Geomorphology and Flooding Shape Fish Distribution in a Large‐scale Temperate Floodplain

Abstract

Natural river‐floodplain systems are characterized by their dynamic hydrology and diverse geomorphology resulting in a wide range of habitats that support high fish diversity and production. Various factors (e.g. hydrological dynamics, water quality, and biotic processes) have been proposed to explain fish distribution in large river floodplains, but it is still widely acknowledged that the mechanisms involved may vary in diverse floodplain systems and that they are not fully understood. To determine how flooding dynamics and floodplain geomorphology influence fish species distributions across the Volga‐Akhtuba floodplain, Russian Federation, we examined the distributions of eight species with respect to variables reflecting floodplain hydrology and geomorphology. On the basis of fish catches in 40 floodplain water bodies at the end of summer in 2006–2008, we found that frequency of occurrence of most fish species remained stable along the time. The distribution of fish species was strongly influenced by the size and shape of water bodies as well as flood extent. Therefore, the long‐term flood variability that drives the geomorphic heterogeneity of the floodplain creates suitable habitats across ranges of fish flow guilds (rheophilic, eurytopic, and limnophilic), resulting in high diversity of the floodplain ichthyofauna. We conclude that this diverse habitat availability is a highly significant factor influencing fish distribution in the Volga‐Akhtuba floodplain. Copyright © 2012 John Wiley & Sons, Ltd.

Comparative use of side and main channels by small‐bodied fish in a large, unimpounded river

“…The ecological importance of side channels to fish varies seasonally with river stage (e.g., Copp, , ; Martens & Connolly, ). For example, side channels can provide habitats that are absent in main channels such as large, shallow, slow current‐velocity (SSCV) patches (Bowen, Bovee & Waddle, ) that vary in importance seasonally as a function of river discharge (e.g., Brown & Hartman, ; Zale & Rider, ; Górski et al ., , ). During runoff, seasonally inundated SSCV patches can provide refugia for small fish and especially larvae that are susceptible to displacement by high water velocities (e.g., Ottaway & Clarke, ; Harvey, ).…”

The Numerical Simulation of Shallow Water: Estimation of the Roughness Coefficient on the Flood Stage

“…Also the role of snow melting in the formation of surface water in the Floodplain is negligible. Regime of water released through the Volga Hydroelectric Power Station fully regulates the rate of water passage in the Floodplain [4]. The volume of water flowing per unit of time is called by a variation of discharge ( ) as shown in Figure 1.…”

Connectivity and complexity of floodplain habitats govern zooplankton dynamics in a large temperate river system

“…Ecological integrity of large river–floodplain systems is closely linked to natural flow regimes (Junk, Bayley & Sparks, ; Bayley, ; Poff et al ., ). Flow variation facilitates high productivity (Junk et al ., ; Amoros & Bornette, ), drives species distributions (Górski et al ., ; Negishi et al ., ) and facilitates high biodiversity (Shiel, Green & Nielsen, ; Tockner & Stanford, ) of river–floodplain systems. Several studies have highlighted the importance of flow and flood pulses, which moderate hydrological connectivity, as major determinants of zooplankton assemblages in river–floodplain systems (Reckendorfer et al ., ; Baranyi et al ., ; Zimmermann‐Timm, Holst & Kausch, ; Napiórkowski, ), in addition to littoral habitat complexity and inshore retention in the main channel (Schiemer et al ., ).…”