Functional diversity of the Middle-Danubian fish fauna, the role of non-native species

Abstract

It is well known that physical appearance and behavior of each species reflects to its habitat preference, feeding habits, etc. Therefore, one can describe the ecological role of species in a community by characterizing their life-history and functional traits. By applying this framework across all species present in the community, we can characterize its funcitonal diversity. The Middle-Danubian hydrosystem is characterised by valuable and diverse fish fauna, at the same time this area is highly exposed to the invasions because of the „natural" range expansion of Pontos-Caspic species and due to the illegal fish stockings. And although several notes deal with the effect of non-native species on the native biota, the role of these species in the invaded communities is still not discovered in detail. The life history traits of the Middle-Danubian fish fauna has already been revealed, but there is no information published about the functional traits of the species living in this area. Thus our primary aim is to explore functional diversity of the fish fauna of this area with special regard to the native and invasive fauna components. For this reason a database containing 15 functional traits describing the food acquisition and locomotion features (e.g. oral gape position, fins surface ratio, etc.) of the analyzed species was compiled. This database recently contains the functional trait data of 73 species can be found in the Middle-Danubian hydrosystem. By multivariate analyses of this dataset, the species' places in the functional trait space was defined, moreover the distribution of non-native species was revealed also. Our results show that the overall distribution of analyzed 23 non-native species in the functional trait space show almost complete overlap with the native ones. Moreover several native-non-native species pairs with highly similar functional traits were revealed (e.g. Rhodeus sericeus and Pseudorasbora parva). These results can help to form reliable conservation plans. The database can provide the basis of further investigations dealing with functional diversity.This work was supported by the "OTKA PD 115801" project.

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