Fish recruitment in a large, temperate floodplain: the importance of annual flooding, temperature and habitat complexity

Abstract

1. Large river floodplains are considered key nursery habitats for many species of riverine fish. The lower Volga River floodplains (Russian Federation) are still relatively undisturbed, serving as a suitable model for studying the influence of flooding and temperature on fish recruitment in floodplain rivers. 2. We examined the interannual variability in recruitment success of young-of-the-year (YOY) fish in the lower Volga floodplain in relation to flood pulse characteristics and rising water temperatures in the spring. We sampled four areas with different flooding regimes, in three consecutive years (2006)(2007)(2008). 3. Extensive areas with a long duration of flooding accommodated high densities of young fish. This suggests that extended inundation improves the recruitment success of river fish. In areas with extensive flooding, the biomass of YOY of most fish species was about three times higher in 2006 and 2007 than in 2008. We hypothesise that low spring temperatures in 2008 may have caused this reduced recruitment and that a flood synchronised with rising temperature enhances recruitment success. 4. Extensive flooding was particularly favourable for species characterised by large body size, delayed maturation, high fecundity and low parental investment, such as pike Esox lucius, roach Rutilus rutilus and ide Leuciscus idus. Gibel carp Carassius gibelio, a species tolerant of high temperature and hypoxia, did particularly well in small waterbodies in the driest parts of the floodplain. 5. Structural characteristics of floodplain waterbodies explained much of YOY fish density. These species-environment associations varied from year to year, but some species such as common bream Abramis brama, roach and gibel carp showed consistent relationships with structural habitat characteristics in all years, despite large interannual fluctuations in flood pulse and spring temperature.

Predicting Floodplain Hypoxia in the Atchafalaya River, Louisiana, USA, a Large, Regulated Southern Floodplain River System

“…We were able to describe the variability in ARBF flood pulses with simple metrics based on water temperature and the start, duration, and magnitude of floodplain inundation. Similar measures have been used to describe flooding relationships with hypoxia (Lewis, ; Townsend and Edwards, ) and the effects of flood dynamics (King et al , ; Balcombe et al , ; Beesley et al , ) and temperature (Gorski et al , ) on larval and juvenile fishes. Short‐duration floods (2005 and 2006) were uncommon in our dataset, and we expected most floods to be characterized by increased incidences of hypoxia through time, given the extended residence of high‐temperature water on the floodplain.…”

“…Although the synchrony of high river stages and high temperatures is an integral part of the flood pulse/aquatic productivity relationship (Junk et al , ; Gorski et al , ), extended summer flooding in the ARBF leads to pervasive hypoxia, reducing the potential benefits of floodplain inundation in this system (Rutherford et al , ; Alford and Walker, ). Fishes have a variety of mechanisms to cope with hypoxia (Chapman et al , ), but the combination of high temperatures and chronically low DO levels in the ARBF is likely stressful for most aquatic organisms, resulting in altered behaviour, physiology, growth, survival, and production (Kelso et al , ; Pollock et al , ; Vanderploeg et al , ; Bonvillain et al , ; Petry et al , ).…”

“…The river/floodplain connection created with the advance of the annual flood pulse can greatly enhance the diversity and productivity of both riverine and floodplain flora and fauna by providing nutrient import and export (Robertson et al , ; Amoros and Bornette, ; Burgess et al , ) and access to floodplain spawning and nursery areas (Ward and Stanford, ; Galat et al , ; Górski et al , ; but refer to Humphries et al , ). However, rising waters can also significantly reduce floodplain dissolved oxygen (DO) levels because of bacterial consumption of dissolved organic carbon from terrestrially derived organic matter in inundated riparian habitats (Baldwin, ; Whitworth et al , ).…”

Restoring in‐stream habitat in urban catchments: Modify flow or the channel?

“…In addition, the duration and frequency of floodplains inundation have been linked with a flow‐mediated exchange of energy, organic matter, and biota (Cienciala & Pasternack, ). Floodplains flow dynamics provide key habitat supporting biota such as fish utilizing it as spawning and rearing habitat (Gorski et al, ).…”

Impacts of Climate Change on Riverine Ecosystems: Alterations of Ecologically Relevant Flow Dynamics in the Danube River and Its Major Tributaries

“…The first ones can be affected through the intensity of habitat destruction and disturbance associated with bed movement and washout during high flow events [21]. On the other hand, many fish species can benefit from those flood and high flow events that restore river-floodplain connectivity, thus leading to an increase in abundance/biomass or enhancing recruitment [47][48][49]. Riparian plant communities are also strongly affected by the duration and depth of flooding, as revealed in a recent meta-analysis by Garssen et al [50].…”