Effects of dams decrease zooplankton functional β‐diversity in river‐associated lakes

Abstract

In river–floodplain systems, the construction of dams causes environmental changes in the natural dynamics of rivers and the associated wetlands, which can affect both the taxonomic and functional composition of communities, and, consequently, ecosystem functioning. We evaluated zooplankton taxonomic and functional β‐diversity in sets of lakes associated with a preserved and a dammed river in a Neotropical floodplain. We expected that both β‐diversity measures would be lower in lakes associated with a dammed river than in lakes associated with a preserved river. β‐Diversity was partitioned into turnover and nestedness components, through multiple‐site dissimilarity measures, and compared with expected null models. We expected that nestedness would be more important for both the β‐diversity measures in lakes associated with the dammed river, whereas species and trait turnover would be more important in lakes associated with the preserved river. Functional β‐diversity was higher among lakes of the preserved river than of the dammed river, while taxonomic β‐diversity was not different between the rivers. Contributions of turnover and nestedness components were similar in the preserved river, whereas that of nestedness was higher in the dammed river, revealing the loss of extreme trait combinations from the functional space. Comparisons between observed and expected β‐diversity revealed a higher trait turnover than would be expected by species turnover in the preserved river, and no differences from the null models were observed in lakes associated with the dammed river. Our results suggest that dissimilarity in trait composition is influenced more by environmental changes associated with river damming than by dissimilarity in species composition such that a functional homogenisation occurs without a change in taxonomic β‐diversity. We propose the maintenance of preserved tributaries in floodplains, which sustain environmental heterogeneity, primarily if the nearby environments are already dammed. Furthermore, we reinforce the necessity of a pluralistic approach, considering both taxonomic and functional aspects of biodiversity in ecosystem management.

Does habitat restoration disturb? A case study of a shallow urban water reservoir in western India using cladoceran zooplankton

“…The decrease in species richness that occurred due to this disturbance event and the high nestedness observed amongst the early-and late-communities indicate the effect of a hierarchical species loss (Baselga, 2010). Similar patterns of high nestedness in zooplankton communities were observed in disturbed habitats (Gianuca et al, 2017, Braghin et al, 2018). Functional diversity of communities provides information on microhabitats, resource use and trophic dynamics in a habitat (Jeppesen et al, 2000), as it connects taxonomic diversity to ecosystem function (Nevalainen & Luoto, 2017).…”

Comparing the diversity and composition of waterbird functional traits between natural, restored, and artificial wetlands

“…Likewise, habitat alterations have been found to selectively change functional composition for a wide range of other aquatic organisms such as plants, zooplankton, or benthic invertebrates (Baattrup-Pedersen, Gothe, Riis, & O'Hare, 2016;Braghin et al, 2018;Januschke, Jahnig, Lorenz, & Hering, 2014).…”

Zooplankton β diversity dynamics and metacommunity structure depend on spatial and temporal scales in a Neotropical floodplain

“…This is because the construction of dams alters the natural dynamics of rivers, leading to a taxonomic and functional simplification of aquatic biota (Oliveira et al., 2018). Other studies in this same floodplain, for example, have already registered a difference in the spatial and temporal patterns of β diversity when comparing the dammed sub‐basin (Paraná) with the conserved sub‐basin (Ivinhema), showing the negative influence of anthropic actions on aquatic ecosystems (Bonecker et al., 2020; Braghin et al., 2018).…”

“…In this sense, it is essential to evaluate biological data in a spatio‐temporal context (Dornelas et al., 2013). However, most studies have considered only spatial scale (Braghin et al., 2018), and few studies have incorporated the influence of temporal variation on β diversity and metacommunity structure (EMS) (e.g. Fernandes et al., 2014; Wojciechowski et al., 2017).…”