A Modern Distribution Of Foraminifera To Reconstruct Environmental Change Offshore Galveston Bay Texas
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A Modern Distribution Of Foraminifera To Reconstruct Environmental Change Offshore Galveston Bay Texas
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Author : Solveig H. Schilling
language : en
Publisher:
Release Date : 2022
A Modern Distribution Of Foraminifera To Reconstruct Environmental Change Offshore Galveston Bay Texas written by Solveig H. Schilling and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
Sand is an important resource for coastal engineering. In Texas, many offshore sand deposits are found buried in Holocene fluvial sediments or estuarine environments like tidal channels or bayhead, flood, and ebb tide deltas. Exploring for these resources requires a comprehensive understanding of the depositional system in which they are buried. The distribution of benthic foraminifera can be used to reconstruct the paleoenvironment of sand-bearing Holocene estuary deposits. The Gulf of Mexico foraminifera have long been tied to specific environments, and facies in which one genera of benthic foraminifera is most abundant (i.e., the predominance facies) represent a promising technique to reconstruct paleoenvironment in Holocene cores. Although predominance facies have been well documented in Galveston Bay, to date, there are no equivalent records directly offshore for comparison, leaving the inner shelf assemblage unconstrained. Additionally, no direct comparisons have been made between ancient estuary assemblages and the modern living assemblages in Galveston Bay. To address this knowledge gap, this project examines the environmental evolution of the Trinity River estuary using benthic foraminifera and core data. The foraminifera trends offshore Galveston Bay show a greater diversity compared to estuary samples, which is likely driven by increased salinity on the inner shelf compared to Galveston Bay. The increased diversity of inner shelf assemblages compared to those of the bay can be used for recognizing offshore assemblages as distinct from estuarine samples in core data. Additionally, the comparison of living and Holocene estuary populations shows ancient samples with much higher dominance of Elphidium than is observed in the modern bay. This non-analogue population suggests environmental conditions (likely salinity) in the Holocene Trinity River estuary varied significantly from modern conditions implying a recent environmental change in the bay
Using Foraminiferal Assemblages To Reconstruct Climate Change In The Northwestern Weddell Sea Antarctic Peninsula
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Author : Anastasia Kyrmanidou
language : en
Publisher:
Release Date : 2018
Using Foraminiferal Assemblages To Reconstruct Climate Change In The Northwestern Weddell Sea Antarctic Peninsula written by Anastasia Kyrmanidou and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Antarctic Peninsula (Antarctica) categories.
The overall objective of this dissertation was to investigate the benthic foraminiferal assemblage dynamics of the northwestern part of the Weddell Sea and to utilize them as oceanographic proxies. Spatial and temporal patterns of foraminiferal assemblages are correlated with other proxies in order to reconstruct and better understand Antarctic Peninsula (AP) paleoenvironmental changes, particularly those pertaining to bottom-water circulation, glacial fluctuations, and biological productivity on the eastern margin of the AP (EAP). This area in the northeast Antarctic Peninsula has experienced significant environmental change evidenced by the collapse of both Larsen-A and Larsen -B ice shelves, involving various preconditioned and sequential transitions in cryosphere and ecosystem dynamics. The first project (Chapter 3) presents an expanded foraminiferal and diatom record from Perseverance Drift, northeastern AP. Using benthic foraminifera and diatoms as paleoenvironmental proxies for paleoproductivity and sea ice conditions in the area, a record extending back to 3400 yr BP, constrained via radiocarbon dating of biogenic calcite was produced. The variability of the recor was compared with existing paleoenvironmental marine records of the AP, which recognize Holocene hypsithermal and cooling events, such as the Mid-Holocene Climatic Optimum and the Neoglacial period. Overall, Holocene climatic variability is complex, with warm and cool phasing occurring at different rates and at different times across the AP (Bentley et al., 2009). Based on the foraminiferal and diatom record of Perseverance Drift, this study recognizes two main intervals of climatic variability. The basal unit of the composite core, characterized by high abundances of Globocassidulina spp. Foraminiferal Assemblage (FA), indicates incursions of Weddell Sea Transitional Water over the drift site. This interval implies a period of 'freshening' of the water column, coinciding with an open-marine or seasonally open-marine environment during the middle-to-late Holocene Climatic Optimum. The upper unit of the composite core displays characteristics of slightly colder climatic conditions as indicated by the absence of calcareous foraminifera Globocassiulina spp. FA and the pronounced presence of agglutinated FAs that are indicative of the presence of heavy sea ice. Therefore, this interval is interpreted to represent the onset of Neoglaciation at the northeastern tip of the AP. The main objective of the second project (Chapter 4) was to understand modern trends in the foraminiferal-environmental relationship in order to be able to accurately interpret the environmental conditions represented in paleo-records from the eastern part of the AP (EAP), and more specifically the formerly ice shelf-covered Larsen A embayment. This project compared already published data reporting on modern foraminiferal assemblage distributions from the Larsen A embayment (collected in March 2000) with new data reporting on modern foraminiferal assemblage distributions (collected in March 2012) from approximately the same sampling locations that follow an inshore to offshore transect designed to serve as a spatial approximation for temporal differences in ice shelf coverage over the past several decades. Additionally, down-core (2012) samples were analyzed and compared with the modern datasets in an attempt to obtain longer-term information regarding the foraminiferal communities' status pre-collapse. The main difference within the span of 12 years separating the sampling efforts is the removal of the calcareous component from the foraminiferal dataset in stations from the inner part of the embayment, situated closer to the ice shelf edge. The down-core foraminiferal data, seem to be following the same pattern as observed in the modern datasets, therefore, providing proof of the concept that distance from the ice shelf edge, in combination with the effects of taphonomical dissolution and locally increased food availability, is a factor that can structure the benthic foraminiferal community composition in environments characterized by ice shelf collapse, such as the Larsen A embayment. The third project (Chapter 5) provides an analysis of foraminiferal assemblages collected from sediment core GC16B near the northern margin of Larsen C ice shelf. Foraminiferal analysis of samples collected from this core revealed a diverse assemblage of calcareous benthic foraminiferal taxa in the upper 20 cm of the core, with very low contribution from agglutinated forms. Owing to the very low absolute diatom abundance values that characterize the core, the high abundance of planktonic foraminiferal taxa relative to benthic foraminiferal taxa, and the dominance patterns of the benthic foraminiferal taxa, different hypothesis pertaining to the source of productivity in this sub-ice shelf environment have been employed involving the transport of advected food supply from the open Weddell Sea and the response of the foraminiferal fauna to less productive (than labile) organic matter as their food source.
Coastal Signals Of Environmental Changes Foraminifera As Benthic Monitors
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Author : Inda Brinkmann
language : en
Publisher:
Release Date : 2022
Coastal Signals Of Environmental Changes Foraminifera As Benthic Monitors written by Inda Brinkmann and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
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.
Ecology And Applications Of Benthic Foraminifera
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Author : John W. Murray
language : en
Publisher: Cambridge University Press
Release Date : 2006-10-26
Ecology And Applications Of Benthic Foraminifera written by John W. Murray and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006-10-26 with Science categories.
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Quantifying Holocene Sea Level Change Using Intertidal Foraminifera
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Author : Benjamin P. Horton
language : en
Publisher:
Release Date : 2006
Quantifying Holocene Sea Level Change Using Intertidal Foraminifera written by Benjamin P. Horton and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Foraminifera, Fossil categories.
Petroleum Abstracts Literature And Patents
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Author :
language : en
Publisher:
Release Date : 1990
Petroleum Abstracts Literature And Patents written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with Petroleum categories.
Estuarine And Coastal Marine Waters
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Author :
language : en
Publisher:
Release Date : 2000
Estuarine And Coastal Marine Waters written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with Ecological risk assessment categories.
Late Quaternary Stratigraphic Evolution Of The Northern Gulf Of Mexico Margin
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Author : John B. Anderson
language : en
Publisher: SEPM Soc for Sed Geology
Release Date : 2004
Late Quaternary Stratigraphic Evolution Of The Northern Gulf Of Mexico Margin written by John B. Anderson and has been published by SEPM Soc for Sed Geology this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with Science categories.
Late Quaternary stratigraphic evolution of the north Gulf of Mexico margin : a synthesis -- High-resolution stratigraphy of a sandy, ramp-type margin, Apalachicola, Florida -- Late Quaternary stratigraphic evolution of the Alabama-west Florida outher continental shelf -- late Quaternary geology of the northeastern Gulf of Mexico shelf : sedimentology, depositional history, and ancient analogs of a major shelf sand sheet of teh modern transgressive systems tract -- Sequence stratigraphy of a continental margin subjected to low-energy and low-sediment-supply environmental boundary conditions : late Pleistocene-Holocene deposition offshore Alabama -- Late Quaternary deposition and paleobathymetry at the shelf-slope transition, ancestral Mobile River delta complex, northeastern Gulf of Mexico -- Depositional architecture of the Lagniappe Delta : sediment characteristics, timing of depositional events, and temporal relations with adjacent shelf-edge deltas -- Foraminiferal biostratigraphy and paleoenvironments of the Pleistocene Lagniappe Delta and related section, northeastern Gulf of Mexico -- Late Quaternary stratigraphic evolution of the west Lousiana-east Texas continental shelf -- Late Quaternary Brazos and Colorado deltas, offshore Texas, their evolution and the factors that controlled their deposition -- Late Quaternary evolution of the wave-storm-dominated Central Texas Shelf -- Late Quaternary evolution of the Rio Grande Delta.
Encyclopedia Of Coastal Science
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Author : M. Schwartz
language : en
Publisher: Springer Science & Business Media
Release Date : 2006-11-08
Encyclopedia Of Coastal Science written by M. Schwartz and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006-11-08 with Science categories.
This new Encyclopedia of Coastal Science stands as the latest authoritative source in the field of coastal studies, making it the standard reference work for specialists and the interested lay person. Unique in its interdisciplinary approach. This Encyclopedia features contributions by 245 well-known international specialists in their respective fields and is abundantly illustrated with line-drawings and photographs. Not only does this volume offer an extensive number of entries, it also includes various appendices, an illustrated glossary of coastal morphology and extensive bibliographic listings.
Ecology And Palaeoecology Of Benthic Foraminifera
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Author : John W. Murray
language : en
Publisher: Routledge
Release Date : 2014-10-13
Ecology And Palaeoecology Of Benthic Foraminifera written by John W. Murray and has been published by Routledge this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-10-13 with Science categories.
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.