The body condition of invasive crayfish Faxonius limosus (Raf., 1817) (Decapoda: Cambaridae) is better in small rivers than in dam reservoirs in Central Europe.

The impact of dam reservoirs on river ecosystems is one of the current major issues in hydrobiology. In addition to the impact on native biodiversity, impoundments may facilitate biological invasions. A successful invasion is presumably related to the individual life history and resource allocation strategy in expanding populations. We tested whether reservoirs affect the body condition of invasive Faxonius limosus in upland streams. We found positive allometry of growth in females but more frequent isometric growth in males, and the form factor a3.0 was significantly higher in males than in females within populations. Fulton's condition factor (K) was calculated for standard carapace lengths of 20 mm (juvenile) and 40 mm (adult). Both mean KCL 20 and KCL 40 were higher in males than in females. Positive allometry of growth in females resulted in a larger mean KCL 40 than KCL 20. The majority of the mean K obtained in reservoirs was similar or lower than the respective condition in streams. The condition of adult females was higher in streams in comparison to reservoirs. The obtained results are in contrast to the hypothesis that reservoirs positively affect individual body conditions and show that these man-made lakes do not provide more favourable habitat conditions for F. limosus than those in the natural aquatic environments of an upland landscape. An advantageous effect of the presence of reservoirs on invasion spread may be possible in more ecologically harsh landscapes, especially in colder climatic zones. Our study is the first to investigate the relationship of the body condition of F. limosus in two contrasting habitats.

Does river channelization increase the abundance of invasive crayfish? Survey of Faxonius limosus in small Central European streams.

The aim of this study was to assess whether regulated river reaches show higher numbers of the spiny cheek crayfish Faxonius limosus, a common freshwater invader in Europe. Man-made alterations of riverine habitats may increase their susceptibility to biological invasions. This phenomenon is commonly studied in the context of dam reservoirs; however, the impact of river channelization and the resulting riverine habitat homogenization on the success of invasive species are mostly lacking. Surveys were conducted in natural and channelised river stretches in five rivers of south-central Poland. General linear mixed model analysis showed that crayfish abundance is usually higher at sites located within regulated reaches. The likely reason for the detected differences in abundance of crayfish may be related to decreased food-web complexity and lack of predators in a homogenised habitat. The results suggest that the channelization of small watercourses may increase the abundance of invasive species F. limosus and its pressure on native European crayfish. However, due to limited data obtained in field, our study should be considered as a pilot one.

Congruence between the prioritisation of conservation problems at the local and national scale: an evaluation by environmental scientists in Poland.

The anthropogenic pressure on the environment depends on the spatial scale. It is crucial to prioritise conservation actions at different spatial scales to be cost-efficient. Using horizon scanning with the Delphi technique, we asked what the most important conservation problems are in Poland at local and national scales. Twenty-six participants, PhD students, individually identified conservation issues important at the local and national scales. Each problem was then scored and classified into broader categories during the round discussions. Text mining, cross-sectional analyses, and frequency tests were used to compare the context, importance scores, and frequency of identified problems between the two scales, respectively. A total of 115 problems were identified at the local scale and 122 at the national scale. Among them, 30 problems were identical for both scales. Importance scores were higher for national than local problems; however, this resulted from different sets of problems identified at the two scales. Problems linked to urbanisation, education, and management were associated with the local scale. Problems related to policy, forestry, and consumerism were more frequent at the national scale. An efficient conservation policy should be built hierarchically (e.g. introducing adaptive governance), implementing solutions at a national scale with the flexibility to adjust for local differences and to address the most pressing issues.

The effect of railways on bird diversity in farmland.

With a length exceeding 210,000 km in Europe, railways are common linear features dissecting landscapes. However, the impact of railway networks on biodiversity is equivocal. In this study, we investigated the effect of railway embankments on bird diversity components in an agricultural landscape in southern Poland. Forty transects including 20 along railways and 20 as controls in open fields were established. Birds were counted twice in 2009, and environmental characteristics were estimated for each transect. Ordination techniques and generalized additive models were used to compare species composition, richness, abundance, conservation status, population trends and phylogenetic and functional diversity indices between railway and field transects. Species richness and phylogenetic diversity but not abundance nor functional diversity were higher along railway transects than along field transects. Diversity indices near railways, mostly species richness and phylogenetic diversity, were positively associated with bush cover, wet meadow cover, wetland cover and the slope of the railway but negatively associated with dry meadow cover and field cover. Our study shows that railway embankments may be beneficial for bird diversity but probably do not alter the functional properties of bird communities as much as open fields. Proper management of these linear habitats may increase their value for birds and contribute to long-term bird community persistence.

Relative Contribution of Matrix Structure, Patch Resources and Management to the Local Densities of Two Large Blue Butterfly Species.

The type of matrix, the landscape surrounding habitat patches, may determine the distribution and function of local populations. However, the matrix is often heterogeneous, and its various components may differentially contribute to metapopulation processes at different spatial scales, a phenomenon that has rarely been investigated. The aim of this study was to estimate the relative importance of matrix composition and spatial scale, habitat quality, and management intensity on the occurrence and density of local populations of two endangered large blue butterflies: Phengaris teleius and P. nausithous. Presence and abundance data were assessed over two years, 2011-12, in 100 local patches within two heterogeneous regions (near Kraków and Tarnów, southern Poland). The matrix composition was analyzed at eight spatial scales. We observed high occupancy rates in both species, regions and years. With the exception of area and isolation, almost all of the matrix components contributed to Phengaris sp. densities. The different matrix components acted at different spatial scales (grassland cover within 4 and 3 km, field cover within 0.4 and 0.3 km and water cover within 4 km radii for P. teleius and P. nausithous, respectively) and provided the highest independent contribution to the butterfly densities. Additionally, the effects of a 0.4 km radius of forest cover and a food plant cover on P. teleius, and a 1 km radius of settlement cover and management intensity on P. nausithous densities were observed. Contrary to former studies we conclude that the matrix heterogeneity and spatial scale rather than general matrix type are of relevance for densities of butterflies. Conservation strategies for these umbrella species should concentrate on maintaining habitat quality and managing matrix composition at the most appropriate spatial scales.