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Optima (dots) and tolerances (error bars) of the species that contributed the most to community dissimilarity in the four models: Spring, summer, autumn and all (the three seasons combined). https://doi.org/10.1371/journal.pone.0199343.g003
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The value of diatoms as bioindicators in contemporary and palaeolimnological studies through transfer function development has increased in the last decades. While such models represent a tremendous advance in (palaeo) ecology, they leave behind important sources of uncertainties that are often ignored. In the present study we tackle two of the mos...
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Paleolimnology studies in tropical reservoirs and urban lakes are relatively scarce. These aquatic ecosystems, however, are subject to a range of environmental impacts, including cultural eutrophication, a process that can be assessed and monitored using paleolimnological methods. Arcellinida (testate lobose amoebae) is a taxonomic group that can b...
Ciliates are unicellular heterotrophic organisms that play a key role in aquatic planktonic and benthic food webs. Advances in sedimentary DNA (sed-DNA) analysis offer the possibility to integrate these bioindicators in paleoenvironmental reconstructions. In this study, we used the top–bottom paleolimnological approach and metabarcoding techniques...
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... The strongest explanatory variable for the Chironomidae community according to the k1:k2 ratio was MJAT (1.4 CCA-based, 1.3 RDA-based; Table 3). Training sets with ratios k1:k2 > 1 are characterized by strong relationships between the examined environmental variable and the assemblage data relative to the remaining variance in the TS and are therefore suitable for developing inference models (Goldenberg Vilar et al. 2018). However, it must be kept in mind that the CCA plot demonstrating the dependency of chironomid assemblages from MJAT exhibits the horseshoe effect, which could affect the results. ...
Here we present a new eastern Baltic Chironomidae training set (TS) containing 35 sites that was collected and merged with neighboring published Finnish (82 lakes) and northern part of the Polish (nine lakes) TSs. Chironomidae, non-biting midges, are known to be strongly responsive to the July air temperature and are widely used to infer palaeotemperature. Several modern analogue-based TSs necessary for calibrating the relationships between mean July air temperature (MJAT) and chironomids are available for Europe. However, none of these is representative of the transitional climate typical for eastern Baltic (Estonia, Latvia, Lithuania). The Finno–Baltic–Polish TS contains 121 sites and covers a geographically continuous 70–50°N latitudinal and 7 °C (12.1–19.2 °C) MJAT gradient. Canonical correspondence analysis revealed that, among the tested environmental variables (pH, water depth, dissolved oxygen, MJAT), the MJAT explains the highest amount of variation, both for the eastern Baltic separately and the Finno–Baltic–Polish TSs. The weighted averaging–partial least squares-based cross-validation test reveals that the Finno–Baltic–Polish TS has a low root mean square error of prediction (0.7 °C) confirming the high reliability of the TS. The temperature optima of the taxa included in the new Finno–Baltic–Polish TS and widely used Swiss–Norwegian TS were examined. The observed dissimilarities can be attributed to the differences in the temperature ranges represented by the TS, the taxonomic identification level, the general cosmopolitan taxa distribution patterns, and the influence of TS-specific geographic position, climatic, or environmental conditions. The new Finno–Baltic–Polish TS adds to the knowledge of the modern distribution of Chironomidae taxa and widens the geographical area of reliable Chironomid-based MJAT reconstructions into the eastern European lowland.
... Secondly, the sample was taken two months from the moment the body was discovered. The structure of diatom communities in the collected environmental samples, including the share of dominant species, may change depending on the season in which the samples were collected [47][48][49], hence in case 036 and 037, the apparent discrepancies observed between organ samples and environmental samples may have been due to the fact that water was absorbed several months earlier. In such cases, greater similarities can be observed with the benthic samples, which include dead diatoms from previous seasons that have fallen to the bottom of aquatic ecosystems. ...
Diatoms (Bacillariophyta) are unicellular photosynthetic organisms commonly occurring in aquatic habitats on Earth. Their autecology makes them almost perfect indicators of environmental conditions and so have high potential for use in forensics. Both eurytopic and stenotopic species are important in site identification: eurytopic forms due to their abundance, and stenotopic forms due to their narrow range of tolerance to environmental conditions. Their presence can hence provide a clear insight into an ecosystem and its microhabitats. The diatoms are useful as significant indicator in diagnosing of drowning. However, to definitively link a corpse with the place where it was found and to indicate whether this was also the crime scene, it is essential that any comparative diatomaceous analyses are performed correctly. The following study presents selected cases in which a comparative diatomaceous analysis was performed. In all cases, the biological samples secured during the autopsy were compared with environmental samples collected from the site of the cadaver disclosure. Our findings show both the possibilities and limitations of using this method in forensics. These forensic investigations need close collaboration between coroners and diatomology experts. It is crucially important to reveal whether the place of corpse finding is the same as the place of drowning.
... Our results demonstrate the sensitivity of diatom communities to the effect of flow alteration even during one single season. It is well known that seasonality influences diatom communities (Goldenberg Vilar et al., 2018;Snell et al., 2019;Soininen & Eloranta, 2004). For example, under spring/summer conditions, water temperature and net radiation, dissolved oxygen and nitrogen availability are key drivers of diatom assemblage composition (Snell et al., 2019). ...
Rivers are intensively managed worldwide through unprecedented flow regime alterations on a global scale. This has led to an increasing interest in the development of quantitative tools to assess the ecological response of organisms to flow alteration. To date, studies reflect a large diversity of responses that make the intensity and prevalence of effects difficult to generalize. The present study analyzed how flow alterations caused by dams affect the structure, composition and traits of diatoms and macrophytes in three Spanish River basins (Cantabric, Ebro and Duero). By using a control‐impact design based mainly in hydrological similarity, our results showed consistent patterns of change in diatom and macrophyte communities. Our study showed a shift from resistant traits such as non‐colonial diatom forms and crust‐forming algae, which are adapted to the extreme events and natural dynamism of unregulated rivers, towards planktonic diatoms, free‐floating algae and the mass development of aquatic plants in hydrological altered sites. Both communities shared common thresholds of response to altered hydrological attributes that could be considered in a flow management context. The hydrological indices that impacted diatom and macrophyte communities the most were related with the magnitude and duration of minimum flows. However, our results also show that it is important to consider the inter‐relationships between the different hydrological attributes such as the seasonal variability of monthly flows, the magnitude of maximum annual extremes, the timing of flow events, and the frequency and rate of flow changes.
... Diatoms have been used to infer past changes in lake water chemistry (Jacques et al., 2016), salinity , nutrient concentrations (Rodríguez-Alcalá et al., 2020), water depth (Gushulak et al., 2017) and climate (Rühland et al., 2015). Several studies have used diatoms to reconstruct past temperature from sediment records using transfer functions (Pienitz et al., 1995;Joynt and Wolfe, 2001;Rühland et al., 2015;Goldenberg Vilar et al., 2018;Reavie and Cai, 2019;Maslennikova, 2020;Sui et al., 2020). Additionally, many physical and chemical variables in lake systems to which diatoms are sensitive (thermal stratification and icecover) are closely linked to changes in temperature. ...
Sedimentary diatoms have been used to quantitatively reconstruct climate‐related variables, such as temperature at different timescales. Even though temperature is often less of a key driver of diatom ecology than other environmental parameters (water chemistry), diatom inference models have been shown to be reliable in deducing past temperature trends. In addition, the oxygen isotope composition (δ18Odiatom) preserved in buried diatom frustules has demonstrated its potential to reflect climatic and hydrological conditions at the time of frustule formation. This study combines results from both diatom‐based climate proxies to reconstruct summer water and mean annual air temperatures, and hydrological trends in Nettilling Lake, Baffin Island, from ca. 5000 to 500 cal a bp. Diatom‐inferred temperatures revealed an overall ca. 2 °C cooling throughout the Late‐Holocene. The δ18Odiatom values showed an increasing trend up to ca. 1900 cal a bp, where they reached their highest values (+24.8‰ at 15 cm) and thereafter decreased to their lowest values (+21.4‰ at 4 cm). These trends were linked to meltwater inflows associated with Penny Ice Cap thaw rate that was in turn controlled by regional climatic conditions which went from intensified cooling during the Neoglacial period to slight warming thereafter. Our results suggest that diatom‐ and diatom‐isotope‐based temperature and hydrological reconstructions can identify trends related to the natural climate system variability. The diatom oxygen isotopes are useful for paleoenvironmental studies of terrestrial aquatic ecosystems, but not for all hydrological systems are the ideal temperature proxy. Hence, the combination of proxies helps to disentangle temperature and hydrological effects for paleoclimatic reconstructions and may support future studies of postglacial environmental change in northern lakes.
Ecology is complex and while there is a modern drive towards a holistic or “ecosystem approach” for managing marine systems, we are still a long way from fully understanding the interactions between the various components of different ecosystems and fully valuing their contributions. Microphytobenthos (MPB), and diatom biofilms, are an excellent example. While they are relatively widespread, their role has often been overlooked in favor of more charismatic species or assemblages. However, the understanding of their ecological importance has increased with a growing body of evidence outlining their important role in system functions ranging from biogeochemical cycles, trophic interactions and a direct influence of sediment dynamics. The latter effect is related to the secretion of extracellular polymeric substances (EPS) which have a number of roles in ecosystem dynamics, including the mediation of sediment erosion. Therefore, it is understandable that characterization of MPB assemblages as ecosystems engineers is becoming more widespread. A more recent development is the debate surrounding the evolutionary impact of ecosystem engineering and whether this is sufficiently distinct and important that it should be considered a separate evolutionary pressure, as described in the “niche construction” theory. Microphytobenthos have already been cited in this debate and this chapter briefly introduces the range of functionality of MPB and discusses their role as ecosystem engineers and their potential place in niche construction theory.
Paleolimnology had increased sharply as an approach for lake management, but most of the paleontological studies have been carried out in temperate and high-latitude regions. 40% of lakes lie within tropical areas, which represent 32% of surface global water bodies. Paleolimnology is a study of the physical, chemical, and biological features of the lakes in the past. Find the future from the past, prediction of the future condition can be developed from the reconstruction of past condition, based on the fossil preserved in the sediment. Ecosystem services of the lakes are hydroelectricity power, source of drinking water, irrigation, fisheries, tourism, socio-economic religious activities. Those functions have been deteriorated due to sedimentation, pollution, and eutrophication. Water security becomes a problem. Lake sediments as archives that record the climatic and environmental changes in the catchment area. VosViewer had been applied to construct and visualize bibliometric publications indexing by Scopus with the keywords paleolimnology, water resource, renewable energy, climate change, and food security. The result shows that there is a strong relationship between paleolimnology, climate change, and food security. Paleolimnology contributed to SDGs number 6(water security and sanitation) has an important role in the achievement of SDGs number 2 of food security through adaptation and mitigation of climate change (SDGs number 13), and terrestrial ecosystem, including lakes. This paper will discuss a paleolimnological approach to reconstruct past environmental changes and their challenges in Indonesia.
