Volga

Changing flood pulse dynamics and their impact on fish recruitment in large rivers

( Volga , Russia )

(awarded by the NWO Water Programme of the Netherlands Organisation for Scientific Research NWO)

Natural river floodplains are among the biologically most productive and diverse ecosystems on earth. The principal driving force for productivity and biodiversity in these systems is the flood pulse, i.e. the temporary flooding of the aquatic-terrestrial transition zones bordering the rivers. In many rivers the natural flood pulse is severely altered by river regulation like dams and dykes, or changes in land use. Superimposed on these impacts, even modest climate changes will have major consequences on the flood dynamics of large rivers. Man-induced alterations in hydrological regimes and the reduction of floodplain wetland areas are considered a major threat for biodiversity and natural resource production, in particular for fish. Changes in the hydrological regime may influence the availability of suitable habitats for fish reproduction and larval growth, and consequently can impact the fish population dynamics considerably. The objective of the project is to analyse temporal and spatial variations in flood pulse dynamics and to relate these to the availability of floodplain habitats for recruitment and reproduction of riverine fish species.

The project is carried out in the Volga -Akhtuba floodplain, Russian Federation , which is a large and almost intact floodplain system. The programme consists of three interrelated projects:

1. a PhD study on the hydrological regime of the Lower Volga and the associate flood pulse dynamics in the Volga -Akhtuba floodplain;
   
2. a PhD study on the ecology and habitat use by selected fish species; and
   
3. a postdoctoral study linking both PhD studies, resulting in a quantitative model describing recruitment success of fish as a function of flood pulse hydrodynamics and habitat availability.