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Author: Magda Guadalupe Cardozo-Mino Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The anthropogenic emissions of CO2 and other climate-active gases lead to a steep increase of global temperatures. Global climate change is particularly amplified in the Arctic (e.g., Serreze et al., 2009; Serreze and Barry, 2011). Increasing temperatures and the rapid sea ice decline have shown profound effects on life in the Arctic ecosystem (Wassmann et al., 2011). Climate model predictions suggest a seasonally sea ice-free Arctic well before the first half of this century (Overland and Wang, 2013; Docquier and Koenigk, 2021). The composition, structure and function of the Arctic microbiome will be altered with distinct effects on the marine system, on primary productivity, carbon fluxes and food web structures. Changes in the composition and structure of primary producers were already observed in Fram Strait (Nöthig et al., 2015), the boundary and highly dynamic zone between the Atlantic and the Arctic Ocean. These changes were reflected in the export flux of particulate organic matter (Lalande et al., 2013), also observable in the benthic communities (Jacob, 2014). Thus, understanding how the microbial communities changed over time under different environmental conditions is a scientific task needed to assess future changes in the Arctic ecosystem. This thesis aimed to understand the composition, distribution and function of bacteria, archaea and eukaryotic communities in Fram Strait across different spatial and temporal scales and their relationship with environmental variables. The overall objective was to identify signature groups and key factors of change, to provide a baseline to the effects of climate change and sea ice retreat. It provides a comprehensive overview of the Arctic microbiome by the incorporation of seawater, sinking particles and sea ice samples to identify key microbial indicators of change and environmental drivers in these communities. Samples were obtained in the frame work of the Long-Term Ecological Research (LTER) site HAUSGARTEN and the FRontiers in Marine Monitoring (FRAM) program. 8 The results of Chapter I and Chapter II highlight the usage of methods free of compositional- bias and meta'omics approaches necessary to understand the role of microbial communities. The observations in Chapter I revealed that different water masses characterized by different physicochemical conditions harboured different active microbial communities. A late phytoplankton bloom dominated by diatoms in the surface waters of the eastern Fram Strait was identified, where members of the Bacteroidetes, Alteromonadales, Oceanospirillales and Rhodobacterales were significantly active. Abundant transcripts of transporters and fundamental cellular functions supported the degradation of organic matter. The deeper waters of Atlantic origin were marked by strong chemolithotrophic activities by members of Thaumarchaeota. In Chapter II I analysed bacterial and archaeal groups in deep-sea waters that benefitted from a phytoplankton bloom at the surface. Chapter III studied the development of microbial composition of sinking particles using a 12-year time-series study. The presence of sea ice and the passing warm anomaly were the drivers of change in these communities. In Chapter IV, microcosm experiments revealed bacterial taxa that responded to eukaryotes and substrates sourced from the sea ice during sea ice melt in seawater. Altogether, the results of this thesis provide baseline knowledge to better assess the effects of climate change on the Arctic microbiome and the consequences for ecosystem functioning and carbon cycling.
Author: Magda Guadalupe Cardozo-Mino Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The anthropogenic emissions of CO2 and other climate-active gases lead to a steep increase of global temperatures. Global climate change is particularly amplified in the Arctic (e.g., Serreze et al., 2009; Serreze and Barry, 2011). Increasing temperatures and the rapid sea ice decline have shown profound effects on life in the Arctic ecosystem (Wassmann et al., 2011). Climate model predictions suggest a seasonally sea ice-free Arctic well before the first half of this century (Overland and Wang, 2013; Docquier and Koenigk, 2021). The composition, structure and function of the Arctic microbiome will be altered with distinct effects on the marine system, on primary productivity, carbon fluxes and food web structures. Changes in the composition and structure of primary producers were already observed in Fram Strait (Nöthig et al., 2015), the boundary and highly dynamic zone between the Atlantic and the Arctic Ocean. These changes were reflected in the export flux of particulate organic matter (Lalande et al., 2013), also observable in the benthic communities (Jacob, 2014). Thus, understanding how the microbial communities changed over time under different environmental conditions is a scientific task needed to assess future changes in the Arctic ecosystem. This thesis aimed to understand the composition, distribution and function of bacteria, archaea and eukaryotic communities in Fram Strait across different spatial and temporal scales and their relationship with environmental variables. The overall objective was to identify signature groups and key factors of change, to provide a baseline to the effects of climate change and sea ice retreat. It provides a comprehensive overview of the Arctic microbiome by the incorporation of seawater, sinking particles and sea ice samples to identify key microbial indicators of change and environmental drivers in these communities. Samples were obtained in the frame work of the Long-Term Ecological Research (LTER) site HAUSGARTEN and the FRontiers in Marine Monitoring (FRAM) program. 8 The results of Chapter I and Chapter II highlight the usage of methods free of compositional- bias and meta'omics approaches necessary to understand the role of microbial communities. The observations in Chapter I revealed that different water masses characterized by different physicochemical conditions harboured different active microbial communities. A late phytoplankton bloom dominated by diatoms in the surface waters of the eastern Fram Strait was identified, where members of the Bacteroidetes, Alteromonadales, Oceanospirillales and Rhodobacterales were significantly active. Abundant transcripts of transporters and fundamental cellular functions supported the degradation of organic matter. The deeper waters of Atlantic origin were marked by strong chemolithotrophic activities by members of Thaumarchaeota. In Chapter II I analysed bacterial and archaeal groups in deep-sea waters that benefitted from a phytoplankton bloom at the surface. Chapter III studied the development of microbial composition of sinking particles using a 12-year time-series study. The presence of sea ice and the passing warm anomaly were the drivers of change in these communities. In Chapter IV, microcosm experiments revealed bacterial taxa that responded to eukaryotes and substrates sourced from the sea ice during sea ice melt in seawater. Altogether, the results of this thesis provide baseline knowledge to better assess the effects of climate change on the Arctic microbiome and the consequences for ecosystem functioning and carbon cycling.
Author: Benjamin Lundquist Saenz Publisher: Stanford University ISBN: Category : Languages : en Pages : 242
Book Description
Sea ice is an important driver of climate patterns and polar marine ecosystem dynamics. In particular, primary production by microalgae in sea ice has been postulated as a sink for anthropogenic CO2, and as a critical resource in the life cycle of Antarctic krill Euphausia superba, a keystone species. Study of the sea ice ecosystem is difficult at regional and global scales, however, because of the expense and logistical difficulties in accessing such a remote and hostile environment. Consequently, models remain valuable tools for investigations of the spatial and temporal dynamics of sea ice and associated ecology and biogeochemistry. Recent advances in model representations of sea ice have called into question the accuracy of previous studies, and allow the creation of new tools to perform mechanistic simulations of sea ice physics and biogeochemistry. To address spatial and temporal variability in Antarctic sea ice algal production, and to establish the bounds and sensitivities of the sea ice ecosystem, a new, coupled sea ice ecosystem model was developed. In the vertical dimension, the model resolves incorporated saline brine, macronutrients concentrations, spectral shortwave radiation, and the sea ice algae community at high resolution. A novel method for thermodynamics, desalination, and fluid transfer in slushy, high-brine fraction sea ice was developed to simulate regions of high algal productivity. The processes of desalination, fluid transfer, snow-ice creation, and superimposed ice formation allowed the evolution of realistic vertical profiles of sea ice salinity and algal growth. The model replicated time series observations of ice temperature, salinity, algal biomass, and estimated fluid flux from the Ice Station Weddell experiment. In the horizontal dimension, sub-grid scale parameterizations of snow and ice thickness allow more realistic simulation of the ice thickness distribution, and consequently, sea ice algal habitat. The model is forced from above by atmospheric reanalysis climatologies, and from below by climatological ocean heat flux and deep-water ocean characteristics. Areal sea ice concentration and motion are specified according to SSM/I passive microwave satellite estimates of these parameters. Sensitivity testing of different snow and ice parameterizations showed that without a sub-grid scale ice thickness distribution, mean ice and snow thickness is lower and bottom sea ice algal production is elevated. Atmospheric forcing from different reanalysis data sets cause mean and regional shifts in sea ice production and associated ecology, even when sea ice extent and motion is controlled. Snow cover represents a first-order control over ice algal production by limiting the light available to bottom ice algal communities, and changes to the regional, rather than mean, snow thickness due to the use of different ice and snow representations are responsible for large differences in the magnitude and distribution of sea ice algal production. Improved convective nutrient exchange in high-brine fraction (slush) sea ice is responsible for up to 18% of total sea ice algal production. A continuous 10-year model run using climatological years 1996-2005 produced a time series of sea ice algal primary production that varied between 15.5 and 18.0 Tg C yr-1. This study represents the first interannual estimate of Antarctic sea ice algal production that dynamically considers the light, temperature, salinity, and nutrient conditions that control algal growth. On average, 64% of algal production occurred in the bottom 0.2 m of the ice pack. Production was spatially heterogeneous, with little consistency between years when examined at regional scales; however, at basin or hemispheric scales, annual production was fairly consistent in magnitude. At a mean of 0.9 g C m-2 yr-1, the magnitude of carbon uptake by sea ice algae will not significantly affect the Southern Ocean carbon cycle. Light availability was the dominant control on sea ice algae growth over the majority of the year; however, severe nutrient limitation that occurred annually during late spring and summer proved to be the largest control over sea ice algal productivity.
Author: Taylor Priest Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The Arctic Ocean is undergoing irreversible perturbations as a result of accelerated climate warming. Of major significance is the expanding influence of Atlantic water that expedites sea-ice decline, alters stratification and vertical mixing of the water column and facilitates northward expansion of temperate biota. Our understanding on how these processes will impact biological communities is severely limited. The Fram Strait is the primary entry route for Atlantic water into the Arctic Ocean and exit point for polar water and sea-ice. With the presence of two major current systems combined with horizontal mixing processes, the Fram Strait is characterised by a longitudinal gradient of hydrographic regimes reflective of Arctic, mixed and Atlantic conditions. This provides an invaluable opportunity to study the ecology of microbes over an environmental gradient and under changing conditions. Furthermore, given its high-latitude position, it also facilitates investigations on how dramatic seasonal transformations in conditions, such as sea-ice cover and light availability, influence microbes in the context of water mass history. This thesis provides an ecological characterisation of microbial communities over temporal and spatial scales in the Fram Strait in an effort to address these topics. In Chapter II, we employed metagenomics from short- and long-read sequencing platforms to gain insights into microbial community composition across water masses in the Fram Strait. As that study incorporated the first PacBio HiFi (long-read) metagenomes from the marine environment, it was necessary to perform a methodological comparison. We show that using PacBio HiFi metagenomes, we are able to recover more metagenome-assembled genomes (MAGs) that, on average, are more complete, less fragmented and more frequently contain complete rRNA gene operons compared to using short-read metagenomes. This not only influenced our investigative toolkit throughout the remainder of this thesis but provides valuable data for future considerations on using long-read metagenomics in the study of marine microbial ecology. From the analysis conducted in Chapter II, we observed a flavobacterial clade that is commonly associated with coastal temperate ecosystems, the NS5 Marine Group, to be prominent in high-latitude waters. This motivated us to delve deeper into this group and understand their diversity and function. By combining cultivation, metagenomics, epifluorescence and transmission electron microscopy, we were able to delineate this group into four novel candidate genera and evidence distinctions in function and spatiotemporal dynamics at the species and genus level (Chapter III). In that study, we also presented the first pure isolate and complete genome for a member of the NS5 Marine Group. In Chapter IV, we performed the first high-resolution temporal analysis on microbial taxonomy and function in Arctic polar waters. Using a four-year 16S amplicon dataset and one annual cycle of PacBio HiFi metagenomes, we evidenced that Atlantic water influx and sea-ice cover had a profound impact on the composition and function of microbial communities. Based on their omnipresence irrespective of conditions, we also identified a small fraction of the community that likely represents the resident microbiome of the Fram Strait. Furthermore, we showed that a transition to low-ice and high Atlantic water influx shifted the community to one dominated by heterotrophic clades that are functionally linked to phytoplankton-derived organic matter. Our findings suggest that the continued expansion of Atlantic water into the Arctic Ocean will be reflected in a Biological Atlantification of the microbial community, with populations adapted to Arctic conditions exhibiting reduced ecological niche space. These changes will have implications for the future ecosystem functioning and the carbon cycle. In Chapter V of this thesis, we combined metagenomics and metatranscriptomics with analytical techniques to characterise the carbohydrate fraction of particulate organic matter and carbohydrate utilisation by microbes in the Atlantic waters of the Fram Strait during late summer. A high spatial heterogeneity was observed in both carbohydrates and their utilisation, which indicated patchiness in local productivity and a responsive microbial community. Carbohydrate utilisation was dominated by distinct microbial assemblages across sampling sites and consisted of populations making use of labile (communal) and more complex (specialist) substrates. We therein proposed that local biological and physical processes are important for continuing to shape the availability and utilisation of carbohydrates into the late summer. In an effort to clearly and concisely convey the main findings from this thesis in the context of its original aims, a detailed description on the current and future state of the Fram Strait and Arctic Ocean microbiome is provided in the discussion. In addition, insights and recommendations on how to apply long-read metagenomes to answer questions on microbial ecology is provided, given its fundamental importance for this thesis and its relative infancy in environmental research applications. Lastly, owing to it representing an underlying theme throughout much of the research conducted, a discussion on the ecological niche concept is provided along with a proposal for its redefinition in marine microbial ecology.
Author: Simon Jungblut Publisher: Springer Nature ISBN: 3030203891 Category : Aquatic biology Languages : en Pages : 378
Book Description
This open access book summarizes peer-reviewed articles and the abstracts of oral and poster presentations given during the YOUMARES 9 conference which took place in Oldenburg, Germany, in September 2018. The aims of this book are to summarize state-of-the-art knowledge in marine sciences and to inspire scientists of all career stages in the development of further research. These conferences are organized by and for young marine researchers. Qualified early-career researchers, who moderated topical sessions during the conference, contributed literature reviews on specific topics within their research field. .
Author: Edward F. DeLong Publisher: Springer ISBN: 9783642301193 Category : Science Languages : en Pages : 567
Book Description
The Prokaryotes is a comprehensive, multi-authored, peer reviewed reference work on Bacteria and Achaea. This fourth edition of The Prokaryotes is organized to cover all taxonomic diversity, using the family level to delineate chapters. Different from other resources, this new Springer product includes not only taxonomy, but also prokaryotic biology and technology of taxa in a broad context. Technological aspects highlight the usefulness of prokaryotes in processes and products, including biocontrol agents and as genetics tools. The content of the expanded fourth edition is divided into two parts: Part 1 contains review chapters dealing with the most important general concepts in molecular, applied and general prokaryote biology; Part 2 describes the known properties of specific taxonomic groups. Two completely new sections have been added to Part 1: bacterial communities and human bacteriology. The bacterial communities section reflects the growing realization that studies on pure cultures of bacteria have led to an incomplete picture of the microbial world for two fundamental reasons: the vast majority of bacteria in soil, water and associated with biological tissues are currently not culturable, and that an understanding of microbial ecology requires knowledge on how different bacterial species interact with each other in their natural environment. The new section on human microbiology deals with bacteria associated with healthy humans and bacterial pathogenesis. Each of the major human diseases caused by bacteria is reviewed, from identifying the pathogens by classical clinical and non-culturing techniques to the biochemical mechanisms of the disease process. The 4th edition of The Prokaryotes is the most complete resource on the biology of prokaryotes. The following volumes are published consecutively within the 4th Edition: Prokaryotic Biology and Symbiotic Associations Prokaryotic Communities and Ecophysiology Prokaryotic Physiology and Biochemistry Applied Bacteriology and Biotechnology Human Microbiology Actinobacteria Firmicutes Alphaproteobacteria and Betaproteobacteria Gammaproteobacteria Deltaproteobacteria and Epsilonproteobacteria Other Major Lineages of Bacteria and the Archaea
Author: Benjamin Lundquist Saenz Publisher: ISBN: Category : Languages : en Pages :
Book Description
Sea ice is an important driver of climate patterns and polar marine ecosystem dynamics. In particular, primary production by microalgae in sea ice has been postulated as a sink for anthropogenic CO2, and as a critical resource in the life cycle of Antarctic krill Euphausia superba, a keystone species. Study of the sea ice ecosystem is difficult at regional and global scales, however, because of the expense and logistical difficulties in accessing such a remote and hostile environment. Consequently, models remain valuable tools for investigations of the spatial and temporal dynamics of sea ice and associated ecology and biogeochemistry. Recent advances in model representations of sea ice have called into question the accuracy of previous studies, and allow the creation of new tools to perform mechanistic simulations of sea ice physics and biogeochemistry. To address spatial and temporal variability in Antarctic sea ice algal production, and to establish the bounds and sensitivities of the sea ice ecosystem, a new, coupled sea ice ecosystem model was developed. In the vertical dimension, the model resolves incorporated saline brine, macronutrients concentrations, spectral shortwave radiation, and the sea ice algae community at high resolution. A novel method for thermodynamics, desalination, and fluid transfer in slushy, high-brine fraction sea ice was developed to simulate regions of high algal productivity. The processes of desalination, fluid transfer, snow-ice creation, and superimposed ice formation allowed the evolution of realistic vertical profiles of sea ice salinity and algal growth. The model replicated time series observations of ice temperature, salinity, algal biomass, and estimated fluid flux from the Ice Station Weddell experiment. In the horizontal dimension, sub-grid scale parameterizations of snow and ice thickness allow more realistic simulation of the ice thickness distribution, and consequently, sea ice algal habitat. The model is forced from above by atmospheric reanalysis climatologies, and from below by climatological ocean heat flux and deep-water ocean characteristics. Areal sea ice concentration and motion are specified according to SSM/I passive microwave satellite estimates of these parameters. Sensitivity testing of different snow and ice parameterizations showed that without a sub-grid scale ice thickness distribution, mean ice and snow thickness is lower and bottom sea ice algal production is elevated. Atmospheric forcing from different reanalysis data sets cause mean and regional shifts in sea ice production and associated ecology, even when sea ice extent and motion is controlled. Snow cover represents a first-order control over ice algal production by limiting the light available to bottom ice algal communities, and changes to the regional, rather than mean, snow thickness due to the use of different ice and snow representations are responsible for large differences in the magnitude and distribution of sea ice algal production. Improved convective nutrient exchange in high-brine fraction (slush) sea ice is responsible for up to 18% of total sea ice algal production. A continuous 10-year model run using climatological years 1996-2005 produced a time series of sea ice algal primary production that varied between 15.5 and 18.0 Tg C yr-1. This study represents the first interannual estimate of Antarctic sea ice algal production that dynamically considers the light, temperature, salinity, and nutrient conditions that control algal growth. On average, 64% of algal production occurred in the bottom 0.2 m of the ice pack. Production was spatially heterogeneous, with little consistency between years when examined at regional scales; however, at basin or hemispheric scales, annual production was fairly consistent in magnitude. At a mean of 0.9 g C m-2 yr-1, the magnitude of carbon uptake by sea ice algae will not significantly affect the Southern Ocean carbon cycle. Light availability was the dominant control on sea ice algae growth over the majority of the year; however, severe nutrient limitation that occurred annually during late spring and summer proved to be the largest control over sea ice algal productivity.
Author: David N. Thomas Publisher: John Wiley & Sons ISBN: 1118778383 Category : Science Languages : en Pages : 666
Book Description
Over the past 20 years the study of the frozen Arctic and Southern Oceans and sub-arctic seas has progressed at a remarkable pace. This third edition of Sea Ice gives insight into the very latest understanding of the how sea ice is formed, how we measure (and model) its extent, the biology that lives within and associated with sea ice and the effect of climate change on its distribution. How sea ice influences the oceanography of underlying waters and the influences that sea ice has on humans living in Arctic regions are also discussed. Featuring twelve new chapters, this edition follows two previous editions (2001 and 2010), and the need for this latest update exhibits just how rapidly the science of sea ice is developing. The 27 chapters are written by a team of more than 50 of the worlds’ leading experts in their fields. These combine to make the book the most comprehensive introduction to the physics, chemistry, biology and geology of sea ice that there is. This third edition of Sea Ice will be a key resource for all policy makers, researchers and students who work with the frozen oceans and seas.
Author: Lars Chresten Lund-Hansen Publisher: Springer Nature ISBN: 3030374726 Category : Science Languages : en Pages : 178
Book Description
The book on sea ice ecology is the ecology of sea ice algae and other microorganism as bacteria, meiofauna, and viruses residing inside or at the bottom of the sea ice, called the sympagic biota. Organisms as seals, fish, birds, and Polar bears relies on sea ice but are not part of this biota. A distinct feature of this ecosystem, is the disappearance (melt) every summer and re-establishing in autumn and winter. The book is organized seasonally describing the physical, optical, biological, and geochemical conditions typical of the seasons: autumn, winter, and spring. These are exemplified with case studies based on author’s fieldwork in Greenland, the Arctic Ocean, and Antarctica but focused on Arctic conditions. The sea ice ecosystem is described in the context of climate change, interests, and effects of a decreasing summer ice extent in the Arctic Ocean. The book contains an up to date description of most relevant methods and techniques applied in sea ice ecology research. This book will appeal to university students at Masters or PhD levels reading biology, geosciences, and chemistry.
Author: David N. Thomas Publisher: John Wiley & Sons ISBN: 0470756926 Category : Technology & Engineering Languages : en Pages : 419
Book Description
Sea ice, which covers up to 7% of the planet’s surface, is a major component of the world’s oceans, partly driving ocean circulation and global climate patterns. It provides a habitat for a rich diversity of marine organisms, and is an extremely valuable source of information in studies of global climate change and the evolution of present day life forms. Increasingly sea ice is being used as a proxy for extraterrestrial ice covered systems. Sea Ice provides a comprehensive review of our current available knowledge of polar pack ice, the study of which is severely constrained by the logistic difficulties of working in such harsh and remote regions of the earth. The book’s editors, Drs Thomas and Dieckmann have drawn together an impressive group of international contributing authors, providing a well-edited and integrated volume, which will stand for many years as the standard work on the subject. Contents of the book include details of the growth, microstructure and properties of sea ice, large-scale variations in thickness and characteristics, its primary production, micro-and macrobiology, sea ice as a habitat for birds and mammals, sea ice biogeochemistry, particulate flux, and the distribution and significance of palaeo sea ice. Sea Ice is an essential purchase for oceanographers and marine scientists, environmental scientists, biologists, geochemists and geologists. All those involved in the study of global climate change will find this book to contain a wealth of important information. All libraries in universities and research establishments where these subjects are studied and taught will need multiple copies on their shelves. David Thomas is at the School of Ocean Sciences, University of Wales, Bangor, UK. Gerhard Dieckmann is at the Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
Author: Magda Guadalupe Cardozo-Mino
Author: Magda Guadalupe Cardozo-Mino
Author: Benjamin Lundquist Saenz
Author: Taylor Priest
Author: Simon Jungblut
Author: Edward F. DeLong
Author: Benjamin Lundquist Saenz
Author: David N. Thomas
Author: Lars Chresten Lund-Hansen
Author: David N. Thomas
Author: John Iacozza