Monitoring newt communities in urban area using eDNA metabarcoding

Newts are amphibians commonly present in small ponds or garden pools in urban areas. They are protected in many countries and their presence is monitored through visual observation and/or trapping. However, newts are not easy to spot as they are small, elusive and often hidden at the bottom of water bodies. In recent years, environmental DNA (eDNA) has become a popular tool for detecting newts, with a focus on individual species using qPCR assays. Here, we assess the effectiveness of eDNA metabarcoding compared to conventional visual surveys of newt diversity in 45 ponds within urban areas of Geneva canton, Switzerland. We designed newt-specific mitochondrial 16S rRNA primers, which assign the majority of amplicons to newts, and were able to detect four species known to be present in the region, including the invasive subspecies Lissotriton vulgaris meridionalis, native to the Italian peninsula, that has been introduced in the Geneva area recently. The obtained eDNA results were congruent overall with conventional surveys, confirming the morphological observations in the majority of cases (67%). In 25% of cases, a species was only detected genetically, while in 8% of cases, the observations were not supported by eDNA metabarcoding. Our study confirms the usefulness of eDNA metabarcoding as a tool for the effective and non-invasive monitoring of newt community and suggests its broader use for the survey of newt diversity in urban area at larger scales.

Amphibian diversity of the Dnipro river within the limits of the Dnipro city agglomeration

Amphibians play an important role in the formation of biodiversity and functioning in most terrestrial and freshwater ecosystems. Urbanization threatens to survive many species due to the destruction of natural ecosystems whose remains become fragmented, isolated, and modified by urbanization processes. The floodplain and coastal ecosystems along both banks of the Dnipro River within the limits of the Dnipro city agglomeration are investigated. The current diversity of amphibians in this territory is represented by six species, which is 55% of the total amount of amphibian fauna of the Dnipropetrovsk region. They are Lissotriton vulgaris, Pelophylаx ridibundus, Pelobates vespertinus, Bombina bombina, Hyla orientalis, and Bufotes viridis. The largest diversity of amphibians was found on the site near the Samara Gulf, where small urbanization and anthropogenic influence are observed. The smallest diversity of amphibians was found for the site of residential community "Pobeda", where only two species of amphibians were revealed. The assessment of the similarity of amphibian communities shows that their diversity is the most similar for ecosystems of the right bank of the Dnipro River near the residential communities "Chervony Kamin", "Pokrovsky", and "Parus" and the ecosystems on the left bank near the Samara Gulf. The most numerous and widespread species is the marsh frog P. ridibundus, which lives along the coastline of the Dnieper River. Its populations are relatively stable according to their high number and distribution. The populations of L. vulgaris, B. bombina, and H. orientalis are under the threat of declining, as evidenced by their low number and dependence on small water bodies. Therefore, the reconstruction of the coastline and any earthwork and building activity should be accompanied by the measures on the preservation of small reservoirs along the Dnieper River. The obtained results develop our knowledge about the actual state of biodiversity and species wealth abundance of the Dnieper River within the northern steppe subzone of Ukraine and may be used for planning of the environmental protection measures.

Evaluation of the Composition of Ichthyofauna in Lakes Free from Commercial Use in a Tightly Protected Area of the Wolin National Park (Poland)

The ichthyological biodiversity of Polish lakes is poorly understood, even in lakes not used for fishing and those under strict protection. With this in mind, the aim of this study was to conduct a comprehensive ichthyological survey of several lakes in the Wolin National Park (Poland). The study was conducted in Domysławskie and Gardno lakes and the anthropogenic Stara Kredownia reservoir. Each fishing exercise was conducted using benthic nets over a 12 h period. The fish caught were measured and weighed, and the species identified. Shannon-Wiener (H) and Simpson biodiversity indices were determined. The catch comprised a total of 4580 fish (of which 4391 were caught in Domysławskie Lake) belonging to 15 species, with a combined weight of 98,165 g. In general, the most prevalent species were non-predatory fish: roach (Rutilus rutilus), freshwater bream (Abramis brama), white bream (Blicca bioerkna), bleak (Alburnus alburnus), and rudd (Scardinius erythrophthalmus). Individually, perch (Perca fluviatilis) and roach (Rutilus rutilus) were the most abundant species. Ichthyofauna diversity varied greatly between the studied water bodies, with 15 species found in Domysławskie Lake and only 6 species in Gardno Lake. In Stara Kredownia Reservoir, no fish were caught, but amphibians were observed, such as great crested newts (Triturus cristatus) and common newts (Lissotriton vulgaris). Based on the results obtained, Lake Domysławskie had a higher species ichthyofauna diversity than the other ‘tench and pike’ lakes. Gardno Lake had a much lower biodiversity.

Smooth newt Lissotriton vulgaris and common toad Bufo bufo populations persisting in the unusually small area of Sommers Island in the Baltic Sea

Sommers Island is an abandoned 20 ha patch of land in the Baltic Sea. It is inhabited by isolated populations of smooth newt (Lissotriton vulgaris) and common toad (Bufo bufo). The island demonstrates the small area in which it is possible to have a stable population of newts and toads for a period of at least several decades, probably much longer. Most reproduction of both species occurred in one pool with an area of about 100 m². The total area of optimal terrestrial habitat is about 2.5 ha, with an additional 3.5 ha of sub-optimal habitat available. The island is inhabited by about 123 adult newts and several dozen adult toads.

Genetic differentiation over a small spatial scale in the smooth newt (Lissotriton vulgaris)

Understanding the distribution of genetic variation is central for both population biology and conservation genetics. Genetic population structure can be primarily affected by the species’ dispersal ability, which is assumed to be limited in many amphibians. In this study, we estimated allelic differentiation metrics and FST indices to investigate genetic variation among natural breeding ponds of smooth newts (Lissotriton vulgaris) over a small spatial scale. Based on six microsatellite loci, we found a small, but significant allelic differentiation among clusters of natural breeding ponds (i.e. ‘local regions’), which result was in line with the calculation of corresponding hierarchical FST values. Analysis of molecular variance also indicated significant between-region variation in the study area. Pairwise estimations showed that only the furthermost regions differed from each other in both differentiation measures, but this difference was not attributable to geographic distances between ponds. Our results provide evidence that hierarchical genetic structure can be characteristic to breeding ponds of smooth newts on a small spatial scale in their natural breeding habitat, but dispersal distance may be less limited than previously thought in these philopatric caudates.

Can We Share? Feeding Strategy in Three Syntopic Newts in Artificial Habitats

Natural aquatic sites are disappearing worldwide, especially in the Mediterranean region where amphibians are frequently forced to move for reproduction to artificial sites designed for irrigation and cattle watering (i.e., wells, tanks and drinking troughs). In artificial aquatic sites, where resources (space and food) are usually limited, trophic niche information can be particularly useful to infer the suitability of habitats for amphibian conservation especially when more than one species co-occurs. In this paper, we focused on three newt species: The Italian newt (Lissotriton italicus), the Italian smooth newt (Lissotriton vulgaris meridionalis) and the Italian crested newt (Triturus carnifex) inhabiting man-made wells widespread in an area in Central Italy characterized by few available natural aquatic sites. Specifically, we analyzed the trophic spectrum of the species, their interactions and overlap, and discussed the potential role of wells in amphibian conservation. Overall, 550 newt individuals occurring in 16 distinct wells were sampled. The study species consumed similar resources, mainly of aquatic origin, with Diptera larvae and Cladocera representing the most important preys. The high degree of diet overlap observed may be due to site oligotrophy and high availability of small-sized prey, and it does not necessarily lead to competition. Newts had similar narrow niche width values and a generalist feeding pattern with high diversity among individuals. Lissotriton italicus and T. carnifex showed wider niche width in isolation than in syntopy condition, probably as a result of interspecific competition and/or intraguild predation. We showed that artificial aquatic sites are important for newt ecology and conservation since they allow up to three species to cohabit, thus representing a good surrogate of natural habitats. The study wells apparently provided suitable trophic conditions for newts in terms of prey availability and catchability. To date, just a few studies have contributed to a greater understanding of newts’ diet in artificial aquatic sites and this gap of knowledge has to be filled to clarify their role in amphibian ecology and conservation.

Zur Bedeutung der ‚Grünbrücke Kiebitzholm‘ (Schleswig-Holstein) für Amphibien

In den Jahren 2006 bis 2010 wurde die Amphibienfauna auf der Grünbrücke bei Kiebitzholm (Schleswig-Holstein, Norddeutschland), an den angrenzenden Straßensäumen beidseitig der Bundesautobahn (BAB) A21 sowie an Stillgewässern im 1,5 km Radius um die Grünbrücke untersucht. Im Untersuchungsgebiet konn- ten sieben Amphibienarten festgestellt werden, darunter Knoblauchkröte (Pelo- bates fuscus), Kreuzkröte (Epidalea calamita) und Moorfrosch (Rana arvalis), die landes- oder bundesweit als bestandsgefährdet gelten. Bei Knoblauchkröte und Moorfrosch handelt es sich zudem um bundesweit bedeutsame Zielarten für den Biotopverbund. Teichmolch (Lissotriton vulgaris), Erdkröte (Bufo bufo), Grasfrosch (Rana temporaria) und Moorfrosch wurden im Untersuchungszeitraum auf der Grünbrücke nachgewiesen. Der Kammmolch (Triturus cristatus) konnte nur auf der östlichen Rampe festgestellt werden. Die Grünbrücke diente den er- fassten Individuen offenbar in erster Linie zur Querung der BAB A21 und nur zum Teil auch als Sommerhabitat. Eine auf der östlichen Rampe angelegte Wildtränke wurde im Jahr 2010 erstmals von Teichmolch, Kammmolch und Moorfrosch als Laichgewässer genutzt. Knoblauchkröte und Kreuzkröte waren im Untersuchungsgebiet besonders selten. Sie traten in einem bzw. zwei Untersuchungsgewässern auf. Während die Kreuz- kröte auf beiden Seiten der Autobahn gefunden wurde, wurde die Knoblauchkröte nur westlich der Straße erfasst. Die übrigen festgestellten Amphibienarten traten in teilweise größeren Populationen auf beiden Seiten der BAB A21 auf. Die Funde dieser Arten auf der Grünbrücke zeigen, dass bereits ein Verbund zwischen diesem Que- rungsbauwerk und den Populationen in der Umgebung realisiert war.