Lake Ohrid Research Articles

The impact of pollution on the quality of the Lake Ohrid water and the Barbus meridionalis petenyi Heckel

The impact of pollution on the quality of the Lake Ohrid water and the Barbus meridionalis petenyi Heckel

A MIS 9/MIS 8 speleothem record of hydrological variability from Macedonia (F.Y.R.O.M.)

The period corresponding to Marine Isotope Stages 9 (MIS 9) offers the opportunity to study orbital and sub-orbital scale climate variability under boundary conditions different from those of better studied intervals such as the Holocene and the Last Interglacial. Yet, it is poorly represented in independently-dated continental archives around the Mediterranean Region. Here, we present a speleothem stable isotope record (δ18O and δ13C) from the Former Yugoslavian Republic of Macedonia (F.Y.R.O.M., southern Balkans), which consists of two periods of growth broadly covering the ca. 332 to 292 ka and the ca. 264 to 248 ka intervals (MIS 9e-b and late MIS 8). We interpret the speleothem δ18O as mostly related to regional hydrology, with variations that can be interpreted as due to changes in rainfall amount, with higher/lower values associated to drier/wetter condition. This interpretation is corroborated by a change in mineralogical composition between aragonite and calcite at ca. 328 ka, which marks increasing precipitation at the onset of MIS 9 and occurs within a trend of decreasing δ18O values. Also the comparison with the multiproxy climate record available from the nearby Lake Ohrid seems to support the proposed interpretation. The MIS 9e interglacial appears to be characterized by wettest conditions between ca. 326 and 321 ka, i.e. lasting ca. 5 kyr. Decreasing precipitation and enhanced millennial scale variability matches the glacial inception (MIS9 d to b), with drier events at ca. 319 ka (ca. 2 kyr long) and 310 ka (ca. 1 kyr long), and a major rainfall reduction between 306 and 298 ka. The latter is followed by a prominent wetter period between 298 and 295 ka, for which carbon data values suggest high infiltration rate. Rainfall decreases again after 295 ka, and remain low until the growth interruption at ca. 292 ka. Resumption of the growth and progressive soil development, expressed by the carbon isotope record, occurred during the late part of MIS 8. Despite the rather high temporal uncertainty (average 6 ka), the speleothem hydrological record complements the environmental information provided by the Lake Ohrid record and also fits well to the framework of regional and extra-regional variability, showing similarities with pollen records from southern and western Europe, both at orbital and at sub-orbital time scale.

Ancient European Lakes: Reservoirs of Hidden Microbial Diversity? The Case of Lake Pamvotis (NW Greece)

Ancient European lakes are clustered within a radius of 300 km around Lake Ohrid. Information concerning microbial diversity in these lakes is limited. We studied diversity of the dominant prokaryotic phylotypes in the sediments in one of these lakes, known as Lake Pamvotis. The analysis was performed in samples from two stations for four seasons of the same year. DNA extraction followed by PCR amplification (16S rDNA), Denaturing Gradient Gel Electrophoresis, cloning and sequencing was applied in order to reveal the sequence signatures of the dominant bacterial and archaeal phylotypes. Bacterial and archaeal cell numbers were quantified by real-time PCR. Several environmental variables measured in parallel, including pH, Nickel, Chromium, Arsenic, Calcium, Total Nitrogen and Total Carbon, were found to affect strongly the prokaryotic abundances. Most of the identified sequences of Bacteria belong to Proteobacteria and most of the sequences of Archaea belong to Euryarchaeota. The great majority of these bacterial (84.21%) and archaeal sequences (95.65%) have no cultivated counterparts in the databases. In addition, many of these bacterial (50.88%) and archaeal sequences (20.65%) correspond to potentially new species. Six of the bacterial sequences constitute a new class of Cyanobacteria which we have named “Lake Pamvotis cluster” (LPC). Our findings highlight Lake Pamvotis as a habitat for several previously unidentified species of Bacteria and Archaea.

Palynology of the Last Interglacial Complex at Lake Ohrid: palaeoenvironmental and palaeoclimatic inferences

In this article, we present new, high-resolution, pollen results obtained from the DEEP site sequence recovered from Lake Ohrid (Albania/FYROM) for the Last Interglacial Complex (LIC), corresponding to Marine Isotope Stage 5 (MIS 5) of the marine isotope stratigraphy. LIC covers the period between 130 and 70 ka and includes the Eemian (Last Interglacial, LI) and the succession of stadial and interstadial phases of the Early Last Glacial.During the LIC, the pollen record shows an alternation of periods characterized by forest and open vegetation, clearly resembling the well-known vegetational succession of other European records. Our results reveal three key phases for the LI: a first period (128-125 ka) with a rapid increase in temperature and precipitation, a central phase (125–118.5 ka) characterized by a slight cooling, and a late phase (118.5–112 ka), with a decline both in temperatures and precipitation. Besides the LI, we identify four more forested periods dominated by mesophilous trees and intercalated by colder and drier steppe phases, during which, however, most arboreal taxa never disappear.During the Early Last Glacial we also identify several abrupt events that can be correlated to the succession of cold events recorded in the Greenland ice core records, associated to a weakening of the North Atlantic Meridional Overturning Circulation.The new high-resolution record indicates that Lake Ohrid is an important site to understand the response of vegetation to fluctuations in regional moisture availability and temperature changes, and thus provides new evidence for the connection between the Mediterranean Region and Northern Hemisphere climate oscillations.

Zooplankton in Ancient and Oligotrophic Lake Ohrid (Europe) in Association with Environmental Variables

AbstractZooplankton is studied in the ancient, tectonic, oligomictic and oligotrophic Lake Ohrid (Macedonia, South Eastern Europe). The main aim of this study was to assess the seasonal and spatial patterns of the zooplankton functional feeding guilds in relation to the environmental conditions. Metalimnion of the lake was detected as the most productive environment, where biomass of the phytoplankton and abundance of the zooplankton reached their maxima. Pelagial zooplankton of low abundance (25 ± 22 ind. L−1) consisted of 16 species including two endemic copepods,Arctodiaptomus steindachneri(Richard, 1897) andCyclops ochridanus(Kiefer, 1932). Copepods obtained remarkable share (60%) in the zooplankton assemblage. Microphagous zooplankton was mainly comprised of the most abundant rotiferKellicottia longispina(Kellicott, 1879) in summer, and copepod nauplii during the springEudiaptomus gracilis(Sars, 1862) andC.ochridanus,and autumnC.ochridanus. Due to their requirements for the bacterio-detritus suspension, this microphagous zooplankton occupied aphotic hypolimnion during the entire study period. Raptorials were typically represented by copepodites and adult copepods in the metalimnion, and were significantly and positively affected by temperature (r= 0.417,p= 0.001), dissolved oxygen (r= 0.463,p= 0.0001) and, particularly, phytoplankton biomass (r= 0.708,p< 0.00001). This is the first study in which the link between the lower and higher trophic levels is investigated in Lake Ohrid.

Linear and non-linear responses of vegetation and soils to glacial-interglacial climate change in a Mediterranean refuge

The impact of past global climate change on local terrestrial ecosystems and their vegetation and soil organic matter (OM) pools is often non-linear and poorly constrained. To address this, we investigated the response of a temperate habitat influenced by global climate change in a key glacial refuge, Lake Ohrid (Albania, Macedonia). We applied independent geochemical and palynological proxies to a sedimentary archive from the lake over the penultimate glacial-interglacial transition (MIS 6–5) and the following interglacial (MIS 5e-c), targeting lake surface temperature as an indicator of regional climatic development and the supply of pollen and biomarkers from the vegetation and soil OM pools to determine local habitat response. Climate fluctuations strongly influenced the ecosystem, however, lake level controls the extent of terrace surfaces between the shoreline and mountain slopes and hence local vegetation, soil development and OM export to the lake sediments. There were two phases of transgressional soil erosion from terrace surfaces during lake-level rise in the MIS 6–5 transition that led to habitat loss for the locally dominant pine vegetation as the terraces drowned. Our observations confirm that catchment morphology plays a key role in providing refuges with low groundwater depth and stable soils during variable climate.

Evidence for a Younger Dryas deglaciation in the Galicica Mountains (FYROM) from cosmogenic 36Cl

This study presents the first cosmogenic 36Cl surface exposure data from a moraine in the Former Yugoslav Republic of Macedonia (FYROM). Five limestone boulders from an end moraine in the Galicica Mountains (40.94°N, 20.83°E, 2050 m a.s.l.) were used for cosmogenic 36Cl surface exposure dating. The 36Cl concentrations from the five boulders are identical within their measurement uncertainties ruling out major effects of inheritance, erosion, or snow cover. The calculated ages are very consistent ranging from 11.3 ± 1.3 to 12.8 ± 1.4 ka (mean 12 ± 0.6 ka) after applying a Ca-spallation production rate of 56 at g−1 a−1 (LSD scaling) and correction for 5 mm ka−1 carbonate weathering and 2% snow shielding. The applied corrections for weathering and snow shielding cause a shift to older ages in the order of magnitude of ca. 5% on average, making the production rate the main impact on exposure ages. The ages point to a moraine formation during the Younger Dryas period, consistent with the timing of the last deglaciation in the Galicica Mountains derived from previous geomorphological studies in the area. The formation of a glacier was likely favoured by several topoclimatic factors, accounting for additional snow input. This interpretation is in line with regional studies on glaciation chronologies from Šara Range (FYROM/Republic of Kosovo), Retezat Mountains (Romania), Mt. Chelmos (Greece), Mount Orjen (Montenegro) and Durmitor (Montenegro). Lake sediment analyses of Prespa (Republic of Albania/FYROM/Greece), Maliq (Republic of Albania) and Dojran lakes (FYROM/Greece) indicate that cold conditions promoted the formation of a local cirque glacier. However, studies of sediment records of the adjacent lakes Ohrid (Republic of Albania/FYROM) and Prespa do not indicate the presence of a proximal glaciation. An explanation might be a combination of the small size of the cirque glacier, generating only small amounts of debris, and the karstic bedrock, which hampers fluvial transport and acts by its aquifer system as a natural sediment trap, as the fluvial transport of the sediments to the lakes is absorbed by the karst system.

New findings of the Campanian Ignimbrite ash within slope deposits of the Treska valley (former Yugoslav Republic of Macedonia)

In this paper, we describe the first finding of the Campanian Ignimbrite tephra layer in a subaerial succession in the Former Yugoslav Republic of Macedonia. The tephra is interbedded within slope deposits mixed with colluvial loess. The identification of this fundamental stratigraphic marker is based on major elements. The investigated succession is correlated to lacustrine records from Ohrid and Prespa lakes, several archives of the central and eastern Mediterranean, and mainland Ukraine and Russia. Field observations and correlation with lacustrine records (i.e. pollen) indicate that accumulation of the volcanic ash occurred in a dry environment characterized by low vegetation cover and important wind activity, which promoted loess deposition. The recognition of the Campanian Ignimbrite tephra allows the correlation of the loess sediments to the H4 event, as defined in the North Atlantic event climatic stratigraphy.

Molecular species delimitation methods provide new insight into taxonomy of the endemic gammarid species flock from the ancient Lake Ohrid

Evidence for cryptic diversity has been accumulated for many animal groups. In reply, effective tools for ordering this diversity by detecting and delimiting new species have been developed. Although molecular methods of species delimitation become fast means to order information upon hidden diversity, cryptic species discoveries are rarely followed by formal species descriptions and implementation of DNA data in species diagnoses, enhancing rather than reducing the taxonomic impediment. DNA-based diagnostic characters may serve as the backbone for a taxonomic description of cryptic species. In this article, we verify an established taxonomy of an ancient lake endemic species flock, through confrontation of the morphological taxonomy and molecular species delimitation methods. The endemic Gammarus species flock inhabiting Lake Ohrid was tested with several distance- and phylogeny-based delimitation methods using the mitochondrial cytochrome oxidase subunit I and 16S ribosomal RNA genes. We described three new species, including the Gammarus sywulaisp. nov., on the basis of morphological and molecular characters and two cryptic species, Gammarus cryptoparechiniformissp. nov. and Gammarus cryptosalemaaisp. nov., diagnosed exclusively on the basis of molecular characters. A simple taxonomic key is provided for provisional morphological identification of the Lake Ohrid Gammarus species.

The environmental and evolutionary history of Lake Ohrid (FYROM/Albania): interim results from the SCOPSCO deep drilling project

Abstract. This study reviews and synthesises existing information generated within the SCOPSCO (Scientific Collaboration on Past Speciation Conditions in Lake Ohrid) deep drilling project. The four main aims of the project are to infer (i) the age and origin of Lake Ohrid (Former Yugoslav Republic of Macedonia/Republic of Albania), (ii) its regional seismotectonic history, (iii) volcanic activity and climate change in the central northern Mediterranean region, and (iv) the influence of major geological events on the evolution of its endemic species. The Ohrid basin formed by transtension during the Miocene, opened during the Pliocene and Pleistocene, and the lake established de novo in the still relatively narrow valley between 1.9 and 1.3 Ma. The lake history is recorded in a 584 m long sediment sequence, which was recovered within the framework of the International Continental Scientific Drilling Program (ICDP) from the central part (DEEP site) of the lake in spring 2013. To date, 54 tephra and cryptotephra horizons have been found in the upper 460 m of this sequence. Tephrochronology and tuning biogeochemical proxy data to orbital parameters revealed that the upper 247.8 m represent the last 637 kyr. The multi-proxy data set covering these 637 kyr indicates long-term variability. Some proxies show a change from generally cooler and wetter to drier and warmer glacial and interglacial periods around 300 ka. Short-term environmental change caused, for example, by tephra deposition or the climatic impact of millennial-scale Dansgaard–Oeschger and Heinrich events are superimposed on the long-term trends. Evolutionary studies on the extant fauna indicate that Lake Ohrid was not a refugial area for regional freshwater animals. This differs from the surrounding catchment, where the mountainous setting with relatively high water availability provided a refuge for temperate and montane trees during the relatively cold and dry glacial periods. Although Lake Ohrid experienced significant environmental change over the last 637 kyr, preliminary molecular data from extant microgastropod species do not indicate significant changes in diversification rate during this period. The reasons for this constant rate remain largely unknown, but a possible lack of environmentally induced extinction events in Lake Ohrid and/or the high resilience of the ecosystems may have played a role.

First establishment of microsatellite markers in clausiliid snails (Mollusca: Gastropoda: Clausiliidae)

BackgroundClausiliidae (door snails) are gastropods with a very high diversity concerning shell morphology, especially of their complex closing apparatus, which provides the most important diagnostic traits for classification of taxa. Due to the high variability, a high number of taxa has been described, though their systematics and taxonomy is partially controversially discussed. Montenegrina is the second most speciose door snail genus in Europe. It is an obligate rock-dwelling land snail and has, compared to its complex systematics, a rather small distribution range in the western parts of the Balkan Peninsula. The different taxa themselves show a very narrow and patchy distribution range. As Montenegrina is comprehensively sampled over the whole distribution range, it is a perfect study system for general questions on speciation and morphological differentiation in land snails. To study the amount of gene flow between geographically close or co-occurring populations, highly polymorphic markers are needed.ResultsThirteen microsatellite loci with a tetranucleotid repeat were isolated and tested in three geographically close Montenegrina populations (two populations of M. dofleini prespaensis from the Prespa Lake, n = 35 and one population from M. stankovici from the Ohrid Lake, n = 20). The number of alleles per locus ranged from 2 to 27. No significant linkage disequilibria between the same two loci were found in all three tested populations. The deviation from Hardy–Weinberg equilibrium reveal only for two loci a significant deviation from HWE in more than one population (Mont_5483 and Mont_4477).ConclusionThe 13 newly established genetic markers will help to gain better insights to the population genetic structure of Montenegrina and might reveal new results about speciation processes in co-occurring taxa. Furthermore, these microsatellite loci could also be tested in other clausiliid species.

Vulnerability of European freshwater catchments to climate change.

Climate change is expected to exacerbate the current threats to freshwater ecosystems, yet multifaceted studies on the potential impacts of climate change on freshwater biodiversity at scales that inform management planning are lacking. The aim of this study was to fill this void through the development of a novel framework for assessing climate change vulnerability tailored to freshwater ecosystems. The three dimensions of climate change vulnerability are as follows: (i) exposure to climate change, (ii) sensitivity to altered environmental conditions and (iii) resilience potential. Our vulnerability framework includes 1685 freshwater species of plants, fishes, molluscs, odonates, amphibians, crayfish and turtles alongside key features within and between catchments, such as topography and connectivity. Several methodologies were used to combine these dimensions across a variety of future climate change models and scenarios. The resulting indices were overlaid to assess the vulnerability of European freshwater ecosystems at the catchment scale (18783 catchments). The Balkan Lakes Ohrid and Prespa and Mediterranean islands emerge as most vulnerable to climate change. For the 2030s, we showed a consensus among the applied methods whereby up to 573 lake and river catchments are highly vulnerable to climate change. The anthropogenic disruption of hydrological habitat connectivity by dams is the major factor reducing climate change resilience. A gap analysis demonstrated that the current European protected area network covers <25% of the most vulnerable catchments. Practical steps need to be taken to ensure the persistence of freshwater biodiversity under climate change. Priority should be placed on enhancing stakeholder cooperation at the major basin scale towards preventing further degradation of freshwater ecosystems and maintaining connectivity among catchments. The catchments identified as most vulnerable to climate change provide preliminary targets for development of climate change conservation management and mitigation strategies.

Spatial variability in the level of infestation of the leaves of horse chestnut by the horse chestnut leaf miner, Cameraria ohridella (Lepidoptera: Gracillariidae) and in the number of adult moths and parasitoids emerging from leaf litter in an urban environment

The horse chestnut leaf miner Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae) was first recorded in Europe near lake Ohrid in the former Yugoslav Republic of Macedonia in 1985 since when it has spread throughout the whole of Europe. The reasons for its spread are well documented. The aim of this study was to assess the population density of the first generation of C. ohridella at eight sites in the urban area of Ceske Budějovice, Czech Republic in two consecutive years. The density was estimated visually in terms of the damage done to horse chestnut leaves by C. ohridella larvae at each site during the vegetative season. The results revealed high variability in the mean percentage of the leaf area damaged ranging from 1.43% to 31.00% and from 0.26% to 23.40% in 2012 and 2013, respectively. The effect of site, year and interaction between these two factors were statistically highly significant. Spatial analysis revealed no autocorrelation in damage among sites indicating that the distribution of C. ohridella is random and not affected by the level of infestation at neighbouring sites. In autumn, samples of leaves were collected and the mortality of diapausing pupae of C. ohridella determined. It ranged from 12.50% to 25.82% and from 10.31% to 22.35% in 2012 and 2013, respectively. There was no significant effect of site and year and their interaction on pupal mortality. The leaf samples were then weighed and put into photo-eclectors, which were placed outdoors. Numbers of adults of C. ohridella and hymenopteran parasitoids that emerged in spring were recorded daily. There were statistically significant associations of the total number of adults that emerged from samples in spring with both site and year as well as their interaction. The number of moths that emerged was positively correlated with the damage done by the first generation of C. ohridella the previous year. Similarly, the total number of parasitoids that emerged was correlated with the number of moths that emerged. The implications of these findings for the optimization of C. ohridella control are discussed.

First integrated tephrochronological record for the last ∼190 kyr from the Fucino Quaternary lacustrine succession, central Italy

We present the first integrated tephrochronological study (major and trace elemental glass composition, Sr and Nd isotope analyses, and 40Ar/39Ar dating) for the last one tenth (∼82 m) of the ∼900 m-thick Quaternary lacustrine succession of the Fucino Basin, the largest and probably only Central Apennine intermountain tectonic depression that hosts a continuous lacustrine succession documenting the Plio-Quaternary sedimentary history up to historical times. Major element glass compositions, determined using a wavelength-dispersive electron microprobe (WDS-EMPA), yielded the geochemical fingerprinting needed for a reliable identification of most of the 23 stratigraphically ordered tephra layers under investigation. These include tephra from Italian volcanoes such as Campi Flegrei, Etna, Colli Albani, Ischia, Vico, Sabatini, and undefined volcanic sources in the Neapolitan area and Latium region. The recognition of key Mediterranean marker tephra layers (e.g. X-5 and X-6) is supported by trace element data acquired by Laser Ablation Inductively Couple Plasma Mass Spectrometry (LA-ICP-MS). The Sr and Nd isotope compositions of selected layers where also determined for circumscribing the volcanic source of distal tephra and for supporting correlations with individual eruptive units. We also propose a new, more expeditious covariation diagram (CaO/FeOtot vs Cl) for identifying the volcanic source of trachytic to phonolitic and tephrytic to phonolitic tephra, that are the most common compositions of pyroclastic rocks from volcanoes of Campania and Latium regions. Finally, we present five new 40Ar/39Ar age determinations, including a new, analytically well-supported, and more precise 40Ar/39Ar age for the widespread Y-7 tephra, and the first 40Ar/39Ar age determinations for one tephra from the Sabatini volcanic district (∼126 ka) and one tephra from Neapolitan volcanic area (Campi Flegrei?; ∼159 ka). These newly dated tephra are widely dispersed (e.g. Monticchio, southern Italy, Adriatic Sea and Lake Ohrid, Macedonia-Abania) and have thus the potential to become important Mediterranean MIS 5 and MIS 6 tephrochronological markers. Altogether the new geochemical data and 40Ar/39Ar ages precisely constrain the chronology of the investigated Fucino succession spanning the last ∼190 ka. In light of these results and by considering that this sedimentary succession possibly extends back to ∼2 Ma, Fucino is likely to provide a very long, continuous tephrostratigraphic record for the Mediterranean area and become a key node in the dense network of tephra correlations of this region.

First record of water bears (Tardigrada) from sponges (Porifera)

Aquatic species of Tardigrada usually inhabit submerged plants or sediment but they are also known as associated with other animals, like barnacles (Crustacea: Cirripedia) or sea cucumbers (Echinodermata: Holothuroidea). In sponges collected from Lake Ohrid (Macedonia) we found individuals of two tardigrade taxa: Isohypsibius sp. and Dactylobiotus sp. This paper provides the first record of Tardigrada from Macedonia (Lake Ohrid) and is the first report of these animals on sponges.

Filling the blank spot: first report on the freshwater crayfish distribution in Albania

The knowledge on the distribution of native and non-native crayfish species in Europe has substantially advanced during last two decades. However, data on the exact distribution of European crayfish are still lacking in some regions of the Balkan Peninsula, e.g. , in Albania. Out of five European crayfish taxa, Astacus astacus and Austropotamobius torrentium are considered to occur in Albanian freshwaters. However, until now the only confirmed localities of the occurrence of any crayfish species in Albania are a single place in the Mat River drainage and Prespa Lake. Five crayfish individuals have been collected recently from two localities in Albania: Ohrid Lake and upper Devolli River (Seman basin), as a result of a repeated sampling in all main Albanian river drainages. All specimens were morphologically and molecularly identified as the noble crayfish, A. astacus , providing confirmation of its presence in this Balkan country. The present paper summarizes historic and current distribution records of the crayfishes in Albania and neighbouring countries as well as provides insight into genetic variability of Albanian A. astacus .

Origin and diversification of Lake Ohrid's endemic acroloxid limpets: the role of geography and ecology.

BackgroundAncient Lake Ohrid, located on the Albania-Macedonia border, is the most biodiverse freshwater lake in Europe. However, the processes that gave rise to its extraordinary endemic biodiversity, particularly in the species-rich gastropods, are still poorly understood. A suitable model taxon to study speciation processes in Lake Ohrid is the pulmonate snail genus Acroloxus, which comprises two morphologically distinct and ecologically (vertically) separated endemic species. Using a multilocus phylogenetic framework of Acroloxus limpets from the Euro-Mediterranean subregion, together with molecular-clock and phylogeographic analyses of Ohrid taxa, we aimed to infer their geographic origin and the timing of colonization as well as the role of geography and ecology in intra-lacustrine diversification.ResultsIn contrast to most other endemic invertebrate groups in Lake Ohrid, the phylogenetic relationships of the endemic Ohrid Acroloxus species indicate that the Balkan region probably did not serve as their ancestral area. The inferred monophyly and estimated divergence times further suggest that these freshwater limpets colonized the lake only once and that the onset of intra-lacustrine diversification coincides with the time when the lake reached deep-water conditions ca 1.3 Mya. However, the difference in vertical distribution of these two ecologically distinct species is not reflected in the phylogeographic pattern observed. Instead, western and eastern populations are genetically more distinct, suggesting a horizontal structure.ConclusionsWe conclude that both geography and ecology have played a role in the intra-lacustrine speciation process. Given the distinct morphology (sculptured vs. smooth shell) and ecology (littoral vs. sublittoral), and the timing of intra-lacustrine diversification inferred, we propose that the onset of deep-water conditions initially triggered ecological speciation. Subsequent geographic processes then gave rise to the phylogeographic patterns observed today. However, the generally weak genetic differentiation observed suggests incipient speciation, which might be explained by the comparatively young age of the lake system and thus the relatively recent onset of intra-lacustrine diversification.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0826-6) contains supplementary material, which is available to authorized users.

A cave response to environmental changes in the Late Pleistocene: a study of Budimirica Cave sediments, Macedonia

Budimirica Cave is a small cave located in the southern part of the Republic of Macedonia, in the Kamenica Valley, a tributary to the Crna Reka and part of the Vardar river drainage network. The response of the cave to Late Pleistocene environmental changes is interpreted based on a detailed study of cave sediments, with previous data being supplemented, reinterpreted and compared to the Ohrid Lake palaeoclimate record. The oldest exposed speleothems in the Budimirica sediment profile were deposited during the MIS 5a (radiometric age of ca 83 ka). Sands to clays in the overburden are characterized by cycles separated by short-lived interruptions in deposition. They were deposited from a number of repeated flood events likely during the MIS 4 stage, the Weichselian (Wurmian) Glaciation, correlating to aggradation in the Kamenica Valley. The top flowstone is correlated with a warmer climate excursion at 45–50 ka (MIS 3) recorded from the Ohrid Lake deposits. The whole section was extensively eroded during the MIS 2 stage, due to strong incision in the Kamenica Valley, indicated by knickpoint retreat. The erosion surface is overlain by a fossil-bearing breccia (with Ursus spelaeus) derived from frost shattering of the cave walls close to the entrance due to climate deterioration and enlargement of the entrance by slope retreat during the MIS 2 stage. Budimirica Cave sediments reflect changes in the Kamenica Valley, as well as the environmental changes during the last glacial-interglacial cycle, with clastic cave sediments deposited during glacial stadials, and erosion and flowstone deposition characteristic of the interstadials. They also allow reconstruction of the evolution of the Kamenica Valley during the Late Pleistocene, with a general trend of valley incision hindered by climate influenced river aggradation, but reinforced by river knickpoint retreat.

Two new fossil Cyclotella (Kützing) Brébisson species from Lake Ohrid, Macedonia/Albania

Lake Ohrid is the oldest existing lake in Europe and it is known for its high diversity with around 200 endemic or relict diatom species recognized. In order to understand this phenomenon, a large project on deep drilling was performed and a core with maximum sediment depth of 569 m which spans > 1.2 million years was recovered. Two new species of Cyclotella were discovered in the core samples, which are described here as Cyclotella cavitata sp. nov. and Cyclotella sollevata sp. nov. The species have been studied with light and scanning electron microscopes, their morphological features and their relevance to other members of the genus Cyclotella are discussed. Cyclotella cavitata sp. nov. is characterized by round to elliptical shape; elliptic and tangentially undulate central area with one to three papillae on the elevated side. Central fultoportulae are absent while marginal fultoportulae internally are located on slightly depressed costae, with short tube openings with two satellite pores surrounded by cowlings. Satellite pores are situated circumferentially. Internally the rimoportula is situated in the marginal area with a sessile labium. Cyclotella sollevata sp. nov. is characterized by round valves with convex or concave central area which is uneven, colliculate, with papillae and granules. Central fultoportulae are present with variable number (9-21), internally with short tube openings with two satellite pores, which are surrounded by cowlings; Internally marginal fultoportulae are located on depressed costae and have short tube openings with two satellite pores situated circumferentially, surrounded by cowlings. The rimoportulae are located in the marginal area with a sessile labium variably orientated. Cyclotella sollevata and Cyclotella cavitata have been observed only in the fossil sediments of Lake Ohrid. Comments on the position of rimoportula, used as synapomorphic character to separate Lindavia from Cyclotella sensu lato are provided.

Natural Hazards in the Albanian Area of Lake Ohrid

AbstractThe Albanian part of the Lake Ohrid area is endangered by several natural hazards like: floods, landslides, rock falls, erosion and wild fires. Those events have caused environmental, social and economical damages, so it’s important to study the factors that had caused them, their costs and the measures that should be taken to prevent, or to reduce their impact. Most of those events have been triggered by climate change, increasing of human pressure on land and unplanned urban development. Rapid urbanization of latest years has imposed people to build their homes or other activities on unsafe places. Climate change is another factor that has influenced in floods and droughts. The presence of the mountainous relief in the Western part combined with damage of vegetation cover, plays an important role in generating landslides and erosion of land. Natural hazards map of this area, created with GIS, shows where are distributed and which are the zones that can be caught by one of those events. Through this map the habitants of this area and local authorities, will know the risks and take necessary measures to prevent those events. Objectives of this study are to determine the risked areas and measures to minimize damages in life losing, economy and environment.