Download or read book Biogeochemical Proxies in Scleractinian Corals Used to Reconstruct Ocean Circulation written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We utilize monthly 14C data derived from coral archives in conjunction with ocean circulation models to address two questions: (1) how does the shallow circulation of the tropical Pacific vary on seasonal to decadal time scales and (2) which dynamic processes determine the mean vertical structure of the equatorial Pacific thermocline. Our results directly impact the understanding of global climate events such as the El Nino-Southern Oscillation (ENSO). To study changes in ocean circulation and water mass distribution involved in the genesis and evolution of ENSO and decadal climate variability, it is necessary to have records of climate variables several decades in length. Continuous instrumental records are limited because technology for continuous monitoring of ocean currents has only recently been available, and ships of opportunity archives such as COADS contain large spatial and temporal biases. In addition, temperature and salinity in surface waters are not conservative and thus can not be independently relied upon to trace water masses, reducing the utility of historical observations. Radiocarbon (14C) in sea water is a quasi-conservative water mass tracer and is incorporated into coral skeletal material, thus coral 14C records can be used to reconstruct changes in shallow circulation that would be difficult to characterize using instrumental data. High resolution [Delta]14C timeseries such as these, provide a powerful constraint on the rate of surface ocean mixing and hold great promise to augment onetime surveys such as GEOSECS and WOCE. These data not only provide fundamental information about the shallow circulation of the Pacific, but can be used as a benchmark for the next generation of high resolution ocean models used in prognosticating climate change.
Download or read book Biogeochemical Proxies of Environmental Change in Surface and Deep sea Corals from the Pacific written by Erin Brendan Roark and published by . This book was released on 2005 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Development and Application of Nutrient and Carbonate System Proxies in the Deep Sea Coral Desmophyllum Dianthus written by Eleni Anagnostou and published by . This book was released on 2011 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deep sea corals are a promising paleoceanographic archive because they offer the potential for high temporal resolution and precise absolute dating. This thesis presents the first rigorous development and calibration of geochemical proxies for phosphate, barium, carbonate ion, and pH, recorded as phosphorus to calcium (P/Ca), barium to calcium (Ba/Ca), uranium to calcium (U/Ca) ratios and boron isotopes ([Greek letter delta]11B), respectively, in the skeleton of the deep sea coral Desmophyllum dianthus (D. dianthus). The [Greek letter delta]11B proxy was applied for the first time to a modern coral located within the deep mixed layer of the South Chatham Rise (New Zealand), showing a change in ocean pH as a result of anthropogenic CO2 emissions, in approximate agreement with atmospheric and surface ocean CO2 measurements from this region. The P/Ca, Ba/Ca, and U/Ca proxies were applied to corals dated to 15.4ka and Heinrich 1 (~16.5ka) to reconstruct the history of phosphate, barium, and carbonate ion concentrations at intermediate depths in the northwest Atlantic. The results demonstrate that dissolved phosphate increased and carbonate ion decreased during cold periods, previously characterized by reduced deep water convection and increased meltwater input. This suggests the presence of a nutrient rich and corrosive intermediate southern source water mass (SSW) at 40oN in west Atlantic, in agreement with previous radiocarbon reconstructions. Coral Ba measurements suggest a contemporaneous increase in the North Atlantic dissolved Ba inventory compared to Holocene. Calculations of the mixing ratio between northern and SSW following the 15.4ka event suggest that SSW was the dominant water mass in northwest Atlantic. The 15ka event occurred within ~100y, the life span of the coral. The initial success of these new geochemical tools is encouraging for the utility of D. dianthus as a geochemical paleoceanographic archive. With further development, these proxies could be used to reconstruct aspects of water mass mixing and biogeochemical processes in intermediate-to-deep waters of the Atlantic and Southern Oceans, locations where D. dianthus is most abundant.
Download or read book Coral Biomineralization Climate Proxies and the Sensitivity of Coral Reefs to CO2 driven Climate written by Thomas Mario DeCarlo and published by . This book was released on 2017 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scleractinian corals extract calcium (Ca2+) and carbonate (CO32−) ions from seawater to construct their calcium carbonate (CaCO3) skeletons. Key to the coral biomineralization process is the active elevation of the CO32− concentration of the calcifying fluid to achieve rapid nucleation and growth of CaCO3 crystals. Coral skeletons contain valuable records of past climate variability and contribute to the formation of coral reefs. However, limitations in our understanding of coral biomineralization hinder the accuracy of (1) coral-based reconstructions of past climate, and (2) predictions of coral reef futures as anthropogenic CO2 emissions drive declines in seawater CO32− concentration. In this thesis, I investigate the mechanism of coral biomineralization and evaluate the sensitivity of coral reef CaCO3 production to seawater carbonate chemistry. First, I conducted abiogenic CaCO32− precipitation experiments that identified the U/Ca ratio as a proxy for fluid CO32− concentration. Based on these experimental results, I developed a quantitative coral biomineralization model that predicts temperature can be reconstructed from coral skeletons by combining Sr/Ca - which is sensitive to both temperature and CO32− - with U/Ca into a new proxy called "Sr-U". I tested this prediction with 14 corals from the Pacific Ocean and the Red Sea spanning mean annual temperatures of 25.7-30.1 °C and found that Sr-U has uncertainty of only 0.5 °C, twice as accurate as conventional coral-based thermometers. Second, I investigated the processes that differentiate reef-water and open-ocean carbonate chemistry, and the sensitivity of ecosystem-scale calcification to these changes. On Dongsha Atoll in the northern South China Sea, metabolic activity of resident organisms elevates reef-water CO32− twice as high as the surrounding open ocean, driving rates of ecosystem calcification higher than any other coral reef studied to date. When high temperatures stressed the resident coral community, metabolic activity slowed, with dramatic effects on reef-water chemistry and ecosystem calcification. Overall, my thesis highlights how the modulation of CO32−, by benthic communities on the reef and individual coral polyps in the colony, controls the sensitivity of coral reefs to future ocean acidification and influences the climate records contained in the skeleton.
Download or read book Coral Biomineralization Climate Proxies and the Sensitivity of Coral Reefs to CO2 driven Climate Change written by Thomas Mario DeCarlo and published by . This book was released on 2017 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scleractinian corals extract calcium (Ca2+) and carbonate (CO2−3) ions from seawater to construct their calcium carbonate (CaCO3) skeletons. Key to the coral biomineralization process is the active elevation of the CO2−3 concentration of the calcifying fluid to achieve rapid nucleation and growth of CaCO3 crystals. Coral skeletons contain valuable records of past climate variability and contribute to the formation of coral reefs. However, limitations in our understanding of coral biomineralization hinder the accuracy of (1) coral-based reconstructions of past climate, and (2) predictions of coral reef futures as anthropogenic CO2 emissions drive declines in seawater CO2−3 concentration. In this thesis, I investigate the mechanism of coral biomineralization and evaluate the sensitivity of coral reef CaCO3 production to seawater carbonate chemistry. First, I conducted abiogenic CaCO3 precipitation experiments that identified the U/Ca ratio as a proxy for fluid CO2−3 concentration. Based on these experimental results, I developed a quantitative coral biomineralization model that predicts temperature can be reconstructed from coral skeletons by combining Sr/Ca - which is sensitive to both temperature and CO2−3 - with U/Ca into a new proxy called “Sr-U”. I tested this prediction with 14 corals from the Pacific Ocean and the Red Sea spanning mean annual temperatures of 25.7-30.1°C and found that Sr-U has uncertainty of only 0.5°C, twice as accurate as conventional coral-based thermometers. Second, I investigated the processes that differentiate reef-water and open-ocean carbonate chemistry, and the sensitivity of ecosystem-scale calcification to these changes. On Dongsha Atoll in the northern South China Sea, metabolic activity of resident organisms elevates reef-water CO2−3 twice as high as the surrounding open ocean, driving rates of ecosystem calcification higher than any other coral reef studied to date. When high temperatures stressed the resident coral community, metabolic activity slowed, with dramatic effects on reef-water chemistry and ecosystem calcification. Overall, my thesis highlights how the modulation of CO2−3, by benthic communities on the reef and individual coral polyps in the colony, controls the sensitivity of coral reefs to future ocean acidification and influences the climate records contained in the skeleton.
Download or read book Isotopic and Elemental Tracers of Cenozoic Climate Change written by Germán Mora and published by Geological Society of America. This book was released on 2005-01-01 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Coral Reefs and Climate Change written by Jonathan Turnbull Phinney and published by American Geophysical Union. This book was released on 2006-01-10 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Coastal and Estuarine Studies, Volume 61. The effects of increased atmospheric carbon dioxide and related climate change on shallow coral reefs are gaining considerable attention for scientific and economic reasons worldwide. Although increased scientific research has improved our understanding of the response of coral reefs to climate change, we still lack key information that can help guide reef management. Research and monitoring of coral reef ecosystems over the past few decades have documented two major threats related to increasing concentrations of atmospheric CO2: (1) increased sea surface temperatures and (2) increased seawater acidity (lower pH). Higher atmospheric CO2 levels have resulted in rising sea surface temperatures and proven to be an acute threat to corals and other reef-dwelling organisms. Short periods (days) of elevated sea surface temperatures by as little as 1–2°C above the normal maximum temperature has led to more frequent and more widespread episodes of coral bleaching-the expulsion of symbiotic algae. A more chronic consequence of increasing atmospheric CO2 is the lowering of pH of surface waters, which affects the rate at which corals and other reef organisms secrete and build their calcium carbonate skeletons. Average pH of the surface ocean has already decreased by an estimated 0.1 unit since preindustrial times, and will continue to decline in concert with rising atmospheric CO2. These climate-related Stressors combined with other direct anthropogenic assaults, such as overfishing and pollution, weaken reef organisms and increase their susceptibility to disease.
Download or read book Special Papers written by and published by . This book was released on 2005 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoceanographic Proxy Development in Scleractinia Stony Corals Throughout the Pacific Ocean written by Logan Brenner and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: It is necessary to consider the environmental specifics of a given region before blindly interpreting paleo-proxy data. Furthermore, coral-based proxy records are supremely powerful tools in exploring and uncovering past climate histories of a given region. Coral-records can supplement and extend the limited instrumental record with centuries to millenia long information on SST and hydroclimate. These data can improve climate models, further our knowledge of coral reef growth, and deepen our understanding of regional hydroclimate, which are all vital to our understanding of global climate.
Download or read book Coral Reefs in the Anthropocene Ocean written by Nathaniel Rust Mollica and published by . This book was released on 2021 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anthropogenic emissions of greenhouse gases are driving rapid changes in ocean conditions. Shallow-water coral reefs are experiencing the brunt of these changes, including intensifying marine heatwaves (MHWs) and rapid ocean acidification (OA). Consequently, coral reefs are in broad-scale decline, threatening the livelihoods of hundreds of millions of people. Ensuring survival of coral reefs in the 21st century will thus require a new management approach that incorporates robust understanding of reef-scale climate change, the mechanisms by which these changes impact corals, and their potential for adaptation. In this thesis, I extract information from within coral skeletons to 1) Quantify the climate changes occurring on coral reefs and the effects on coral growth, 2) Identify differences in the sensitivity of coral reefs to these changes, and 3) Evaluate the adaptation potential of the keystone reef-building coral, Porites. First, I develop a mechanistic Porites growth model and reveal the physicochemical link between OA and skeletal formation. I show that the thickening (densification) of coral skeletal framework is most vulnerable to OA and that, under 21st century climate model projections, OA will reduce Porites skeletal density globally, with greatest impact in the Coral Triangle. Second, I develop an improved metric of thermal stress, and use a skeletal bleaching proxy to quantify coral responses to intensifying heatwaves in the central equatorial Pacific (CEP) since 1982. My work reveals a long history of bleaching in the CEP, and reef-specific differences in thermal tolerance linked to past heatwave exposure implying that, over time, reef communities have adapted to tolerate their unique thermal regimes. Third, I refine the Sr-U paleo-thermometer to enable monthly-resolved sea surface temperatures (SST) generation using laser ablation ICPMS. I show that laser Sr-U accurately captures CEP SST, including the frequency and amplitude of MHWs. Finally, I apply laser Sr-U to reconstruct the past 100 years of SST at Jarvis Island in the CEP, and evaluate my proxy record of bleaching severity in this context. I determine that Porites coral populations on Jarvis Island have not yet adapted to the pace of anthropogenic climate change.
Download or read book Modern Ocean Ground Truthing of Nitrogen Isotopes in Scleractinian Corals written by Victoria Hoi-Yee Luu and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Natural Climate Variability on Decade to Century Time Scales written by National Research Council and published by National Academies Press. This book was released on 1996-08-30 with total page 645 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume reflects the current state of scientific knowledge about natural climate variability on decade-to-century time scales. It covers a wide range of relevant subjects, including the characteristics of the atmosphere and ocean environments as well as the methods used to describe and analyze them, such as proxy data and numerical models. They clearly demonstrate the range, persistence, and magnitude of climate variability as represented by many different indicators. Not only do natural climate variations have important socioeconomic effects, but they must be better understood before possible anthropogenic effects (from greenhouse gas emissions, for instance) can be evaluated. A topical essay introduces each of the disciplines represented, providing the nonscientist with a perspective on the field and linking the papers to the larger issues in climate research. In its conclusions section, the book evaluates progress in the different areas and makes recommendations for the direction and conduct of future climate research. This book, while consisting of technical papers, is also accessible to the interested layperson.
Download or read book Physiology and Biogeochemistry of Corals Subjected to Repeat Bleaching and Combined Ocean Acidification and Warming written by Verena Schoepf and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Coral skeletal carbon isotopes are important paleo-climate proxies and have the potential to record past bleaching events. However, they are often confounded by strong kinetic isotope effects that can mask the bleaching signal in the skeleton and compromise overall accuracy of the proxy. A proposed data correction to remove kinetic isotope effects was tested for the first time using bleached corals. In addition, it was tested if photosynthesis to respiration (P/R) ratios can be reliably calculated from coral isotopes. We found that the data correction did not effectively remove kinetic isotope effects, and that isotope-based P/R ratios are in poor agreement with P/R ratios measured by respirometry. Therefore, the data correction should not be routinely applied to paleo-climate reconstruction, and P/R ratios should be obtained by respirometry only.
Download or read book Geochemistry of Slow growing Corals written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Three WHOI fellowships supported my time in the Joint Program: Stanley W. Watson Foundation Fellowship, Paul M. Fye Teaching Fellowship and the Ocean and Climate Change Institute Fellowship (OCCI). Research funding from NSF (OCE-0402728) and WHOI to Konrad Hughen, Anne Cohen, and Michael McCartney supported this project. Research support was also awarded to the author from the OCCI and the education office Ditty Bag Fund.
Download or read book Encyclopedia of Paleoclimatology and Ancient Environments written by Vivien Gornitz and published by Springer Science & Business Media. This book was released on 2008-10-31 with total page 1062 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of Springer’s Major Reference Works, this book gives the reader a truly global perspective. It is the first major reference work in its field. Paleoclimate topics covered in the encyclopedia give the reader the capability to place the observations of recent global warming in the context of longer-term natural climate fluctuations. Significant elements of the encyclopedia include recent developments in paleoclimate modeling, paleo-ocean circulation, as well as the influence of geological processes and biological feedbacks on global climate change. The encyclopedia gives the reader an entry point into the literature on these and many other groundbreaking topics.
Download or read book Corals and Coral Reefs of the Gal pagos Islands written by Peter W. Glynn and published by Univ of California Press. This book was released on 1983-01-01 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: 00 This scientifically thorough,lucidly written work explores the nature, development, and extent of the archipelago's reef-building corals. Also included is an annotated list of the Scleractianian Corals by John W. Wells This scientifically thorough,lucidly written work explores the nature, development, and extent of the archipelago's reef-building corals. Also included is an annotated list of the Scleractianian Corals by John W. Wells
Download or read book Handbook of Environmental Isotope Geochemistry written by Mark Baskaran and published by Springer Science & Business Media. This book was released on 2011-10-13 with total page 944 pages. Available in PDF, EPUB and Kindle. Book excerpt: Applications of radioactive and stable isotopes have revolutionized our understanding of the Earth and near-earth surface processes. The utility of the isotopes are ever-increasing and our sole focus is to bring out the applications of these isotopes as tracers and chronometers to a wider audience so that they can be used as powerful tools to solve environmental problems. New developments in this field remain mostly in peer-reviewed journal articles and hence our goal is to synthesize these findings for easy reference for students, faculty, regulators in governmental and non-governmental agencies, and environmental companies. While this volume maintains its rigor in terms of its depth of knowledge and quantitative information, it contains the breadth needed for wide variety problems and applications in the environmental sciences. This volume presents all of the newer and older applications of isotopes pertaining to the environmental problems in one place that is readily accessible to readers. This book not only has the depth and rigor that is needed for academia, but it has the breadth and case studies to illustrate the utility of the isotopes in a wide variety of environments (atmosphere, oceans, lakes, rivers and streams, terrestrial environments, and sub-surface environments) and serves a large audience, from students and researchers, regulators in federal, state and local governments, and environmental companies.
