Knowledge and management of aquatic ecosystems (formerly Bulletin Français de la Pèche et de la Pisciculture), an international journal on freshwater ecosystem

Many species with complex life cycles, such as caudate amphibians, migrate from terrestrial to aquatic habitats for reproduction. However, movements between reproductive ponds within a breeding season have rarely been studied and are usually considered to be limited. Our aim was to determine whether this pattern occurs frequently in Alpine newts (Mesotriton alpestris) inhabiting complexes of small ruts on muddy forest tracks. We analysed capture-recapture data for individually marked newts as a function of locality, sex, body condition and hydroperiod throughout the breeding season. More than one third of the newts changed their ruts. Movements occurred more often towards ruts that did not dry during the breeding season. The body condition of males that changed ponds (but not that of females) was higher compared to that of resident newts in one of the studied populations. The relatively high frequency of movements between ruts can be seen as an adaptive strategy in unpredictable habitats which have a high probability of drying. The promiscuous pattern of newts also favours low site tenacity, because few sexual partners are available in each rut. Because of the broad occurrence of this kind of habitat, future studies should take into account these movements to better understand newt population dynamics and how to apply adequate conservation measures.

Because biological invasions can cause many negative impacts, accurate predictions are necessary for implementing effective restrictions aimed at specific high-risk taxa. The pet trade in recent years became the most important pathway for the introduction of non-indigenous species of reptiles worldwide. Therefore, we decided to determine the most common species of lizards, snakes, and crocodiles traded as pets on the basis of market surveys in the Czech Republic, which is an export hub for ornamental animals in the European Union (EU). Subsequently, the establishment and invasion potential for the entire EU was determined for 308 species using proven risk assessment models (RAM, AS-ISK). Species with high establishment potential (determined by RAM) and at the same time with high potential to significantly harm native ecosystems (determined by AS-ISK) included the snakes Thamnophis sirtalis (Colubridae), Morelia spilota (Pythonidae) and also the lizards Tiliqua scincoides (Scincidae) and Intellagama lesueurii (Agamidae).

Sexual selection based on visual stimuli was recently studied in several amphibian species with permanent or temporary dichromatism. The Alpine newt (Ichthyosaura alpestris) is a Caudate species with prominent sexual dichromatism during the breeding period. We focused on the intersexual differences in the orange, carotenoid-base ventral colouration of this widespread European species. We used an image analysis approach to compare the content of the red colour and saturation of the belly in 80 male and 62 female aquatic adult newts captured during spring migration in two localities in the Czech Republic. Both studied colour parameters of the ventral side of the Alpine newt are connected with sex. Males have significantly higher values of saturation on both localities, but the relationship with red content was not so clear. Individual characteristics (body condition, body length) affect colour variables of males and females similarly. Effect of body condition on colour variables was not demonstrated. Therefore we presume that the pronounced colouration of males is a cue facilitating detection, localisation or interspecies identification, rather than a direct component of male quality as assessed by females.

The Alpine newt (Ichthyosaura alpestris) is sensitive to habitat destruction and alteration, and as a result there has been a decline in their populations across Europe. Due to historical landscape changes, the populations of Alpine newts drawn from lowlands and hilly areas have recently been primarily found in artificial habitats, such as wheel ruts. In some areas inhabited by the Alpine newt range, wheel ruts are the only available habitat for newt breeding, and thus the only one allowing the maintenance of their populations. However, our knowledge about this type of habitat is limited. Therefore, 60 wheel ruts in a hilly forested area in the Czech Republic were checked for the presence of Alpine newt larvae. Their characteristics were measured (conductivity, pH, dissolved oxygen, depth, water coverage, plants, presence of prey, hydroperiod). The presence of larvae was positively associated with higher values of pH, coverage of water plants, and the presence of prey. The strongest predictor was the hydrological stability of wheel ruts, and newts were found to prefer non-drying ruts. From the conservation point of view, this means that the suitability of wheel ruts for Alpine newts can be estimated quite easily. This can essentially be performed on the basis of visual inspection if it is carried out through the breeding season of newts.