Статті в журналах з теми "Deep and elongated lake"

Parallel evolution of the body shape and trophic-related traits has been detected between sympatric pairs of lake-dwelling characin fishes in Mesoamerica. Here, we evaluated the variation in and the ontogenetic allometric trajectories of trophic morphology between sympatric Astyanax morphs (elongate and deep-body) in two geographic systems, Lake Catemaco (Mexico) and San Juan River basin (Nicaragua and Costa Rica). Using geometric morphometrics, we determined the shape variation and disparity in the premaxillary bone, and the patterns of allometric trajectories between morphs in each system. We found a higher differentiation and disparity in the premaxilla shape between morphs from San Juan River basin than between the Lake Catemaco ones. We found shared (parallel evolution) patterns of divergence between systems, which included allometric trajectories showing a positive correlation between the premaxilla shape and log centroid size, as well as trajectories being extended in the elongated-body morph (truncated in the deep-body morph). Regarding the unique patterns of divergence, we recovered parallel allometric trajectories between morphs from Lake Catemaco, while the San Juan River basin morphs showed divergent trajectories. Our results are congruent with the hypothesis that divergence in trophic morphology can be considered a triggering factor in the divergence in the genus Astyanax from Mesoamerica.

Wave processes are well known for developing spit systems in large or elongated lakes by inducing longshore sediment transport for spit migration, while bathymetric interaction is less studied. In this study, we investigate the combined effects of wave processes, antecedent topography and lake level changes on the development of Holocene spit systems in the Danish lake Mossø. Wave climate prediction and a digital elevation model were used to provide a conceptual model for the development of the spits system, while optically stimulated luminescence (OSL) dating of spit sand and antecedent topography analyzed via boreholes and seismic survey data were used to evaluate effects on spit migration other than wave setting. We found that spit migration stagnated during the Holocene when reaching areas of deeper waters, but continued following shallowing after deep basin infilling with lacustrine sediments. During periods of bathymetrically induced stagnation of prominent spits, less stable or more slowly migrating spits became prominent in the development of the spit system. No clear effects on spit migration caused by lake level fluctuations could be demonstrated. However, such fluctuations may have been important for the stabilization of spits and subsequent development of a major barrier shoreline.

Abstract. A three-level nested regional air pollution model has been used to study the processes leading to high ozone concentrations in the southern Great Lakes region of North America. The highest resolution simulations show that complex interactions between the lake-breeze circulation and the synoptic flow lead to significant enhancements in the photochemical production and transport of ozone at the local scale. Mass tracking of individual model processes show that Lakes Erie and St. Clair frequently act as photochemical ozone production regions, with average mid-day production rates of up to 3 ppbv per hour. Enhanced ozone levels are evident over these two lakes in 23-day-average surface ozone fields. Analysis of other model fields and aircraft measurements suggests that vertical circulation enhances ozone levels at altitudes up to 1500 m over Lake St. Clair, whereas subsidence enhances ozone over Lake Erie in a shallow layer only 250 m deep. Mass tracking of model transport shows that lake-breeze surface convergence zones combined with the synoptic flow can then carry ozone and its precursors hundreds of kilometers from these source areas, in narrow, elongated features. Comparison with surface mesonet ozone observations confirm the presence, magnitude, and timing of these features, which can create local ozone enhancements on the order of 30 ppbv above the regional ozone levels. Sensitivity analyses of model-predicted ozone and HOx concentrations show that most of the region is VOC-limited, and that the secondary oxidation pathways of aromatic hydrocarbons have a key role in setting the region's ozone and HOx levels.

AbstractA thick succession of continental redbeds was deposited in a 50 km wide intra-arc basin on the Andean active continental margin in the Atacama region of northern Chile during early Cretaceous times. Upper Jurassic to early Cretaceous marine limestones were buried by the seaward progradation of a succession of coastal dunes, saline lakes and sandflats. Aeolian dune fields migrating towards the east across these coastal plains became stabilized by the growth of vegetation. Interdune alluvial areas between the sand dunes and dune fields developed into extensive alluvial braid plains which were in turn superimposed by alluvial fans. These fans were inundated by a regionally extensive saline lake produced by tectonic or volcanic damming of the sedimentary basin. This lake dried up leaving a large area of playa-lake mudflats. The climate was warm and semi-arid with a low and seasonal rainfall. Parts of the area supported a substantial vegetation of woody plants, together with a vertebrate fauna of dinosaurs, pterosaurs and crocodiles. The continental redbeds were derived from a volcanic source and were deposited on continental crust in a deep but narrow, north-south elongated, fault-bounded graben. This extensional basin formed in an intra-arc setting within an active andesitic volcanic chain. Upwards-coarsening sedimentary successions were the product of uplift of the fault-bounded margins of the basin.

Glaciers and numerous glacial lakes that are produced by glacier melting are key indicators of climate change. Often overlooked, supra-glacial lakes develop in the melting area in the low-lying part of a glacier and appear to be highly variable in their size, shape, and location. The lifespan of these lakes is thought to be quite transient, since the lakes may be completely filled by water and burst out within several weeks. Changes in supra-glacial lake outlines and other surface features such as supra-glacial rivers and crevasses on the glaciers are useful indicators for the direct monitoring of glacier changes. Synthetic aperture radar (SAR) is not affected by weather and climate, and is an effective tool for study of glaciated areas. The development of the Chinese GaoFen-3 (GF-3) SAR, which has high spatial and temporal resolution and high-precision observation performance, has made it possible to obtain dynamic information about glaciers in more detail. In this paper, the classical Canny operator, the variational B-spline level-set method, and U-Net-based deep-learning model were applied and compared to extract glacial lake outlines and other surface features using different modes and Chinese GF-3 SAR imagery in the Mount Everest Region of the Himalayas. Particularly, the U-Net-based deep-learning method, which was independent of auxiliary data and had a high degree of automation, was used for the first time in this context. The experimental results showed that the U-Net-based deep-learning model worked best in the segmentation of supra-glacial lakes in terms of accuracy (Precision = 98.45% and Recall = 95.82%) and segmentation efficiency, and was good at detecting small, elongated, and ice-covered supra-glacial lakes. We also found that it was useful for accurately identifying the location of supra-glacial streams and ice crevasses on glaciers, and quantifying their width. Finally, based on the time series of the mapping results, the spatial characteristics and temporal evolution of these features over the glaciers were comprehensively analyzed. Overall, this study presents a novel approach to improve the detection accuracy of glacier elements that could be leveraged for dynamic monitoring in future research.

Intense lake-effect snowfall results from a long-lake-axis-parallel (LLAP) precipitation band that often forms when the flow is parallel to the long axis of an elongated body of water, such as Lake Ontario. The intensity and persistence of the localized precipitation along the downwind shore and farther inland suggests the presence of a secondary circulation that helps organize such a band, and maintain it for some time as the circulation is advected inland. Unique airborne vertical-plane dual-Doppler radar data are used here to document this secondary circulation in a deep, well-organized LLAP band observed during intensive observing period (IOP) 2b of the Ontario Winter Lake-effect Systems (OWLeS) field campaign. The circulation, centered on a convective updraft, intensified toward the downwind shore and only gradually weakened inland. The question arises as to what sustains such a circulation in the vertical plane across the LLAP band. WRF Model simulations indicate that the primary LLAP band and other convergence zones observed over Lake Ontario during this IOP were initiated by relatively shallow airmass boundaries, resulting from a thermal contrast (i.e., land-breeze front) and differential surface roughness across the southern shoreline. Airborne radar data near the downwind shore of the lake indicate that the secondary circulation was much deeper than these shallow boundaries and was sustained primarily by rather symmetric solenoidal forcing, enhanced by latent heat release within the updraft region.

Lacustricola margaritatus, a new species inhabiting small streams and swamps in the Lake Victoria basin in north-western Tanzania and southern Uganda, and the Lake Kyoga basin in central Uganda, is described. Lacustricola margaritatus is a small species with a moderately deep body, moderate dimorphism and pronounced dichromatism. It is distinguished from all other Procatopodidae by the following unique combination of characters: live male body colour pattern with vertically-elongated iridescent light blue patches at scale centres, forming a striped appearance of dotted longitudinal lines on the flanks, particularly evident in the two or three series below the mid-longitudinal line; male having deeply coloured unpaired fins with orange-brown in the proximal and median parts and a narrow black distal band; male with a yellow base along the pectoral fin; female with dark grey scale margins and dark grey patches on scales along mid-longitudinal series creating a narrow dark grey stripe; both sexes showing inconspicuous postopercular blotch; and in both sexes, the cephalic sensory system is entirely situated in open grooves at all levels. The new species has previously often been misidentified as L. pumilus, originally described as inhabiting the Lake Tanganyika basin in north-eastern Zambia, or 'L.' centralis, from the Lake Rukwa basin in south-western Tanzania. Lacustricola margaritatus differs from the above two species by morphometric and meristic characters, body and fin colouration, and in arrangement of the cephalic sensory system.

Abstract. When lakes experience surface cooling, the shallow littoral region cools faster than the deep pelagic waters. The lateral density gradient resulting from this differential cooling can trigger a cold downslope density current that intrudes at the base of the mixed layer during stratified conditions. This process is known as a thermal siphon (TS). TSs flush the littoral region and increase water exchange between nearshore and pelagic zones; thus, they may potentially impact the lake ecosystem. Past observations of TSs in lakes are limited to specific cooling events. Here, we focus on the seasonality of TS-induced lateral transport and investigate how seasonally varying forcing conditions control the occurrence and intensity of TSs. This research interprets 1-year-long TS observations from Rotsee (Switzerland), a small wind-sheltered temperate lake with an elongated shallow region. We demonstrate that TSs occur for more than 50 % of the days from late summer to winter and efficiently flush the littoral region within ∼10 h. We further quantify the occurrence, intensity, and timing of TSs over seasonal timescales. The conditions for TS formation become optimal in autumn when the duration of the cooling phase is longer than the time necessary to initiate a TS. The decrease in surface cooling by 1 order of magnitude from summer to winter reduces the lateral transport by a factor of 2. We interpret this transport seasonality with scaling relationships relating the daily averaged cross-shore velocity, unit-width discharge, and flushing timescale to the surface buoyancy flux, mixed-layer depth, and lake bathymetry. The timing and duration of diurnal flushing by TSs relate to daily heating and cooling phases. The longer cooling phase in autumn increases the flushing duration and delays the time of maximal flushing relative to the summer diurnal cycle. Given their scalability, the results reported here can be used to assess the relevance of TSs in other lakes and reservoirs.

The structure of the pectoral fins spine of 4 catfish species Heterobranchus longifilis, Clarias gariepinus, Chrysichthys auratus, Synodontis schall and Synodontis serratus were described. The fish specimens were collected from Asyut City and Lake Nasser about 319 and 900 Km south of the capital Cairo, Egypt respectively on 10 November 2017 are described. The species examined showed variation in the shape of the spine-shaft tip varies from finely to broadly and rounded pointed; the curvature of the spine-shaft is either straight or curved partially or complete; the anterior serrae varies between is either broad or irregular; the anterior ridge groove is well developed, deep, and curved, with some pores in some species; the anterior dentations varies between short and sometimes are merged together or curved and their number decreased towards the tip; the posterior dentations can vary between absent or long and numerous and sometimes increased in their number towards the tip of the spine; the dorsal, anterior and ventral processes are well developed structures, with rounded, flange-like, and the shape of the basal fossa varies in having narrow, elongated, boat-shape, with high walls at sides; and very wide fossa and lunate in shape. It is usually deep with high walls.

Fossil fishes from the Paraná Basin are represented by actinopterygians, chondrichthyans, coelacanths and dipnoans. This diverseichthyofauna comprises mainly fragmentary material with few complete specimens. This paper presents a new Upper Permianray-finned fish from the Rio do Rasto Formation of the Paraná Basin, southern Brazil. The holotype and only known specimen ofParanaichthys longianalis gen. nov. et sp. nov. is an almost complete poorly preserved specimen of a deep-bodied fish that be-longs to the collection of the Museu de Ciências e Tecnologia-PUCRS, Porto Alegre, Brazil. The head is slightly deep posteriorlyand the oral cavity presents a crushing dentition. The anal fin is remarkably large and long. The heterocercal caudal fin presentsthe chordal and hypochordal lobe equally in size. Flank scales are deeper than long and covered with ganoine. The dermal bonesare also covered by ganoine and present elongated odontodes. The rostral region and the anterior portion of the mandible are cov-ered with conical odontodes. The elongated and long based anal fin is considered apomorphic for this new fish. A reconstructionattempting to correct taphonomic distortions is presented. The systematic relationships of the new taxon suggest that it is relatedto the platysomids. Its crushing dentition indicates a diet based on hardfood, such as conchostraceans and small mollusks, bothvery common in the Rio do Rasto Formation. The new genus and species inhabited rivers and lakes during the Wordian-Captanian (Guadalupian, Permian 268 to 260 M.y.).

“Dock Village” terrain is, as its name implies, a region that contains settlements reminiscent of docks, in terms of their elongated shape, their outward upward tilt, and their location in the center of low, wide valleys. Dock village terrain features deep, fertile soil suitable for farming. Taihu Lake contains a number of classic examples of dock villages. Dock villages are relatively independent and hidden, characteristics that not only play a role in security and defense, but also, more importantly, are associated with enhanced climate adaptability, a relative lack of cold weather, and equable levels of heat and humidity. The dock village reflects the wisdom and distillation of traditional Chinese ecological practices and is highly valued as a research topic. Based on microclimate theory and ENVI-met software, four microclimate indices, namely, air temperature, wind speed, wind direction, and relative humidity, were simulated and analyzed in this study. The correlation between spatial characteristics and microclimate was studied from four perspectives: plane space, cross-section space, vertical section space, and linear development space. This research summarizes the historical context and evolution of the dock village spatial form in the construction of contemporary human settlements. It also provides scientific suggestions for the protection and sustainable development of ancient villages.

Abstract This paper presents the results of the study on the concentration of heavy metals and persistent organic pollutants (POPs), including PAHs and PCBs, in the bottom sediments of Lake Gopło. This lake is significantly elongated (about 25 km); its longitudinal profile is diversified, and there are deeps and thresholds impeding the flow of water. The shoreline is varied, which is characteristic of tunnel valley lakes. The catchment has a typical agricultural character with a point arrangement of industrial centres. The analysis of the diversity of the concentration of heavy metals and POPs was based on 37 samples from two representative cores: one collected in the northern part of the lake, the catchment of which shows an industrial character, and the second one in the southern part where the catchment is agricultural in character. In the sediments, the content of the following heavy metals was analysed: Cu, Pb, Cd, Zn, Ni, Cr, Hg and As, as well as PAHs and PCBs. The sediment age was determined by the 210Pb dating method. In order to assess the contamination level of the bottom sediments with heavy metals, the contamination factor (CF) and degree of contamination (DC) were calculated. Moreover, the impact of the changes in the catchment’s land use over the past 100 years was determined. The results showed that the sediments from the industrial part of the lake significantly exceed the geochemical background for both the heavy metals from the group identified as industrial pollution and from the group of agricultural pollutants. The southern core shows only a slight increase in the amount of pollution from the agricultural group, lack of industrial pollution and a low degree of contamination. A slight increase in persistent organic pollutants is also recorded, without any apparent effect on the state of the deposited sediment. The 210PB dating enabled the main stages of human impact to be determined: the pre-industrial revolution, from the beginning of industrialisation to the 1950s, intensive human impact from the 1960s to the 1980s, and a gradual decrease in the human impact starting from the 1990s. In addition, attention was paid to the changing sedimentation rate.

AbstractIce dolines on the Larsen Ice Shelf, Antarctica, are observed to be elongated depressions a few hundred meters across and up to 19 m deep. One-meter resolution imagery is used to quantify these dimensions. Elevation profiles across five dolines are derived by photoclinometry. Landsat and radar imagery is also used to show that dolines can form in a single melt season and persist for years. Dolines occur in clusters and in direct proximity to surface meltwater lakes. Field observations suggest dolines form by collapse into a subsurface cavity. A direct hydraulic connection with the underlying ocean is believed necessary to drain water that would otherwise collect in dolines. A formation hypothesis is discussed consistent with these observations and with energy-and hydrostatic-imbalance considerations.

Before its 2010 eruption, Sinabung Volcano was a Btype volcano, in its Indonesian classification. A series of explosions featuring 1-5 km high phreatic-ash columns occurred from August 27, 2010 untill September 7, 2010. SO2 flux measured during the eruptions showed sizeable gas emission and the youngest volcanic product has age of 1200 years BP obtained from 14C dating. At the end of August 2010, four continuous seismic stations were established around the volcano, and 6 additional stations were deployed in October 2010. Deformation monitoring was conducted temporarily till in February 2011, four continuous GPS stations were installed. All were set up through collaboration between Indonesian and Japanese academic and government institutions. Hypocenter calculations using data of 4 seismic stations fromSeptember to October 2010 showed two concentrations for shallow volcanic earthquakes (VTB) 0.5-2 km beneath the crater and for deep volcanic earthquakes (VTA) 2.5-14 km beneath the crater. These epicenters defined a northeast-southwest lineament, near an elongated sinistral fault zone between Sinabung and Sibayak volcanoes. Earthquake sources went deeper northeastward. Results using the data of 10 stations from November 2010 to February 2011 showed that earthquakes were concentrated at depths of 4-6 km beneath Lake Lau Kawar. Tilt and Electro-optic Distance Measurement (EDM) measurements from August to September 2010 showed no significant changes We inferred that since the last explosion in 7 September 2010, stabilization process both in pressure and energy were low.

Seismic and core data from north Okanagan Valley, a deep (~700 m of fill), elongate (~3 km wide by 45 km long) basin located in the Cordillera of south-central British Columbia, reveal a thick sequence of fine and coarse elastics. The architecture of the basin fill was delineated using 16 km of high-resolution, reflection seismic profiles, and 30 lithologic logs. Using a depositional systems approach, four systems were identified: subglacial fluvial, glaciolacustrine, alluvial fan, and channel. The subglacial fluvial system consists of a basal suite of compact, stratified to poorly stratified coarse clastics deposited beneath glacial ice under high hydrostatic pressure. Older sediments were almost completely excavated from the basin fill during periods of maximum subglacial flow during Late Wisconsinan glaciation. One of the outcomes of this study is that it lends support to the notion that Late Wisconsinan glaciers were capable of almost totally eroding older Pleistocene basin deposits while depositing thick sequences of subglacial fluvial sediments. During deglaciation, the basin was occupied by a lake in which laminated silt and clay were deposited (glaciolacustrine system). The wedge-shaped alluvial fan system interfingers with the finer clastics of the basin fill. Incised into the upper part of the basin fill are channel sediments forming the channel depositional system. Two stages in the evolution of the north Okanagan basin were identified: in the first stage (~10 ka), lake sediments were rapidly accumulating coeval with the formation of alluvial fans and fan deltas; the second stage shows the present-day architecture of the basin fill.

Abstract A simple diagnostic model, reproducing circulation in lakes and marginal seas in which low-density waters are found close to the coasts while high-density waters dominate the offshore areas, is developed. An explicit solution is obtained for the central transverse section of an elongated basin, assuming that the Boussinesq and hydrostatic approximations are valid and that the alongshore variability vanishes. The model reveals cyclonic circulation that may either extend throughout the vertical (type C) or may top anticyclonic circulation developed in the bottom layer (type C/A). With the amplitude of the imposed density anomaly being fixed, the flow type is controlled by the frictional processes and by the basin dimensions. In a typical basin, type C/A flow is supported by weak bottom and vertical friction and by moderate lateral friction, unlike type C flow, which is supported by moderate bottom and vertical friction and by weak lateral friction. Strong frictional influence, especially in the basin interior, suppresses the flow everywhere. The flow is also suppressed in a basin that is narrow O(1 km) and shallow O(10 m), even without the frictional control being too strong. A basin that is narrow and deep favors type C/A flow, whereas a basin that is wide and shallow tends to support type C flow. The theoretical findings are related to observations, particularly those originating from the Adriatic Sea where type C flow prevails but may occasionally be replaced by type C/A flow, as well as to previous modeling results.

The temperature of a small elongated lake (2.3 km by 0.1-0.6 km; maximum depth of 46 m) located in a mountaneous area was measured during July-September period over three years (2018-2020) at the depth close to the lake surface (0.2 m). Concurrent standard meteorological variables were measured in the vicinity of the lake. Criteria based on atmospheric and lake conditions were defined to detect the days with persistent lake-land breeze (LLB) events. The results showed that 17.7% of the investigated days were associated with LLB events. These days were accompanied by elevated energy in the normalized wavelet spectra for the wind speed at period of 24 hours. Daytime onshore lake breezes were mainly channeled in the along-lake direction due to the surrounding topography. Accordingly, during the daytime, diurnal wind veering was distorted. However, during the nighttime, a clear clockwise wind rotation was present. In addition, the results exhibited a clear relationship between the lake-land temperature difference and the strength of the LLBs.

The Republic of Altai has a large length of watercourses and significant areas of lakes of fishery importance. The collection of materials was carried out in the field season of 2018 on the lakes: Uch-Kol (Three Lakes), Kamyshevoye and Lake without a name, located within the borders of Kosh-Agach district of the Altai Republic. Research has covered the entire water area. In the course of the research it was noted that Lake Uch-Kol consists of three successive basins with a total area of 7.9 hectares. The upper lake basin has an area of 5.5 hectares. The average lake basin has an area of 1.8 hectares. The lower lake basin has an area of 0.6 ha. Higher aquatic vegetation in the pond is missing. Lake zooplankton is represented by one species of Cladocera and two species of Copepoda. Lake Zoobenthos Uch-Kol is represented by a representative of the r. Gammarus. The area of Kamyshevoye Lake is 7.4 ha. The pond has a slightly elongated shape from west to east. In the zooplankton of the reservoir of mass development, branchy and rotifers reach. Chironomid larvae and caddisfruits dominate in the structure of zoobenthos. The area of the lake without a name is 29.4 hectares. The reservoir has a form elongated from the northeast to the southwest. In terms of numbers and biomass, Copepoda copepads are the dominant group in zooplankton. The dominant position in the zoobenthos composition is occupied by caddis flies and gammarids. All studied water bodies have low biological productivity. Phytoplankton is represented mainly by diatoms and green algae. The ichthyological fauna of Lake Uch-Kol and Lake Kamyshevoye is represented by an oligoid type of ichthyocenosis. The ichthyological fauna in the Lake without a name is missing.

The cultural development and contacts on Bornholm during the late Palaeolithic and MesolithicThis paper presents the current status of research concerning the late Palaeolithic and Mesolithic cultures on the island of Bornholm in the Baltic Sea. Due to the island’s geographical position between Scandinavia and continental Europe, it can reveal important regional knowledge of all cultures throughout prehistoric times. The article also discusses subjects relating to island-archaeology, such as migration and possible isolation. Furthermore, the results show an updated picture of the settlement pattern on Bornholm during the Mesolithic. Finally, the archaeological finds reveal cultural as well as social contacts between hunter/gatherer societies in the Western Baltic and Bornholm. During the last few decades, the Mesolithic research on Bornholm has been focusing on the Maglemosian Culture. Systematic surveys in search of Maglemosian settlements were not conducted until the early 1980s. As an added bonus from these surveys, some late Palaeolithic and late Mesolithic sites were registered on Bornholm for the first time. Today, more than 125 Maglemosian settlements are recorded, but most of them are still a result of surface collections. Unfortunately, the preservation of organic material is not good on these sites, as they are found on Late Glacial shoreline deposits, i.e. on sandy soil. The Mesolithic habitants were forced to adapt and adjust to a very different raw material situation, and this gives the lithic industry during the Maglemosian Culture an extremely small and microlithic appearance. The lithic material from the Maglemosian Culture on Bornholm reveals some important regional aspects, which have similarities with Maglemosian settlements in Scania. These similarities are primarily caused by the same size of the raw nodules. The raw materials from Bornholm are all from the Maastrichtien and located in secondary deposits brought to the island with the different glaciers from the Quaternary Period. The most common flint type is »kugleflint« (nodular flint), often of good quality and not larger than four to six cm. The second most common material is the Kristianstad flint, which is dark grey and quite coarse and often up to 10-15 cm in size. The other two flint types are grey Danien, which is coarse to fine grained and tends to vary between four to six cm to around 10-15 cm in size. The use of local raw materials makes it easier to find the lithics from the Maglemosian Culture (Figs. 1 & 10). Many of the registered Mesolithic sites are a result of several survey projects.The first survey project concentrated on inland sites located abnormally far from any water resources. We retrieved information from old maps about the old bogs and lakes, which had been drained through the last 100 years. By raising the ground water level on modern maps using GIS, it was possible to recreate the size of the former inland lakes and hereby reconstruct the landscape and the lake. The majority of the Maglemosian sites turned out to be located exactly on the edge of these former lakes. The second survey project involved sites lying near the different creeks on Bornholm. These sites were repeatedly visited during all the phases of the Maglemosian Culture. What caused the habitants to return to a certain area over a 1000 years period? One of the reasons could be the access to migrating salmon and trout. Recent biological research of the trout population from the Kobbe and Bagå creeks indicates that a large number of migrating trout still migrates up the major streams, which may coincide with some of the Maglemosian hotspots. The geographical development in the Baltic region can be divided into some main stages, the Baltic Ice Lake stage, 12000-9300 cal BC, the Yoldia Sea stage, 9300-8500 cal BC, and the Ancylus Lake stage, 8500-7000 cal BC, (Figs. 2 A-D). From the Baltic Ice Lake stage until the beginning of the Ancylus Lake stage, approx. 8200 cal BC, the island was either the northern part of a peninsula covering an area from Rügen in Germany to Bornholm, or an island with a substantial land bridge towards Rügen. In the following phases, from 8200-7200 cal BC, the sea level of the Ancylus Lake was low, and due to continued transgressions, the land bridge was flooded and several smaller islands were created between Pomerania, Rügen, and Bornholm. The size and geographical spreading of these smaller islands is still heavily debated. However, it is clear that Bornholm became an island some time during the Boreal period. The late Palaeolithic finds occur randomly on some Maglemosian sites on the island (Fig.3). A particularly interesting find is the elk antler harpoon found in Vallensgård Mose (Fig. 6). This double rowed harpoon is of a type known from both the Ahrensburg and the Sviderian Cultures. So far, the only excavated Palaeolithic site on Bornholm is in Vallensgård Mose (“mose” is a peat bog). The assemblage from Vallensgård Mose consists of lithic material, found in a layer, which was cryoturbated during permafrost in the Dryas III. The lithic material consists of blade and flake cores, flakes, blades, one end scraper and one tanged point. The raw material is high quality Senonian flint (Figs. 4-5). The typological dating and technological observations from the blade core suggests that the Vallensgård Mose material belongs to the Bromme, the Swiderian, or the Ahrensburgian Period. The question as to which technological complex the Vallensgård material belongs remains open and can only be answered through future excavations of the site. The key to an understanding of the settlement pattern during the late Palaeolithic cultures is the fact that reindeer tend to migrate along fixed routes. However, is it possible to relate an actual reindeer migration route to Bornholm? The datings prove that reindeer were present throughout the entire Late Glacial. The reindeer remains found on Bornholm display no certain signs of human working (cut marks and marrow fracturing). If we consider the datings of reindeer remains from Bornholm, an actual reindeer migration route to or through Bornholm can neither be established nor excluded. The absence of the Ahrensburgian Culture on Bornholm could be caused by the smaller size of the raw materials on Bornholm. This could have forced the Ahrensburgian lithic production to adapt a new technology, which had a Mesolithic character. A climatic explanation for the absence of Ahrensburg material could also be made – for instance that the harsh climate around the Baltic Ice Lake frightened off the Ahrensburg humans, as argued by Svante Björck. According to him, we should expect no scenarios with human activity near the shores of the Baltic Ice Lake. However, this is contradictive to the find of a longitudinally split metatarsal from elk from the bay of Køge Bugt. The faunal picture from the Preboreal containing reindeer elks and beavers proves that Bornholm had a complete package of migrating animals during this period. The reindeers and elks became extinct in the early Boreal when Bornholm became an island. The isolation did not have any effect on other larger mammals, such as red deer, roe deer, and wild boar, which migrated to Bornholm during the late Preboreal and the early Boreal. These animals had the ability to reproduce and adapt to a warmer climate and a denser forest during the Boreal and the Atlantic period. These faunal changes had an impact on the hunter-gatherers who migrated to the island during the Preboreal. A limited number of finds have been registered from the Preboreal phase (9.500-8.000 Cal. BC.) on Bornholm. At Lundebro, a few microliths and blanks were found, which show similarities with the early Mesolithic Barmose Phase, (Figs. 7-8). The pieces are up to three times broader on the average than the typical blades from the Middle and Later Maglemosian phases on Bornholm. This proves that the later habitants on Bornholm were forced to adapt and adjust to a very different raw material situation. From the later Boreal phases, a large number of Maglemosian settlements with different topographic characteristics have been registered. Two different types of coastal sites have been observed on Bornholm, with major difference in accumulation, use, and exploitation of the settlement area (Figs. 7, 20-21). Kobbebro was settled repeatedly, which resulted in a 70 cm thick cultural layer. Less than 500 m from Kobbebro, two other sites – Melsted and Nr. Sandegård – have been excavated. At these sites, a different picture of a coastal site type with separate flint concentrations emerges. All the sites are dominated by microliths, which indicates that hunting played an important role. The coastal sites have been located 100 to 200 metres from the Ancylus Lake, which played an important economic part, as indicated by the repeated habitation. Seal hunting could have taken place in the Ancylus Lake during the Maglemosian Culture, as the ringed seal migrated into the Gulf of Bothnia during the late glacial period. The inland settlements on Bornholm are located on higher elevated grounds near a lake, a stream, or a forced passage. So far, they are only known from surface finds. Another type of settlements is the observation site, which revealed differences in size and duration. The larger site Loklippen is located on elevated ground approx. 115 m above the sea, with a broad outlook over the Vallensgård Mose and near a forced passage, where hunters shoot their pray even today (Figs. 12-14). A big surprise was the fact that the inhabitants of the Loklippen site used quartz as raw material. This rather untraditional, yet systematic, flake production indicates that they were forced to use unconventional materials such as quartz. Quartz assemblages dominate the early Mesolithic settlements in Central and Northern Sweden, with the settlement of Hjälmsjön as the southernmost site dominated by a quartz material. This could prove a direct contact between hunter-gatherers in Bornholm and in Scania, as revealed by the systematic production of quartz flakes. A smaller type of observation site was excavated at Smedegade in Klemensker. This site had a more typical appearance compared to other observation sites and covered an area of four to eight square metres. The site had a limited lithic assemblage and so it was interpreted as a short-term hunting station. However, the situation at Loklippen proves that certain observation sites were more frequently used. The last type of site is the transit camp, which lies on a sandy plateau near a spring and a creek, where the conditions for water transportation, fishing, hunting, and gathering are favourable. Ålyst and Hullegård are two such sites that were visited repeatedly during the Maglemosian Culture, and so contain a complex of smaller or larger settlements. The main lithic production is blades for the production of microliths (Figs. 19-20, 24). The microliths at Ålyst can be dated typologically from the beginning of the Boreal phase (8000 cal BC) until the end of the Boreal period (7000 cal BC) (Fig. 22). Finds from Ålyst indicate that there was also a more permanent settlement that lasted for up to one or two months. It became clear when visible structural evidence representing two oval-shaped huts was found (Figs. 16-18). The two huts show remarkable similarities as to orientation, size, entrance area, fireplaces, and pits, as well as to the combination of lithic tool types. However, differences are seen with respect to the microliths. Lanceolates with lateral retouch and triangular microliths dominate in Hut I, while the microlith inventory of Hut II was confined to lanceolates with lateral retouch. The two huts are probably not contemporary, which can be established by future C-14 dating of the different features from the huts. There are also problems concerning the flint concentrations in the two huts: are they altogether contemporary with the huts? To prove this hypothesis, it is necessary to do extensive refitting between the flint concentrations, the postholes, and the pits both inside and outside the huts. The huts are 7 x 4 m, which gives them an inner area of 30 square metres. The Ålyst huts are thus of a middle size hut structure, compared to the rest of the Maglemosian huts from Northern Europe. Could the oval shaped huts be a normal hut type connected to the Maglemosian Culture in the Western Baltic? If we look at some of the huts found in the Western Baltic, there are indeed parallels to the oval shaped hut at Tingby and Årup in Scania and at Wierzhowo 6 in the north eastern part of Poland, (Figs. 9 & 19). The similarities are particularly remarkable between the Ålyst huts and the Årup hut. These hut structures show similarities in orientation, dimensions, position of the postholes, lithic material, typological dating, etc. (Fig. 18). The striking parallel gives rise to interesting questions about cultural influences and regionalism during the Early Mesolithic in the Western Baltic. The connection between Årup in North-Eastern Scania and Ålyst on Bornholm should be considered as more than chance. However, at the present it is still unclear whether the oval-shaped hut type has a special geographical or topographical distribution in southern Scandinavia. The settlement pattern on Bornholm is influenced by a regional mobility strategy connected to the special geographical conditions on the peninsula. These observations also illustrate the regional differences between the Maglemosian societies and their ability to change mobility patterns and to adapt to the local situation. This opens up for the discussions regarding the coastal vs. inland problem in Southern Scandinavia. The discussion should consider the geographical differences, which could lead to a different mobility strategy in each region of the Maglemosian Culture. Especially the sites from Holmegård, Sværdborg, and Lundby are located closer to the Ancylus Lake than to the Kattegat coast during the Maglemosian Culture. This location could lead to a commuting strategy between the inland lakes and the Ancylus Lake, with sporadic contacts to the marine areas as indicated by several objects of marine origin and the imported flint. This hypothesis – which is supported by the Carbon-13 values from Zealand and from the Barum Woman in Scania – indicates a mobility strategy orientated towards the Ancylus Lake rather than towards the marine coast along Kattegat. All the areas surrounding the Ancylus Lake, including Bornholm, probably had similar mobility and settlement patterns orientated towards the freshwater lake. The settlement pattern around the inland lakes changed drastically in the late Maglemosian Period when Bornholm had become an island. The main difference on Bornholm between the settlement pattern of the island and the settlement patterns from the earlier periods is the apparently deliberate rejection of the inland as a habitation zone and the concentration of settlements in the coastal zone. A possible explanation for this major change could be that some important resources were lost as the larger inland lakes became overgrown and filled with sediments. A similar pattern and decline in site number has been observed around some of the flat-bottomed lakes on Zealand, such as Barmose, Lundby, Sværdborg, and Holmegård. Part of the repeated settlement pattern on Bornholm proves that some of the creeks were used through more than a thousand years during the Maglemosian Culture. This may have had both historical and ecological causes. Some locations may be recognized as specifically orientated towards a certain gender, or a specific season. Furthermore, some sites could be devoted to the exploitation of specific resources of primarily symbolic or mythological rather than economical causes. However, it is clear that the island was occupied and used by hunter-gatherers who shared a landscape with territorial and ideological components. The repeated use of certain hotspots in the landscape could indicate bordered territories determined by the creeks. One family group would hunt and fish in one particular creek, whereas others were connected to another creek. Unfortunately, it is impossible at the present to locate these territorial borders due to the incomplete picture of the site distribution. The settlement patterns presented in this paper must be regarded as preliminary and subject to later modifications, mainly because the dating base for the sites is their content of microliths. As for Bornholm, a preliminary regional microlithic typology with four phases has been suggested (Fig. 22). However, we face serious problems in fine-tuning the typo-chronology of the Maglemosian Culture. If this phase could be split into minor segments, the sites would appear much more sporadic compared to the current picture of the habitation. The repeated settlement pattern and the fact that the typological and functional expressions are unchanged during the Maglemosian Culture indicate that the societies on Bornholm had a continuing social and cultural contact with other groups or tribes within the Maglemosian Culture. Towards the end of the Maglemosian Culture, the habitation became sporadic, and the possibilities of creating contact with other cultural groups became limited and difficult because Bornholm was an island. It is however important to keep in mind that Bornholm seems to have never been completely isolated, and that it had a continuous social and cultural contact with the later Kongemose and Ertebølle Cultures. This is currently supported by the fact that the first Kongemose site (Sandemandsgård) has been registered at Bornholm (Figs. 23-24). Furthermore, a submerged site was located on Southern Bornholm at Boderne at a depth of four to five metres (Figs. 23 & 25). This indicates a now submerged landscape around Bornholm, which was settled in the Mesolithic. The use of this submerged landscape and its impact on the settlement pattern is currently uncertain. These arguments demonstrate that Bornholm was never out of sight or out of mind for the hunter-gatherers of the Kongemose and early Ertebølle Cultures. During the following late Ertebølle Period, a large habitation along the Littorina coast is registered on the island. One of these sites is Troldskoven, which is of particular interest as it is the only settled cave site in Denmark (Figs. 23 & 26). It was found by a coincidence when a German tourist excavated the site in 1939 and collected a large lithic material. The material was subsequently lost under the World War II. During the following years, the site was more or less forgotten until we took an interest in the cave.In 2004, we conducted a small survey and dry sieving of the surface of the cave and found lithic material. This could indicate that the cave was inhabited during the Early Ertebølle Culture. However, it is not possible to conclude any final dating of the assemblage until more investigations of the cave have been conducted. Another important late Ertebølle site on Bornholm is Grisby. This site demonstrates fishing and hunting – in particular on marine mammals. The artefacts from Grisby include imported lithic artefacts, Limhamn axes, and groove-decorated ceramics with an elongated cylinder-shaped base (Fig.27). All these artefacts are characteristic of the East Scandinavian Ertebølle sites, which were part of an established network across the Baltic Sea. These factors could be the basis of a swift transition to the Neolithic.To sum up, Bornholm in the late Palaeolithic was the northern part of a peninsula or an island with a substantial land bridge, which covered an area from Rügen and Pomerania to Bornholm. The settlement in the late Palaeolithic is sporadic, although the excavated site in the bog Vallensgård Mose indicates possible contacts with Rügen. This material presumably belongs to either the Bromme or the Ahrensburgian Culture in the Allerød or Dryas III. During the Dryas III and Preboreal, faunal remains of reindeer and elks have been registered on Bornholm, but there is no evidence of settlements in the Ahrensburg Culture and only little evidence from the earliest Maglemosian Culture. In the following Boreal phases, a large migration to the island along with a warmer climate and a changed fauna has been registered. During the late Maglemosian Culture, Bornholm became an isolated island and the settlement pattern changed. The number of inhabited sites was reduced and the settlements concentrated near the coast. In the Maglemosian Culture, it has been possible from the archaeological material to observe continuous social and cultural contacts with other Maglemosian societies in the Western Baltic, as exemplified by the changes in flint technology and the similarities concerning the hut structures in this region. These facts illustrate how geographic developments challenge a hunter/gatherer group exceedingly and prove their ability to adapt to changed conditions, as seen during the Maglemosian Culture in the Baltic region. During the following Kongemose and early Ertebølle cultures, the island had a sporadic habitation, but new finds, especially underwater sites, could change the impression of the settlement distribution. In the late Ertebølle Culture, an increasing number of coastal sites have been registered on the island, and this clearly proves cultural contacts with Scania. Finally, the consistent contacts between Bornholm, Scania, Rügen, and Pomerania could be one of the main reasons why the process of neolithisation seems to have been swift compared to other parts of Southern Scandinavia. The prehistory on Bornholm also has its peculiarities with an exotic quartz production during the Maglemosian Culture and the first cave site attached to the Ertebølle Culture observed in Denmark. In this article, we have described how the geographical changes have challenged the Mesolithic hunter-gatherers to the extreme. One of their most important faculties was the ability to exploit and maintain cultural as well as social contacts with other Late Palaeolithic and Mesolithic societies in the Baltic region.Claudio Casati og Lasse SørensenAfdeling for ArkæologiSaxo-InstituttetKøbenhavns Universitet

The present study is a part of the comprehensive works concerned with the complete record of the Paleogene small benthic foraminiferal content in the Ranikot and Laki Formations of the Nammal Gorge, Salt and Sor Ranges of Pakistan. The first part was concerned with the Miliolina and Lagenina foraminiferal assemblage of Haque from Pakistan, and followed by the second part which concerned with the Rotaliid assemblage of the same author of Pakistan. The third part is concerned with the Textulariid part and presented in this study. Twenty one Early Paleogene Pakistanian smaller Textulariid (Agglutinated) benthic foraminiferal species and subspecies from the Ranikot and Laki Formations of the Nammal Gorge, Salt and Sor Ranges of Pakistan have been studied and are systematically listed. This systematic description provides a list of modern synonyms, short remarks about morphological features, and some annotations about taxa with problematic generic status. These species are: Spiroplectinella ushbali, Gaudryina nitida, Siphogaudryina daviesi, S. elongata, S. nammalensis, Verneuilina laevigata, Tritaxia elongata, T. limbata, Dorothia nammalensis, Marssonella nammalensis, Bigenerina khirthari, B. metingensis, B. nodosa, Textularia crookshanki, T. haquei, T. punjabensis, Clavulinoides lakiensis, C. spatha, C. symmetrica, Valvulina n. nammalensis, V. nammalensis longa. Most of the recorded species are an endemic to Pakistan, except five species Siphogaudryina elongata, Tritaxia elongata, T. limbata, Textularia crookshanki and T. punjabensis are recorded in some Northern Tethys (France, Hungary) and Southern Tethys (India, Iran, UAE, Egypt, Algeria). The paleoenvironmental interpretations of the identified species in the study area of Pakistan were deposited in somewhat deep water and open-marine environments. The abundance of pelagic Pakistanian benthic foraminiferal assemblages indicate an open connection to the Tethys, which represents middle-outer neritic environment (100-200 m depth) and shows an affinity with the Atlantic-Tethyan Regions: “Midway Type Fauna “.

Dendrorchis retrobiloba Volonterio & Ponce de León, 2005 was first described from the swim bladder of Astyanax fasciatus (Cuvier, 1819) from Montevideo, Uruguay. In this study, we necropsied specimens of A. aff. fasciatus collected from Lake Guaíba, in Rio Grande do Sul, Brazil, for the analysis of their helminths. The digeneans were identified as D. retrobiloba by their elongated body, oral sucker longer than ventral sucker, and 2 posterior lobes. This is the first report of D. retrobiloba in A. aff. fasciatus from Lake Guaíba and extends the known geographic distribution of this parasite.

Diabetes mellitus is a commonly occurring chronic metabolic disorder which has affected almost 400 million people around the world. It can lead to vascular structure alterations and various renal, cardiovascular, and neurologicalcomplications claiming several lives. Since diabetes mellitus results is vascular structure changes, NailfoldCapillaroscopy(NFC) based approach can be employed for the detection of diabetes. NFC is an inexpensive, non-invasive method which involves acquisition of images of capillaries in the nail bed region using a USB digital microscope. Qualitative parameters of the capillaries such as tortuosity, hemorrhages, angiogenesis, elongated capillariesand quantitative parameters like length, width and mean capillary density are considered for diabetes detection. About 600 capillary images of healthy and diabetic subjects were collected and further data augmentation was performed to increase this to 1018 images dataset. This paper focuses on using NFC to obtain capillary images and employdeep learning-based object detection algorithm to localize these capillary loops on the nailbed and differentiate them into five classes namely, normal, wide, elongated, tortuosity and hemorrhages. This classification is of prominent significance to medical practitioners as this helps in gauging the severity and progressionof the disorder.

AbstractLake Erenciuc is situated in the Danube Delta (Romania) and was created in the abandoned riverbed of the Sfântu Gheorghe arm. It is the largest meander lake in Romania. During spring–summer, the physico-chemical parameters of water have been measured in seven lake sampling points and one at the Sfântu Gheorghe branch, which supplies the lake through Erenciuc channel. The area around Lake Erenciuc belongs to the category of strictly protected areas within the Danube Delta Biosphere Reserve. The following water quality parameters were measured: temperature (T: °C); pH (pH units); Luminescent Dissolved Oxygen (LDO: mg dm−3); Dissolved Oxygen saturation (DO: %); water tension (U: mV); Electrical Conductivity (EC: μS cm−1); Total Dissolved Solids concentration (TDS: mg dm−3). The recorded values are easily differentiated across the entire length of the elongated lake path, especially between inflow (upstream) and outflow (downstream). The parameters recorded during the spring–summer period, with high flow rates and high water levels, demonstrate good lake water quality, especially oxygenation. The study also demonstrates that high waters refresh and recalibrate the water quality in isolated lake basins.

Lake Ontario marine seismic data reveal major Grenville crustal subdivisions beneath central and southern Lake Ontario separated by interpreted shear zones that extend to the lower crust. A shear zone bounded transition between the Elzevir and Frontenac terranes exposed north of Lake Ontario is linked to a seismically defined shear zone beneath central Lake Ontario by prominent aeromagnetic and gravity anomalies, easterly dipping wide-angle reflections, and fractures in Paleozoic strata. We suggest the central Lake Ontario zone represents crustal-scale deformation along an Elzevir–Frontenac boundary zone that extends from outcrop to the south shore of Lake Ontario.Seismic images from Lake Ontario and the exposed western Central Metasedimentary Belt are dominated by crustal-scale shear zones and reflection geometries featuring arcuate reflections truncated at their bases by apparent east-dipping linear reflections. The images show that zones analogous to the interpreted Grenville Front Tectonic Zone are also present within the Central Metasedimentary Belt and support models of northwest-directed crustal shortening for Grenvillian deep crustal deformation beneath most of southeastern Ontario.A Precambrian basement high, the Iroquoian high, is defined by a thinning of generally horizontal Paleozoic strata over a crestal area above the basement shear zone beneath central Lake Ontario. The Iroquoian high helps explain the peninsular extension into Lake Ontario forming Prince Edward County, the occurrence of Precambrian inlier outcrops in Prince Edward County, and Paleozoic fractures forming the Clarendon–Linden structure in New York.

Diatoms, magnetic susceptibility, organic content, and14C ages of sediments from a 26-m core suggest that Lake Chalco, in the southern part of the basin of Mexico, went through a series of major fluctuations during the late Pleistocene and the Holocene. Before ca. 39,00014C yr B.P. the lake was very deep (about 8–10 m), alkaline, and saline. It then became shallow (<2 m) for most of the time between ca. 39,000 and 22,500 yr B.P. Chalco deepened to about 4–5 m about the time of a major eruption of nearby Popocatepetl volcano ca. 22,000 yr B.P. The lake remained relatively deep and fresh until ca. 18,500 yr B.P., when lower levels and alternating acidic to freshwater conditions were established. After 14,500 yr B.P. lake level rose slightly, but by ca. 10,000 yr B.P. Chalco became very shallow (<2 m), remaining as a low, alkaline saline marsh until ca. 6000 yr B.P. This period corresponds with the Playa cultural phase, during which the earliest human settlements in the basin were established. After ca. 6000 yr B.P. Chalco became a fresh to slightly alkaline shallow lake a few meters deep.

A new deep water drilling system was developed and applied to recover deeply buried sediments for scientific analyses in one of the deep rift valley lakes of Africa—Malawi. This approach overcame the difficulty of maintaining position over a drill site in a remotely located, large, deep lake. Environmental conditions in Lake Malawi are similar to deep water marine settings and, as such, a marine approach was adopted for the Lake Malawi Drilling Project (LMDP). In February and March 2005, the modified pontoon, Viphya, successfully completed a scientific drilling expedition in Lake Malawi. This expedition recovered core at depths greater than 380 m below lake-floor in water depths as great as 600 m. The major refit of Viphya included installation of a moonpool, bridge, crew accommodations, mess, washroom, power system, dynamic positioning, and a drilling system. These major modifications required early pontoon surveys and naval architectural analyses and design work prior to their commencement. The expedition also used modified scientific coring tools with a marine geotechnical drilling rig for the first time, resulting in excellent core recovery and quality.