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Abstract: Water temperature is a physical property influencing abiotic and biotic parameters in an aquatic ecosystem. In different Central European rivers and lakes, a general trend of water temperatures in the range of +0.05 to +0.8 °C per decade was identified. Our case study analyses whether similar patterns apply to the headwaters of the Volga River, in the East European plain. Based on a dataset of water temperatures for 2008–2015, we investigated the spatial and temporal distribution of water temperature along the Tudovka River and estimated backward as well as predicted future changes from development scenarios throughout the 21st century. Stochastic models were applied to track trends and variations in water temperature. Furthermore, the correlation between water temperature and air temperatures was used to model historical water temperatures and to predict possible changes in the future, under the effects of climate change. Based on climate change scenarios, an increase of the mean water temperatures as well as changes regarding the ice cover can be expected until the end of this century. The conditions described for the headwaters of the Volga River system represent a valuable dataset for medium and large rivers in the East European plain and serve as a basis for future management. [ABSTRACT FROM AUTHOR]

Branchiobdellid annelids are usually found as commensal symbionts associated with crayfish populations, but knowledge of their dispersion and ecology in Europe is generally scarce. We hypothesized that their geographic extension of species and populations may mirror the distribution history of their hosts. We analysed potential host specificities and the geographic distribution of species from the Italian and Austrian Tyrol and Carinthia by characterizing the morphological and genetic features. On the three indigenous crayfish species Astacus astacus, Austropotamobius pallipes and Austropotamobius torrentium, we identified four branchiobdellid species based on morphological characteristics: Branchiobdella hexodonta, Branchiobdella pentodonta, Branchiobdella balcanica and Branchiobdella parasita. In contrast to the morphological classification, phylogenetic analysis using mitochondrial cytochrome c oxidase I (CO-I) sequences identified five main lineages: B. balcanica, B. hexodonta, Branchiobdella italica, B. parasita and B. pentodonta. The arrangement of branchiobdellid species corresponded generally to the geographical distribution of their crayfish hosts' locations but also confirmed previous assumptions of crayfish translocations. Our study provides the first application of ideas on the association of freshwater crayfish and their ectosymbionts to be used for discussing the biogeography of crayfish populations. The phenotypical and genotypical analysis also demonstrated so far ignored effects of human activities at both macro-ecological and micro-ecological levels. [ABSTRACT FROM AUTHOR]

The morphology of an animal is known to reflect both genetic variation and adaptation to the environment. Thus, phenotypic criteria have been used to characterize indigenous crayfish populations. Twenty-one morphometric parameters were measured on crayfish from 25 waterbodies in the Austrian and Italian parts of Tyrol. They were analysed with hierarchical cluster analysis to obtain the population structure based on morphological similarity between and within the freshwater crayfish species Astacus astacus (noble crayfish), Austropotamobius torrentium (stone crayfish) and Austropotamobius pallipes (white-clawed crayfish). Furthermore, a stepwise discriminant analysis was applied to the morphometric data to test their differentiating power between populations. Both analyses resulted in a clear differentiation of species and populations, and reflected geographic separations. Thus, the developed morphometric methods were shown to be applicable to characterize the phenotype in freshwater crayfish and seem appropriate to be used for stock identification and the effective characterization of management units in decapod crustaceans. [ABSTRACT FROM AUTHOR]