Natural and anthropogenic radionuclides are used to study a suite of environmental processes. Yet their applications in aquatic systems are hindered by a general lack of knowledge regarding the underlying concepts of radioactivity, the occurrence of radionuclides in ecosystems, and the equations used to describe their decay mechanisms in environmentally applicable ways. The goal of this lecture is to provide upper level undergraduate and graduate students with a basic understanding of how the naturally occurring uranium‐thorium radioactive decay series can be used to address a range of environmentally relevant questions in marine systems. The lecture begins with a brief introduction to uranium‐thorium series decay patterns and their distribution in the marine environment. The remaining lecture focuses on four case studies that cover a range of applications where uranium‐thorium series radionuclides are used and includes: scavenging, air‐sea gas exchange, tracing groundwater, and sedimentation/age dating. This lecture is the second of a four‐part lecture series on radionuclides in the marine environment.
Natural and anthropogenic radionuclides are used to study a suite of environmental processes. Yet their applications in aquatic systems are hindered by a general lack of knowledge regarding the underlying concepts of radioactivity, the occurrence of radionuclides in ecosystems, and the equations used to describe their decay mechanisms in environmentally applicable ways. The goal of this lecture is to provide upper level undergraduate and graduate students with a basic understanding of how cosmogenic and anthropogenically produced radionuclides can be used to address a range of environmentally relevant questions in marine systems. The lecture begins with a brief introduction to cosmogenic and anthropogenic radionuclide production and sources to the marine environment. The remaining lecture focuses on specific case studies using these radionuclides in a range of applications including: ocean circulation and mixing, particle scavenging, and sedimentation/age dating. This lecture is the third of a four‐part lecture series on radionuclides in the marine environment.
Natural and anthropogenic radionuclides are used to study a suite of environmental processes. Yet their applications in aquatic systems are hindered by a general lack of knowledge regarding the underlying concepts of radioactivity, the occurrence of radionuclides in ecosystems, and the equations used to describe their decay mechanisms in environmentally applicable ways. The goal of this lecture is to provide upper level undergraduate and graduate students with a basic understanding of the fundamentals of radiochemistry, including the origin and stability of elements, radioactive decay mechanisms, and the fundamental equations that govern radioactive decay. This lecture is the first of a four‐part lecture series on radionuclides in the marine environment.
This lecture (∼ 45-55 slides) will be aimed at senior undergraduate students and graduate students in aquatic sciences with little background in phycology. This lecture could be used in a Aquatic Ecology or Sciences (Limnology) course, an Ecology course, a Phycology course, Environmental Science. Cyanobacteria that may lead to blooms encompass a wide range of different functional groups. We will present: 1) the evolutionary history of cyanobacteria (2-3 slides) (this helps explain some of their present-day traits) 2) basic biology and physiological/ecological traits of planktonic cyanobacteria that are most often associated with visible biomass accumulations (“blooms”) in freshwater/brackish systems of various regions of the world. Traits to be considered include: capacity for N fixation, nutrient uptake and storage (C, N, P), siderochromes, buoyancy regulation (gas vacuoles, mucilage), life cycles, growth rates vs. loss rates (resistance to grazing), allelopathy (negative vs. positive biotic interactions) Functional groups. Planktonic genera may also produce toxins, contributing to harmful algal blooms. (∼12-14 slides). 3) Cyanotoxins: the principal types of toxins produced and their effects (persistence) will be compared, along with theories as to the biological function of these compounds. (∼ 6 slides) 4) Specific case studies of blooms types under different climates: e.g. scum-forming, metalimnetic, dispersed (∼6) 5) The factors that appear to explain and control cyanobacterial dominance will be presented, including nutrient effects, temperature, and food chain changes. These factors vary across temporal and spatial scales. Evidence for eutrophication and climate change in mediating directly or indirectly the frequency and severity of freshwater cyanobacterial blooms will be considered (∼8-10). 6) Research avenues Controversial or unresolved topics: e.g. invasiveness?, cosmopolitan or geographically restricted (e.g. endemism? in hot spring taxa), toxin concerns and bioaccumulation), nitrogen fixation (“pretenders”), nutrient stoichiometry. Unexplored diversity at different levels (molecular, chemical, taxonomic), techniques for controlling cyanobacteria blooms, the future for cyanobacteria under climate change scenarios (∼4) 7) General references, web resourcess and primary articles. (∼2) 8) Questions and potential experiments for instructors and students will be provided at the end of the lecture (supplementary slides).
The oxygen flux between benthic systems and the water above is a widely used proxy for benthic primary production and organic carbon mineralization and is one of the most measured variables in marine and freshwater research. This presentation reviews the relatively new aquatic eddy covariance technique for measuring this flux. Because the approach relies on measurements that integrate over a large area (multiple m2) without disturbing the benthic system or the natural drivers of flux, it allows non‐invasive studies of whole‐system benthic metabolism that are not possible with any other approach. After summarizing the basic principles of eddy covariance, the instruments used, and key steps in the data evaluation, the rapidly growing body of research utilizing aquatic eddy covariance is presented with examples of the new kinds of insights that can be attained. These examples focus on benthic surfaces where traditional flux methods are difficult or problematic to apply and include highly dynamic benthic environments such as coral reefs, Arctic sediments, dense seagrass meadows, and permeable sands. Finally, future applications of the technique, new areas for development, and avenues to disseminate data and outcomes between new and experienced users are recommended.
Dissolution of atmospheric CO 2 in seawater has lowered ocean pH and carbonate ion concentrations with impacts on marine organisms and ecosystems. The geological record contains long‐term evidence for a variety of global environmental perturbations, including ocean acidification, and the biotic responses associated with them, and can provide insight into consequences of current anthropogenic acidification. This e‐lecture focuses on the paleo‐perspective of ocean acidification, proxy evidence for pH changes and several events exhibiting evidence for elevated atmospheric CO 2 , global warming, and ocean acidification over the past ˜300 million years are reviewed. Comparison between these events and the present suggests that the current and projected rate of acidification may be unprecedented in past events with unknown consequences for marine life and humans who depend on it. The target audiences for this e‐Lecture are upper division undergraduate students and graduate students with some previous background in oceanography and paleoceanography. This could be a lecture in an “introduction to paleoceanography” class that discusses archives and proxies or a lecture in a topical “ocean acidification” class covering paleo ocean acidification. Depending on audience background the lecture may take 50 minutes (students versed in paleoceanography) or 90 minutes (novice students).
A suite of parallel anthropogenic changes affects contemporary marine ecosystems. Excessive carbon dioxide (CO 2 ) pollution results in warmer, more acidic oceans with lower dissolved oxygen (DO) levels, meanwhile the emission of reactive nitrogen/phosphorus results in eutrophication, excessive microbial degradation and thus metabolic hypoxia and acidification. Despite decades of empirical research how each individual stressor of the ‘climate‐change syndrome’ (i.e., temperature, CO 2 , DO) affects the fitness of marine organisms, we still know little about the combined effects of these stressors. This lecture gives an overview over the nascent field of multi‐stressor approaches evaluating the climate sensitivity of marine organisms across taxa. In most studied cases, combined effects of these stressors exceeded those observed individually. Effects of combined warming, acidification, and deoxygenation have mostly been additive (no stressor interaction) or synergistically negative (stressor interaction). The occurrence and strength of synergistic stressor interactions in some species, life history stages, and traits comprises a vexing challenge but hints at potentially greater sensitivities of organisms to marine climate change than previously recognized. This lecture is intended for post‐secondary students, providing them with illustrated examples from the most resent literature, while aiding in communicating the urgent need for empirical data from multi‐stressor approaches.
The number of ocean acidification (OA) studies has increased significantly over the last decade. Most of this was due to studies on biological responses of organisms to OA. The lack of a protocol to document biological response OA data prevents the research community from properly archiving, discovering, accessing, and utilizing this important body of OA data sets. In this e‐Lecture, we present how to document an OA data set by explaining major components of a metadata template, which can be applied to a broad spectrum of OA studies, including those studying the biological responses to OA. The major metadata components include Investigators, Title, Abstract, Temporal coverage, Spatial coverage, Geographic names, Location of organism collection, Platforms, Variable metadata clusters, Publications describing the data set, and Supplementary information. Of these components, Variable metadata clusters (variables and their metadata sub‐elements) are treated as the focal point of the template. In addition to variable name , other metadata elements include the observation type, whether it is an in‐situ observation, manipulation condition, or response variable, biological subject, life stage of the biological subject, etc. Information about how to access the metadata template files is also stated.
Summary The processes occurring in the upper several meters of marine sediments have a profound effect on the local and global cycling of many elements. For example, the balance between organic carbon preservation and remineralization in sediments represents the key link between carbon cycling in active, surface reservoirs in the oceans, atmosphere, and on land, and carbon that cycles on much longer, geological time scales, i.e., in sedimentary rock, and in coal and petroleum deposits. Understanding processes occurring in surficial marine sediment is also important in the accurate interpretation of paleoceanographic sediment records, since sediment processes can sometimes significantly alter the primary “depositional” signal recorded in the sediments. In coastal and estuarine sediments nitrogen and phosphorus remineralization in the sediments can provide a significant fraction of the nutrients required by primary producers in the water column. Similarly, in coastal and estuarine sediments subjected to elevated anthropogenic inputs of certain toxic metals, sediment processes affect the extent to which these sediments represent “permanent” versus “temporary” sinks for these metals. The geochemistry of marine sediments is controlled by both the composition of the material initially deposited in the sediments and the chemical, biological or physical processes that affect this material after its deposition. These processes fall within the general category of what is commonly referred to as early diagenesis. One very crucial aspect of the study of early diagenesis in marine sediments is that the oxidation, or remineralization, of organic matter deposited in the sediments is either the direct or indirect causative agent for many of these early diagenetic changes. Given this pivotal role that organic matter remineralization plays in many early diagenetic processes, significant efforts have gone into understanding and quantifying these processes. This lecture provides a brief introduction to marine sediment geochemistry focusing on the basic controls on organic matter remineralization in sediments. It is based on a lecture I recently gave to an undergraduate geology class in stratigraphy. I believe that it could also be useful in an undergraduate class in general oceanography, low temperature geochemistry or environmental geochemistry. Lecture summary The geochemistry of marine sediments is controlled by both the composition of the material initially deposited in the sediments and the chemical, biological or physical processes that affect this material after its deposition. These processes fall within the general category of what is commonly referred to as early diagenesis. One key aspect of the study of early diagenesis in marine sediments is that the oxidation, or remineralization, of sediment organic matter is either the direct or indirect causative agent for many early diagenetic changes. Given the pivotal role that organic matter remineralization plays in early diagenetic processes, significant efforts have gone into understanding and quantifying these processes. This lecture provides a brief introduction to marine sediment geochemistry, focusing on the basic controls of organic matter remineralization in sediments. I believe that the lecture could be useful in an undergraduate class in general oceanography, low temperature geochemistry or environmental geochemistry. It could also be useful in introductory graduate classes in these latter two areas.
SummaryThe goal of this lecture is to provide aquatic scientists and interested laymen with an overview of the potential, methods and exemplary analyses of DNA preserved in lake sediments. This area is an emerging field, as new techniques are opening up avenues for novel studies of the sediment record. Numerous papers in this field have recently been published in Science, PNAS and PLoS ONE. Like many new fields, there are challenges as well as exciting lines of future inquiry, which we dedicate part of the lecture towards.This lecture starts by providing a brief introduction to paleolimnology, with an emphasis on how DNA studies can expand this field. We then provide information on the ways in which DNA can be archived in sediments & how analyses can differ, depending on the question and target. Examples of the common genetic markers used and how DNA may be sequenced are also highlighted in the methods section. In the second portion of the lecture, we focus on the applications of sedimentary DNA: 1) to the study of particular phytoplankton group dynamics; 2) to the analysis of zooplankton DNA preserved in resting eggs; and, 3) to uncover community‐wide changes in plankton. Finally, we close the lecture with a discussion on challenges and future directions in the field. Advances in the development and calibration of different extraction techniques, as well as further enhancement of genetic libraries and bioinformatics pipelines, are all areas ripe for new research.This lecture has been prepared with a diverse audience in mind. For example, undergraduate or graduate courses that could be interested in our material include Aquatic Ecology, Limnology, Oceanography, Microbial Ecology, Environmental Genomics and Paleoecology. This lecture could also serve as a useful introduction to non‐specialist audiences that are interested in the potential of the DNA archive preserved in lake sediments (including funding agencies).
SummaryThis lecture is designed for undergraduates, to show how satellites contribute to the understanding of ocean dynamics. Satellite sensors can measure properties of the surface ocean with a sampling coverage unachievable from ocean‐going research vessels. The four geophysical variables of the ocean that satellites can observe are sea‐surface temperature, surface winds, the relative height of the sea surface, and the color of the ocean. Sea surface temperature is measured by sensing the infrared radiation emanating from the ocean. Surface winds are deduced from the roughness of the surface ocean using a radar on the satellite. Sea surface height is estimated from knowing, very accurately the altitude of the satellite relative to the earth. Ocean color is measured with a spectrometer on board the satellite. The lecture will give students appreciation of the power of satellite oceanography, while also considering its limitations. This lecture avoids overly technical information and the particulars of the various satellites, in favor of a description of how the measurements are made that can be understood at the undergraduate level. Students are encouraged to make use of satellite data, which is publicly available.
Summary The Biological Carbon Pump includes all those processes in the ocean that cause organic carbon formed photosynthetically by phytoplankton (primary production) in the sunlit surface layer (the euphotic zone) to be removed from contact with the atmosphere. It is a mechanism that sequesters carbon dioxide (CO 2 ) for weeks to hundreds or even millions of years (geological time‐scales). Together with the physical carbon pump, the biological carbon pump constitutes the ocean's CO 2 sink, and these two major processes in the global carbon cycle have removed about 2‐ 2.5 Pg Carbon per year (last decade average)(I Pg=10 15 g). Today, about half of the CO 2 emitted from fossil fuel burning and land use changes remains in the atmosphere, and the other half is captured by land sinks and the ocean. The modern carbon cycle is often completely separated from the short- and long-term carbon cycles of the geological past, and students from biology or biogeochemistry rarely learn about these processes and the respective timescales in a joint lecture. The purpose of this interdisciplinary lecture thus is to cover processes related to the biological carbon pump and how it functions, while paying close attention to the relevant timescales in the global carbon cycle. Note that we focus mainly on the production and sinking of particulates, we do not delve into detailed mechanisms of carbon sequestration due to the removal of dissolved organic matter. Topics will include an introduction to the different carbon pumps (biological, carbonate and physical), followed by a detailed process-oriented introduction to the biological carbon pumps. This will also include the organismal aspects, such as an introduction to phytoplankton, primary production, distribution of primary producers in the global ocean, and the role of zooplankton in the biological carbon pump. More mechanistic aspects follow, such as the concepts of new and export production, the flux attenuation and the role of mineral ballasting. We cover specific aspects of the lecture as modules (Excursions) that give the reader/lecturer the chance to explore some topics in greater detail. These "Excursions" are entitled "Instrumentation: Quantifying Particle Flux", "Particle Sinking and Degradation" and "The Biological Carbon Pump on Geological Timescales". The lecture is intended for senior undergraduates/graduates students and can be used in courses such as Oceanography, Biogeochemistry, Geology, and Environmental Life Sciences.
SummaryIn 1892, François A. Forel created and defined the new science of Limnology as “the oceanography of lakes.” His aim was to establish an integrative discipline for the aquatic sciences in which diverse types of lake studies, from physics, chemistry and biology, to anthropology and economics, would complement and inform each other to produce a meaningful synthesis. Forel grew up in Morges, Switzerland, on the shores of Lake Geneva (lac Léman), and then left for 11 years to universities in France and Germany to study the natural sciences and medicine. Shortly after his return to Switzerland, he was appointed Professor of Anatomy and Physiology at the Academy of Lausanne. In the first years back at the lake, he made important discoveries about deep‐living benthic animals and surface seiches that reinforced his early decision to adopt Lake Geneva as his “laboratory and aquarium” and to devote his career to limnological research. Forel's remarkable breadth of interests and expertise culminated in 288 reports and publications, including the first text book in general limnology (published 1901), and the seminal, three‐volume monograph on the Limnology of Lake Geneva (1892, 1895 and 1904). Forel's success was the result of his passion for lakes and lake science, an ability to pose and critically evaluate insightful questions about the natural world, a flair for observation and new technologies, a rigorous, encyclopedic ability to collect and synthesize all available information, and a natural talent for networking and collaboration. His view of lakes as coupled physical‐chemical‐biotic‐human systems is particularly relevant to facing the challenges of global change, and the associated rapid shifts in ecosystem services at a planetary scale.This e‐Lecture is rich in images including previously unpublished photographs of materials held in the Forel Archives at the Lake Geneva Museum, Nyon, Switzerland. The e‐Lecture also places Forel's work in the broader historical context of the development of limnology in Europe, North America and beyond. Central in this presentation is a description of Forel's goal to achieve an integrated synthesis in his lake studies, and his view of humans as a powerful biotic component within the lake ecosystem.
Rising atmospheric carbon dioxide (CO2), primarily from human fossil fuel combustion, reduces ocean pH and causes wholesale shifts in seawater carbonate chemistry. The process of ocean acidification is well documented in field data, and the rate will accelerate over this century unless future CO2emissions are curbed dramatically. Acidification alters seawater chemical speciation and biogeochemical cycles of many elements and compounds. One well-known effect is the lowering of calcium carbonate saturation states, which impacts shell-forming marine organisms from plankton to benthic molluscs, echinoderms, and corals. Many calcifying species exhibit reduced calcification and growth rates in laboratory experiments under high-CO2conditions. Ocean acidification also causes an increase in carbon fixation rates in some photosynthetic organisms (both calcifying and noncalcifying). The potential for marine organisms to adapt to increasing CO2and broader implications for ocean ecosystems are not well known; both are high priorities for future research. Although ocean pH has varied in the geological past, paleo-events may be only imperfect analogs to current conditions.
This lecture is designed to acquaint the viewer with the importance of small-scale phytoplankton-bacteria interactions to upper ocean biogeochemistry. Specific attention is placed on the role of the microbial loop as a major carbon flux pathway. The primary focus is on the role of membrane-bound ectohydrolytic enzymes, particularly ectoproteases, as a fundamental biochemical strategy employed by marine bacteria to degrade or ‘process’ phytoplankton organic matter. In doing so, these small-scale biochemical processes exert a profound influence on the biogeochemical cycling of a variety of elements in the upper ocean.
This lecture provides an overview of climate and biological changes in Pacific-influenced Arctic marine ecosystems. It reviews and examines the major contributing factors to these changes, including changing conditions of sea ice, freshwater input, and the alteration of marine ecosystems. Examples of these factors are provided to illustrate the potential impacts that will have broad-reaching implications for long-term ecosystem structures. This lecture also reviews the progress of various programs undertaken during recent years (i.e. Bering Sea Research Program, Canada's Three Oceans, the Russian/US Long-term Census of the Arctic Ocean, and the Western Arctic Shelf-Basin Interactions) which have provided insights into the key processes influencing ecosystem function and change in the northern Bering and Chukchi shelf regions. Data sets from these programs are included in this L&O e-Lecture, in the context of biological response to sea ice changes in the Pacific Arctic region, with accompanying discussion by the L&O e-Lecture author.
Summary Our limited intuition of the small-scale world of the plankton has biased the way we describe and understand ocean ecology. Classical approaches consider fluxes of energy and matter between species and populations to describe marine ecosystems but biological interactions occur between individuals rather than between the abstract entities of ‘populations’ or “trophic levels.” A complementary approach is to derive system properties from mechanistic insights in individual functioning and interactions. Plankton live in a world that is radically different from ours, and to which we have limited access. Visualization is central to developing an intuition for this world, which together with insights in small-scale fluid physics may allow a mechanistic understanding of individual interactions and deduction of properties of populations and ecosystems. This lecture demonstrates the mechanistic approach through a number of examples, including numerous videos.
The overall goal of this lecture is to provide limnology (and oceanography) students an overview of the various methods and approaches currently being used by scientists to study the timing and magnitude of environmental changes affecting aquatic systems at time scales of decades, centuries, and millennia. The lecture includes the steps that paleolimnologists follow in their sedimentary analyses, including core collection, core sampling, dating, and a summary of the main indicators and climate proxies. Smol has also integrated into the lecture slides that highlight research that he and his co-workers have undertaken over the years. The lecture concludes with three case studies: the history of lake acidification, the occurrences of drought on the prairies, and the nature of climate change in the Arctic.
