Michael N Styllas | University of Savoie (original) (raw)

Papers by Michael N Styllas

Research paper thumbnail of A novel rainwater circular solution as a distributed intervention to increase the resilience of water scarce decentralized communities: A Real World Demonstration in the Mykonos Mediterranean Island

Zenodo (CERN European Organization for Nuclear Research), Jun 8, 2023

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Research paper thumbnail of Table S5 from The dark side of the moon: first insights into the microbiome structure and function of one of the last glacier-fed streams in Africa

Figshare, 2023

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Research paper thumbnail of Table S3 from The dark side of the moon: first insights into the microbiome structure and function of one of the last glacier-fed streams in Africa

Figshare, 2023

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Research paper thumbnail of Earthquakes, Tsunamis and HarboursA Geoarchaeological GPR-Based Approach for Depicting the Spatial Characteristics of Human Structures and Natural Hazards in Ancient Falasarna Harbour

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Research paper thumbnail of A simple approach to define Holocene sequence stratigraphy using borehole and cone penetration test data

Sedimentology, Dec 11, 2013

Cone penetration testing has been widely used since the 1950s for determining the subsurface geot... more Cone penetration testing has been widely used since the 1950s for determining the subsurface geotechnical conditions of unconsolidated sediments. This paper highlights the potential value of cone penetration testing as an aid to define the stratigraphic structure of Holocene sedimentary deposits. By calibrating cone penetration test logs with adjacent borehole logs and by utilizing all the available information produced during geotechnical surveying, stratigraphic models that accurately describe the vertical and lateral boundaries, as well as the stacking pattern, of Late Quaternary systems can be constructed. The widespread application and technical simplicity of cone penetration testing, combined with simple data interpretation via correlation with adjacent borehole logs, yield a useful and inexpensive tool for sedimentological investigations. This methodology is illustrated using data from 36 cone penetration tests and 11 boreholes on the Holocene deltaic plain of the Aliakmon River, Greece. Sedimentological and stratigraphic information from core log correlations, the spatial distribution of cone penetration test parameters, sediment grain size and per cent concentration of organic matter are utilized. The results suggest, that in sequence stratigraphic terms, the delta is divided into a lowstand systems tract composed by fluvial gravels and sands (U0) of Late Pleistocene age, as well as from red oxidized clays, and a transgressive systems tract represented by fluvial channel sands (U1), overlain by a thin transgressive sand sheet of coastal origin (U2), characterized by fining upward trends. The highstand systems tract is constituted by a variety of stratigraphic units (U3 to U7) and depositional environments, characterized by coarsening upward sequences, representing both aggradational and progradational facies, and dominated by the presence of three prograding wedges. Detailed definition of the thickness, vertical boundaries and stacking pattern of the resolved stratigraphic units, presented as a two‐dimensional stratigraphic model, demonstrates the applicability of the proposed method.

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Research paper thumbnail of Sediment accumulation and human impacts in Tillamook Bay, Oregon

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Research paper thumbnail of Natural Processes Versus Human Impacts During the Last Century: A Case Study of the Aliakmon River Delta

The handbook of environmental chemistry, 2017

The Aliakmon River flows down from the northwestern mountains of Greece and is one of the largest... more The Aliakmon River flows down from the northwestern mountains of Greece and is one of the largest fluvial systems in the Greek territory. Basin climate and geology favour the high rates of sediment production and transport and, consequently, the formation of an extensive (9.2% of basin area) bird-foot Holocene delta. Three phases (A, B and C) of human impacts over the past 90 years have caused pronounced changes on the natural evolution of the delta. During Phases A and B, a 50% increase of deltaic sedimentation rates in relation to Holocene pre-anthropogenic rates and an enrichment of deltaic deposits with heavy minerals occurred. Phase C, characterised by damming, increasing agricultural and industrial activities and population growth, resulted in 90% decrease in sedimentation rates compared to Phase B, a regulated hydrological regime with high electrical conductivity and nutrient concentrations of surface water, enhanced erosion of river channel and deltaic deposits and degradation of habitats along the lower Aliakmon River delta. Future climate scenarios and increasing environmental pressures are not compatible with current water use strategy and, given the vulnerability of the system (reservoirs and delta) to projected climate trends, stress for a new strategic natural resource management plan.

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Research paper thumbnail of Tracing a Late Holocene glacial climatic signal from source to sink under intensifying human erosion of Eastern Mediterranean landscapes

Mediterranean geoscience reviews, Apr 1, 2020

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Research paper thumbnail of Η εξέλιξη των δελταϊκών ιζηματογενών αποθέσεων του ποταμού Αλιάκμονα στο Θερμαϊκό κόλπο από φυσικούς και ανθρωπογενείς παράγοντες κατά το ολόκαινο

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Research paper thumbnail of Global emergent responses of stream microbial metabolism to glacier shrinkage

Nature geoscience, Mar 1, 2024

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Research paper thumbnail of Variations of Sea Level and Sea Surface Temperature in the Caldera of Santorini Island , Southern Aegean Sea

Bulletin of the Geological Society of Greece, Jul 23, 2018

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Research paper thumbnail of Homogeneous selection promotes microdiversity in the glacier-fed stream microbiome

Microdiversity, the organization of microorganisms into groups with closely related but ecologica... more Microdiversity, the organization of microorganisms into groups with closely related but ecologically different sub-types, is widespread and represents an important linchpin between microbial ecology and evolution. However, the drivers of microdiversification remain largely unknown. Here we show that selection promotes microdiversity in the microbiome associated with sediments in glacier-fed streams (GFS). Applying a novel phylogenetic framework, we identify several clades that are under homogeneous selection and that contain genera with higher levels of microdiversity than the rest of the genera. Overall these clades constituted ∼44% and ∼64% of community α-diversity and abundance, and both percentages increased further in GFS that were largely devoid of primary producers. Our findings show that strong homogeneous selection drives the microdiversification of specialized microbial groups putatively underlying their success in the extreme environment of GFS. This microdiversity could ...

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Research paper thumbnail of Genomic and metabolic adaptations of biofilms to ecological windows of opportunity in glacier-fed streams

Nature Communications, Apr 20, 2022

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Research paper thumbnail of A Tropical Cocktail of Organic Matter Sources: Variability in Supraglacial and Glacier Outflow Dissolved Organic Matter Composition and Age Across the Ecuadorian Andes

Journal Of Geophysical Research: Biogeosciences, May 1, 2023

The biogeochemistry of rapidly retreating Andean glaciers is poorly understood, and Ecuadorian gl... more The biogeochemistry of rapidly retreating Andean glaciers is poorly understood, and Ecuadorian glacier dissolved organic matter (DOM) composition is unknown. This study examined molecular composition and carbon isotopes of DOM from supraglacial and outflow streams (n = 5 and 14, respectively) across five ice capped volcanoes in Ecuador. Compositional metrics were paired with streamwater isotope analyses (δ18O) to assess if outflow DOM composition was associated with regional precipitation gradients and thus an atmospheric origin of glacier DOM. Ecuadorian glacier outflows exported ancient, biolabile dissolved organic carbon (DOC), and DOM contained a high relative abundance (RA) of aliphatic and peptide‐like compounds (≥27%RA). Outflows were consistently more depleted in Δ14C‐DOC (i.e., older) compared to supraglacial streams (mean −195.2 and −61.3‰ respectively), perhaps due to integration of spatially heterogenous and variably aged DOM pools across the supraglacial environment, or incorporation of aged subglacial OM as runoff was routed to the outflow. Across Ecuador, Δ14C‐DOC enrichment was associated with decreased aromaticity of DOM, due to increased contributions of organic matter (OM) from microbial processes or atmospheric deposition of recently fixed and subsequently degraded OM (e.g., biomass burning byproducts). There was a regional gradient between glacier outflow DOM composition and streamwater δ18O, suggesting covariation between regional precipitation gradients and the DOM exported from glacier outflows. Ultimately, this highlights that atmospheric deposition may exert a control on glacier outflow DOM composition, suggesting regional air circulation patterns and precipitation sources in part determine the origins and quality of OM exported from glacier environments.

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Research paper thumbnail of Global biogeography of the glacier-fed stream microbiome

<p> </p><p>Glacier-fed streams (GFSs) serv... more <p> </p><p>Glacier-fed streams (GFSs) serve as headwaters to many of the world’s largest river networks. Although being characterized by extreme environmental conditions (i.e., low water temperatures, oligotrophy) GFSs host an underappreciated microbial biodiversity, especially within benthic biofilms which play pivotal roles in downstream biogeochemical cycles. Yet, we still lack a global overview of the GFS biofilm microbiome. In addition, little is known on how environmental conditions shape bacterial diversity, and how these relationships drive global distribution patterns. This is particularly important as mountain glaciers are currently vanishing at a rapid pace due to global warming. Here, we used 16S rRNA gene sequencing data from the Vanishing Glaciers project to conduct a first comprehensive analysis of the benthic microbiome from 148 GFSs across 11 mountain ranges. Our analyses revealed marked biogeographic patterns in the GFS microbiome, mainly driven by the replacement of phylogenetically closely related taxa. Strikingly, the GFS microbiome was characterized by pronounced level of endemism, with >58% of the Amplicon Sequence Variants (ASVs) being specific to one mountain range. Consistent with the marked dissimilarities across mountain ranges, we found a very small taxonomic core including only 200 ASVs, yet accounting for >25% of the total relative abundance of the ASVs. Finally, we found that spatial effects such as dispersal limitation, isolation and spatially autocorrelated environmental conditions overwhelmed the effect of the environment by itself on benthic biofilm beta diversity. Our findings shed light on the previously unresolved global diversity and biogeography of the GFS microbiome now at risk across the world’s major mountain ranges because of rapidly shrinking glaciers.</p>

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Research paper thumbnail of Glacier-Fed Stream Biofilms Harbor Diverse Resistomes and Biosynthetic Gene Clusters

Microbiology spectrum, Feb 14, 2023

Antimicrobial resistance is an omnipresent phenomenon in the anthropogenically influenced ecosyst... more Antimicrobial resistance is an omnipresent phenomenon in the anthropogenically influenced ecosystems. However, its role in shaping microbial community dynamics in pristine environments is relatively unknown.

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Research paper thumbnail of Towards a global biogeography of the glacier-fed stream benthic microbiome

Research Square (Research Square), Apr 3, 2023

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Research paper thumbnail of Benthic Biofilms in Glacier-Fed Streams from Scandinavia to the Himalayas Host Distinct Bacterial Communities Compared with the Streamwater

Applied and Environmental Microbiology, Jun 28, 2022

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Research paper thumbnail of Glacier shrinkage will accelerate downstream decomposition of organic matter and alters microbiome structure and function

Global Change Biology, Apr 1, 2022

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Research paper thumbnail of The dark side of the moon: first insights into the microbiome structure and function of one of the last glacier-fed streams in Africa

Royal Society Open Science

The glaciers on Africa's ‘Mountains of the Moon' (Rwenzori National Park, Uganda) are pre... more The glaciers on Africa's ‘Mountains of the Moon' (Rwenzori National Park, Uganda) are predicted to disappear within the next decades owing to climate change. Consequently, the glacier-fed streams (GFSs) that drain them will vanish, along with their resident microbial communities. Despite the relevance of microbial communities for performing ecosystem processes in equatorial GFSs, their ecology remains understudied. Here, we show that the benthic microbiome from the Mt. Stanley GFS is distinct at several levels from other GFSs. Specifically, several novel taxa were present, and usually common groups such as Chrysophytes and Polaromonas exhibited lower relative abundances compared to higher-latitude GFSs, while cyanobacteria and diatoms were more abundant. The rich primary producer community in this GFS likely results from the greater environmental stability of the Afrotropics, and accordingly, heterotrophic processes dominated in the bacterial community. Metagenomics revealed...

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Research paper thumbnail of A novel rainwater circular solution as a distributed intervention to increase the resilience of water scarce decentralized communities: A Real World Demonstration in the Mykonos Mediterranean Island

Zenodo (CERN European Organization for Nuclear Research), Jun 8, 2023

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Research paper thumbnail of Table S5 from The dark side of the moon: first insights into the microbiome structure and function of one of the last glacier-fed streams in Africa

Figshare, 2023

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Research paper thumbnail of Table S3 from The dark side of the moon: first insights into the microbiome structure and function of one of the last glacier-fed streams in Africa

Figshare, 2023

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Research paper thumbnail of Earthquakes, Tsunamis and HarboursA Geoarchaeological GPR-Based Approach for Depicting the Spatial Characteristics of Human Structures and Natural Hazards in Ancient Falasarna Harbour

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Research paper thumbnail of A simple approach to define Holocene sequence stratigraphy using borehole and cone penetration test data

Sedimentology, Dec 11, 2013

Cone penetration testing has been widely used since the 1950s for determining the subsurface geot... more Cone penetration testing has been widely used since the 1950s for determining the subsurface geotechnical conditions of unconsolidated sediments. This paper highlights the potential value of cone penetration testing as an aid to define the stratigraphic structure of Holocene sedimentary deposits. By calibrating cone penetration test logs with adjacent borehole logs and by utilizing all the available information produced during geotechnical surveying, stratigraphic models that accurately describe the vertical and lateral boundaries, as well as the stacking pattern, of Late Quaternary systems can be constructed. The widespread application and technical simplicity of cone penetration testing, combined with simple data interpretation via correlation with adjacent borehole logs, yield a useful and inexpensive tool for sedimentological investigations. This methodology is illustrated using data from 36 cone penetration tests and 11 boreholes on the Holocene deltaic plain of the Aliakmon River, Greece. Sedimentological and stratigraphic information from core log correlations, the spatial distribution of cone penetration test parameters, sediment grain size and per cent concentration of organic matter are utilized. The results suggest, that in sequence stratigraphic terms, the delta is divided into a lowstand systems tract composed by fluvial gravels and sands (U0) of Late Pleistocene age, as well as from red oxidized clays, and a transgressive systems tract represented by fluvial channel sands (U1), overlain by a thin transgressive sand sheet of coastal origin (U2), characterized by fining upward trends. The highstand systems tract is constituted by a variety of stratigraphic units (U3 to U7) and depositional environments, characterized by coarsening upward sequences, representing both aggradational and progradational facies, and dominated by the presence of three prograding wedges. Detailed definition of the thickness, vertical boundaries and stacking pattern of the resolved stratigraphic units, presented as a two‐dimensional stratigraphic model, demonstrates the applicability of the proposed method.

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Research paper thumbnail of Sediment accumulation and human impacts in Tillamook Bay, Oregon

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Research paper thumbnail of Natural Processes Versus Human Impacts During the Last Century: A Case Study of the Aliakmon River Delta

The handbook of environmental chemistry, 2017

The Aliakmon River flows down from the northwestern mountains of Greece and is one of the largest... more The Aliakmon River flows down from the northwestern mountains of Greece and is one of the largest fluvial systems in the Greek territory. Basin climate and geology favour the high rates of sediment production and transport and, consequently, the formation of an extensive (9.2% of basin area) bird-foot Holocene delta. Three phases (A, B and C) of human impacts over the past 90 years have caused pronounced changes on the natural evolution of the delta. During Phases A and B, a 50% increase of deltaic sedimentation rates in relation to Holocene pre-anthropogenic rates and an enrichment of deltaic deposits with heavy minerals occurred. Phase C, characterised by damming, increasing agricultural and industrial activities and population growth, resulted in 90% decrease in sedimentation rates compared to Phase B, a regulated hydrological regime with high electrical conductivity and nutrient concentrations of surface water, enhanced erosion of river channel and deltaic deposits and degradation of habitats along the lower Aliakmon River delta. Future climate scenarios and increasing environmental pressures are not compatible with current water use strategy and, given the vulnerability of the system (reservoirs and delta) to projected climate trends, stress for a new strategic natural resource management plan.

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Research paper thumbnail of Tracing a Late Holocene glacial climatic signal from source to sink under intensifying human erosion of Eastern Mediterranean landscapes

Mediterranean geoscience reviews, Apr 1, 2020

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Research paper thumbnail of Η εξέλιξη των δελταϊκών ιζηματογενών αποθέσεων του ποταμού Αλιάκμονα στο Θερμαϊκό κόλπο από φυσικούς και ανθρωπογενείς παράγοντες κατά το ολόκαινο

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Research paper thumbnail of Global emergent responses of stream microbial metabolism to glacier shrinkage

Nature geoscience, Mar 1, 2024

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Research paper thumbnail of Variations of Sea Level and Sea Surface Temperature in the Caldera of Santorini Island , Southern Aegean Sea

Bulletin of the Geological Society of Greece, Jul 23, 2018

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Homogeneous selection promotes microdiversity in the glacier-fed stream microbiome

Microdiversity, the organization of microorganisms into groups with closely related but ecologica... more Microdiversity, the organization of microorganisms into groups with closely related but ecologically different sub-types, is widespread and represents an important linchpin between microbial ecology and evolution. However, the drivers of microdiversification remain largely unknown. Here we show that selection promotes microdiversity in the microbiome associated with sediments in glacier-fed streams (GFS). Applying a novel phylogenetic framework, we identify several clades that are under homogeneous selection and that contain genera with higher levels of microdiversity than the rest of the genera. Overall these clades constituted ∼44% and ∼64% of community α-diversity and abundance, and both percentages increased further in GFS that were largely devoid of primary producers. Our findings show that strong homogeneous selection drives the microdiversification of specialized microbial groups putatively underlying their success in the extreme environment of GFS. This microdiversity could ...

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Research paper thumbnail of Genomic and metabolic adaptations of biofilms to ecological windows of opportunity in glacier-fed streams

Nature Communications, Apr 20, 2022

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Research paper thumbnail of A Tropical Cocktail of Organic Matter Sources: Variability in Supraglacial and Glacier Outflow Dissolved Organic Matter Composition and Age Across the Ecuadorian Andes

Journal Of Geophysical Research: Biogeosciences, May 1, 2023

The biogeochemistry of rapidly retreating Andean glaciers is poorly understood, and Ecuadorian gl... more The biogeochemistry of rapidly retreating Andean glaciers is poorly understood, and Ecuadorian glacier dissolved organic matter (DOM) composition is unknown. This study examined molecular composition and carbon isotopes of DOM from supraglacial and outflow streams (n = 5 and 14, respectively) across five ice capped volcanoes in Ecuador. Compositional metrics were paired with streamwater isotope analyses (δ18O) to assess if outflow DOM composition was associated with regional precipitation gradients and thus an atmospheric origin of glacier DOM. Ecuadorian glacier outflows exported ancient, biolabile dissolved organic carbon (DOC), and DOM contained a high relative abundance (RA) of aliphatic and peptide‐like compounds (≥27%RA). Outflows were consistently more depleted in Δ14C‐DOC (i.e., older) compared to supraglacial streams (mean −195.2 and −61.3‰ respectively), perhaps due to integration of spatially heterogenous and variably aged DOM pools across the supraglacial environment, or incorporation of aged subglacial OM as runoff was routed to the outflow. Across Ecuador, Δ14C‐DOC enrichment was associated with decreased aromaticity of DOM, due to increased contributions of organic matter (OM) from microbial processes or atmospheric deposition of recently fixed and subsequently degraded OM (e.g., biomass burning byproducts). There was a regional gradient between glacier outflow DOM composition and streamwater δ18O, suggesting covariation between regional precipitation gradients and the DOM exported from glacier outflows. Ultimately, this highlights that atmospheric deposition may exert a control on glacier outflow DOM composition, suggesting regional air circulation patterns and precipitation sources in part determine the origins and quality of OM exported from glacier environments.

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Research paper thumbnail of Global biogeography of the glacier-fed stream microbiome

<p> </p><p>Glacier-fed streams (GFSs) serv... more <p> </p><p>Glacier-fed streams (GFSs) serve as headwaters to many of the world’s largest river networks. Although being characterized by extreme environmental conditions (i.e., low water temperatures, oligotrophy) GFSs host an underappreciated microbial biodiversity, especially within benthic biofilms which play pivotal roles in downstream biogeochemical cycles. Yet, we still lack a global overview of the GFS biofilm microbiome. In addition, little is known on how environmental conditions shape bacterial diversity, and how these relationships drive global distribution patterns. This is particularly important as mountain glaciers are currently vanishing at a rapid pace due to global warming. Here, we used 16S rRNA gene sequencing data from the Vanishing Glaciers project to conduct a first comprehensive analysis of the benthic microbiome from 148 GFSs across 11 mountain ranges. Our analyses revealed marked biogeographic patterns in the GFS microbiome, mainly driven by the replacement of phylogenetically closely related taxa. Strikingly, the GFS microbiome was characterized by pronounced level of endemism, with >58% of the Amplicon Sequence Variants (ASVs) being specific to one mountain range. Consistent with the marked dissimilarities across mountain ranges, we found a very small taxonomic core including only 200 ASVs, yet accounting for >25% of the total relative abundance of the ASVs. Finally, we found that spatial effects such as dispersal limitation, isolation and spatially autocorrelated environmental conditions overwhelmed the effect of the environment by itself on benthic biofilm beta diversity. Our findings shed light on the previously unresolved global diversity and biogeography of the GFS microbiome now at risk across the world’s major mountain ranges because of rapidly shrinking glaciers.</p>

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Research paper thumbnail of Glacier-Fed Stream Biofilms Harbor Diverse Resistomes and Biosynthetic Gene Clusters

Microbiology spectrum, Feb 14, 2023

Antimicrobial resistance is an omnipresent phenomenon in the anthropogenically influenced ecosyst... more Antimicrobial resistance is an omnipresent phenomenon in the anthropogenically influenced ecosystems. However, its role in shaping microbial community dynamics in pristine environments is relatively unknown.

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Research paper thumbnail of Towards a global biogeography of the glacier-fed stream benthic microbiome

Research Square (Research Square), Apr 3, 2023

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Research paper thumbnail of Benthic Biofilms in Glacier-Fed Streams from Scandinavia to the Himalayas Host Distinct Bacterial Communities Compared with the Streamwater

Applied and Environmental Microbiology, Jun 28, 2022

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Research paper thumbnail of Glacier shrinkage will accelerate downstream decomposition of organic matter and alters microbiome structure and function

Global Change Biology, Apr 1, 2022

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Research paper thumbnail of The dark side of the moon: first insights into the microbiome structure and function of one of the last glacier-fed streams in Africa

Royal Society Open Science

The glaciers on Africa's ‘Mountains of the Moon' (Rwenzori National Park, Uganda) are pre... more The glaciers on Africa's ‘Mountains of the Moon' (Rwenzori National Park, Uganda) are predicted to disappear within the next decades owing to climate change. Consequently, the glacier-fed streams (GFSs) that drain them will vanish, along with their resident microbial communities. Despite the relevance of microbial communities for performing ecosystem processes in equatorial GFSs, their ecology remains understudied. Here, we show that the benthic microbiome from the Mt. Stanley GFS is distinct at several levels from other GFSs. Specifically, several novel taxa were present, and usually common groups such as Chrysophytes and Polaromonas exhibited lower relative abundances compared to higher-latitude GFSs, while cyanobacteria and diatoms were more abundant. The rich primary producer community in this GFS likely results from the greater environmental stability of the Afrotropics, and accordingly, heterotrophic processes dominated in the bacterial community. Metagenomics revealed...

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Research paper thumbnail of Chapter Title Natural Processes Versus Human Impacts During the Last Century: A Case Study of the Aliakmon River Delta

The Aliakmon River flows down from the northwestern mountains of Greece and is one of the largest... more The Aliakmon River flows down from the northwestern mountains of Greece and is one of the largest fluvial systems in the Greek territory. Basin climate and geology favour the high rates of sediment production and transport and, consequently, the formation of an extensive (9.2% of basin area) bird-foot Holocene delta. Three phases (A, B and C) of human impacts over the past 90 years have caused pronounced changes on the natural evolution of the delta. During Phases A and B, a 50% increase of deltaic sedimentation rates in relation to Holocene pre-anthropogenic rates and an enrichment of deltaic deposits with heavy minerals occurred. Phase C, characterised by damming, increasing agricultural and industrial activities and population growth, resulted in 90% decrease in sedimentation rates compared to Phase B, a regulated hydrological regime with high electrical conductivity and nutrient concentrations of surface water, enhanced erosion of river channel and deltaic deposits and degradation of habitats along the lower Aliakmon River delta. Future climate scenarios and increasing environmental pressures are not compatible with current water use strategy and, given the vulnerability of the system (reservoirs and delta) to projected climate trends, stress for a new strategic natural resource management plan. Keywords (separated by '-')

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Research paper thumbnail of Chapter Title Natural Processes Versus Human Impacts During the Last Century: A Case Study of the Aliakmon River Delta

The Aliakmon River flows down from the northwestern mountains of Greece and is one of the largest... more The Aliakmon River flows down from the northwestern mountains of Greece and is one of the largest fluvial systems in the Greek territory. Basin climate and geology favour the high rates of sediment production and transport and, consequently, the formation of an extensive (9.2% of basin area) bird-foot Holocene delta. Three phases (A, B and C) of human impacts over the past 90 years have caused pronounced changes on the natural evolution of the delta. During Phases A and B, a 50% increase of deltaic sedimentation rates in relation to Holocene pre-anthropogenic rates and an enrichment of deltaic deposits with heavy minerals occurred. Phase C, characterised by damming, increasing agricultural and industrial activities and population growth, resulted in 90% decrease in sedimentation rates compared to Phase B, a regulated hydrological regime with high electrical conductivity and nutrient concentrations of surface water, enhanced erosion of river channel and deltaic deposits and degradation of habitats along the lower Aliakmon River delta. Future climate scenarios and increasing environmental pressures are not compatible with current water use strategy and, given the vulnerability of the system (reservoirs and delta) to projected climate trends, stress for a new strategic natural resource management plan. Keywords (separated by '-')

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Research paper thumbnail of MEDCLIVAR 2018 - Abstract Styllas et al.

THE LATEGLACIAL AND HOLOCENE GLACIAL HISTORY OF THE NORTHEAST MEDITERRANEAN MOUNTAINS INFERRED FROM IN-SITU PRODUCED COSMIC RAY EXPOSURE DATINGS OF PALEO-GLACIERS DEPOSITS. IMPLICATIONS FOR THE RELATIVE ROLES OF EXTERNAL AND INTERNAL CLIMATE FORCING., 2018

A new glacial chronology from Mount Olympus in Greece, based on 20 36Cl in situ produced cosmic r... more A new glacial chronology from Mount Olympus in Greece, based on 20 36Cl in situ produced
cosmic ray exposure (CRE) datings is used to complement existing CRE chronologies from the
northeast Mediterranean (NEM) region. The new 36Cl ages of the glacial landforms range from
15.6 ± 2.0 to 0.6 ± 0.08 ka, spanning the Lateglacial and the Holocene. Based on the
Probability Density Functions of all existing CRE ages, the Lateglacial is partitioned in three
distinct phases (LG1-3): an initial phase of glacial moraine stabilization at 15.06 ± 0.53 ka with
subsequent deglaciation starting at ~14 ka (LG1) evident in Mount Pelister, Sâra Range, Galicica
Mountains, Mount Olympus, Rila Mountains and Mount Uludag. LG1 was followed by a transition
to conditions marginal for glaciation at 13.3 ± 1.21 ka (LG2), recorded only on Mount Olympus
that was characterized by enhanced aeolian activity (westerlies) and large amounts of
windblown snow. Glacial conditions characterized by low temperatures and low precipitation,
returned to the NEM mountains at 11.9 ± 0.56 ka (LG3), but they were not widespread as they
are found on Sâra Range, Mount Uludag, Mount Chelmos and Mount Olympus. NEM glacial
phases LG1-3 occurred during a period of increasing obliquity and peak eccentricity and exhibit
an out-of-phase behaviour with the local solar insolation record from Duhlata Cave. Phases LG1
and LG3 occurred during solar insolation maxima and also coincided with a shutdown of the
Atlantic Meridional Overturning Circulation (AMOC), whereas LG2 occurred during insolation
minima with concurrent establishment of the AMOC. The Holocene glacial phases (HOL1-3) are
recorded only in Mount Olympus. An early Holocene glacier stillstand (HOL1) at 9.6 ± 1.1 ka,
occurred during peak obliquity, increasing solar insolation close to the record's peak values and
is locally associated with a lagged recovery of north Aegean Sea Surface Temperatures (SST's).
No glacier activity is observed during the mid-Holocene (~9.0 – 3.0 ka). The Late Holocene
glacier expansions, include a moraine stabilization phase (HOL2) at 2.5 ± 0.3 ka, a period that
coincides with solar insolation minima (Homeric Low), combined with a negative North Atlantic
Oscillation (NAO) phase, which resulted in locally wet conditions, as recorded in Skala Marion
Cave speleothem record. The last phase of glacial activity (HOL3) corresponds to the early part
of the Little Ice Age (0.6 ± 0.08 ka). A link between the Holocene glaciations with the north
Atlantic climatic regime is evident, as HOL1, 2 and 3 glacial phases, broadly correspond to Bond
6, 2 and 0 events. The new Lateglacial and Holocene glacial chronology emphasizes the relative
controls of internal and external forcing along the headwaters of the major Northeast
Mediterranean fluvial systems, is in pace with numerous regional and local terrestrial and marine
proxies and establishes the basis for a source-to-sink approach to paleoenvironmental
reconstrunctions.

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Research paper thumbnail of Mediterranean perennial snowfields and ice bodies on the brink of extinction. The story of Mount Olympus, Greece

In the broader context of rapid environmental and climatic changes in the Mediterranean region, a... more In the broader context of rapid environmental and climatic changes in the Mediterranean region, a new 36 Cl nuclide glacial chronology from two small (0.5km 2) cirques on Mount Olympus in Greece (Throne of Zeus and Megala Kazania) is presented, spanning the Lateglacial and the Holocene. The new chronology contemplates few existing Surface Exposure Datings (SED) from cirques in the southern Balkan Mountains. Cirque glacier behaviour and solar radiation are out-of-phase during the Lateglacial and in-phase during the Holocene. The most recent glaciation episode occurred during the Little Ice Age (LIA) and has been confined only in the sheltered northwest facing cirque of Megala Kazania (MK), which is characterized by steep 500m-high headwalls and by large amounts of windblown and avalanching snow. Perennial snowfields and permanent ice bodies survived within the MK cirque during the entire 20 th century, despite the fact that the local ELA has been situated above Mount Olympus summit (2918m). Since 2010, pronounced shrinking of the snowfields has led to the exposure and melting of the basal ice, bringing them on the brink of extinction, due to reduced snowfall and increasing summer temperatures. The last ice of Mount Olympus, is preserved within vertical caves, guarding the last climatic information of the Ancient Greek Gods.

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