Against a background of increasing land use intensification on favorable agricultural areas and land abandonment on less arable areas in the Alps, the aim of this investigation was to detect whether and how 10 differently used types of grassland can be distinguished by site factors, plant species composition, and biodiversity. By using a very large number of vegetation surveys (936) that were widely distributed in the Central Alps, site parameters and species composition of the different land use types were compared by discriminant analyses and various biodiversity indices. Results showed that land use is a significant factor affecting the development of different grassland communities with site factors playing a subordinate, yet important role. The 10 land use types studied can be clearly differentiated from one another by single species as well as by species composition. Our study found that the number of plant communities along with the number of species decreases constantly and significantly with increasing land use intensity and on abandoned land. For example, on average, extensively used meadows have more than three times as many species as intensively used meadows. Further, the most even distribution of species (Evenness index) is reached in intensively used meadows, whereas on pastures and abandoned land, some species become dominant forcing other species to recede. The results confirm that due to current trends in agriculture, such as land abandonment and land use intensification, plant diversity in the Alps is decreasing considerably.

No abstract

No abstract

The marble trout, a lineage of the Salmo trutta complex, is endemic to the Southern Alpine region. Although it is endangered throughout its entire distribution range, population genetic data were lacking for the central area, including the upper Etsch/Adige River system (South Tyrol, Northern Italy). A total of 672 Salmo trutta specimens, comprising phenotypic marble trout and phenotypic brown trout, from 20 sampling sites throughout South Tyrol were analysed by sequencing the complete mitochondrial DNA control region. Thirteen distinct haplotypes were identified, which clustered within three major genetic lineages: the Marmoratus (MA), the Atlantic (AT) and the Danubian (DA) lineage. 41.7% of the investigated individuals carried haplotypes of the MA lineage, 47.9% of the AT lineage and 10.4% of the DA lineage. It is noticeable that AT haplotypes were present at all sampling sites and no ''pure'' marble trout population with exclusively MA haplotypes was found. This points to a considerable impact of stocking with allochthonous brown trout, given that there is no evidence for natural colonisation by individuals of the AT lineage. However, our data indicate, for at least four localities, a limited gene flow between the native marble trout and hatchery-reared strains. Future conservation and rehabilitation measures will thus have to concentrate on the identification of remnant pure marble trout individuals from such mixed populations.

Long-term hypoxia is a general phenomenon on the Italian Adriatic coastline, and is mainly caused by continuous eutrophication. The sensitivity of sole Solea solea to long-term hypoxia was investigated. Healthy S. solea obtained from trawls were kept at l g°C in aquana for at least 2 mo. The fish were exposed to hypoxia after a preacclimation penod of 30 h at normoxia Oxygen levels dunng normoxla were kept constant at 80% air saturahon (16.6 kPa, 6 . 4 mg I-' OZ); during hypoxia oxygen levels were set at 60, 40, 20, 12 or 6 % air saturation (4.8, 3.2, 1.6, 1.0, 0.5 m g I-'). During the expenment oxygen consumption was measured continuously. At the end of each experiment, blood samples were taken from anaesthetized specimens. Oxygen consumption patterns were statistically analyzed. A novel technique is described for the determination of the standard metabolic rate and the scope for activity of free-slulmmng animals. The resting metabolic rate and the scope for activity showed significant changes at reduced oxygen levels Activ~ty levels declined progressively starting at 40 % air saturation Restlng levels remained constant between 80 and 20 % air saturation, but fell below the standard metabohc rate at 12 and 6 % Blood lactate levels were increased at 12 and 6 % , indicating anaerobic metabolism. Data show that 40% air saturation should be considered as a limiting level, while the incipient lethal level lies between 12 and 20%.

Genetic studies on crayfish have shown that the differences between crayfish populations can be greater than it is assumed at the first view. Studies have demonstrated that some of these differences are not only found in the genome but are also expressed in the morphology of crayfish. Statistical analysis of a large set of morphological parameters from several autochthonous crayfish populations of Astacus astacus (Linnaeus, 1758) and Austropotamobius pallipes (Lereboullet, 1858) were applied in order to define distinct characteristics of different populations. Preliminary results of a multivariate discriminant analysis suggest that some morphological parameters are useful attributes to identify distinct populations. A positive correlation was obtained between carapace shape, described as the ratio postorbital length/width of carapace, and carapace curvature. Our results showed that the development and application of methods to characterize the uniqueness of individual populations is important, especially when they may have adapted in various ways to specific environmental conditions due to separation for a long time. Key-words:Crayfish, endangered species, morphometry, environmental adaptation. VARIATIONS MORPHOLOGIQUES DES POPULATIONS D'ASTACUS ASTACUS L. ET D'AUSTROPOTAMOBIUS PALLIPES (LEREBOULLET) RÉSUMÉDes études génétiques sur des écrevisses ont démontré que les différences entre les populations d'écrevisses peuvent être plus importantes qu'on ne pouvait le supposer a priori. Des études ont démontré que certaines différences ne sont pas uniquement génétiques mais aussi morphologiques. Des analyses statistiques sur un grand nombre de paramètres morphologiques sur plusieurs populations d'Astacus astacus (Linnaeus, 1758) et d'Austropotamobius pallipes (Lereboullet, 1858) ont été menées pour définir des caractères distinctifs des différentes populations. Les résultats préliminaires d'une analyse multivariée discriminante suggèrent que quelques caractéristiques morphologiques sont utiles pour identifier des populations distinctes. Si la forme de la carapace, ici décrite par le coefficient de la longueur post orbitale/largeur de la carapace, et la courbure de la carapace sont utilisés, une corrélation positive entre ces deux paramètres est obtenue.

No abstract

Apple proliferation (AP), caused by 'Candidatus Phytoplasma mali', is an economically important disease affecting many apple-growing areas in Europe. A new TaqMan real-time PCR assay was established for absolute quantification of 'Ca. P. mali' by using a single-copy gene of the host plant as a reference, which is amplified with the pathogen DNA in a single-tube reaction. Normalised estimates of phytoplasma concentration are ultimately expressed as the number of phytoplasma cells per host plant cell. The assay was used to monitor the 'Ca. P. mali' titre over the course of two growing seasons in roots and branches of symptomatic and asymptomatic but AP-positive apple trees. All 252 root samples from symptomatic and asymptomatic trees tested positive, with an average number of 59.8±5.68 (standard error) and 55.1±9.83 'Ca. P. mali' per host cell, respectively. From the 378 shoot samples analysed, 81% of the symptomatic and only 20% of the asymptomatic samples were AP-positive with an average number of 9.4±1.04 and 0.7±0.13 'Ca. P. mali' per host cell, respectively. This strengthens evidence that not the pathogen occurrence alone but the presence of a certain quantity of 'Ca. P. mali' in the aerial tree sections is involved in symptom expression. In addition, pronounced seasonality of the phytoplasma concentration was found, not only in branches, but also for the first time in roots of symptomatic and asymptomatic apple trees. Highest phytoplasma levels in roots were detected from December to May.