NE Greece Research Articles

Fuzzy linear regression analysis for groundwater response to meteorological drought in the aquifer system of Xanthi plain, NE Greece

Abstract This paper studies, through the principles of fuzzy set theory, groundwater response to meteorological drought in the case of an aquifer system located in the plains at the southeast of Xanthi, NE Greece. Meteorological drought is expressed through standardized Reconnaissance Drought Index (RDISt) and Standardized Precipitation Index (SPI), which are calculated for various reference periods. These drought indices are considered as independent variables in multiple fuzzy linear regression based on Tanaka's model, while the observed water table regarding two areas is used as a dependent variable. The fuzzy linear regression of Tanaka is characterized by the inclusion constraints where all the observed data must be included in the produced fuzzy band. Hence, each fuzzy output can get an interval of values where a membership degree corresponds to each of them. A modification of the Tanaka model by adding constraints is proposed in order to avoid irrational behavior. The results show that there was a significant influence of the meteorological drought of the previous hydrological year, while geology plays an important role. Furthermore, the use of RDISt improves the results of fuzzy linear regressions in all cases. Two suitability measures and a measure of comparison between fuzzy numbers are used.

Applying Remotely Sensed Environmental Information to Model Mosquito Populations

Vector borne diseases have been related to various environmental parameters and environmental changes like climate change, which impact their propagation in time and space. Remote sensing data have been used widely for monitoring environmental conditions and changes. We hypothesized that changes in various environmental parameters may be reflected in changes in mosquito population size, thus impacting the temporal and spatial patterns of vector diseases. The aim of this study is to analyze the effect of environmental variables on mosquito populations using the remotely sensed Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) obtained from Landsat 8, along with other factors, such as altitude and water covered areas surrounding the examined locations. Therefore, a Multilayer Perceptron (MLP) Artificial Neural Network (ANN) model was developed and tested for its ability to predict mosquito populations. The model was applied in NE Greece using mosquito population data from 17 locations where mosquito traps were placed from June to October 2019. All performance metrics indicated a high predictive ability of the model. LST was proved to be the factor with the highest relative importance in the prediction of mosquito populations, whereas the developed model can predict mosquito populations 13 days ahead to allow a substantial window for appropriate control measures.

Migration of Arc Magmatism Above Mantle Wedge Diapirs With Variable Sediment Contribution in the Aegean

AbstractCompiled data show the age progression of magmatic centers along the two approximately linear profiles from NE Greece and NW Turkey to the South Aegean Volcanic Arc. The age progression reveals the southwestward migration of arc magmatic activity from Oligocene to present, perpendicular to the Hellenic Trench. This is in accordance with the migration of the Aegean subduction zone due to the collision of oceanic and continental blocks, trench retreat, mantle flow, and coeval extension. We suggest that the subduction of large volumes of sediments and their contribution to the sub‐arc magma source controlled the composition of calc‐alkaline to high‐K calc‐alkaline and shoshonitic arc magmas during the past 30 Ma. The magma geochemistry and the approximately linear age‐progressive migration of magmatic activity suggest focused ascent of mixed material from the subducted slab into the mantle wedge, most likely in the form of mélange diapirs. Geochemical data along the profile reveals increasing Sr and decreasing Nd isotopes during Upper Miocene in agreement with the ongoing subduction of continental blocks, low subduction rates, and development of an accretionary wedge. The different K‐rich arc magmas reflect the variable subduction of sediments, whereas crustal assimilation often plays a minor role. Magmas with variable 87Sr/86Sr, P/Nd, and Ba/La indicate a variable contribution of clastic, phosphate‐bearing, and barite‐bearing sediments. Low‐degree partial melting in sediment‐dominated mélange diapirs causes the formation of shoshonitic magmas with high Sr and P2O5 contents and high La/Yb in the northern Aegean.

Field Performances of Mediterranean Oaks in Replicate Common Gardens for Future Reforestation under Climate Change in Central and Southern Europe: First Results from a Four-Year Study

Climate change imposes severe stress on European forests, with forest degradation already visible in several parts of Europe. Thus adaptation of forestry applications in Mediterranean areas and central Europe is necessary. Proactive forestry management may include the planting of Mediterranean oak species in oak-bearing Central European regions. Five replicate common gardens of Greek and Italian provenances of Quercus ilex, Q. pubescens and Q. frainetto seedlings (210 each per plantation) were established in Central Italy, NE Greece (two) and Southern Germany (two, including Q. robur) to assess their performance under different climate conditions. Climate and soil data of the plantation sites are given and seedling establishment was monitored for survival and morphological parameters. After 3 years (2019) survival rates were satisfactory in the German and Italian sites, whereas the Greek sites exerted extremely harsh conditions for the seedlings, including extreme frost and drought events. In Germany, seedlings suffered extreme heat and drought periods in 2018 and 2019 but responded well. Provenances were ranked for each country for their performance after plantation. In Greece and Italy, Q. pubescens was the best performing species. In Germany, Q. pubescens and Q. robur performed best. We suggest that Greek or Italian provenances of Q. pubescens may be effectively used for future forestation purposes in Central Europe. For the establishment of Quercus plantations in Northern Greece, irrigation appears to be a crucial factor in seedling establishment.

Genetic diversity and spatial structure of the imperiled European population of Malus trilobata in Greece

Malus trilobata, is a rare tree species occurring in several small and disjunct populations in the eastern part of the Mediterranean basin. The main European population is found in the region of Evros (NE Greece) and is divided in five distinct subpopulations following the species geographical pattern. The genetic diversity of approximately the entire population (69 trees) was analyzed using nuclear microsatellite and random genomic markers. Polymorphism was discovered in 29 out of 45 genomic marker loci (64.44%), while for nuclear microsatellite markers, all three loci were polymorphic with an average of 3.75 alleles per locus. Our results unraveled a specific grouping pattern for both markers. Both genetic markers exhibited relatively low genetic diversity which is in accordance with the prevalent perception that species with fragmented distributions tend to have low genetic diversity, while the differentiation among individuals, revealed a patchy pattern among small groups of trees separated by roads, firebreaks or distance. These results indicate a high genetic fragmentation level for the main European population of M. trilobata, while the presence of roads, firebreaks, conifer plantations and agricultural land, seem to function as potential barriers to gene flow. Consequently, and since it is well-documented that bees hesitate to change foraging patches, as long as their food is abundant, the observed genetic differentiation patterns could be partially attributed to the foraging and flight behavior of bees, which are the main pollinators of the species. The low levels of available genetic diversity combined with the small overall population and repeated events of forest fires inside the M. trilobata distribution, perils the survival of the species and imposes the necessity for a thoroughly organized conservation strategy.

Detecting geothermal anomalies using Landsat 8 thermal infrared remotely sensed data

The potential to map geothermal anomalies using remote sensing information has attracted recently much research, reflecting thus the increasing interest for renewable energy resources. Aim of the present work is to highlight areas with geothermal anomalies, as demonstrated by increased Land Surface Temperature (LST) values, that could potentially indicate possible locations for geothermal field development. We hypothesized that an area with increased geothermal potential can possibly have a surface expression through increased LST, that discriminates it from other areas of low geothermal interest. LST is known to be affected by increased heat flow but also from other parameters such as altitude, land cover and meteorological conditions. Therefore, there is need to develop a methodology capable to extract LST signals corresponding to the geothermal component. To delineate areas with constantly higher LST values from surrounding locations, we analyzed Landsat 8 derived LST time series, and accounted for different land cover types and altitudes. To test our hypothesis, we used a well-known geothermal field in Aristino-Alexandroupolis, NE Greece, where it was shown that spatial means of winter LST were significantly greater within geothermal zones. Furthermore, our results indicated that areas within geothermal fields demonstrate winter LST values greater than a certain threshold value for each different land cover type. Therefore, we developed a logical operator algorithm and applied our methodology to Thrace basin – NE Greece. The produced geothermal potential map depicted correctly spot areas, which make part of the known geothermal fields in Eastern Macedonia and Thrace Tertiary sedimentary basins, but also indicated other possible sites with increased potential for future research.

The formation of shoshonitic magma and its relationship to porphyry-type mineralisation: the Maronia pluton in NE Greece

The Oligocene shoshonitic Maronia pluton in NE Greece is part of an age-progressive belt of calc-alkaline intrusions and associated with a porphyry Cu-Mo±Re±Au mineralisation. We present new data on mineral and whole rock compositions as well as Sr, Nd and Pb isotopes of the monzodioritic to granitic rocks from Maronia, including the mineralised microgranite, which crosscuts the main intrusion. The age progression of the plutons in NE Greece follows the southward-directed trench retreat implying that the magmas formed during subduction of continental lithosphere after the closure of the Pindos ocean. The shoshonitic magmas of Maronia were generated by hydrous melting of a phlogopite-bearing mantle that was enriched by 3-5% of slab-derived sediment melts. A lower degree of melting controls the higher K, LILE and incompatible element contents of the shoshonitic magmas in comparison to the neighbouring calc-alkaline magmas. The mafic shoshonitic rocks in NE Greece contain much higher P2O5 contents than the associated calc-alkaline magmas, which probably reflects subducted phosphate-rich sediments in their source. Constant Sr- and Nd-isotopes with increasing SiO2 contents imply minimal crustal assimilation and that felsic magmas including the mineralised porphyritic granite were generated by fractional crystallisation of mafic magmas. Amphibole and apatite analyses provide evidence for the intrusion of S-poor, Cl-rich magmas at 5 to 6 km depths, followed by rapid uplift and exsolution of magmatic fluids. Late granitic dikes at Maronia indicate that volatiles, sulphur and metals became enriched during the late stages of the magma evolution.

Implementation of geochemical modeling in post-mining land uses, the case of the abandoned open pit lake of the Kirki high sulfidation epithermal system, Thrace, NE Greece

Open pit exploitation of the Kirki high sulfidation epithermal deposit (Thrace, NE Greece) resulted in the formation of an acidic pit lake by infilling of the open cast by rain and draining waters after mine closure. Three case-specific PHREEQC geochemical models were developed including “Direct Precipitation”, “Evaporation”, and “Mixing with Rain water” to simulate the environmental conditions through the year, and to investigate the behavior of the acidic and rich in heavy metals waters of the pit lake. Scanning Electron Microscopy examination revealed the predominance of jarosite species and goethite in the mineral precipitate, followed by lower amounts of hematite, schwertmannite and anglesite. According to PHREEQC modeling, jarosite species formation is favored during both dry and wet periods, while the presence of schwertmannite, goethite, hematite and anglesite depicts the fluctuation of the physicochemical conditions through the year. These phases play a key role in controlling the As and Pb dissolved concentrations, mainly through adsorption and co-precipitation; whereas, the soluble metals Zn, Cd and Mn remain dissolved. The current status of the Kirki open pit system is the most stable for the environment; therefore, a case-specific remediation plan focused on both the protection of the environment and the preservation of the Kirki open pit is proposed. The socio-economic benefits of such an approach could include increased tourist numbers due to case-oriented tourism, enhancement of local economy, education; whereas, this approach is also cost effective relative to other proposed remediation measures.

Multi-Stage Introduction of Precious and Critical Metals in Pyrite: A Case Study from the Konos Hill and Pagoni Rachi Porphyry/Epithermal Prospects, NE Greece

The Konos Hill and Pagoni Rachi porphyry-epithermal prospects in northeastern Greece are characterized by abundant pyrite that displays important textural and geochemical variations between the various ore stages. It is commonly fine-grained and anhedral in the porphyry-related mineralization (M- and D-type veins), while it forms idiomorphic, medium- to coarse-grained crystals in the late, epithermal style veins (E-type). Porphyry-style pyrite from both prospects is characterized by an enrichment in Co, Se, Cu, and minor Zn, and a depletion in other trace elements, like Bi, Mo, Ag, etc. Pyrite in epithermal-style mineralization is mostly characterized by the presence of As, Bi, Pb, Ni, and Se. Gold in pyrite from all mineralization stages occurs as a non-stoichiometric substituting element, and its abundance correlates with As content. Arsenic in pyrite from Konos Hill records an increase from the porphyry stage to the epithermal stage (along with gold); however, at Pagoni Rachi, the highest Au and As contents are recorded in D-type pyrite and in the epithermal stage. The composition of the studied pyrite marks changes in the physico-chemical conditions of the ore-forming fluids and generally follows the geochemical trends from other porphyry-epithermal systems elsewhere. However, a notable enrichment of Se in the porphyry-style pyrite here is a prominent feature compared to other deposits and can be considered as an exploration tool towards Au-enriched mineralized areas.

Mineralogical Constraints on the Potassic and Sodic-Calcic Hydrothermal Alteration and Vein-Type Mineralization of the Maronia Porphyry Cu-Mo ± Re ± Au Deposit in NE Greece

The Maronia Cu-Mo ± Re ± Au deposit is spatially related to a microgranite porphyry that intruded an Oligocene monzonite along the Mesozoic Circum-Rhodope belt in Thrace, NE Greece. The magmatic rocks and associated metallic mineralization show plastic and cataclastic features at the south-eastern margin of the deposit that implies emplacement at the ductile-brittle transition, adjacent to a shear zone at the footwall of the Maronia detachment fault. The conversion from ductile to brittle deformation caused a rapid upward magmatic fluid flow and increased the volume of water that interacted with the host rocks through high permeable zones, which produced extensive zones of potassic and sodic-calcic alteration. Potassic alteration is characterized by secondary biotite + K-feldspar (orthoclase) + magnetite + rutile + quartz ± apatite and commonly contains sulfides (pyrite, chalcopyrite, pyrrhotite). Sodic-calcic alteration consists of actinolite + sodic-calcic plagioclase (albite/oligoclase/andesine) + titanite + magnetite + chlorite + quartz ± calcite ± epidote-allanite. The high-oxidation state of the magmas and the hydrothermal fluid circulation were responsible for the metal and sulfur enrichments of the aqueous fluid phase, an increase in O2 gas content, the breakdown of the magmatic silicates and the production of the extensive potassic and sodic-calcic alterations. Brittle deformation also promoted the rapid upward fluid flow and caused interactions with the surrounding host rocks along the high temperature M-, EB-, A- and B-type veins.

A simple method for water balance estimation based on the empirical method and remotely sensed evapotranspiration estimates

Abstract Developing a methodology for water balance estimation is a significant challenge, especially in areas with little or no gauging. This is because direct measurements of all the water balance components are not feasible. To overcome this issue, we propose a simple methodology based on the predefined empirical relationship between remotely sensed evapotranspiration (ET), i.e. Moderate Resolution Imaging Spectroradiometer (MODIS) ET and groundwater recharge (GR), and readily available precipitation data at the monthly time step. The developed methodology was applied in seven catchments in NE Greece using time series of precipitation and remotely sensed ET from 2009 to 2019. The potential of the proposed method to accurately estimate the water balance was assessed by the comparison of the individual water balance components against modeled values. Three performance metrics were examined and indicated that the methodology produces a satisfactory outcome. Our results indicated mean ET accounting for approximately 54% of precipitation, mean GR of 24% and mean surface runoff approximately 22% of precipitation in the study area. The proposed approach was implemented using freely available remotely sensed products and the free R software for statistical computing and graphics, offering thus a convenient and inexpensive alternative for water balance estimation, even for basins with limited data availability.

Evaluating the benefits of a potential industrial symbiosis network within the boundaries of a protected area, using the method of life cycle assessment

Anthropogenic activities within the boundaries of protected areas are creating challenges that can cause significant damage to the ecosystem and biodiversity. Especially on cases where heavy industrial activities take place within, or near, the boundaries of protected areas, the preservation of nature is at high risk. In this paper, we utilise the method of life cycle assessment (LCA) to assess the existing environmental situation of a protected area in NE Greece with anthropogenic activities. Moreover, the potential implementation of industrial symbiosis is examined, in order to minimise the environmental impacts within the boundaries of the protected area. LCA is used to compare the existing situation and the symbiotic scenario. Several symbiotic activities were identified leading to reduced carbon dioxide emissions in the area (14.5% reduction), reduced amount of oil consumption for heating needs (98 kt of oil annually), as well as reduced total energy consumption for electricity.

Trace Elements in Magnetite from the Pagoni Rachi Porphyry Prospect, NE Greece: Implications for Ore Genesis and Exploration

Magnetite is a common accessory phase in various types of ore deposits. Its trace element content has proven to have critical implications regarding petrogenesis and as guides in the exploration for ore deposits in general. In this study we use LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry) analyses of trace elements to chemically characterize magnetite from the Pagoni Rachi Cu–Mo–Re–Au porphyry-style prospect, Thrace, northern Greece. Igneous magnetite mostly occurs as euhedral grains, which are commonly replaced by hematite in fresh to propylitic-altered granodiorite porphyry, whereas, hydrothermal magnetite forms narrow veinlets or is disseminated in sodic/potassic-calcic altered (albite + K-feldspar + actinolite + biotite + chlorite) granodiorite porphyry. Magnetite is commonly associated with chalcopyrite and pyrite and locally exhibits martitization. Laser ablation ICP-MS analyses of hydrothermal magnetite yielded elevated concentrations in several trace elements (e.g., V, Pb, W, Mo, Ta, Zn, Cu, and Nb) whereas Ti, Cr, Ni, and Sn display higher concentration in its magmatic counterpart. A noteworthy enrichment in Mo, Pb, and Zn is an unusual feature of hydrothermal magnetite from Pagoni Rachi. High Si, Al, and Ca values in a few analyses of hydrothermal magnetite imply the presence of submicroscopic or nano-inclusions (e.g., chlorite, and titanite). The trace element patterns of the hydrothermal magnetite and especially the decrease in its Ti content reflect an evolution from the magmatic towards the hydrothermal conditions under decreasing temperatures, which is consistent with findings from analogous porphyry-style deposits elsewhere.

Temperature and moisture variability in the eastern Mediterranean region during Marine Isotope Stages 11–10 based on biomarker analysis of the Tenaghi Philippon peat deposit

The Mediterranean region is highly sensitive to climate change, particularly with regard to warming and increasing aridity. Understanding its past climate history during periods similar to the Holocene is key to understand the long-term dynamics that accompany anthropogenic climate change. Marine Isotope Stage (MIS) 11 (ca. 424–367 ka BP) is considered one of the best Holocene analogues. Despite detailed insight from Atlantic marine records and European continental records, MIS 11 temperature and rainfall evolution in the Mediterranean remains poorly understood.We present a detailed record of MIS 11–10 climate change at Tenaghi Philippon, a telmatic peatland in NE Greece. We use microbial membrane lipids (brGDGTs), the δD of n-C29 (δDwax) and distribution of n-alkanes derived from plant leaf waxes, and levoglucosan concentrations to reconstruct changes in temperature, rainfall sources and vegetation burning. Glacial-interglacial temperature patterns indicate strong Atlantic influence in the Eastern Mediterranean region.Low δDwax values and high temperatures indicate a predominance of Atlantic-sourced winter precipitation during MIS 11, and vice versa during MIS 10. The latter is attributed to a suppression of the Mediterranean storm track, probably due to a persistent high-pressure cell over most of the European continent, mainly in response to an extended ice cover during the glacial. The levoglucosan record is consistent with rapid change to drier conditions and increased vegetation burning from MIS 11 to 10. Millennial-scale oscillations allow to characterise cooling episodes previously recorded at other sites, with conditions of decreased winter precipitation, while suggesting increased seasonality during the interglacial optimum.

Barn Owl (Tyto alba) prey in Evros (Greece) and the discovery of a new mammal for the Greek fauna

ABSTRACTSmall mammals are key elements of terrestrial ecosystems, yet in south-eastern Europe many questions about their taxonomy and distribution remain unanswered. This is particularly true for the small mammal fauna of Greece. We investigated the distribution of small mammals in the district of Evros (NE Greece) through Tyto alba pellet analysis and live-trapping in 19 localities (29 samplings). We collected remains from a total 2434 individual vertebrates through pellet analyses and captured 110 small mammals through live trapping. We provide data on the distribution and community composition in the corresponding localities, for 17 small mammal species (11 rodents and 6 insectivores). Our findings include the first record of Myomimus roachi in Greece, a result facilitated by the yearly dynamics of Microtus sp. populations, as well as the first record of Sorex minutus in Evros. The Barn owl’s main prey (by percentage, allocated to genera) were Crocidura (29.7%) Mus (27%) Microtus (23.2%) and Apodemus (13%).

Wild vegetables do not lie: Comparative gastronomic ethnobotany and ethnolinguistics on the Greek traces of the Mediterranean Diet of southeastern Italy

ABSTRACT Bio-cultural and historical aspects of the “wild plant” portion of the Mediterranean Diet are still very much understudied despite the large number of bio-medical studies on the topic. The current gastronomic ethnobotanical and ethnolinguistic field study focused on the wild leafy vegetables used among Greek populations in SE Italy and NE Greece. A total of 52 folk taxa, corresponding to 58 wild botanical species, were recorded. The frequency of consumption of these wild ingredients was higher in NE Greece than in SE Italy, although approximately one-third of the recorded wild taxa overlapped in the two study sites. Most of these common species were designated by cognates, having in most cases a clear Greek origin, while one-third of the recorded wild vegetables in SE Italy were also used by another Greek diaspora living in SW Italy. The majority of the original Greek wild vegetables are synanthropic weeds. It is likely that the culinary uses of these species originated in the Near East during the post-Neolithic period before they migrated west to Italy and the Mediterranean Basin via Greece and Greek diasporas.

Reconciling the Greenland ice-core and radiocarbon timescales through the Laschamp geomagnetic excursion

Cosmogenic radionuclides, such as 10Be and 14C, share a common production signal, with their formation in the Earth's upper atmosphere modulated by changes to the geomagnetic field, as well as variations in the intensity of the solar wind. Here, we use this common production signal to compare between the radiocarbon (IntCal) and Greenland ice-core (GICC05) timescales, utilising the most pronounced cosmogenic production peak of the last 100,000 years – that associated with the Laschamp geomagnetic excursion circa 41,000 years ago. We present 54 new 14C measurements from a peat core (‘TP-2005’) from Tenaghi Philippon, NE Greece, contiguously spanning between circa 47,300 and 39,600 cal. BP, demonstrating a distinctive tripartite structure in the build up to the principal Laschamp production maximum that is not present in the consensus IntCal13 calibration curve. This is the first time that a continuous, non-reservoir corrected 14C dataset has been generated over such a long time span for this, the oldest portion of the radiocarbon timescale. This period is critical for both palaeoenvironmental and archaeological applications, with the replacement of Neanderthals by anatomically modern humans in Europe around this time. By placing our Tenaghi Philippon 14C dataset on to the Hulu Cave U-series timescale of Cheng et al. (2018) via Bayesian statistical modelling, the comparison of TP-2005 14C with Greenland 10Be fluxes also implicitly relates the underlying U-series and GICC05 timescales themselves. This comparison suggests that whilst these two timescales are broadly coherent, the IntCal13 timescale contains erroneous structure circa 40,000 cal. BP.

Eastern Mediterranean volcanism during marine isotope stages 9 to 7e (335–235 ka): Insights based on cryptotephra layers at Tenaghi Philippon, Greece

Tephra layers preserved in distal sedimentary archives represent chronicles of explosive volcanism that can complement the often more fragmentary information from near-source volcanic deposits to establish complete volcanic histories. With regard to these aspects, the Middle Pleistocene of the Eastern Mediterranean region stands out as it has a complex and diverse, but as yet largely unexplored record of volcanic eruptions. Here we present the first distal tephra record for the Eastern Mediterranean region spanning from 335 to 235 ka (corresponding to Marine Isotope Stages [MIS] 9 to 7e); our record has been derived from peat cores from the iconic terrestrial climate archive of Tenaghi Philippon (NE Greece). We have identified twenty-seven cryptotephra layers that represent eruptions from diverse Mediterranean sources. Six cryptotephra layers can be linked to Campanian volcanoes, and another six layers are tentatively correlated to Aeolian Arc volcanism. Of the ten cryptotephra layers that we have identified as deriving from the Aegean Arc, eight originate from Santorini volcano and two are tentatively attributed to either Kos or Milos. Five cryptotephra layers have yet unknown origins.Most of the identified cryptotephras represent previously undocumented eruptions. We provide age estimates for all cryptotephras and, by extension, for the underlying eruptions based on orbitally tuned pollen data from the same cores. The only cryptotephra layer in the 335–235 ka record from Tenaghi Philippon that represents a previously known eruption has a palynostratigraphically derived age of c. 289 ka and can be tentatively linked to the Seiano Ignimbrite from the Campanian Volcanic Zone; this represents the first time that this eruption can be traced beyond its proximal area. The documentation and geochemical characterization of tephra layers from different Mediterranean sources in the Tenaghi Philippon peat cores for MIS 9–7e is an important step towards the integration of regional Mediterranean tephrostratigraphic information for the Middle Pleistocene.

Range expansion in the land snail species Carinigera buresi (Clausiliidae): long-distance dispersal by ancient marble transport?

The clausiliid Carinigera buresi has a distribution that, considering its low vagility, is enigmatically disjunct. Carinigera buresi pharsalica occurs in Thessaly in central Greece, over 200 km outside the main range of C. buresi in NE Greece – SW Bulgaria. This range disjunction has led to the hypothesis that in antiquity the ancestors of C. buresi pharsalica were transported by the marble trade from NE Greece to Thessaly. To explore this hypothesis, we included samples from the NE Greek island of Thasos (the only area within the range of C. buresi from which marble was widely transported in antiquity) in a time-calibrated molecular phylogeny of C. buresi. Maximum likelihood (GARLI) and time-calibrated Bayesian (BEAST) analyses of mitochondrial cytochrome c oxidase subunit I (COI) from samples collected throughout the range of C. buresi indicate that the ancestral C. buresi pharsalica COI lineage reached Thessaly not from Thasos, but from the NE Greek mainland. This happened between 1,740 and 83,000 yr BP according to the BEAST analyses. Although this time interval does not entirely pre-date the earliest phase of marble transport in the region, we consider this mode of dispersal unlikely for two reasons: (1) our data show that C. buresi pharsalica must be older than estimated on the basis of geological calibration points; (2) our findings indicate that the dispersal event that brought C. buresi pharsalica to Thessaly did not follow ancient marble transport routes. We suggest dispersal via floating objects or aerial dispersal by birds as alternative hypotheses to dispersal by the historic marble trade. Unexpectedly, our phylogenetic analyses also showed the COI haplotype of C. buresi from the city of Kavala to be nested among COI haplotypes from northern Thasos. This suggests possible human-aided dispersal of C. buresi from Thasos to Kavala.

Estimating Groundwater Abstractions at the Aquifer Scale Using GRACE Observations

Groundwater monitoring requires costly in situ networks, which are difficult to maintain over long time periods, especially in countries facing economic recession such as Greece. Our work aims at providing a methodology to estimate groundwater abstractions at the aquifer scale using publicly available remotely sensed data from the NASA’s Gravity Recovery and Climate Experiment (GRACE) together with publicly available meteorological observations that serve as input variables to an Artificial Neural Network (ANN) method. The methodology was demonstrated in an alluvial aquifer in NE Greece for a 10-year period (2005–2014), where irrigation agriculture poses a serious threat to both groundwater resources and their dependent ecosystems. To generalize the developed model, an ensemble of 100 ANNs was created by the initial weight randomization approach and output was computed by averaging the output of each individual model. Scaled Root Mean Square Error and Nash–Sutcliffe coefficient were used to test the model efficiency. Both of these performance metrics indicated that monthly groundwater abstractions can be estimated efficiently and that the developed methodology offers an inexpensive substitute for in situ groundwater monitoring when in situ networks are not available or cannot operate properly.