Abstract
AbstractAimExotic species are a major threat to biodiversity and have modified native communities worldwide. Invasion processes have been extensively studied, but studies on species richness and beta diversity patterns of exotic and native species are rare. We investigate such patterns among exotic and native fish communities in upland and lowland rivers to explore their relationship with environmental drivers.LocationNorthern Italy.MethodsExotic and native fish beta diversity patterns were investigated separately in lowland and upland sites using Local Contribution to Beta Diversity (LCBD) and Species Contribution to Beta Diversity (SCBD) analyses. To examine the main environmental variables affecting the LCBD, a Boosted Regression Trees (BRT) method was used. Community dispersion among and within stream orders was investigated with the PERMDISP test.ResultsIn lowland sites, exotic species richness was higher than native species richness, especially in large rivers and drainage canals. An opposite trend was found in upland sites, where native species richness was higher than exotic species richness, especially in large rivers. No clear LCBD patterns were found along stream orders in the lowland, whereas higher stream orders in the upland showed the highest LCBD. Its patterns in upland and lowland sites were related to a number of factors, such as total suspended solids and total phosphorus. Community dispersion among stream orders did not show a relationship with environmental heterogeneity. SCBD values were positively correlated with species occupancy in the study area, and native species showed higher SCBD values than exotic species only in the uplands.Main conclusionsLarge rivers in the uplands are important in maintaining native fish diversity and should be protected against invasive fish. In contrast, most lowland rivers have suffered from biological homogenization. Some rare native species can show low contribution to beta diversity, but still need conservation actions due to their risk of local extinction.
Highlights
The importance of biodiversity for ecosystem functioning and resilience, as well as for humans through the supply of ecosystem services, is widely acknowledged (Cardinale et al, 2012; Hooper et al, 2005; Worm et al, 2006)
We examined if a relationship between species occupancy and species contribution to beta diversity existed
Native richness showed an increase across stream order only in the uplands, whereas in the lowlands, native species richness decreased in large rivers and drainage canals network
Summary
The importance of biodiversity for ecosystem functioning and resilience, as well as for humans through the supply of ecosystem services (e.g., food, pest control, fisheries), is widely acknowledged (Cardinale et al, 2012; Hooper et al, 2005; Worm et al, 2006). Different measures of beta diversity have been proposed (e.g., Baselga, 2010; Tuomisto, 2010), and recently, Legendre and De Cáceres (2013) proposed a method that estimates the overall beta diversity, and quantifies the Local Contribution to Beta Diversity (LCBD) by single sites and the Species Contribution to Beta Diversity (SCBD) by individual species. Both LCBD and SCBD can be considered as measures of the uniqueness of sites and species for a region and have been used to investigate species distribution shifts in fish communities (Kuczynski, Legendre, & Grenouillet, 2017) and other taxa such as diatom communities (Jyrkänkallio‐Mikkola, Siljander, Heikinheimo, Pellikka, & Soininen, 2018) and stream invertebrates (Heino & Grönroos, 2017; Sor, Legendre, & Lek, 2018; Tonkin, Heino, Sundermann, Haase, & Jähnig, 2016)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
