Paleontological methods in environmental science

Long term environmental changes, induced both by natural and anthropogenic causes, cannot be assessed by looking solely at historical records of temperature, rainfall, water quality, etc. Frequently, such records are nonexistent. Where they do exist, they are often too short to be of much use. However, sediments contain a stratigraphic record of environmental change that allows comparison of the historic period influenced largely by humans, with prehistoric time when climate was the major determinant of environmental conditions.The stratigraphic record contains various fossilized organic materials which reflect environmental conditions at the time of the their deposition. Most abundant are pollen and spores of aquatic and terrestrial plants. Correspondence between pollen assemblages and vegetation has been found in all parts of the world. Therefore stratigraphic changes in pollen taxa reveal much information regarding the vegetational history of a region. Knowledge of the ecological requirements of various taxa can then be used to infer past climatic conditions. For example, dominance of Juglans (walnut) pollen indicates wet conditions while abundance of Pteridium (bracken fern) spores is an indicator of fire, suggesting drier conditions. Pollen can also be used to trace human disturbance to the environment. Sharp increases in the pollen of Ambrosia (ragweed) in sediment cores indicate large scale land clearance by man.Seeds preserved in sediments provide another measure of temporal vegetational change. Generally, seeds are not dispersed far from the parent plant; hence they provide a more local record of vegetation than pollen. A decrease in seeds of aquatic plants and increase in seeds of higher ground taxa when accompanied by increased sedimentation rates is an indicator of infilling of an aquatic environment. If unaccompanied by increased sedimentation, the change more likely represents lowering of sea level. Disappearance of seeds of taxa sensitive to turbidity and eutrophication provide another long term record of human disturbance.Distributions of diatoms are affected by temperature, salinity, oxygen, light availability and nutrient levels in the water. Therefore changes in diatom species preserved in the sediments can be used as indicators of climate, turbidity, anoxia and eutrophication in aquatic ecosystems.Many inorganic substances preserved in sediments also provide a long term record of changes in the environment. Nitrogen and phosphorus can be measured in cores and used as a surrogate record of water quality in lakes and estuaries. Sharp increases in sedimentary accumulation of metals record wastewater discharge and fuel emissions, related to human activity.

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Distribution and ecological segregation on regional and microgeographic scales of the diploidCentaurea asperaL., the tetraploidC. seridisL., and their triploid hybrids (Compositae)

PeerJ ◽

10.7717/peerj.5209 ◽

2018 ◽

Vol 6 ◽

pp. e5209 ◽

Cited By ~ 2

Author(s):

Alfonso Garmendia ◽

Hugo Merle ◽

Pablo Ruiz ◽

Maria Ferriol

Keyword(s):

Anthropogenic Disturbance ◽

Large Scale ◽

Latitudinal Gradient ◽

Soil Parameters ◽

Fine Scale ◽

Contact Zones ◽

Ecological Requirements ◽

Adaptive Processes ◽

Sympatric Cytotypes

Although polyploidy is considered a ubiquitous process in plants, the establishment of new polyploid species may be hindered by ecological competition with parental diploid taxa. In such cases, the adaptive processes that result in the ecological divergence of diploids and polyploids can lead to their co-existence. In contrast, non-adaptive processes can lead to the co-existence of diploids and polyploids or to differentiated distributions, particularly when the minority cytotype disadvantage effect comes into play. Although large-scale studies of cytotype distributions have been widely conducted, the segregation of sympatric cytotypes on fine scales has been poorly studied. We analysed the spatial distribution and ecological requirements of the tetraploidCentaurea seridisand the diploidCentaurea asperain east Spain on a large scale, and also microspatially in contact zones where both species hybridise and give rise to sterile triploid hybrids. On the fine scale, the position of eachCentaureaindividual was recorded along with soil parameters, accompanying species cover and plant richness. On the east Spanish coast, a slight latitudinal gradient was found. TetraploidC. seridisindividuals were located northerly and diploidC. asperaindividuals southerly. Tetraploids were found only in the habitats with strong anthropogenic disturbance. In disturbed locations with well-developed semi-fixed or fixed dunes, diploids and tetraploids could co-exist and hybridise. However, on a fine scale, although taxa were spatially segregated in contact zones, they were not ecologically differentiated. This finding suggests the existence of non-adaptive processes that have led to their co-existence. Triploid hybrids were closer to diploid allogamous mothers (C. aspera) than to tetraploid autogamous fathers (C. seridis). This may result in a better ability to compete for space in the tetraploid minor cytotype, which might facilitate its long-term persistence.

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An On-Going Monitoring Project of a New Timber Structure

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.778.757 ◽

2013 ◽

Vol 778 ◽

pp. 757-764 ◽

Cited By ~ 2

Author(s):

Francesca Lanata

Keyword(s):

Structural Health Monitoring ◽

Health Monitoring ◽

Environmental Conditions ◽

Environmental Changes ◽

Construction Material ◽

Structural Response ◽

Timber Structures ◽

The Real ◽

Structural Health

Structural design, regardless of construction material, is based mainly on deterministic codes that partially take into account the real structural response under service and environmental conditions. This approach can lead to overdesigned (and expensive) structures. The differences between the designed and the real behaviors are usually due to service loads not taken into account during the design or simply to the natural degradation of materials properties with time. This is particularly true for wood, which is strongly influenced by service and environmental conditions. Structural Health Monitoring can improve the knowledge of timber structures under service conditions, provide information on material aging and follow the degradation of the overall building performance with time.A long-term monitoring control has been planned on a three-floor structure composed by wooden trusses and composite concrete-wood slabs. The structure is located in Nantes, France, and it is the new extension to the Wood Science and Technology Academy (ESB). The main purpose of the monitoring is to follow the long-term structural response from a mechanical and energetic point of view, particularly during the first few service years. Both static and dynamic behavior is being followed through strain gages and accelerometers. The measurements will be further put into relation with the environmental changes, temperature and humidity in particular, and with the operational charges with the aim to improve the comprehension of long-term performances of wooden structures under service. The goal is to propose new improved and optimized methods to make timber constructions more efficient compared to other construction materials (masonry, concrete, steel).The paper will mainly focus on the criteria used to design the architecture of the monitoring system, the parameters to measure and the sensors to install. The first analyses of the measurements will be presented at the conference to have a feedback on the performance of the installed sensors and to start to define a general protocol for the Structural Health Monitoring of such type of timber structures.

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Pleistocene Branchiopods (Cladocera, Anostraca) from Transbaikalian Siberia Demonstrate Morphological and Ecological Stasis

Water ◽

10.3390/w12113063 ◽

2020 ◽

Vol 12 (11) ◽

pp. 3063

Author(s):

Anton A. Zharov ◽

Anna N. Neretina ◽

D. Christopher Rogers ◽

Svetlana A. Reshetova ◽

Sofia M. Sinitsa ◽

...

Keyword(s):

Environmental Conditions ◽

Seasonal Variations ◽

Environmental Changes ◽

Daphnia Pulex ◽

Steppe Zone ◽

Water Bodies ◽

Large Branchiopods ◽

Community Types ◽

High Diversity

Pleistocene water bodies have been studied using the paleolimnological approach, which traces environmental changes using particular subfossils as ecological proxies, rather than analysis of the paleocommunities themselves. Within a given taphocoenosis, the presence and quantity of animals are related to environmental conditions rather than to community types where relationships between taxa are stabilized during their long-term co-occurrence and are (at least partially) more important than the particular environmental conditions at the time of deposition, which may have experienced significant seasonal and inter-seasonal variations. Here, we analyze Branchiopoda (Crustacea) of two paleolocalities in the Transbaikalian Region of Russia: Urtuy (MIS3) and Nozhiy (older than 1.5 million years). Cladocerans Daphnia (Ctenodaphnia) magna, D. (C.) similis, D. (Daphnia) pulex, Ceriodaphnia pulchella-reticulata, C. laticaudata, Simocephalus sp., Moina cf. brachiata, M. macropopa clade, Chydorus cf. sphaericus, Capmtocercus sp. and anostracans Branchinecta cf. paludosa, and Streptocephalus (Streptocephalus) sp. are found in two localities. With the exception of the last taxon, which now occurs in the southern Holarctic, all other taxa inhabit the Transbaikalian Region. Within Eurasia, the steppe zone has the greatest diversity of large branchiopods and a high diversity of some cladocerans, such as subgenus Daphnia (Ctenodaphnia) and Moina sp. Here we demonstrated that the branchiopod community in shallow steppe water bodies has been unchanged since at least the Pleistocene, demonstrating long-term morphological and ecological stasis.

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Monitoring the Spatial and Temporal Variations in The Water Surface and Floating Algal Bloom Areas in Dongting Lake Using a Long-Term MODIS Image Time Series

Remote Sensing ◽

10.3390/rs12213622 ◽

2020 ◽

Vol 12 (21) ◽

pp. 3622

Author(s):

Mengmeng Cao ◽

Kebiao Mao ◽

Xinyi Shen ◽

Tongren Xu ◽

Yibo Yan ◽

...

Keyword(s):

Water Quality ◽

Human Activities ◽

Water Surface ◽

Algal Bloom ◽

Environmental Changes ◽

Climatic Factors ◽

Dongting Lake ◽

Dynamic Learning ◽

Traditional Methods

Significant water quality changes have been observed in the Dongting Lake region due to environmental changes and the strong influence of human activities. To protect and manage Dongting Lake, the long-term dynamics of the water surface and algal bloom areas were systematically analyzed and quantified for the first time based on 17 years of Moderate Resolution Imaging Spectroradiometer (MODIS) observations. The traditional methods (index-based threshold algorithms) were optimized by a dynamic learning neural network (DL-NN) to extract and identify the water surface area and algal bloom area while reducing the extraction complexity and improving the extraction accuracy. The extraction accuracy exceeded 94.5% for the water and algal bloom areas, and the analysis showed decreases in the algal bloom and water surface areas from 2001–2017. Additionally, the variations in the water surface and algal bloom areas are greatly affected by human activities and climatic factors. The results of these analyses can help us better monitor human contamination in Dongting Lake and take measures to control the water quality during certain periods, which is crucial for future management. Moreover, the traditional methods optimized by the DL-NN used in this study can be extended to other inland lakes to assess and monitor long-term temporal and spatial variations in algal bloom areas and can also be used to acquire baseline information for future assessments of the water quality of lakes.

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The Role of Chloroplast Membrane Lipid Metabolism in Plant Environmental Responses

Cells ◽

10.3390/cells10030706 ◽

2021 ◽

Vol 10 (3) ◽

pp. 706

Author(s):

Ron Cook ◽

Josselin Lupette ◽

Christoph Benning

Keyword(s):

Environmental Conditions ◽

Environmental Changes ◽

Photosynthetic Apparatus ◽

Life Forms ◽

Membrane Lipid ◽

Chloroplast Membrane ◽

Class Composition ◽

Environmental Responses

Plants are nonmotile life forms that are constantly exposed to changing environmental conditions during the course of their life cycle. Fluctuations in environmental conditions can be drastic during both day–night and seasonal cycles, as well as in the long term as the climate changes. Plants are naturally adapted to face these environmental challenges, and it has become increasingly apparent that membranes and their lipid composition are an important component of this adaptive response. Plants can remodel their membranes to change the abundance of different lipid classes, and they can release fatty acids that give rise to signaling compounds in response to environmental cues. Chloroplasts harbor the photosynthetic apparatus of plants embedded into one of the most extensive membrane systems found in nature. In part one of this review, we focus on changes in chloroplast membrane lipid class composition in response to environmental changes, and in part two, we will detail chloroplast lipid-derived signals.

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DNA from lake sediments reveals the long-term dynamics and diversity of <i>Synechococcus</i> assemblages

Biogeosciences ◽

10.5194/bg-10-3817-2013 ◽

2013 ◽

Vol 10 (6) ◽

pp. 3817-3838 ◽

Cited By ~ 24

Author(s):

I. Domaizon ◽

O. Savichtcheva ◽

D. Debroas ◽

F. Arnaud ◽

C. Villar ◽

...

Keyword(s):

16S Rrna ◽

Environmental Conditions ◽

Trophic Status ◽

Community Dynamics ◽

Environmental Changes ◽

Quantitative Polymerase Chain Reaction ◽

Additive Models ◽

Phosphorus Concentration ◽

Rrna Gene

Abstract. While picocyanobacteria (PC) are important actors in carbon and nutrient cycles in aquatic systems, factors controlling their interannual dynamics and diversity are poorly known due to the general lack of long-term monitoring surveys. This study intended to fill this gap by applying a DNA-based paleolimnological approach to sediment records from a deep subalpine lake that has experienced dramatic changes in environmental conditions during the last century (eutrophication, re-oligotrophication and large-scale climate changes). In particular, we investigated the long-term (100 yr) diversity and dynamics of Synechococcus,, PC that have presumably been affected by both the lake trophic status changes and global warming. The lake's morphological and environmental conditions provided the ideal conditions for DNA preservation in the sediment archives. Generalised additive models applied to quantitative PCR (qPCR; quantitative Polymerase Chain Reaction) results highlighted that an increase in summer temperature could have a significant positive impact on the relative abundance of Synechococcus, (fraction of Synechococcus, in total cyanobacteria). The diversity of Synechococcus, in Lake Bourget was studied by phylogenetic analyses of the 16S rRNA gene and the following internally transcribed spacer (ITS). Up to 23 different OTUs (based on 16S rRNA), which fell into various cosmopolitan or endemic clusters, were identified in samples from the past 100 yr. Moreover, the study of ITS revealed a higher diversity within the major 16S rRNA-defined OTUs. Changes in PC diversity were related to the lake's trophic status. Overall, qPCR and sequencing results showed that environmental changes (in temperature and phosphorus concentration) affected Synechococcus, community dynamics and structure, translating into changes in genotype composition. These results also helped to re-evaluate the geographical distribution of some Synechococcus, clusters. Providing such novel insights into the long-term history of an important group of primary producers, this study illustrates the promising approach that consists in coupling molecular tools and paleolimnology to reconstruct a lake's biodiversity history.

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Variational Bayesian Approach to Condition-Invariant Feature Extraction for Visual Place Recognition

Applied Sciences ◽

10.3390/app11198976 ◽

2021 ◽

Vol 11 (19) ◽

pp. 8976

Author(s):

Junghyun Oh ◽

Gyuho Eoh

Keyword(s):

Large Scale ◽

Environmental Changes ◽

Place Recognition ◽

Stochastic Variational Inference ◽

Invariant Features ◽

Variational Autoencoder ◽

Model Condition ◽

Visual Place Recognition ◽

Perceptual Changes

As mobile robots perform long-term operations in large-scale environments, coping with perceptual changes becomes an important issue recently. This paper introduces a stochastic variational inference and learning architecture that can extract condition-invariant features for visual place recognition in a changing environment. Under the assumption that a latent representation of the variational autoencoder can be divided into condition-invariant and condition-sensitive features, a new structure of the variation autoencoder is proposed and a variational lower bound is derived to train the model. After training the model, condition-invariant features are extracted from test images to calculate the similarity matrix, and the places can be recognized even in severe environmental changes. Experiments were conducted to verify the proposed method, and the experimental results showed that our assumption was reasonable and effective in recognizing places in changing environments.

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Design Methods for the Development of Wastewater Land Disposal Systems

Water Science & Technology ◽

10.2166/wst.1993.0020 ◽

1993 ◽

Vol 27 (1) ◽

pp. 77-86 ◽

Cited By ~ 4

Author(s):

K. Thoma ◽

P. A. Baker ◽

E. B. Allender

Keyword(s):

Water Quality ◽

Large Scale ◽

Water Quality Management ◽

Water Quality Assessment ◽

System Specification ◽

Wastewater Disposal ◽

North West ◽

Environmental Monitoring System ◽

Land Disposal

Recent changes in legislation governing water quality management of receiving water bodies have led to a reappraisal of wastewater land disposal techniques. However, more stringent regulations have also necessitated the development of a multi-disciplinary planning approach, to ensure that land based wastewater disposal is functionally and environmentally sustainable in the long-term. Of principal concern are the long term impact of nutrients, salt and other potential contaminants on the soils of the receiving site and on downstream water quality. Assessment of hydrological, soil physical and geological characteristics, together with civil construction and service considerations, assist in the determination of receiving-site selection, application area and balance storage volume, irrigation method, environmental monitoring system specification etc. Analysis and interpretation of wastewater and soil chemical characteristics determines the pre-application water treatment required, and aliows long-term monitoring of the effect of wastewater disposal on the receiving-site soils. Two case-studies are presented. One describes the planning and design of a recently commissioned land-disposal system using industrial wastewater from a chemical process plant to irrigate a Eucalypt plantation in western metropolitan Melbourne. The other reports on the on-going assessment and planning of a large-scale land-disposal system proposed to accommodate the treated sewage effluent from a large north-west Victorian regional city.

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Effects of anthropogenic disturbance on 13C and 15N of aquatic plants from a semiarid wetland

10.32942/osf.io/f9cwh ◽

2019 ◽

Author(s):

Lilia Serrano-Grijalva ◽

Raul Ochoa-Hueso ◽

Raquel Sánchez-Andrés ◽

Santos Cirujano ◽

Salvador Sánchez-Carrillo

Keyword(s):

Water Quality ◽

Aquatic Plants ◽

Vascular Plants ◽

Environmental Changes ◽

Anthropogenic Impacts ◽

Vascular Plant ◽

Regional Scale ◽

Nitrogen And Phosphorus ◽

Isotopic Signatures ◽

La Mancha

Wetlands provide a great variety of environmental services to society, but they are currently globally threatened by human activities. We evaluated the effects of anthropogenic disturbances on the ecological quality of semiarid wetlands from central Spain (La Mancha Húmeda) through the natural abundance of isotopes (13C and 15N) of aquatic plants. We measured water quality and also compiled historical information about land-use and socioeconomic characteristics at local (100 m around the lagoon) and regional (sub-basin) scales. We then related this information to isotopic signatures of three types of aquatic plants: (i) charophytes, (ii) marginal aquatic macrophytes and (iii) vascular plants. Aquatic plants exposed to high levels of nitrogen showed very low δ13C values, consistent with negative physiological effects. Vascular aquatic plants were the group that best reflected the effects of nutrient enrichment in wetlands and lagoons through significant correlations between their δ15N values and total nitrogen and phosphorus concentrations in water. Demographic factors did not exert a clear influence on aquatic plant isotopic signatures, although we observed inverse correlations between the coverage of natural vegetation at regional scale and δ13C of marginal plants and δ15N of vascular plants. Furthermore, the isotopic signatures of Phragmites australis, present in 96% of the studied la-goons, were not significantly correlated with any of the environmental quality variables evaluated. Although δ13C signatures of Typha dominguensis and Cladium mariscus increased significantly due to changes in water quality, their narrow isotopic variability at the regional scale limits their use as a bioindicators of environmental changes in this wetland system. Finally, we propose the use of δ15N measured in the vascular plant Salicornia sp. as the most suitable bio-indicator of anthropogenic impacts in La Mancha Húmeda region, a highly emblematic system of semiarid Mediterranean wetlands that is unique in the Mediterranean region of Europe.

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Spatial and Long-Term Temporal Changes in Water Quality Dynamics of the Tonle Sap Ecosystem

Water ◽

10.3390/w13152059 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2059

Author(s):

Savoeurn Soum ◽

Peng Bun Ngor ◽

Thomas E. Dilts ◽

Sapana Lohani ◽

Suzanne Kelson ◽

...

Keyword(s):

Water Quality ◽

Land Use ◽

Water Level ◽

Inorganic Nitrogen ◽

Flood Pulse ◽

Nutrient Ratios ◽

Nitrogen And Phosphorus ◽

Watershed Land Use ◽

Tonle Sap

Tonle Sap lake-river floodplain ecosystem (TSE) is one of the world’s most productive freshwater systems. Changes in hydrology, climate, population density, and land use influence water quality in this system. We investigated long term water quality dynamics (22 years) in space and time and identified potential changes in nutrient limitation based on nutrient ratios of inorganic nitrogen and phosphorus. Water quality was assessed at five sites highlighting the dynamics in wet and dry seasons. Predictors of water quality included watershed land use, climate, population, and water level. Most water quality parameters varied across TSE, except pH and nitrate that remained constant at all sites. In the last decade, there is a change in the chemical nutrient ratio suggesting that nitrogen may be the primary limiting nutrient across the system. Water quality was strongly affected by development in the watershed i.e., flooded forest loss, climatic variation, population growth, and change in water level. Seasonal variations of water quality constituents were driven by precipitation and hydrology, notably the Mekong’s distinct seasonal flood pulse.

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