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  • 1
    Online-Ressource
    Online-Ressource
    Austin :University of Texas Press,
    Schlagwort(e): Electronic books.
    Beschreibung / Inhaltsverzeichnis: No detailed description available for "Environmental Studies of a Marine Ecosystem".
    Materialart: Online-Ressource
    Seiten: 1 online resource (269 pages)
    Ausgabe: 1st ed.
    ISBN: 9780292772793
    Sprache: Englisch
    Anmerkung: Intro -- Contributors -- Foreword -- Preface -- Overview -- 1. Introduction -- 2. Marine Pelagic Environment -- 3. Pelagic Biota -- 4. Marine Benthic Environment -- 5. Benthic Biota -- 6. Ecosystem Characteristics -- Appendix A. Overall Base Line Results -- Appendix B. Maps of Variables' Geographic Distributions -- References -- Index.
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  • 2
    Publikationsdatum: 2021-02-08
    Beschreibung: As plastic waste pollutes the oceans and fish stocks decline, unseen below the surface another problem grows: deoxygenation. Breitburg et al. review the evidence for the downward trajectory of oxygen levels in increasing areas of the open ocean and coastal waters. Rising nutrient loads coupled with climate change—each resulting from human activities—are changing ocean biogeochemistry and increasing oxygen consumption. This results in destabilization of sediments and fundamental shifts in the availability of key nutrients. In the short term, some compensatory effects may result in improvements in local fisheries, such as in cases where stocks are squeezed between the surface and elevated oxygen minimum zones. In the longer term, these conditions are unsustainable and may result in ecosystem collapses, which ultimately will cause societal and economic harm.
    Materialart: Article , PeerReviewed
    Format: text
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Publikationsdatum: 2024-02-07
    Beschreibung: Highlights: • The epoch of the Anthropocene, a period during which human activity has been the dominant influence on climate and the environment, has witnessed a decline in oxygen concentrations and an expansion of oxygen-depleted environments in both coastal and open ocean systems since the middle of the 20th century. • This review paper provides a synthesis of system-specific drivers of low oxygen in a range of case studies representing marine systems in the open ocean, on continental shelves, in enclosed seas and in the coastal environment. • Identification of similar and contrasting responses within and across system types and corresponding oxygen regimes is shown to be informative both in understanding and isolating key controlling processes and provides a sound basis for predicting change under anticipated future conditions. • Case studies were selected to achieve a balance in system diversity and global coverage. • Each case study describes system attributes, including the present-day oxygen environment and known trends in oxygen concentrations over time. • Central to each case study is the identification of the physical and biogeochemical processes that determine oxygen concentrations through the tradeoff between ventilation and respiration. • Spatial distributions of oxygen and time series of oxygen data provide the opportunity to identify trends in oxygen availability and have allowed various drivers of low oxygen to be distinguished through correlative and causative relationships. • Deoxygenation results from a complex interplay of hydrographic and biogeochemical processes and the superposition of these processes, some additive and others subtractive, makes attribution to any particular driver challenging. • System-specific models are therefore required to achieve a quantitative understanding of these processes and of the feedbacks between processes at varying scales. Abstract: The epoch of the Anthropocene, a period during which human activity has been the dominant influence on climate and the environment, has witnessed a decline in oxygen concentrations and an expansion of oxygen-depleted environments in both coastal and open ocean systems since the middle of the 20th century. This paper provides a review of system-specific drivers of low oxygen in a range of case studies representing marine systems in the open ocean, on continental shelves, in enclosed seas and in the coastal environment. Identification of similar and contrasting responses within and across system types and corresponding oxygen regimes is shown to be informative both in understanding and isolating key controlling processes and provides a sound basis for predicting change under anticipated future conditions. Case studies were selected to achieve a balance in system diversity and global coverage. Each case study describes system attributes, including the present-day oxygen environment and known trends in oxygen concentrations over time. Central to each case study is the identification of the physical and biogeochemical processes that determine oxygen concentrations through the tradeoff between ventilation and respiration. Spatial distributions of oxygen and time series of oxygen data provide the opportunity to identify trends in oxygen availability and have allowed various drivers of low oxygen to be distinguished through correlative and causative relationships. Deoxygenation results from a complex interplay of hydrographic and biogeochemical processes and the superposition of these processes, some additive and others subtractive, makes attribution to any particular driver challenging. System-specific models are therefore required to achieve a quantitative understanding of these processes and of the feedbacks between processes at varying scales.
    Materialart: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Ecology, Evolution, and Systematics 33 (2002), S. 235-263 
    ISSN: 0066-4162
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract The second largest zone of coastal hypoxia (oxygen-depleted waters) in the world is found on the northern Gulf of Mexico continental shelf adjacent to the outflows of the Mississippi and Atchafalaya Rivers. The combination of high freshwater discharge, wind mixing, regional circulation, and summer warming controls the strength of stratification that goes through a well-defined seasonal cycle. The physical structure of the water column and high nutrient loads that enhance primary production lead to an annual formation of the hypoxic water mass that is dominant from spring through late summer. Paleoindicators in dated sediment cores indicate that hypoxic conditions likely began to appear around the turn of the last century and became more severe since the 1950s as the nitrate flux from the Mississippi River to the Gulf of Mexico tripled. Whereas increased nutrients enhance the production of some organisms, others are eliminated from water masses (they either emigrate from the area or die) where the oxygen level falls below 2 mg l-1 or lower for a prolonged period. A hypoxia-stressed benthos is typified by short-lived, smaller surface deposit-feeding polychaetes and the absence of marine invertebrates such as pericaridean crustaceans, bivalves, gastropods, and ophiuroids. The changes in benthic communities, along with the low dissolved oxygen, result in altered sediment structure and sediment biogeochemical cycles. Important fisheries are variably affected by increased or decreased food supplies, mortality, forced migration, reduction in suitable habitat, increased susceptibility to predation, and disruption of life cycles.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 368 (1994), S. 619-621 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The Mississippi river, the largest river of the North American continent, drains 40% of the conterminous United States, and is third, sixth and eighth largest in the world in terms of length, sediment yield and discharge, respectively6. Land-use changes this century have resulted in a doubling of ...
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Publikationsdatum: 2016-10-25
    Beschreibung: We establish the cyst-theca relationship of the cyst species Trinovantedinium pallidifulvum Matsuoka 1987 based on germination experiments of specimens isolated from the Gulf of Mexico. We show that the motile stage is a new species, designated as Protoperidinium louisianensis. We also determine its phylogenetic position based on single-cell PCR of a single cell germinated from the Gulf of Mexico cysts. To further refine the phylogeny, we determined the LSU sequence through single-cell PCR of the cyst Selenopemphix undulata isolated from Brentwood Bay (Saanich Inlet, BC, Canada). The phylogeny shows that P. louisianensis is closest to P. shanghaiense, the motile stage of T. applanatum, and is consistent with the monophyly of the genus Trinovantedinium. Selenopemphix undulata belongs to a different clade than Selenopemphix quanta (alleged cyst of P. conicum), suggesting that the genus Selenopemphix is polyphyletic.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    Publikationsdatum: 2019-07-17
    Beschreibung: Azadinium poporum produces a variety of azaspiracids and consists of several ribotypes, but information on its biogeography is limited. A strain of A. poporum (GM29) was incubated from a Gulf of Mexico sediment sample. Strain GM29 was characterized by a plate pattern of po, cp, x, 4′, 3a, 6″, 6C, 5S, 6‴, 2⁗, a distinct ventral pore at the junction of po and the first two apical plates, and a lack of an antapical spine, thus fitting the original description of A. poporum. The genus Azadinium has not been reported in waters of the United States of America before this study. Molecular phylogeny, based on large subunit ribosomal DNA (LSU rDNA) and internal transcribed spacer (ITS) sequences, reveals that strain GM29 is nested within the well-resolved A. poporum complex, but forms a sister clade either to ribotype B (ITS) or ribotype C (LSU). It is, therefore, designated as a new ribotype, termed as ribotype D. LSU and ITS sequences similarity among different ribotypes of A. poporum ranges from 95.4% to 98.2%, and from 97.1% to 99.2% respectively, suggesting that the LSU fragment is a better candidate for molecular discrimination. Azaspiracid profiles were analyzed using LC–MS/MS and demonstrate that strain GM29 produces predominantly AZA-2 with an amount of 45 fg/cell. The results suggest that A. poporum has a wide distribution and highlights the risk potential of azaspiracid intoxication in the United States.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    facet.materialart.
    Unbekannt
    NOAA/National Centers for Coastal Ocean Science | Silver Spring, MD
    In:  http://aquaticcommons.org/id/eprint/14643 | 403 | 2014-02-24 00:12:08 | 14643 | United States National Ocean Service
    Publikationsdatum: 2021-06-30
    Beschreibung: Nutrient overenrichment from human activities is one of the major stresses affecting coastal ecosystems. There is increasing concern in many areas around the world that an oversupply of nutrients from multiple sources is having pervasive ecological effects on shallow coastal and estuarine areas. These effects include reduced light penetration, loss of aquatic habitat, harmfid algal blooms, a decrease in dissolved oxygen (or hypoxia), and impacts on living resources. The largest zone of oxygen-depleted coastal waters in the United States, and the entire western Atlantic Ocean, is found in the northern Gulf of Mexico on the Louisiana-Texas continental shelf. This zone is influenced by the freshwater discharge and nutrient flux of the Mississippi River system.This report describes the seasonal, interannual, and long-term variability in hypoxia in the northern Gulf of Mexico and its relationship to nutrient loading. It also documents the relative roles of natural and human-induced factors in determining the size and duration of the hypoxic zone.
    Schlagwort(e): Ecology ; Environment ; Fisheries ; Management
    Repository-Name: AquaDocs
    Materialart: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 167
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    facet.materialart.
    Unbekannt
    Louisiana Universities Marine Consortium | Chauvin, LA
    In:  http://aquaticcommons.org/id/eprint/26966 | 30 | 2020-02-21 19:30:30 | 26966 | Louisiana Universities Marine Consortium (LUMCON)
    Publikationsdatum: 2021-07-24
    Beschreibung: In June 1985, a focused study was initiated to assess the spatial and temporal extent, intensity, and potential causes of oxygen depletion in the northern Gulf of Mexico. Hypoxic bottom waters were studied along two transects (one off Cat Island Pass near Cocodrie and one off Belle Pass off Port Fourchon) in the Mississippi River Delta Bight area. Eight 2-day cruises were conducted aboard the R/V R.J. Russell or the R/V Pelican along these two transects between mid-June and mid-October. Sampling was most intense (bi-weekly) from mid-June through early September. A reduced sampling scheme (4 stations along the Cat Island Pass transect) was continued through the end of the year. In addition, two shelf-wide cruises were conducted from the Mississippi River to the Texas border during July and September.
    Beschreibung: Related data report: http://aquaticcommons.org/26970/
    Schlagwort(e): Oceanography ; Gulf of Mexico ; hypoxia
    Repository-Name: AquaDocs
    Materialart: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 146
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    facet.materialart.
    Unbekannt
    Louisiana Universities Marine Consortium | Chauvin, LA
    In:  http://aquaticcommons.org/id/eprint/26970 | 30 | 2020-02-21 19:32:14 | 26970 | Louisiana Universities Marine Consortium (LUMCON)
    Publikationsdatum: 2021-07-24
    Beschreibung: In June 1985, a focused study was initiated to assess the spatial and temporal extent, intensity, and potential causes of oxygen depletion in the northern Gulf of Mexico. Two shelf-wide, quasi-synoptic cruises were conducted from the Mississippi River to the Texas border during mid-July and early September, 1985. Cruises were conducted aboard the R/V Pelican on 15-20 July and 10-13 September. Stations were occupied along ten transects in 5 to 80 m water depth. Stations for Pelican Cruise I extended farther offshore and farther to the west than those for Pelican Cruise II. In addition to these shelf-wide cruises, hypoxic bottom waters were studied more frequently along two transects in the Mississippi River Delta Bight area.
    Beschreibung: Related data report: http://aquaticcommons.org/26966/
    Schlagwort(e): Oceanography ; Gulf of Mexico ; hypoxia
    Repository-Name: AquaDocs
    Materialart: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 150
    Standort Signatur Einschränkungen Verfügbarkeit
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