From drought to flood: annual variation in larval fish assemblages in larval fish assemblages in a heavily regulated lowland temperate river

摘要: Flow regimes are a major factor influencing fish spawning and recruitment in large rivers (Agostinho et al. 2004; Sparks 1995; Welcomme 1985; Winemiller 2005). The flood pulse concept is a riverine production model designed for large unaltered river systems with productive floodplains in the temperate, subtropical, or tropical regions (Junk et al. 1989). This model assumes that the majority of the primary production in rivers originates directly or indirectly from interactions with the floodplain and not from downstream transport of organic matter produced elsewhere in the basin (Junk et al. 1989). The flood pulse concept proposes that the strength of fish recruitment is linked to prey availability as a function of floodplain inundation. In temperate river systems high temperatures and high flows must coincide for successful utilisation of the floodplain by fishes for spawning and recruitment (Junk et al. 1989). This emphasises the importance of the lateral connectivity between the river channel and the floodplain for primary production, providing spawning cues, and food and habitat for fish (Junk et al. 1989). Following the principles of the flood pulse concept (Junk et al. 1989), the flood recruitment model was developed for Australian temperate rivers by Harris and Gehrke (1994). The flood recruitment model proposes two methods by which increased flows may enhance recruitment in river fish: flooding directly triggers spawning, or flooding indirectly enhances the survival of larvae and juveniles by providing suitable food and habitat on the inundated floodplain (Harris and Gehrke 1994). Despite widespread acceptance of the principles of the flood pulse …