Land use effects in riverscapes: Diversity and environmental drivers of stream fish communities in protected, agricultural and urban landscapes

Abstract

Increasing agriculture and urbanization inevitably lead to changes in the biodiversity of stream ecosystems. However, few studies examined comprehensively how biodiversity is distributed within and among protected, agricultural and urban land use types in streams. We studied environmental characteristics of streams and patterns of species richness and other community attributes of stream fish communities in these three characteristic land use types in the catchment of the Danube River, Hungary. Land use separated streams to some degree based on their environmental characteristics. However, both between stream environmental and fish community variability were high in most types, and comparable to land use type level differences in case of many streams. A variety of environmental gradients influenced fish community structure rather independently of land use type, which was also influenced by spatial drivers. Non-native fishes modified the structure of native fish communities, especially in agricultural streams, although their modification effect varied more among individual streams than among land use types. In conclusion, land use type proved to be a poor predictor of fish communities in this human modified landscape. We found that even intensively managed areas (i.e. agricultural and urban) can contribute to the maintenance of fish diversity in this biogeographic region, or at least their potential can be comparable to those streams which flow in protected areas. Thus, conservation management should focus on maintaining streams in more natural condition in protected areas and/or use the potential of non-protected agricultural and urban streams in maintaining fish diversity in human modified landscapes.

Impacts of Urbanization on Stream Fish Assemblages: The Role of the Species Pool and the Local Environment

“…These results suggest the relatively low predictability of stream fish assemblages in this human-modified landscape (see also Erős et al, 2012), or at least that urbanization in itself was an insufficient predictor of fish assemblage characteristics. Our findings thus confirm other studies, which found highly variable and sometimes even weak responses of fish to land use gradients (e.g., Utz et al, 2010;Tóth et al, 2019). In contrast, most studies showed clear negative influence of increasing urbanization on fish assemblages (Helms et al, 2005;Morgan and Cushman, 2005;Slawski et al, 2008).…”

“…Thus, we could characterize only a relatively short urbanization gradient, due to the lack of large metropolitan areas in Hungary, not like those found in other countries (e.g., USA). Nevertheless, documenting patterns and understanding processes in the early phase of urbanization is important to provide evidence for possible future effects, especially since urbanization processes are ongoing intensively in this region (Tóth et al, 2019).…”

“…Moreover, former variance partitioning analyses indicated a statistically non-significant effect of spatial distance among sampling sites across Hungary on fish assemblages (adj. R 2 = 0.061; p = 0.131) (Tóth et al, 2019). Based on these results, we chose not to include these spatial variables in our variance partitioning models.…”

Landscape features and study design affect elements of metacommunity structure for stream fishes across the eastern U.S.A.

“…Urbanised landscapes have been associated with a variety of changes to stream habitats including increased nutrient input, sedimentation, runoff, and channelisation (Allan, 2004). Decreases in species richness associated with increased urban land use has been documented for fish communities across the globe (Edge et al., 2017; Tóth et al., 2019; Wang et al., 2001). Even if regional species pools are similar, unique species groupings can still be observed in metacommunities because of interspecific differences in tolerance to urbanisation (Utz et al., 2010), which is a similar notion to why urbanisation could impact turnover (Johnson et al., 2013).…”

Low-head dams induce biotic homogenization/differentiation of fish assemblages in subtropical streams

“…Habitat modifications in upland streams associated with anthropogenic activities may cause endemic fish species population declining and even local extinguishing (Dorobek et al, 2015;Tóth et al, 2019), which further alters both taxonomic and functional compositions (Dala-Corte et al, 2016;Leitão et al, 2018). However, habitat modifications may also favor the occurrence and spread of alien and/or native invaders into upland streams (Scott & Helfman, 2001;Dala-Corte et al, 2019).…”