Fish recruitment on floodplains: the roles of patterns of flooding and life history characteristics

Abstract

Floodplain inundation in rivers is thought to enhance fish recruitment by providing a suitable spawning environment and abundant food and habitat for larvae. Although this model has not previously been tested in Australian rivers, it is often extrapolated to fishes of the Murray-Darling Basin. Fortnightly sampling of larvae and juveniles was conducted in the unregulated Ovens River floodplain during spring–summer of 1999 (non-flood year) and 2000 (flood year). The only species that increased in larval abundance during or shortly after flooding was an introduced species, common carp (Cyprinus carpio). Additionally, the peak abundance of larvae on the floodplain occurred during a rapidly declining hydrograph under low flow conditions in isolated billabongs and anabranches. The low use of the inundated floodplain for recruitment contradicts previous models. We propose a model of the optimum environmental conditions required for use of the inundated floodplain for fish recruitment. The model suggests that the notion of the flood pulse alone controlling fish recruitment is too simplistic to describe all strategies within a system. Rather, the life history adaptations in the fauna of the system and aspects of the hydrological regime such as duration and timing of inundation will control the response of a river's fish fauna to flooding.

Influence of hydrology on the fish body condition in a large subtropical floodplain

“…On the other hand, optimum conditions for fish recruitment were present during the 2010 flood pulse, with high temperature values, a long duration and the covering of an extensive floodplain area (King et al, 2003). Abrial et al (2014), in the same study area, registered higher richness and fish abundance values after this flooding, and individuals were mainly small in size (juveniles), a fact associated with the previous greater connectivity in the floodplain.…”

Pools and rapids as spawning and nursery areas for fish in a river stretch without floodplains

“…This result indicates that the larvae in more advanced stages tend to prefer calmer environments that, according to Houde (2002) and Werner (2002), offer better conditions for their development. Several authors (Humphries et al, 1999;King et al, 2003;King, 2004) maintain that in regions of rivers that do not present a floodplain, the main channel provides lateral habitats along the banks that are adequate for larvae development.…”

“…This model has been used for native fish in floodplain rivers in several locations (Castro et al, 2002;King, 2004). Several studies (Humphries et al, 1999;Galat & Zweimüller, 2001;King et al, 2003) have questioned the generalization of this model because the main river channel, in its diverse structural mosaic, can also offer favorable conditions for the development of larvae through the lateral habitats located along the banks, which are characterized by a low flow speed and the subsidence of thin particles. In addition, Humphries et al (2002) mention the possibility of several species being able to spawn and recruit in the main channel of the river during the low water period, when the access to floodplain environments is unavailable.…”

Spatiotemporal variation in flow-dependent recruitment of long-lived riverine fish: Model development and evaluation

“…Habitat choices by spawning adults may determine the fate of their young (Houde, 2009;Humphries et al, 1999;King et al, 2003;Mion et al, 1998). Because of high vulnerability to extreme flow events, river flow can have larger effects on growth and survival of larval sturgeon than on juveniles and adults (Humphries et al, 1999).…”

“…For riverine fishes, flow regime changes in spawning and rearing grounds may bring about changes in temperature regime and food availability that could disrupt early life stage processes such as timing and location of spawning and settlement (Humphries et al, 1999;King et al, 2003;Nunn et al, 2007).…”