Native and non-native fish across aquatic habitats in the Ebro Delta

Miguel Clavero, Nati Franch, Verónica López, Quim Pou-Rovira, Josep Maria Queral

FiSHMED 2021.002: 21p

Abstract : We describe the variability in the composition of fish communities in the Ebro Delta (NE Iberian Peninsula) and report the habitat preferences of the most common species. The Ebro Delta is a large coastal wetland that has been inten- sively modified, mainly for rice cultivation involving the input of a large amount of low-conductivity waters into an originally brackish and saline system. We de- fined nine main habitat types within the Ebro Delta (the river, inflow channels, rice fields, outflow channels, springs, marshes, lagoons, lagoon mouths and bays) and sampled fish communities in them by establishing 376 sampling sites, in which we set 1431 fyke nets. We captured more than 120,000 fish belonging to 52 species, of which 37 were native and 15 were non-native. The ichthyofauna of the Ebro Delta is strongly structured in relation to habitat type, following varia- tions in water salinity, and there is a clear segregation of native and non-native fish species. Native species are clearly dominant in the more saline habitats, namely bays, the lagoons, lagoon mouths and marshes, while non-natives domi- nate the aquatic habitats related to rice cultivation (inflow and outflow channels as well as rice fields). Freshwater springs are dominated by non-natives in terms of abundance, but not in terms of richness. Since the decline and loss of native fish species in the Ebro Delta seems linked to the massive inflow of low- conductivity waters for rice irrigation, fish conservation must focus in reducing the influence of those outflows on the remaining natural and semi-natural wet- lands.

Keywords : coastal wetlands, biodiversity conservation, invasive species, threatened species, fyke nets, rice

Citation : ClaveroM,FranchN,LópezV,Pou-RoviraQ,QueralJM(2021)Nativeandnon-nativefish across aquatic habitats in the Ebro Delta. Fishes in Mediterranean Environments 2021.002: 21p. https://doi.org/10.29094/FiSHMED.2021.002

https://doi.org/10.29094/FiSHMED.2021.002

Article first published online : 22 November 2021

FiSHMED is an international scientific journal edited by 
the Iberian Society of Ichthyology – SIBIC