Diatom Analysis Research Articles

Causes of ecosystem transformations variability in lakes of the european part of Russia and Western Siberia (diatom analysis)

On the basis of author's graphical analysis method, the typification of lake ecosystems transformation scenarios depending on the size of lakes was carried out. It was confirmed that the type of transformation depends not only on size of the lake, but also on the landscape and climatic region in which it is located. The distinctive features of lake ecosystems transformation types in the European part of Russia and in Western Siberia were analyzed and compared.

Fossil diatoms from the Volga Delta Holocene sediments (Damchik region) as indicators of the paleoecological conditions of sedimentation

The results of fossil diatoms investigation from the deltaic sediments are presented. Samples were obtained from the core DM-1 and two Holocene outcrops from the Damchik region of the Astrakhan Nature Reserve. In the core samples eight periods of sedimentation based on diatom analysis were identified: the sediments formed in shallow freshwater basins and deltaic channels. The samples from the outcrops were investigated in much greater detail.

Paleoecological study of bottom sediments of the lake Goluboye (Karelian Isthmus) according to the results of diatom analysis

The study of paleogeography of lakes is an actual and important direction in modern science. As part of the study of lakes in the North-West of the Karelian Isthmus, this analysis will establish the dynamics of salinity of objects, which will allow to reconstruct changes in the level of the Baltic Sea in the Holocene.

Holocene diatom assemblages from Dunderbukhta sediments, West Svalbard

The diatom analysis results of sediment samples from Dunderbukta area (Wedel Jarlsberg Land, West Svalbard) are presented in this paper. The diatom flora consists of four ecological groups, which ratio indicates three ecological zones. These zones show environmental changes of the area in early–middle Holocene that is demonstrating periods of regression and temperature trends.

Biostratigraphy of the Holocene deposits of the Azov Sea based on the results of diatom analysis

The difference in composition of diatom flora dominant species of the Taganrog Bay with the flora that existed in the New Azov and Ancient Azov time at open part of the Azov Sea was described. It is noted that dominant at the Sea representatives of the genus Actinocyclus Ehr. are rare in the bottom sediments of the Taganrog Bay, unlike Thalassiosira incerta Makarova and T. decipiens (Grunow) E.G. Jørg., that got a massive development in there.

Modeling of ecological conditions in the Euxine Basin in the Sarmatian and Maeotian by methods of diatom analysis

The associations and ecological conditions of the existence of modern diatoms of the North-West (Pridneprovsky), Prikerchensky and Eastern regions of the subtidal zone of the Black Sea are considered. Based on the unity of the composition of the Present and Sarmatian-Meotian diatom flora, an attempt has been made to model some of the ecological c situation of the Late Miocene Euxinian basin.

Diatom complexes from bottom sediments of small lakes of the Imandra depression

The study of diatom complexes in the bottom sediments of 2 small nameless lakes on the western coast of Imandra Lake (Murmansk region) was carried out. The features of the historical dynamics of diatom flora in response to changes in the environment and climate in the Holocene are described. Diatom analysis revealed the effects of tectonic activity in the area of the Imandra Lake depression, accompanied by a sharp increase in the water level, which is confirmed by lithological data.

Combustion features from short-lived intermittent occupation at a 1300-year-old Coast Salish rock shelter, British Columbia: The microstratigraphic data

Short-lived occupation sites are the most common component of the archaeological record at the regional scale level, but are often underrepresented due to their low amount of cultural material and greater visibility of larger sites. Small ephemeral sites can however provide unique information regarding land and resource use, travel routes, harvesting practices, group size, food processing, ceremonial activities and chronology of occupation, especially in pre-urban societies. One of the most prominent proxies for short-lived occupation is combustion features, defined as accumulations of ash, burnt bones, heat-altered sediments and stone tools. These features provide insights into behavioral evolution, food consumption, settlement patterns and foraging strategies, and the preservation of the archaeological record. To obtain this information, a microscopic level of investigation is required in order to address the chemical and mineralogical characteristics of combustion features. We deployed such kind of microarchaeological approach to the study of combustion features at the DjRr-4 rock shelter along the Indian River, British Columbia, settled by Coast Salish peoples at least 1300 years ago. Using a combination of micromorphology of sediments, phytolith and diatom analysis, paleobotany, zooarchaeology, lithic analysis and radiocarbon dating, we were able to show that the shelter was used intermittently over short time spans as a base camp for hunting, likely as a station along a trail that connected the coast to interior regions. Our results are consistent with chronological data for the region and with the adoption of bow and arrow by Coast Salish peoples.

Environmental assessment of Lake Manzala inferred from diatom analysis of the lake surface sediments

The distribution patterns of diatoms in the surface sediments of Manzala Lake have been studied in detail. A total of 110 diatom species belonging to 48 genera have been identified from samples consist mainly of greenish gray mud with relatively some muddy sand sediments. The distribution pattern of the recorded diatom taxa displayed changes in the floristic composition due to changes in the ecological conditions such as salinity, pH, and some chemical elements, which are related to sea-level fluctuations, freshwater influences, waste discharge from the drains and climatic changes. Multivariate statistical techniques including hierarchical ascending clustering and Canonical correspondence analyses were used to identify ecological groups of diatoms and to estimate which environmental variables were important in diatom distribution. Five diatom ecological groups were identified and classified the lake into five distinct ecological zones.

Freshwater diatom transfer to clothing: Spatial and temporal influences on trace evidence in forensic reconstructions

Environmental indicators are increasingly sought and analysed in a range of forensic reconstructions. Although the majority of casework and research studies are concerned with the criminal investigation of terrestrial habitats (soils, sediments, plants etc.), freshwater environments are also frequently encountered as crime scenes. As such, microalgae, particularly diatoms, may provide useful circumstantial trace evidence following their transfer to a victim or perpetrator. Diatom analysis is a relatively underused technique in forensic ecology, although an increased empirical research focus is beginning to recognise the evidential value of a transferred assemblage. This study aimed to examine three of the spatial and temporal variables known to influence the extent of an initial transfer of trace particulates, within the context of freshwater diatoms to clothing. A series of experiments were designed to consider the impact of recipient surface characteristics (clothing type), source environment conditions (seasonality), and morphological (type of diatom) variability, on the total number (no. per cm2) and species richness (total no. sp.) of an evidential diatom sample recovered from clothing. Nine commonly used clothing materials were immersed in a freshwater river at three times of year – the early and late spring and in the winter. Diatoms were recovered using a H2O2 extraction technique and examined microscopically. The results demonstrated that diatom transfer to clothing varies significantly, with a greater abundance and a higher species richness transferred to coarse woven surfaces including acrylic, linen, and viscose. Significantly fewer diatoms were transferred to clothing in the winter, in line with seasonal fluctuations in the source environment diatom community. Furthermore, variation in the relative abundance of particular diatom species was identified between clothing types, provisionally suggesting that morphological characteristics may also support or limit the transfer of material. These findings highlight that, although clothing may offer a valuable repository of freshwater diatom trace evidence, the interpretation of evidential material should be approached within an exclusionary framework. Thus, empirical data has been generated to develop evidence bases within forensic ecology, demonstrating some of the spatial and temporal factors which may contribute to or limit the transfer of evidence.

A 12,700-year history of paleolimnological change from an Andean microrefugium

We present a 12,6700-yr limnological history of Lake Miski, a high-elevation lake in a wet section of the Peruvian Andes. While many shallow Andean lakes dried up during the mid-Holocene, loss-on-ignition, magnetic susceptibility, and diatom analysis showed that Lake Miski was a constant feature in the landscape. Overall, fluctuations in the fossil diatom communities of Lake Miski tracked changes in insolation, but this was not the only mechanism influencing observed variability. We identify periods when insolation and interactions with the Pacific Ocean may have played a role in structuring local climate and diatom assemblages. The true mid-Holocene Dry Event (MHDE) is manifested in this record between 8000 and 5000 cal BP, but the carbonate stratigraphy and the diatom community indicated that although the level of the lake decreased, it never completely dried out, instead there was higher availability of planktic habitat and stronger mixing than in much of the Holocene. High rates of biological change observed during the late-Holocene in other records from Peru associated with human amplification of climatic signals were not observed in Lake Miski, as this lake may have been too wet and remote to be strongly influenced by human activity. Because of the presence of a woodland microrefugium, Lake Miski was suggested to have been an unusually climatically stable and wet location during the regional drying associated with the MHDE. Our new limnological information provides additional insights relating to this discussion. The presence of the observed woodland apparently withstood fluctuations that induced state changes in the lake and diatom flora, underscoring that microrefugia do not equate to ‘unchanging’ hydrologies or climates.

Taxonomy and ecology of order Surirellales (Bacillariophyceae) in tropical reservoirs in Southeastern of Brazil

Abstract Aim The aim of this study was to inventory the diatom species of order Surirellales present in the surface sediments of tropical reservoirs (São Paulo State, Brazil) and to correlate their distribution with environmental (pH, total phosphorus, and total nitrogen) and spatial predictors. Methods Samplings were carried out in 31 reservoirs from 2009 to 2014. Vertical profile of water samples was collected in the summer and winter along the reservoirs, and their water column mean results were used to characterize each sampling site. We measured water transparency, euphotic zone, water depth, pH, dissolved oxygen, total nitrogen, and total phosphorus. Surface sediment samples (2 cm top) were collected for diatom analyses. A partial RDA was performed between species abundance data (response matrix) and environmental and spatial variables (predictor matrices). Results 14 species of Surirellales were identified from the surface sediment samples, five of them being identified only at the genus level. Overall, partial RDA showed that the species distribution is constrained by both environmental and spatial predictors. Species were mainly ordinated in relation to pH and light availability. Conclusion Our results demonstrated that the Surirellales species revealed ecological preferences to low nutrient concentrations, neutral to slightly acidic waters, and higher light availability. Moreover, our results suggest that both environmental and spatial factors are important for their species distribution.

Evolution of the Valley Ecosystems in the Lower Reaches of the Bikin River in the Late Pleistocene and Holocene

Reconstructions of changes in vegetation, climate and sedimentation conditions in the valley of the lower reaches of the Bikin river lower reaches (Northern Primorye) for the last 70 thousand years were made from results of palynological and diatom analyses, radiocarbon dating of peat samples, plant detritus and woody remains contained in the alluvial and biogenic deposits of floodplain and above the floodplain terraces exposed by profiles. New evidence was obtained for multiple and significant transformations of natural environment of the region for several climatic cycles during the Late Pleistocene and Holocene corresponding to marine isotope stages MIS 4–1. It was established that the final phase of MIS 4 was dominated by ecosystems of mari and dark coniferous taiga, the interglacial stage of MIS 3 by communities of birch forests with the involvement of broad–leaved plants, and the glacial stage of MIS 2 by birch open woodland with larch and spruce as well as by sphagnum bogs and dwarf birch. In the Early Holocene (Q1IV) there occurred a rapid expansion of deciduous plants. During the Holocene Optimum, about 6.5 ka, the ecosystems were dominated by polydominant forests. The maximum development of oak–deciduous forests with conifers is recorded about 5 ka. The transition from the Middle to Late Holocene (Q2IV–Q3IV) is characterized by a reduction in the proportion of pine and broad–leaved vegetation and by the development of small–leaved and dark coniferous plant communities. It is found that in the second half of the Late Holocene (Little Climatic Optimum), pine–oak forests began to dominate the landscapes, and the end of that period developed the contemporary ecosystems.

PUTATIVE RECORDS OF THE HOLOCENE TSUNAMI IN LACUSTRINE BOTTOM SEDIMENTS NEAR THE TERIBERKA SETTLEMENT (KOLA PENINSULA, RUSSIA)

The results of lithological analysis, diatom analysis and radiocarbon dating of bottom sediments from the basin of a lake located at an elevation of 17 m above sea level near the Teriberka settlement (Barents Sea coast, Kola Peninsula) are presented. The stages of the lake evolution were revealed based on a comprehensive investigation of its bottom sediments. The lake basin was covered by sea at the end of the Pleistocene. The lake became isolated from the sea approximately 11500 cal. yrs BP, but was re-filled with sea water after 10400 cal. yrs BP due to the Tapes transgression. In lower part of the Tapes sediments, there is a disturbance of the sediment sequence, represented by a mixture of sand, gyttja and plant residues. According to radiocarbon dates, this disturbed hori­zon was deposited between 10400 and 8200 cal. yrs BP. An abrupt increase in the con­tent of marine diatoms was found in this horizon. The disturbed sediments have possibly formed as a result of the Storegga tsunami. When the horizon of tsunamigenic sediments was forming, the sea level was slightly above the threshold for discharge from the lake (ca. 18 m above modern sea level). The second local event (tsunami?) occurred after 8220 cal. yrs BP, when the coastline was already below the lake threshold. As a result of this event, an interlayer of sandy sediments formed in the bottom sediments within gyttja.

Geoarchaeological evidence of landscape transformations at the Neolithic and Bronze Age settlement of Nea Raedestos in the Anthemous River valley, central Macedonia, Greece

AbstractA paleoenvironmental reconstruction of the landscape of Nea Raedestos Toumba in the Anthemous River valley in central Macedonia, Greece is undertaken using multidisciplinary geoarchaeological methods. The archaeological site is a settlement mound (tell or toumba) that dates to the Neolithic period and the Bronze Age. The tell’s location on the alluvial plain prompted a multidisciplinary investigation to reconstruct the influence of landscape changes on prehistoric settlements in the valley with an emphasis on alluvial sequences. An electrical resistivity tomography survey and three cores were drilled to study the sedimentary environments in and around the archaeological site. Sedimentologic and palynological analysis combined with accelerator mass spectrometry radiocarbon dating show that the oldest habitation layers at the site, from the Middle and Late Neolithic, were located next to a small, periodically drying water body surrounded by ruderal vegetation. Diatom analysis suggests that this water body was supplied by saline/brackish groundwater. The water body was open until the Early Bronze Age, when it was filled and buried by floodplain sediments. This flooding phase at Nea Raedestos likely occurred at the same time as an increase in fluvial aggradation in the neighboring Thessaloniki Plain, which is dated to the beginning of the third millennium BC.

Reconstructing the Trophic History of an Alpine Lake (High Tatra Mts.) Using Subfossil Diatoms: Disentangling the Effects of Climate and Human Influence

Diatom analysis was undertaken on a 200-year sediment record in an alpine lake (Popradské pleso, Tatra Mountains, Central Europe). Due to its remote character and well-documented human influence since the mid-nineteenth century, it allows a study of the relationship between anthropogenic pressures and diatom assemblages. Altogether, 122 diatom taxa of 40 genera were identified, and two major taxonomic shifts were revealed in the stratigraphic record. The timing of the first significant shift in ~ 1850 precludes the possibility of being caused by direct human activities, since according to historic documents there was neither continuous human presence nor grazing in the valley before that time. In addition, the direct effect of organic pollution early in the 1960s connected with the operation of a tourist hotel was not clearly reflected in the diatom signal. The diatom-inferred total phosphorus (DI-TP) reconstruction indicated the highest TP content well before the most direct wastewater pollution from a newly built hotel. There was a considerable effect of climate to diatom assemblage structure as well as diatom life forms. Our results suggest that direct organic pollution influenced the diatom communities less than expected, and the main driver of change was climate warming. We hypothesize that it is because of the short residence time of the lake, since it has both strong inlet and outlet, and it has been showed that the inlet had significant effect on benthic communities in the past. At the same time, fish manipulation could have been the reason for some fluctuation in DI-TP unrelated to climate and organic pollution.

Environmental evolution of western Baltic Sea in the Holocene in the light of multidisciplinary investigations of sediments cores from Arkona Basin

A multidisciplinary investigation performed on gravity cores, supplemented by a new radiocarbon dating of macrofossils, outlined the environmental evolution of Arkona Basin in the Holocene. Studies comprising the analysis of diatoms, geochemistry, grain size, and radiocarbon dating clarified the knowledge about the age and environmental changes during freshwater and marine transgressions and regressions. The acoustic profiling method allowed proper interpretation of the analysis results from sediment cores and created a proper lithostratigraphic model of the investigated basin. Baltic Ice Lake and Yoldia Sea sediment layers were identified acoustically and cores penetrated the final regression surface of the Baltic Ice Lake. The analyses of cores concentrated on Ancylus Lake and Littorina Sea sediments. Two phases of the Ancylus Lake stage were identified. The peaks of loss on ignition in the cores, observed as a strong acoustic reflector, were identified as a marker of Ancylus Lake regression between the first, high-water level phase and the second, shallow-water phase. The age of onset of Littorina transgression was estimated at around 7000–7200 cal BP and was younger than some previous estimations. The retrieved age confirmed the suggestion that the marine environment appeared first in Mecklenburg Bay and then after a few hundred years in Arkona Basin as an intensive transgression. The appearance of Littorina Sea revealed a fast shift of the environment from lacustrine to marine. The first phase of the Littorina stage was recognised as a rapidly increasing water level and high-energy environment; the second showed rapidly increasing salinity in the calmer conditions of sedimentation.

Morphometry of the diatom Fragilariopsis kerguelensis from Southern Ocean sediment: High-throughput measurements show second morphotype occurring during glacials

Abstract Fragilariopsis kerguelensis is one of the most abundant diatoms in the sediments of the Southern Ocean. Its morphometric features have been proposed as proxies, based on links with, for example, iron availability, sea surface temperature and glacial/interglacial conditions. We investigated morphometric changes in F. kerguelensis valves in a well-studied sediment core record, focusing on transition periods between glacials and interglacials. By applying a high-throughput diatom imaging and morphometry workflow, we found two clearly distinct morphotypes which were differentiated by their rectangularity. One of them occurred preferentially in glacial samples, whilst the other persisted throughout. This indicates that their relative abundances depend on environmental conditions and thereby points to the possibility that paleo-proxies based on F. kerguelensis valve morphometric features might in the future benefit from differentiating these two morphotypes. As an initial exploration of this idea, we show that the abundance ratio of both morphotypes correlates well with paleo-temperatures which had been reconstructed using independent data from the same core. Distinguishing between the two morphotypes only became possible by image analysis for precisely measuring diatom valve outlines and area, highlighting the potential of such methods for diatom analyses.

La arqueología desde el microscopio. Aportes interdisciplinarios de las diatomeas a las problemáticas arqueológicas

Actualmente, las problemáticas arqueológicas generaran datos no solo desde la propia de la disciplina sino también desde teorías y metodologías provenientes de otras disciplinas. La Diatomología, una disciplina que forma parte de las Ciencias Biológicas, ha demostrado ser una importante herramienta para la Arqueología. El análisis de diatomeas ha sido aplicado en reconstrucciones paleoambientales, en el análisis de procesos de formación de sitio, en material arqueológico como el estudio de procedencia de materia prima para la cerámica, en el estudio del manejo prehistórico del agua y suelos, en los restos bioarquelógicos y, por último, en la conservación del patrimonio tangible. El objetivo del presente trabajo es realizar una revisión crítica de la evolución y estado actual de los análisis diatomológicos en cuestiones arqueológicas, principalmente incluyendo los estudios latinoamericanos. Para ello se propone discutir las potencialidades y limitaciones de estos estudios, con el fin de generar un puente conceptual que sea de utilidad para investigadores interesados en trabajar con estas líneas.

New Data on the Ages of the Matituk and Pomyr Formations of Northern Sakhalin

New diatom analysis data are obtained for the rocks of the Matituk and Pomyr Formations of Northern Sakhalin that assign these formations to the Late Miocene and Pliocene, respectively.