, 1986), Erbo River System, Europe (Gallardo et al, 2007) and the Murray Darling River System, Australia (Humphries et al, 1999;King et al, 2003). Following the identification of critical management issues of the large river systems, prevailing conditions of biotic assemblages in changes in large river floodplain lakes were reviewed from the case studies of Europe, North America and Australia (Fisher et al, 2000;Lewis et al, 2000). Then a comprehensive review was undertaken on the use of microcrustaceans to understand the complex ecosystem processes and configure effective management strategies when they are exposed to a range of external disturbances including climate change over temporal and spatial scales.…”

“…The alteration of these river channels influences morphology consequently the habitat of a wide range of biota in the reaches which are significant source of energy transfer across the food web. For example, fish of the Orinoco River use the main channel primarily for migration and dispersal depends largely on floodplains for growth and subsistence (Lewis et al, 2000). Diversity and length of the food chains increase in natural flow regimes of many large river systems (Maddock et al, 2004).…”

“…Interaction between the channel and floodplain systems and between the channel and groundwater aquifers plays a significant role for rapid ecosystem changes in floodplain lakes ecosystems, since the temporal dimensions of these ecosystems are largely integrated and dynamic (Fig. 1, Ward, 1989;Lewis et al, 2000). Ward, 1989).…”