Search Results (9)

Facultative paedomorphosis, the retention of larval traits in sexually mature individuals, plays a crucial role in species ecology and evolution and is influenced by complex interactions between environmental factors. Here, we compile all known cases of paedomorphosis in all newt species in Greece and report 20 new localities, mainly in Northern Pindos National Park. Our results indicate that paedomorphosis tends to occur more frequently in stable aquatic environments in combination with unfavourable external conditions (lack of precipitation and higher temperatures). Furthermore, species-specific patterns related to the occurrence of paedomorphosis were also unveiled: Mesotriton alpestris prefers high-elevation and permanent ponds; Lissotriton graecus occurs predominantly in artificial, lowland ponds; and Triturus macedonicus is associated with a stable hydroperiod and fish absence. Overall, conservation strategies should explicitly account for paedomorphic populations, emphasizing the value of artificial ponds, which are able to support this life-history strategy. Lastly, the Northern Pindos Mountain Range emerges as a major European intra-specific diversity hotspot. Full article

Surveys and excavations carried out between 2004 and 2019 around the Vlach town of Samarina, in the Pindos Mountains of Western Macedonia (Greece), have yielded potsherds that can be attributed to different historical periods. The data collected so far suggest a long human presence in this region of the northern Pindos spanning from the Middle Pleistocene to the late Middle Ages. The ceramic fragments from the Historical Camp (HC), Kirkouri (KRK), the Holy Cross Church (SMC), Mt. Anitsa (Anitsa), Avgo (VGO), the Mirminda Pass (VLC), Mt. Vasilitsa (VSL), and the saddle between Mts. Bogdhani and Gurguliu have been studied in detail. Despite their fragmentary state, a database has been created with the morphological and typological characteristics of the potsherds and the sites from which they were retrieved. Coarse and fine ware potsherds have been identified. According to their manufacturing characteristics, they can be attributed to different Roman and medieval periods. A diassarion of the Larissa mint shows that connections between the mountain highlands and the lowlands were already active during the period of Emperor Augustus. The Samarina potsherds are probably related to the movements of Vlach shepherds, who spent long periods in these mountains with their flocks. This impression is confirmed by the presence of one vessel wall fragment which was directly in contact with fire and a few small vessel bases. The presence of ceramic vases is closely linked to the transportation of primary or secondary food supplies in a pre-cooked form or as liquids. We know that Vlach shepherds, as many other groups of Eurasian shepherds, never manufactured ceramic vessels even in their villages. Instead, they used different types of wooden and metal containers for cooking, drinking, and other tasks associated with pastoral activities, such as keeping milk and making cheese and butter, for example. Following these observations, our aim has been to define the vessel types used by the Vlach shepherds, which exhibit some kind of uniformity from the Roman to the Middle Ages. Full article

The impoundment of Aoos springs was created in 1990 to facilitate hydroelectric production, and fish fauna has been enriched through the years due to deliberate or accidental fish stockings, with certain invasive alien fish species arising (i.e., Lepomis gibbosus, Carassius gibelio), some of which are ranked among the most dangerous species for global biodiversity. A three-year monitoring survey was conducting to map the nesting areas of Pumpkinseed, L. gibbosus, to assess the effectiveness of electrofishing as an active method to reduce the spread of the corresponding species and to identify the impact of the L. gibbosus on native species. The largest percentage of nests was found in areas with silty-sand bottoms (53.4%) and low vegetation. The potential nesting area was estimated at 1.97 km² and the area of confirmed nesting was 0.33 km². The species appeared to nest in a small area, compared to the potential nesting area. The results also indicate that a significant percentage of the target species (71.6% of the total number of species) was removed, with an average time per sampling of 1.2 ± 1 h, whereas the impact on the other native species was minimal. These results are important for designing and implementing programs for the eradication or reduction of L. gibbosus in the impoundment of Aoos springs. Full article

The ecosystem structure of a Mediterranean high-altitude artificial lake (Aoos Springs, Northwest Greece) was assessed and quantified using the Ecopath with Ecosim model. The artificial lake was created in 1990 for hydroelectric production and the fish fauna has been enriched across years due to deliberate or accidental fish stockings, as well as the introduction of the invasive pumpkinseed (Lepomis gibbosus), which may cause adverse effects on aquatic ecosystems and their biota. The model considered 20 species/taxa groups with biological data gathered during 2021–2022 from field surveys, interviews with recreational anglers and literature. The results revealed that the artificial lake of Aoos is a resilient ecosystem to unexpected events with low intensity of fisheries exploitation. The biomass of the introduced invasive species Lepomis gibbosus is low, due to the low biomass level of its diet, Chironomidae and zoobenthic organisms as well as other fish species. Full article

In the present study, the biology of the pumpkinseed Lepomis gibbosus in the artificial lake of Aoos, located in northwestern Greece, was investigated. The samplings of the pumpkinseed were conducted from the shore using a portable electrofishing device over a 4-month period (July 2021–October 2021). A total of 581 specimens were caught, with an average length of 62 mm. The sex ratio of female to male was estimated to be 1.0:1.7, and the percentage of mature specimens was estimated for all of the months to be above 52%, matching the highest percentage in July (57.4%). The b value of the length–weight relationship ranged from 3.16 in September to 3.31 in July. The value of the L∞ and K was estimated to be equal to 119 mm and 0.36 years⁻¹, respectively, and the value of φ′ was equal to 3.707. The total mortality was estimated to be equal to 1.63 ± 0.48 y⁻¹ (R² = 0.96), and the natural and fishing mortalities were 0.83 and 0.80, respectively. The maximum age was 6 years, and the theoretical maximum age was 8 years. In the current study, the value of the L∞ was estimated to be near the European average but significantly lower than the North American one, whereas the value of the K was slightly higher than the European average. The small size of the specimens obtained in Aoos Springs was most likely owed to the combined impact of the investigated lake’s high altitude and low food availability, resulting in a limited factor for species expansion. Full article

In this study, we used genetic approaches to assess the conservation status of a protected amphibian species, the Macedonian crested newt, Triturus macedonicus, in Northern Pindos National Park (Epirus, Greece). Mitochondrial DNA sequences and multilocus genotypes of individuals from 38 breeding sites were used to infer their phylogenetic position and to detect and measure genetic variation patterns, population genetic structure, and levels of gene flow. The examined individuals fell within two major clades of the Macedonian crested newt phylogeny, being geographically separated by the Aoos River valley and Vikos Gorge. Both groups constitute separate gene pools, bearing private haplotypes and alleles, and the groups were found to be highly differentiated in both their mitochondrial and microsatellite markers. Thus, they meet all of the criteria needed to be characterized as evolutionary significant units (ESUs) that deserve a separate conservation status. Within each ESU, the particularly high inter-population differentiation and low migration rates imply a lack of connectivity between breeding sites and local isolation in favorable habitats. Our results can inform future programs and actions towards the conservation and management of the Macedonian crested newt in the area. Full article

In order to optimize the appropriate conservation actions for the brown bear (Ursus arctos L.) population in Greece, we estimated the census (Nc) and effective (Ne) population size as well as the genetic status of brown bear sub-populations in three National Parks (NP): Prespa (MBPNP), Pindos (PINDNP), and Rhodopi (RMNP). The Prespa and Pindos sub-populations are located in western Greece and the Rhodopi population is located in eastern Greece. We extracted DNA from 472 hair samples and amplified through PCR 10 microsatellite loci. In total, 257 of 472 samples (54.5%) were genotyped for 6–10 microsatellite loci. Genetic analysis revealed that the Ne was 35, 118, and 61 individuals in MBPNP, PINDNP, and RMNP, respectively, while high levels of inbreeding were found in Prespa and Rhodopi but not in Pindos. Moreover, analysis of genetic structure showed that the Pindos population is genetically distinct, whereas Prespa and Rhodopi show mutual overlaps. Finally, we found a notable gene flow from Prespa to Rhodopi (10.19%) and from Rhodopi to Prespa (14.96%). Therefore, targeted actions for the conservation of the bears that live in the abovementioned areas must be undertaken, in order to ensure the species’ viability and to preserve the corridors that allow connectivity between the bear sub-populations in Greece. Full article

Earth observation data can provide important information for tree species diversity mapping and monitoring. The relatively recent advances in remote sensing data characteristics and processing systems elevate the potential of satellite imagery for providing accurate, timely, consistent, and robust spatially explicit estimates of tree species diversity over forest ecosystems. This study was conducted in Northern Pindos National Park, the largest terrestrial park in Greece and aimed to assess the potential of four satellite sensors with different instrumental characteristics, for the estimation of tree diversity. Through field measurements, we originally quantified two diversity indices, namely the Shannon diversity index (H’) and Simpson’s diversity (D1). Random forest regression models were developed for associating remotely sensed spectral signal with tree species diversity within the area. The models generated from the use of the WorldView-2 image were the most accurate with a coefficient of determination of up to 0.44 for H’ and 0.37 for D1. The Sentinel-2 -based models of tree species diversity performed slightly worse, but were better than the Landsat-8 and RapidEye models. The coefficient of variation quantifying internal variability of spectral values within each plot provided little or no usage for improving the modelling accuracy. Our results suggest that very-high-spatial-resolution imagery provides the most important information for the assessment of tree species diversity in heterogeneous Mediterranean ecosystems. Full article

This paper deals with (both supervised and unsupervised) classification of multispectral Sentinel-2 images, utilizing the abundance representation of the pixels of interest. The latter pixel representation uncovers the hidden structured regions that are not often available in the reference maps. Additionally, it encourages class distinctions and bolsters accuracy. The adopted methodology, which has been successfully applied to hyperpsectral data, involves two main stages: (I) the determination of the pixel’s abundance representation; and (II) the employment of a classification algorithm applied to the abundance representations. More specifically, stage (I) incorporates two key processes, namely (a) endmember extraction, utilizing spectrally homogeneous regions of interest (ROIs); and (b) spectral unmixing, which hinges upon the endmember selection. The adopted spectral unmixing process assumes the linear mixing model (LMM), where each pixel is expressed as a linear combination of the endmembers. The pixel’s abundance vector is estimated via a variational Bayes algorithm that is based on a suitably defined hierarchical Bayesian model. The resulting abundance vectors are then fed to stage (II), where two off-the-shelf supervised classification approaches (namely nearest neighbor (NN) classification and support vector machines (SVM)), as well as an unsupervised classification process (namely the online adaptive possibilistic c-means (OAPCM) clustering algorithm), are adopted. Experiments are performed on a Sentinel-2 image acquired for a specific region of the Northern Pindos National Park in north-western Greece containing water, vegetation and bare soil areas. The experimental results demonstrate that the ad-hoc classification approaches utilizing abundance representations of the pixels outperform those utilizing the spectral signatures of the pixels in terms of accuracy. Full article