Non-native fish occurrence and biomass in Western Palearctic waterbodies in relation to abiotic and biotic predictors

CAROLINA TROCHINE; BRUCET, SANDRA; ARGILLIER, CHRISTINE; ARRANZ, IGNASI, ET AL. (+11 COAUTORES)

Portland

Congreso; ESA 2017 Annual Meeting; 2017

Ecological Society of America (ESA)

Background/Question/MethodsInvasion of non-native species is considered a majorthreat to global biodiversity. Among the vertebrates, fishes are the mostnumerous taxon and their invasion biology is relatively well studied. Forfreshwater fishes, continental and global records indicate that severalbioregions are threatened by taxonomic homogenisation, i.e. an increasedsimilarity of fish faunas caused by invasion of the same fish species into manyregional species pools. The Palearctic realm has experienced drastic changes infaunal composition relative to former times. Here we analysed the occurrence, richness and biomass contribution ofnon-native fish species in 1943 standing waterbodies from 14 countries of theWestern Palearctic, based on standardised fish catches by multi-meshgillnetting. We ask if 1) non-native fish occurrence in single lakes would be lower, due to itsisolated nature, than that suggested from catchment-scale data (c. 60%), 2) strong geographical gradients are linked to the occurrence ofnon-natives, 3) the contribution by non-natives to the local fish communitybiomass is correlated with local richness and the trophic level of native andnon-native species.Results/ConclusionsNon-native fish species occurred in 304 of 1943 waterbodies(16%). If the average number of occupied waterbodies per country was weightedby number of waterbodies per country, the grand mean occurrence of non-nativesin Western Palearctic waterbodies was 10%. Exotic (non-native to thePalearctic) and translocated (non-native only to parts of the Palearctic) specieswere found in 164 (8.4%) or 235 (12.1%) of the waterbodies, respectively. Theoccurrence and local richness of non-native fish species increased withtemperature, precipitation and lake area and were substantially higher inreservoirs than in natural lakes. High local biomass contributions of non-nativespecies were strongly correlated with low richness of native species and high richnessof non-native species, whereas the trophic level of the fish species had only aweak effect. We conclude that lakes are less vulnerable to invasions bynon-native fish than rivers, and hence the average occurrence is relatively low.While large-scaleclimatic drivers are primary determinants of fish species richness andcommunity composition, local species richness of natives and non-natives maydetermine the local biomass contribution of non-natives and hence predict thestrength of community and ecosystem effects exerted by non-native species.