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Aquatic microorganisms are tidily related to the carbon cycle in aquatic systems, especially in respect to its accumulation and emission to atmosphere. In one hand, the autotrophs are responsible for the carbon input to the ecosystems and trophic chain. On the other hand, the heterotrophs traditionally play a role in the carbon mineralization and, since microbial loop theory, may play a role to carbon flow through the organisms. However, it is not yet clear how the heterotrophs contribute to carbon retention and emission especially from tropical aquatic ecosystems. Most of the studies evaluating the role of microbes to carbon cycle in inland waters were performed in high latitudes and only a few studies in the tropical area. In the prospective of global changes where the warm tropical lakes and rivers become even warmer, it is important to understand how microorganisms behave and interact with carbon cycle in the Earth region with highest temperature and light availability. This research topic documented microbial responses to natural latitudinal gradients, spatial within and between ecosystems gradients, temporal approaches and temperature and nutrient manipulations in the water and in the sediment.
Microorganisms are fundamental members of aquatic and marine ecosystems capable of affecting the macroecology of these systems by serving as the foundation of complex food chains, biogeochemical processes, and disease dynamics. Though recognized as foundational, scientists continue to struggle to apply basic ecological concepts of like community, spatiotemporal variability, gradients, and disturbance regimes to microorganisms in meaningful ways due to the vast differences in scale between macrobial sampling designs and microbial existence. However, until new ecological concepts have been generated for understanding microbial populations, we must continue to sample varied habitats at multiple spatial and temporal scales with the hope of capturing both unique and common characteristics of these communities that will allow us to predict their responses to a changing environment. The ability to predict microbial behavior has particular importance for human health; for that reason, this research focused on bacterial members of the greater microbial community that have been associated with illness and disease in humans utilizing both culture and molecular techniques followed by multiple-regression analyses. In Chapter 1, the intention was to examine bacterial populations at broad spatial and temporal scales within 6 freshwater reservoirs in the foothills of the Sierra Nevada Mountains. We sought to understand whether microbial water quality within reservoirs was driven by upstream conditions and subsequently predictive of downstream outcomes. Specifically, this research sought to understand the variability of fecal indicator bacteria (Escherichia coli and fecal coliforms) and pathogens (E. coli O157:H7, Non-O157 shiga toxin-producing E. coli and Salmonella) along both horizontal and vertical profiles within California reservoirs as it related to upstream river sources and downstream irrigation water supplies. Continued monitoring and modeling of both bacterial indicators and enteric pathogens are critical to our ability to estimate the risk of surface irrigation water supplies and make appropriate management decisions. In this study, the extreme variability in microbial populations across both space and time made successful predictions largely impossible and underlined the extreme importance of sampling these dynamic communities at scales where their behavior can be observed, particularly where human health may be impacted. I sought to further refine the scale of examination in Chapter 2 which moved from the freshwater of the Sierras to the marine habits of coastal California. In these systems the bacterial genus Vibrio is both endemic and occasionally pathogenic. Thus, we strove for greater understanding of how four members of Vibrio, V. alginolyticus, V. parahaemolyticus, V. cholerae, and V. vulnificus, referred to as “the big four” of global human illness, interact with their environment and respond to changing conditions. We examined finer-scale spatial and temporal variability of the “big four” in one bay of Northern California, Tomales Bay, highly popular with tourists and known as a premier region for shellfish production. As with Chapter 1, bacterial populations were highly dynamic in both space and time. However, these data were more easily modeled by capturing weekly, daily, and occasionally hourly changes to the environment during seasonal storms and sub-meter differences in sediment characteristics during acute tidal cycles. As with the previous chapter, pathogen prevalence or concentration in water, sediment, or shellfish did not correlate (p>0.1) with concentrations of fecal indicator bacteria, suggesting the need for revisions to the current regulatory monitoring efforts. For the third and final chapter I chose to manipulate the environment experienced by microorganisms in a manner that is common to intertidal sand and mudflats along most coastlines, recreational clamming activity. The impact of physical disturbance by clamming activity on microbial communities of intertidal sand flats has received relatively little attention, though the state of California estimates that 20-40K clams are taken from California bays annually, suggesting many people are performing the behavior and a large volume of sediment is being moved. I examined these impacts through a replicated cross-factorial longitudinal experiment on two emergent islands at the mouth of Tomales Bay. By following these exact sites through time we were able to reveal a wealth diversity within a single species of Vibrio, V. alginolyticus, and examine how that diversity changed through recurring tidal cycles. Further, while it was apparent that our targeted species were not significantly (p>0.05) impacted by our experimental disturbances, there were clear differences in the responses of indicator bacteria (fecal coliforms and enterococci) and vibrios by location and across time. These data illustrate that a great deal remains to be discovered about human influence over microbial communities in coastal systems, opening the door for further refinement in study designs. Taken as a whole, this series of studies has helped to further highlight the need of studies that examine microbial populations not only at scales that are relevant to the organism under investigation, but to the humans that may encounter them and fall ill. I sought to provide suggestion to aid the regulatory community in modifying current guidelines in the interest of public health and to encourage the ecological community to continue to evaluate the impact of scale on our ability to make inferences and gain understanding of these unseen and complex microbial communities.
The globally important nature of wetland ecosystems has led to their increased protection and restoration as well as their use in engineered systems. Underpinning the beneficial functions of wetlands are a unique suite of physical, chemical, and biological processes that regulate elemental cycling in soils and the water column. This book provides an in-depth coverage of these wetland biogeochemical processes related to the cycling of macroelements including carbon, nitrogen, phosphorus, and sulfur, secondary and trace elements, and toxic organic compounds. In this synthesis, the authors combine more than 100 years of experience studying wetlands and biogeochemistry to look inside the black box of elemental transformations in wetland ecosystems. This new edition is updated throughout to include more topics and provide an integrated view of the coupled nature of biogeochemical cycles in wetland systems. The influence of the elemental cycles is discussed at a range of scales in the context of environmental change including climate, sea level rise, and water quality. Frequent examples of key methods and major case studies are also included to help the reader extend the basic theories for application in their own system. Some of the major topics discussed are: Flooded soil and sediment characteristics Aerobic-anaerobic interfaces Redox chemistry in flooded soil and sediment systems Anaerobic microbial metabolism Plant adaptations to reducing conditions Regulators of organic matter decomposition and accretion Major nutrient sources and sinks Greenhouse gas production and emission Elemental flux processes Remediation of contaminated soils and sediments Coupled C-N-P-S processes Consequences of environmental change in wetlands# The book provides the foundation for a basic understanding of key biogeochemical processes and its applications to solve real world problems. It is detailed, but also assists the reader with box inserts, artfully designed diagrams, and summary tables all supported by numerous current references. This book is an excellent resource for senior undergraduates and graduate students studying ecosystem biogeochemistry with a focus in wetlands and aquatic systems.
Biochar is the carbon-rich product when biomass (such as wood, manure or crop residues) is heated in a closed container with little or no available air. It can be used to improve agriculture and the environment in several ways, and its stability in soil and superior nutrient-retention properties make it an ideal soil amendment to increase crop yields. In addition to this, biochar sequestration, in combination with sustainable biomass production, can be carbon-negative and therefore used to actively remove carbon dioxide from the atmosphere, with major implications for mitigation of climate change. Biochar production can also be combined with bioenergy production through the use of the gases that are given off in the pyrolysis process. This book is the first to synthesize the expanding research literature on this topic. The book's interdisciplinary approach, which covers engineering, environmental sciences, agricultural sciences, economics and policy, is a vital tool at this stage of biochar technology development. This comprehensive overview of current knowledge will be of interest to advanced students, researchers and professionals in a wide range of disciplines.
The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides policymakers with regular assessments of the scientific basis of human-induced climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks, with a focus on resilience, risk management response options, and adaptation measures, considering both their potential and limitations. It brings together knowledge on physical and biogeochemical changes, the interplay with ecosystem changes, and the implications for human communities. It serves policymakers, decision makers, stakeholders, and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.
This unique textbook takes a broad look at the rapidly expanding field of freshwater microbiology. Concentrating on the interactions between viruses, bacteria, algae, fungi and micro-invertebrates, the book gives a wide biological appeal. Alongside conventional aspects such as phytoplankton characterisation, seasonal changes and nutrient cycles, the title focuses on the dynamic and applied aspects that are not covered within the current textbooks in the field. Complete coverage of all fresh water biota from viruses to invertebrates Unique focus on microbial interactions including coverage of biofilms, important communities on all exposed rivers and lakes. New information on molecular and microscopical techniques including a study of gene exchange between bacteria in the freshwater environment. Unique emphasis on the applied aspects of freshwater microbiology with particular emphasis on biodegradation and the causes and remediation of eutrophication and algal blooms.
This open access book synthesizes leading-edge science and management information about forest and rangeland soils of the United States. It offers ways to better understand changing conditions and their impacts on soils, and explores directions that positively affect the future of forest and rangeland soil health. This book outlines soil processes and identifies the research needed to manage forest and rangeland soils in the United States. Chapters give an overview of the state of forest and rangeland soils research in the Nation, including multi-decadal programs (chapter 1), then summarizes various human-caused and natural impacts and their effects on soil carbon, hydrology, biogeochemistry, and biological diversity (chapters 2–5). Other chapters look at the effects of changing conditions on forest soils in wetland and urban settings (chapters 6–7). Impacts include: climate change, severe wildfires, invasive species, pests and diseases, pollution, and land use change. Chapter 8 considers approaches to maintaining or regaining forest and rangeland soil health in the face of these varied impacts. Mapping, monitoring, and data sharing are discussed in chapter 9 as ways to leverage scientific and human resources to address soil health at scales from the landscape to the individual parcel (monitoring networks, data sharing Web sites, and educational soils-centered programs are tabulated in appendix B). Chapter 10 highlights opportunities for deepening our understanding of soils and for sustaining long-term ecosystem health and appendix C summarizes research needs. Nine regional summaries (appendix A) offer a more detailed look at forest and rangeland soils in the United States and its Affiliates.
This document presents key messages and the state-of-the-art of soil pollution, its implications on food safety and human health. It aims to set the basis for further discussion during the forthcoming Global Symposium on Soil Pollution (GSOP18), to be held at FAO HQ from May 2nd to 4th 2018. The publication has been reviewed by the Intergovernmental Technical Panel on Soil (ITPS) and contributing authors. It addresses scientific evidences on soil pollution and highlights the need to assess the extent of soil pollution globally in order to achieve food safety and sustainable development. This is linked to FAO’s strategic objectives, especially SO1, SO2, SO4 and SO5 because of the crucial role of soils to ensure effective nutrient cycling to produce nutritious and safe food, reduce atmospheric CO2 and N2O concentrations and thus mitigate climate change, develop sustainable soil management practices that enhance agricultural resilience to extreme climate events by reducing soil degradation processes. This document will be a reference material for those interested in learning more about sources and effects of soil pollution.