Freshwater fish biodiversity restoration in floodplain rivers requires connectivity and habitat heterogeneity at multiple spatial scales

Stoffers, T.; Buijse, A.D.; Geerling, Gertjan; Jans, Luc; Schoor, Margriet M.; Poos, Jan Jaap; Verreth, J.A.J.; Nagelkerke, L.A.J.

doi:10.1016/j.scitotenv.2022.156509

Cited by 31 publications

(31 citation statements)

References 90 publications

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“…This high variability in abundance between different periods has also been recorded in other river systems (Bednarski et al, 2008;Marschall et al, 2021). Changes in the flow and amount of rainfall have been suggested as plausible explanations for the variation in fish reproductive success in rivers with floodplain areas (King et al, 2009;Andrews et al, 2020;Stoffers et al, 2022). In fact, most species associated with the neutral period showed a positive relationship to flow, pH, and electrical conductivity, but precipitation was less important.…”

Section: Figuresupporting

confidence: 64%

Effects of anomalous climatic events on the structure of fish larvae assemblages in the eastern Amazon

Cajado

Oliveira

Silva

et al. 2022

Front. Environ. Sci.

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The reproduction of neotropical fish is linked to environmental stimuli that act as triggers in this process. Thus, it is possible to affirm that specific environmental changes can delimit most fish’s period and reproductive success. El Niño Southern Oscillation phenomena (ENSO) influence rainfall and, consequently, hydrological dynamics, affecting several fish population aspects, especially reproductive aspects. However, in the Amazon, empirical evidence of the effect of anomalous climatic events on fish reproduction is incipient. In this sense, we investigated the taxonomic and functional structure of parental fish larvae stocks and how species modulate their reproductive activities before (2013 and 2014) and during La Niña (2018) and El Niño (2019) events. The data evidence that the larval assemblages suffered alterations in the taxonomic and functional composition between the three analyzed periods and a pattern of temporal distribution with a high influence of environmental variables. Flow, pH, and electrical conductivity were the most important variables to modulate fish reproductive intensity between periods. The species seem to respond to combinations of these variables that reflect environmental conditions conducive to biological recruitment according to their ecological characteristics, allowing the perpetuation or decline of their abundance in each period. All species of commercial interest associated with the neutral period showed a sharp decline in the subsequent moments. These results suggest that the incidence of anomalous climatic events added to regional fisheries exploitation can negatively affect the phenology and demographic patterns of larvae assemblages on a short temporal scale. During the neutral period, the community was dominated by larvae of periodic large, herbivores, piscivores, epibenthic maneuverable, and nektonic burst swimmers. The decrease in the abundance of certain functional groups at the neutral and La Niña period favored an accelerated ecological succession during the El Niño period, due to the increase of species from basal trophic levels (planktivores), generalists (omnivores), highly resilient (intermediate strategists), sedentary, short-distance migrants and little commercially exploited. Thus, the results contribute to the understanding of the interactions between anomalous climatic events and the reproduction of fish with different ecological characteristics in the Amazon River.

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Section: Figuresupporting

confidence: 64%

Effects of anomalous climatic events on the structure of fish larvae assemblages in the eastern Amazon

Cajado

Oliveira

Silva

et al. 2022

Front. Environ. Sci.

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“…When the sample's handling time interfered with the health of the fish, representative subsamples were obtained. This usually happened when the overall number of fish surpassed 200 (Stoffers et al 2022a).…”

Section: J Ju Uv Ve En Ni Il Le Es Smentioning

confidence: 99%

“…Daily river water level data were collected at permanent monitoring locations closest to individual restoration projects. River-floodplain connectivity was calculated by combining daily water-level data with project inlet and outlet height (see also Stoffers et al (2022a)). Connectivity for certain water levels was validated by checking satellite images of restoration projects at specific dates .…”

Section: Case Studiesmentioning

confidence: 99%

“…Floodplains are among the most diverse and productive freshwater ecosystems in the world due to their complex gradient of aquatic and terrestrial habitats (Welcomme 1979;Junk et al 1989;Ward et al 1999). They are considered extremely valuable nursery areas for many fishes due to the relatively large areas of heterogeneous riparian habitat (Stoffers et al 2022a), the presence of physical structures (Grenouillet et al 2002;Schneider & Winemiller 2008), high primary production (Nunn et al 2012;Górski et al 2016), and a permanent lateral connection with the main channel (Grift et al 2003;Stoffers et al 2021).…”

Section: Introductionmentioning

confidence: 99%

“…The Nederrijn/Lek has three weir complexes to control water levels for water supply and navigation, while the Waal and IJssel are free-flowing branches. Over 60 floodplain restoration projects have been carried out since the 1990s to improve flood security and ecological quality of the Dutch Rhine (Stoffers et al 2022a). In this study, we assessed the functioning of 18 floodplain restoration projects (including nearby situated groyne fields in the main channel) as nursery area for young-of-the-year (YOY) fish throughout three growing seasons (April until September 2018-2020) (Fig.…”

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confidence: 99%

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Surviving and growing in dynamic floodplains : Habitat heterogeneity drives communities of young fish in the lower river Rhine

Stoffers¹

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Lowland river-floodplain systems, such as the Rhine, contain a complex gradient of aquatic and terrestrial habitats that contribute to a high level of biological and structural diversity, ranking them among the most diverse and productive freshwater ecosystems in the world (Welcomme 1979;Junk et al. 1989;Ward et al. 1999). The ecological importance of the Rhine was however hardly recognised until the 1970s. In the past, poor water quality as a result of water pollutants (Wolff 1978), regulated discharges (Cowx & Welcomme 1998), and extensive river modifications resulted in a major decline in floodplain habitat diversity, availability, and quality. This had a major impact on its ecological functioning (Van Urk & Smit 1989; Van den Brink et al. 1996;Middelkoop 1997). Numerous ecological groups, especially (migratory) riverine fishes, are sensitive to changes in water quality and habitat availability, and their populations have severely declined as a result (

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A habitat connectivity reality check for fish physical habitat model results and decision‐making for river restoration

Hansen,

Schneider,

Hägele

2023

Ecol Sol and Evidence

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Fish physical habitat models are a tool for guiding restoration efforts in lotic ecosystems, but often they overestimate restoration outcomes because currently they do not incorporate habitat connectivity. This persistent issue can, in extreme cases, result in little or no improvement to fish populations after the restoration, wasting valuable conservation resources. We present a case study where practitioners applied a fish habitat model for multiple life stages of gravel spawning fishes to a 52‐km stretch of the Iller River but did so at a microscale implementation by setting up a model based on cross sections with a maximum of 200 m distance from each other. This approach provided an opportunity to assess the connectivity of habitats for gravel spawning fishes, that is, European Grayling (Thymallus thymallus) and Common Nase (Chondrostoma nasus), integrating probabilities to find suitable habitats for all life‐history stages and seasonal movements. We used the assessed habitat estimates (availability of distinct habitat types within reaches defined by the 200 m cross sections) to calculate the minimum distance a fish would need to overcome to change from one habitat type into the other as it hypothetically ‘grew up’ from egg to full spawning adult. This approach can be interpreted as a life cycle habitat check as it considers all habitat types that are necessary to fulfil the life cycle of gravel spawning fishes including their size, distance and flow direction‐related orientation (e.g. larvae habitats only used when downstream of spawning areas). Our results show that the assumption of complete connectivity would require long movement distances for vulnerable life stages to find suitable habitat. This puts the high priority on the creation of migration corridors and passability of migration barriers in question. Without consideration of habitat types for all life stages of a species and their spatial context, restoration will not be successful. Shortly said: A perfect migration corridor does not necessarily provide habitat connectivity. We recommend the application of the habitat connectivity approach when predicting the effect of restoration measures and particularly setting the priority of measures for mitigation of fish migration.

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Freshwater fish biodiversity restoration in floodplain rivers requires connectivity and habitat heterogeneity at multiple spatial scales

Cited by 31 publications

References 90 publications

Effects of anomalous climatic events on the structure of fish larvae assemblages in the eastern Amazon

Effects of anomalous climatic events on the structure of fish larvae assemblages in the eastern Amazon

Surviving and growing in dynamic floodplains : Habitat heterogeneity drives communities of young fish in the lower river Rhine

A habitat connectivity reality check for fish physical habitat model results and decision‐making for river restoration

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