Download or read book Evaluating the Frequency Magnitude and Biogeochemical Consequences of Under ice Phytoplankton Blooms written by Courtney Michelle Payne and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Arctic Ocean has changed substantially because of climate change. The loss of sea ice extent and thickness has increased light availability in the surface ocean during the ice-covered portion of the year. Sea ice loss has also been a factor in the observed increases in sea surface temperatures and likely impacts surface ocean nutrient inventories. These changing environmental conditions have substantially altered patterns of phytoplankton net primary production (NPP) across the Arctic Ocean. While NPP in the Arctic Ocean was previously considered insubstantial until the time of sea ice breakup and retreat, the observation of massive under-ice (UI) phytoplankton blooms in many of the Arctic seas reveals that the largest pulse of NPP may be produced prior to sea ice retreat. However, estimating how much NPP is generated during the UI part of the year is challenging, as satellite observations are hampered by sea ice cover and very few field campaigns have targeted UI blooms for study. This thesis uses a combination of laboratory experiments, biogeochemical modeling, and an analysis of satellite remote sensing data to better understand how the magnitude and spatial frequency of UI phytoplankton blooms has changed over time in the Arctic Ocean, as well as to assess the likely biogeochemical consequences of these blooms. In Chapter 2, I present a one-dimensional ecosystem model (CAOS-GO), which I used to evaluate the magnitude of UI phytoplankton blooms in the northern Chukchi Sea (72°N) between 1988 and 2018. UI blooms were produced in all but four years over that period, accounted for half of total annual NPP, and were the primary drivers of interannual variability in NPP. Further, I found that years with large UI blooms had reduced rates of zooplankton grazing, leading to an intensification of the mismatch between phytoplankton and zooplankton populations. In Chapter 3, I used the same model configuration to investigate the role of UI bloom variability in controlling sedimentary processes in the northern Chukchi Sea. I found that, as total annual NPP increased from 1988 to 2018, there were increases in particle export to the benthos, nitrification in the water column and the sediments, and sedimentary denitrification. These increases in particle export to the benthos and denitrification were driven by higher rates of NPP early in the year (January-June) and were highest in years where under-ice blooms dominate, indicating the importance of UI NPP as drivers of these biogeochemical consequences. Additionally, I tested the system's sensitivity to added N, finding that, if N supply in the region increased, 30\% of the added N would subsequently be lost to denitrification. I subsequently deployed this model in the southern Chukchi Sea (68°N) to understand latitudinal differences in UI bloom importance across the region (Chapter 4). I found that UI blooms were far less important contributors to total NPP in the southern Chukchi Sea. Further, I found that their importance was waning over time; NPP generated in the UI period from 2013-2018 was only 34\% of the 1988-1993 mean. This lower rate of UI NPP was driven by a far shorter UI period as sea ice retreated nearly six weeks earlier than in the northern Chukchi Sea. However, low UI NPP was associated with higher rates of both total NPP and sedimentary denitrification in the southern Chukchi Sea than in the north. In Chapter 5, I used satellite remote sensing to determine how UI bloom frequency changed across the Arctic between 2003 and 2021. I found that UI blooms are a widespread feature and can be generated across 40\% of the observable seasonal sea ice zone in the Arctic Ocean. While there was an increase in observable area as sea ice retreated, there was no change in UI area, driving a nearly 10\% decline in the proportion of UI bloom prevalence. The Chukchi Sea was identified as both the region with the highest prevalence of UI blooms and the region most responsible for the decline in UI blooms. Finally, to understand the functional relationship between co-limiting light and nutrient conditions on phytoplankton growth, I conducted a laboratory experiment (Chapter 6). Phytoplankton growth under co-limiting conditions, which is frequently observed in the field, is often modeled using one of two functional relationships, but these relationships produce vastly different predictions of phytoplankton bloom magnitude. Although this laboratory experiment aimed to quantify the functional relationship of light and nutrient limitation on phytoplankton growth, I faced challenges in quantifying the nitrogen (N) concentration and was unable to meaningfully distinguish between these two functional relationships. However, this work also demonstrated that there is little difference between these functional relationships in areas like the Arctic Ocean, where nutrient concentrations can be rapidly depleted, diminishing from non-limiting to scarce over just a few days. Together, the results of this dissertation suggest that UI phytoplankton blooms can substantially contribute to total NPP, drive reductions in food availability, and change the rate of nitrogen loss. However, this work also demonstrates that UI blooms, which have likely been an important source of NPP across the Arctic since at least the 1980s, are likely an ephemeral feature, with their prevalence likely to decline in coming years as sea ice retreat shifts earlier.

Download or read book Quantifying Net Primary Production in a Changing Arctic Ocean written by Katelyn Marie Lewis and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Situated at the northernmost region of the planet, the Arctic Ocean (AO), the smallest of the world's oceans, supports a rich, but vulnerable, ecosystem. Despite seemingly inhospitable conditions, the extreme seasonal pulses of primary production by phytoplankton in the AO fuel an abundant food-web composed of both endemic and migratory higher trophic level organisms. Alas, the Arctic is warming at approximately twice the global rate in response to anthropogenic climate change and the rising temperatures in this region have already triggered profound ecological changes. In the oceans, disappearing sea ice has shifted the phytoplankton growing season earlier in the year and led to a significant increase in net primary production (NPP). In order to understand the multi-layered effects of AO biogeochemistry and ecology as the climate continues to warm, it is imperative to accurately monitor changes in the magnitude and timing of NPP. Because of the harsh conditions that make the region both difficult and expensive to access for most of the year, field measurements in the AO are relatively limited. Luckily, satellite remote sensing can supplement limited in situ measurements by imaging the ocean surface from space. However, because of the unique oceanic optical conditions and phytoplankton photophysiology, global ocean color algorithms fail to accurately estimate Chl a when applied to the AO. Hence, this dissertation work utilizes in situ bio-optical measurements to inform accurate parameterization of ocean color algorithms which are then applied to assess long term changes of AO NPP. To understand the phytoplankton photophysiological responses to environmental changes as the Arctic Ocean shifts seasonally from ice-covered to open water, we evaluated photoacclimation strategies of phytoplankton during the low-light, high-nutrient, ice-covered spring and the high-light, low-nutrient, ice-free summer (Chapter 2). Field results show that phytoplankton effectively acclimated to reduced irradiance beneath the sea ice and that abundant nutrients enable pre-bloom phytoplankton to become "primed" for increases in irradiance. I used these bio-optical measurements to characterize regional and seasonal patterns in phytoplankton photophysiology and optical conditions to examine the impact on ocean color remote sensing in the Chukchi Sea (Chapter 1) and the AO (Chapter 3). Results show that phytoplankton pigment packaging (an acclimation to low light) and high absorption by colored dissolved organic matter (CDOM), especially on the interior shelves, cause default ocean color ocean algorithms to overestimate chlorophyll a (Chl a) at low phytoplankton biomass, but underestimate at high biomass throughout the AO. By assembling the largest database of in situ measurements for these waters, I successfully parameterized multiple ocean color algorithms to optimize retrievals of Chl a, absorption by CDOM and detritus, and backscattering of particles. Using the new ocean color algorithm parameterized for the Arctic Ocean, we show that primary production increased by 57% between 1998 and 2018 (Chapter 4). Surprisingly, while increases were due to widespread sea ice loss during the first decade, the subsequent rise in primary production was driven primarily by increased phytoplankton concentration, which could only be sustained by an influx of new nutrients. This suggests a future Arctic Ocean that, as long as there are enough nutrients, can support higher trophic-level production and additional carbon export. Together, the results of this dissertation demonstrate that the unique bio-optical properties of the AO must be addressed in order to accurately employ satellite remote sensing and, when doing so, we reveal dramatic ecosystem changes in response to anthropogenic climate change.

Download or read book On The Biophysical Factors That Control Under Ice Phytoplankton Bloom Onset in the Central Canadian Archipelago written by Matthew Gale and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Influence of Climate Change on the Changing Arctic and Sub Arctic Conditions written by Jacques Nihoul and published by Springer. This book was released on 2009-01-25 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current warming trends in the Arctic may shove the Arctic system into a seasonally ice-free state not seen for more than one million years. The melting is accelerating, and researchers were unable to identify natural processes that might slow the deicing of the Arctic. Such substantial additional melting of Arctic and Antarctic glaciers and ice sheets would raise the sea level worldwide, flooding the coastal areas where many of the world's population lives. Studies, led by scientists at the National Center for Atmospheric Research (NCAR) and the University of Arizona, show that greenhouse gas increases over the next century could warm the Arctic by 3-5°C in summertime. Thus, Arctic summers by 2100 may be as warm as they were nearly 130,000 years ago, when sea levels eventually rose up to 6 m higher than today.

Download or read book Controls on Polar Ice Algal Communities and Their Coupling to Spring Phytoplankton Communities written by Virginia Selz and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Sea ice algae, primary producers inhabiting sea ice, are a vital food source for upper trophic levels in spring prior to the development of summer phytoplankton blooms. As ice algae melt out of the sea ice they are eaten by zooplankton, exported to the benthos, or hypothesized to remain in the water column and seed phytoplankton blooms. Over the last few decades, ice conditions have dramatically changed on regional scales in the Arctic and Antarctic. This dissertation work seeks to understand how these drastic environmental changes impact early spring primary producers. Even though ice algal measurements have increased in recent years, they are still relatively scarce given the hostile nature of polar regions. In this dissertation, I expand ice algal measurements in the Chukchi Sea pack ice and provide the first measurements of spring ice algae along the west Antarctic Peninsula, while advancing our understanding of the linkages between ice algal and phytoplankton communities in polar oceans using a combination of fieldwork and ecosystem modeling. In the Arctic, I characterized the biomass, physiology, and community composition of the spring ice algal bloom and identified drivers of bloom decline in the Chukchi Sea. Furthermore, I explored the ice algal seeding hypothesis using multivariate statistical analyses and growth model simulations constrained with paired ice and water column taxonomic composition and algal physiology field data (Chapter 1). To go beyond annual snapshots of ice algal communities, I applied a 1-D sea ice ecosystem state model to the Chukchi Sea region and examined how changing sea ice conditions impacted ice algal production over the 1980 to 2015 period (Chapter 2). Results from these studies suggest that ice algal production has decreased 22% over time due to sea ice melting earlier in the spring season. Ice algal production is likely to continue to decline into the future as ice continues to melt earlier in spring. Our field study suggests that declines in Chukchi Sea ice algal communities will have little effect on the timing of under-ice phytoplankton blooms. In the Antarctic (Chapter 3), I characterized the taxonomic composition and physiological characteristics of the high biomass slush ice layer and used a combination of experiments to explore the fate of ice algae following ice melt. Combined, results from field samples and experiments suggest that the sea ice environment along the wAP does act as a reservoir and seeds water column populations of certain taxa that are better adapted to both low and high light conditions than their water column counterparts in spring. However, the dominant taxa seeded by sea ice has a higher sinking rate compared to other phytoplankton groups and therefore sinks following ice melt and does not persist in phytoplankton and contribute to summer phytoplankton blooms. Comparison of the ice algal communities and the linkages between ice algae and phytoplankton communities of the Arctic and Southern Oceans shows lower trophic level responses to environmental change in polar marine ecosystems are diverse and dependent on the system in question. Understanding how physical and biological drivers impact lower trophic levels is important to advance our knowledge on how continued climatic change will impact regional food web processes as well as broader global biogeochemical cycles.

Download or read book Microbiology of the Rapidly Changing Polar Environments written by Julie Dinasquet and published by Frontiers Media SA. This book was released on 2018-07-05 with total page 315 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marine and freshwater polar environments are characterized by intense physical forces and strong seasonal variations. The persistent cold and sometimes inhospitable conditions create unique ecosystems and habitats for microbial life. Polar microbial communities are diverse productive assemblages, which drive biogeochemical cycles and support higher food-webs across the Arctic and over much of the Antarctic. Recent studies on the biogeography of microbial species have revealed phylogenetically diverse polar ecotypes, suggesting adaptation to seasonal darkness, sea-ice coverage and high summer irradiance. Because of the diversity of habitats related to atmospheric and oceanic circulation, and the formation and melting of ice, high latitude oceans and lakes are ideal environments to investigate composition and functionality of microbial communities. In addition, polar regions are responding more dramatically to climate change compared to temperate environments and there is an urgent need to identify sensitive indicators of ecosystem history, that may be sentinels for change or adaptation. For instance, Antarctic lakes provide useful model systems to study microbial evolution and climate history. Hence, it becomes essential and timely to better understand factors controlling the microbes, and how, in turn, they may affect the functioning of these fragile ecosystems. Polar microbiology is an expanding field of research with exciting possibilities to provide new insights into microbial ecology and evolution. With this Research Topic we seek to bring together polar microbiologists studying different aquatic systems and components of the microbial food web, to stimulate discussion and reflect on these sensitive environments in a changing world perspective.

Download or read book Sailing Bear Cub written by Paula C. Vickery and published by FriesenPress. This book was released on 2022-01-13 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using offshore sailing as an analogy to sailing ones’ own life, the author reflects back on her life-long affiliation with water and boats and how they are intertwined with relationships in her life. From one woman’s perspective, this memoir describes how a family built a sailboat, cut society’s comfort cord and began a five-year sailing adventure to the South Pacific. This memoir is an excellent read for sailing “doers, doners, and dreamers”. It is full of adventure, and humor. The author was able to glean an awareness and insight into many cultures in Oceania and shares descriptive experiences with people she encountered. It is a glimpse of off the beaten track places. The author describes an extraordinary life that most people can’t even fathom, as well as lessons she learned and how she coped while the winds of life were filling her sails.

Download or read book The Organic Carbon Cycle in the Arctic Ocean written by Rüdiger Stein and published by Springer Science & Business Media. This book was released on 2011-06-27 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flux, preservation, and accumulation of organic carbon in marine systems are controlled by various mechanisms including primary p- duction of the surface water, supply of terrigenous organic matter from the surrounding continents, biogeochemical processes in the water column and at the seafloor, and sedimentation rate. For the world's oceans, phytoplankton productivity is by far the largest organic carbon 9 source, estimated to be about 30 to 50 Gt (10 tonnes) per year (Berger et al. 1989; Hedges and Keil 1995). By comparison, rivers contribute -1 about 0. 15 to 0. 23 Gt y of particulate organi.

Download or read book Unraveling Mechanisms Underlying Annual Plankton Blooms in the North Atlantic and Their Implications for Biogenic Aerosol Properties and Cloud Formation written by Kristina Dee Anne Mojica and published by Frontiers Media SA. This book was released on 2021-11-23 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ocean Biogeochemistry written by Michael J.R. Fasham and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oceans account for 50% of the anthropogenic CO2 released into the atmosphere. During the past 15 years an international programme, the Joint Global Ocean Flux Study (JGOFS), has been studying the ocean carbon cycle to quantify and model the biological and physical processes whereby CO2 is pumped from the ocean's surface to the depths of the ocean, where it can remain for hundreds of years. This project is one of the largest multi-disciplinary studies of the oceans ever carried out and this book synthesises the results. It covers all aspects of the topic ranging from air-sea exchange with CO2, the role of physical mixing, the uptake of CO2 by marine algae, the fluxes of carbon and nitrogen through the marine food chain to the subsequent export of carbon to the depths of the ocean. Special emphasis is laid on predicting future climatic change.

Download or read book The Ocean and Cryosphere in a Changing Climate written by Intergovernmental Panel on Climate Change (IPCC) and published by Cambridge University Press. This book was released on 2022-04-30 with total page 755 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Methods of Seawater Analysis written by Klaus Grasshoff and published by John Wiley & Sons. This book was released on 2009-07-30 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the book first appeared in 1976, Methods of Seawater Analysis has found widespread acceptance as a reliable and detailed source of information. Its second extended and revised edition published in 1983 reflected the rapid pace of instrumental and methodological evolution in the preceding years. The development has lost nothing of its momentum, and many methods and procedures still suffering their teething troubles then have now matured into dependable tools for the analyst. This is especially evident for trace and ultra-trace analyses of organic and inorganic seawater constituents which have diversified considerably and now require more space for their description than before. Methods to determine volatile halocarbons, dimethyl sulphide, photosynthetic pigments and natural radioactive tracers have been added as well as applications of X-ray fluorescence spectroscopy and various electrochemical methods for trace metal analysis. Another method not previously described deals with the determination of the partial pressure of carbon dioxide as part of standardised procedures to describe the marine CO2 system.

Download or read book Real time Coastal Observing Systems for Marine Ecosystem Dynamics and Harmful Algal Blooms written by Babin, Marcel and published by UNESCO. This book was released on 2008-06-05 with total page 880 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proliferation of harmful phytoplankton in marine ecosystems can cause massive fish kills, contaminate seafood with toxins, impact local and regional economies and dramatically affect ecological balance. Real-time observations are essential for effective short-term operational forecasting, but observation and modelling systems are still being developed. This volume provides guidance for developing real-time and near real-time sensing systems for observing and predicting plankton dynamics, including harmful algal blooms, in coastal waters. The underlying theory is explained and current trends in research and monitoring are discussed.Topics covered include: coastal ecosystems and dynamics of harmful algal blooms; theory and practical applications of in situ and remotely sensed optical detection of microalgal distributions and composition; theory and practical applications of in situ biological and chemical sensors for targeted species and toxin detection; integrated observing systems and platforms for detection; diagnostic and predictive modelling of ecosystems and harmful algal blooms, including data assimilation techniques; observational needs for the public and government; and future directions for research and operations.

Download or read book The Ecology of Phytoplankton written by C. S. Reynolds and published by Cambridge University Press. This book was released on 2006-05-04 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: This important new book by Colin Reynolds covers the adaptations, physiology and population dynamics of phytoplankton communities. It provides basic information on composition, morphology and physiology of the main phyletic groups represented in marine and freshwater systems and in addition reviews recent advances in community ecology.

Download or read book The Pacific Arctic Region written by Jacqueline M. Grebmeier and published by Springer. This book was released on 2014-06-10 with total page 461 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Pacific Arctic region is experiencing rapid sea ice retreat, seawater warming, ocean acidification and biological response. Physical and biogeochemical modeling indicates the potential for step-function changes to the overall marine ecosystem. This synthesis book was coordinated within the Pacific Arctic Group, a network of international partners working in the Pacific Arctic. Chapter topics range from atmospheric and physical sciences to chemical processing and biological response to changing environmental conditions. Physical and biogeochemical modeling results highlight the need for data collection and interdisciplinary modeling activities to track and forecast the changing ecosystem of the Pacific Arctic with climate change.

Download or read book Second Assessment of Climate Change for the Baltic Sea Basin written by The BACC II Author Team and published by Springer. This book was released on 2015-04-03 with total page 515 pages. Available in PDF, EPUB and Kindle. Book excerpt: ​This book is an update of the first BACC assessment, published in 2008. It offers new and updated scientific findings in regional climate research for the Baltic Sea basin. These include climate changes since the last glaciation (approx. 12,000 years ago), changes in the recent past (the last 200 years), climate projections up until 2100 using state-of-the-art regional climate models and an assessment of climate-change impacts on terrestrial, freshwater and marine ecosystems. There are dedicated new chapters on sea-level rise, coastal erosion and impacts on urban areas. A new set of chapters deals with possible causes of regional climate change along with the global effects of increased greenhouse gas concentrations, namely atmospheric aerosols and land-cover change. The evidence collected and presented in this book shows that the regional climate has already started to change and this is expected to continue. Projections of potential future climates show that the region will probably become considerably warmer and wetter in some parts, but dryer in others. Terrestrial and aquatic ecosystems have already shown adjustments to increased temperatures and are expected to undergo further changes in the near future. The BACC II Author Team consists of 141 scientists from 12 countries, covering various disciplines related to climate research and related impacts. BACC II is a project of the Baltic Earth research network and contributes to the World Climate Research Programme.

Download or read book Sea Ice written by David N. Thomas and published by John Wiley & Sons. This book was released on 2017-03-06 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.