Shallow-water Benthic Foraminifera as Proxy for Natural Versus Human-induced Environmental Change PDF Download

Author:
Publisher:
ISBN: 9789057441363
Category :
Languages : en
Pages : 152

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Author: Irina Polovodova Asteman
Publisher: Sudwestdeutscher Verlag Fur Hochschulschriften AG
ISBN: 9783838131757
Category :
Languages : en
Pages : 128

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The Baltic Sea ecosystem undergoes a high environmental variability due to the occasional ventilation of deep water by highly saline Kattegat water, which enters the Baltic through the narrow and shallow Danish Straits. During the past two decades, the frequency of major inflows decreased and led to extended periods of stagnation with reduced deep-water oxygenation. At the same time, a growing economy caused a significant anthropogenic pollution in the area. The anthropogenic influx of different pollutants caused eutrophication, oxygen depletion and left elevated levels of trace metals in the sediments. These environmental changes are seen today at all trophic levels of living organisms and affected even one of the smallest inhabitants of the Baltic Sea: benthic foraminifera. In this thesis, foraminifera are evaluated as proxies of recent environmental change of both natural and anthropogenic origin in two shallow fjords of the Kiel Bight (SW Baltic Sea).

Author: Inda Brinkmann
Publisher:
ISBN: 9789187847677
Category :
Languages : en
Pages : 0

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Climate changes, tightly linked to anthropogenic activities, are significantly altering environments and ecosystems globally, such as by increasing marine and coastal deoxygenation or occurrences of extreme weather events. The significance of paleoenvironmental and -climate reconstructions, as well as monitoring of current conditions, for unravelling baseline natural variation, today's changes and potential future impacts, has been recognised by the Intergovernmental Panel on Climate Change (IPCC) reports. However, to access past records of physical and chemical environmental variables, and comprehensively assess ecosystem reactions, reliable and sensitive proxies are critical. This thesis' focus lies on benthic foraminifera--unicellular protists with mineralised or organic test, abundantly inhabiting ocean and coastal sediments--and their calibration as indicator for a variety of environmental conditions in field-sampling approaches. The research projects follow two general strategic tracks: (I) a biogeochemical assessment of trace-elemental ratios in foraminiferal calcium-carbonate tests using high-resolution, micro-analytical techniques; (II) a molecular approach investigating foraminiferal environmental DNA derived from coastal sediments. Papers I and II concern the calibration of the benthic foraminiferal Mn/Ca proxy for marine oxygenation conditions in modern field studies. Trace-element concentrations and distributions were measured by plasma-, laser- and synchrotron-based analyses in a high-resolution, individual-foraminifera approach, and interpreted in the context of ambient physical and chemical conditions of the water column, pore-waters and sediments (including oxygen and manganese concentrations). Investigating two coastal systems with almost permanently severely oxygen-deficient bottom-waters (Santa Barbara Basin, Paper I), and undergoing a seasonal oxygenation cycle across the low- to well-oxygenated range (Gullmar Fjord, Paper II), respectively, demonstrated the utility of the Mn/Ca proxy for indicating low-oxygen conditions specifically. Continued calibration efforts under consideration of ambient oxygenation and redox regimes may open further possibilities of quantitative oxygen reconstructions. Paper III explores the use of coastal, benthic Ba/Ca records as indicator of riverine runoff and drought on land across the years 2018 and 2019, characterised by severe heat and drought, and warm and wet conditions, respectively. Benthic Ba/Ca correlated significantly with the hydroclimate conditions, as inferred from extensive meteorological and hydrological data sets of the region, highlighting qualitative proxy potential for paleo-drought reconstructions. Based on ambient sediment and pore-water geochemistry, we discuss mediation of water-column transport and pore-water Ba cycling by Fe and Mn oxides. All three investigations of these geochemical proxies (Paper I-III) highlighted the significance of biological controls on foraminiferal TE/Ca, which are species-specific and, thus, should be a deciding factor in choosing proxy candidate species. In particular the influences of micro-habitat distribution and utilised metabolic pathways by foraminifera are discussed in detail. In Paper IV foraminiferal biodiversity and assemblage responses to natural and anthropogenic environmental trends in a fjord system (Swedish west coast) are documented in a metabarcoding approach. Environmental DNA successfully tracked biodiversity and community composition changes associated with contrasting ecosystems but showed damped sensitivity to environmental variability on sub-annual time-scales. Overlaps and discrepancies between molecular and traditional, observation-based assessment techniques, as well as future trajectories to resolve uncertainties are discussed. Overall, this thesis solidifies and expands the currently available proxy toolbox for reconstructions of both coastal low-oxygen, as well as terrestrial hydroclimate conditions. The findings contribute towards filling current knowledge gaps pertaining to biotic impacts on foraminifera-derived biogeochemical signals and methodological uncertainties in metabarcoding approaches and highlight the significance of implementing molecular techniques in conventional foraminiferal assemblage studies.

Author: Barun K. Sen Gupta
Publisher: Springer Science & Business Media
ISBN: 0306481049
Category : Science
Languages : en
Pages : 368

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From the reviews: "This is now the definitive, authoritative text on applied foraminiferal micropaleontology and should be in the library of all practicing micropaleontologists." (William A. Berggren, Woods Hole Oceanographic Institution in Micropaleontology, 47:1 (2001)"During the last 20 years there has been an explosion of publications about foraminifera from an amazing variety of disciplines: basic cell biology, algal symbiosis, biomineralization, biogeography, ecology, pollution, chemical oceanography, geochemistry, paleoceanography, and geology. This book summarizes contributions by leading researchers in these diverse fields. It is not just another text on the biology of foraminifera. Rather, Barun Sen Gupta has accomplished his objective to "write an advanced text for university students that would also serve as a reference book for professionals"." (Howard J. Spero, University of California at Davis in Limnology and Oceanography, 45:8 (2000).

Author: John W. Murray
Publisher: Routledge
ISBN: 1317899873
Category : Science
Languages : en
Pages : 408

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This is an important and authoritative review of foraminiferal ecology, the first for over a decade. Professor Murray relates ecological data on living forms of foraminifera to the palaeoecology of fossil species, and defines in detail areas of global distribution.

Author: Fabio Francescangeli
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Foraminifera are unicellular eukaryotes widespread in all marine environments. Modern benthic foraminifera own specific characteristics (i.e., high abundance, high diversity, easy to collect, well preserved) that make them good tools to highlight global and local environmental changes. Over the recent past the estuarine areas of the Hauts-de-France region, experienced differential degree of human disturbance. The principal objectives of this work are within this area, 1) to describe the benthic foraminiferal distributions and 2) to investigate their response to short- (annual and seasonal) and long-term (hundred years) environmental changes. This has been performed across both pristine and anthopogenized intertidal areas of the region. Faunal analyses have been coupled with sedimentological and geochemical analyses, to better understand the control of environmental parameters on driving spatial and temporal variations of benthic foraminifera. Different intertidal living foraminiferal assemblages are distinguished reflecting the main environmental drivers identified in the Hauts-de-France region. Long-term scale observations have allowed distinguishing both natural and human-induced environmental transformations through monitoring benthic foraminiferal changings. The study demonstrates the potential of foraminifera as bioindicators for application in environmental monitoring.

Author: Bruce William Hayward
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 280

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Author: Olugbenga Temitope Fajemila
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: National Research Council
Publisher: National Academies Press
ISBN: 0309054494
Category : Science
Languages : en
Pages : 645

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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.

Author: Jan Zalasiewicz
Publisher: Cambridge University Press
ISBN: 110847523X
Category : Medical
Languages : en
Pages : 385

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Reviews the evidence underpinning the Anthropocene as a geological epoch written by the Anthropocene Working Group investigating it. The book discusses ongoing changes to the Earth system within the context of deep geological time, allowing a comparison between the global transition taking place today with major transitions in Earth history.