Amphibian situation in urban environment – history of the common toad Bufo bufo in Kraków (Poland)

Abstract

Rapid urbanization processes are not neutral to the environment, especially amphibians. Their double-environment lifestyle makes them particularly vulnerable to negative changes in the environment. Inventory research on batrachofauna carried out in urban areas usually provides data on its current state, but there is little information about changes in its composition over the years. The aim of the study was to investigate the situation of amphibians in urban areas of Kraków (Poland) over the last 90 years. As an example of amphibian species the common toad Bufo bufo (Linnaeus, 1758) was selected, because of its widespread occurrence and high environmental plasticity. Three periods were chosen for the analysis: 1) before the Second World War (1928-1939), when the nature of the city seemed to be the least exposed to treats, 2) after the rapid urban transformation associated with the expansion of the territory of the city (1986-1992), and 3) the present time. In order to determine the current situation of amphibians, in 2011-2012, 30 water bodies of Kraków were inventoried, with particular emphasis on the common toad. The occurrence of the same species in the city over the last 90 years was shown. The proportion of occupied habitat (POH) by the common toad (POH=0.57) is currently similar to the pre-Second World War proportion (POH=0.58). Between these two periods, there was a significant increase in the number of Bufo bufo in Kraków (POH=0.86). At that time the common toad was the only amphibian which increased, while the others declined. These results may suggest the high resistance of the species to the negative impact of urbanization during this period (loss and fragmentation of habitat and pollution). However, its resistance is limited, as evidenced by the recent decline of the species, just as most other amphibians of Kraków.

Water quality of urban water bodies – a threat for amphibians?

“…Assuming, that all water bodies were characterized then by a similar species composition, the condition of their water could also be similar. Our research revealed that water bodies identified as HES were in majority, which proves the loss of amphibian species and is consistent with the previous studies (Guzik et al 1996;Kawa et al 2011;Budzik et al 2013). As we expected, the values of most chemical indicators were higher in HES than in LES.…”

“…1) was not a random sample, because it was prepared on the basis of data from the previous inventory in the years 1986years -1992years (Guzik et al 1996. Although our sample size is fairly small, it seems to be representative, in terms of historical amphibian species presence (Guzik et al 1996) and their current state (Kawa et al 2011;Budzik et al 2013). Three amphibian species (Hyla arborea, Pelobates fuscus, Pseudepidalea viridis), which were noted by Guzik (1996), were not found in 15 currently investigated water bodies.…”

“…Three amphibian species (Hyla arborea, Pelobates fuscus, Pseudepidalea viridis), which were noted by Guzik (1996), were not found in 15 currently investigated water bodies. However, the other research (Kawa et al 2011;Budzik et al 2013) showed that the species are still present in some sites in the city. Our present results suggest local extinction of these species and a significant reduction in the number of habitats of B. bombina (80%) and L. vulgaris (77%) (Fig.…”

“…The study area encompassed urban area of Kraków, mostly the central part of the city. In recent years, there were vast urban transformations, which resulted in the loss and isolation of many amphibian habitats (Budzik et al 2013). The set of 15 water bodies (Fig.…”

“…Amphibian species richness in each water body was surveyed in the spring (March -June) period of 2011 and 2012. The presence of amphibians was identified by both visual and auditory surveys using standard methods (for details see Budzik et al 2013). All observed green frogs were classified as Pelophylax kl.…”