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

(Poster)

Péter Takács
takacs.peter@okologia.mta.hu

Balaton Limnological Institute, CER, Hungarian Academy of Sciences, Hungary, Hungary
,
Bálint Bánó
Georgikon Faculty of Agriculture, Pannon University, Keszthely, Hungary, Hungary
,
Tibor Erős
Balaton Limnological Institute, CER, Hungarian Academy of Sciences, Hungary, Hungary

DOI: 10.17011/conference/eccb2018/108126

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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.

Main references:
Erős, T. (2005). Life-history diversification in the Middle Danubian fish fauna-a conservation perspective. Large Rivers, 289-304.
Takács P, Czeglédi I, Ferincz Á, Sály P, Specziár A, Vitál Z, Weiperth A, Erős T, (2017) Non-native fish species in Hungarian waters: historical overview, potential sources and recent trends in their distribution Hydrobiologia, 795: 1-22.
Villéger, S., Mason, N. W., & Mouillot, D. (2008). New multidimensional functional diversity indices for a multifaceted framework in functional ecology. Ecology, 89(8), 2290-2301.

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INTRO:
In order to discover the role of non-native species "invading" the Middle-Danubian hydrosystem, Takács et al. analysed the functional trait space of 73 species found there (including both native and non-native species). This was done through identifying 15 traits relevant to food acquisition and locomotion. It was shown that the analysed 23 non-native species show almost complete overlap with the analysed native species in the functional trait space.
MERITS:
It seems like an interesting concept in order to explore how non-native species compete with native species and map out which species exactly would be competing with one another.
CRITIQUE:
Not being an expert on the topic I would have liked to get a short explanation of potential conservation implications. Ecologically, it makes sense there is some overlap between native and non-native species as otherwise these non-native species would probably not have been able to fit the available niches to settle in the area. Rare traits among native species come to mind as perhaps being of particular concern, but that's just my interpretation.
DISCUSSION:
I can believe that it carries important conservation implications but exactly what is unclear to me as stated above.

- - -
INTRO:
This study is an attempt to characterize the functional diversity of native and non-native fish species of the Middle-Danubian catchment. More specifically, the authors want to evaluate how much non-native species overlap with native ones in functional space. To this aim, the authors compiled a trait database with 15 morphological traits to characterize 73 species from this region and applied multivariate functional indices on the dataset.
MERITS:
The compilation of functional traits datasets is important as studies evaluating biodiversity patterns in a functional perspective may improve the generalization of their results. The study applies this perspective to evaluate how native and non-native fish species overlap in functional space.
CRITIQUE:
It is not very clear whether there is spatial component in their analysis (i.e., information about communities in space) or if the analysis was conducted on species regardless of their distribution. In the second sentence the authors mention communities but in the methods/results they do not talk about them. Moreover, the abstract needs a English review given that there are many grammatical errors and phrases that are oddly constructed. For instance:
"Therefore by some appropriate life history and functional traits, we can desribe the role of a certain species in the community, moreover the community complexity can be revealed appropriately also. "
I would change to something like:
"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."

Anyway, this is just an example. Other sentences need to be re-written as well.
Also the authors mention "life-history, morphological and functional traits". It is not clear if these are 3 different things, or if functional traits encompass both morphological and life-listory traits. Please clarify this point.
DISCUSSION:
Non-native species are amonst the greatest threaths to biodiversity worldwide. Understanding what are their effects in the functional space of communities may ultimatively inform us on how they will affect ecosystem functions and services. To this aim compiling datasets on functional traits is very important. While this work seems to move towards this goal, it is unclear whether they analyzed fish communities in the Danubian catchment, or if they just evaluated the regional functional space of the entire species pool from this catchment. I think there are the elements of a very but I suggest clarifying this point and working on the English in order for this work to impact I think it deserves.