A Late Holocene Reconstruction of Coastal Salt Marsh Net Accretion Rates and Environmental Change from Three Sites in Southern Californa PDF Download
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Author: Lauren Nicole Brown
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
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Book Description
Coastal marshes are complex ecogeomorphic feedback systems that require further investigation on the Southern California coast to understand potential responses to sea level rise (SLR). Long-term accretion rates - deposition and erosion of mineral and organic matter - form a basis of understanding processes in the marsh related to SLR responses. From sediment cores, I reconstruct the net accretion rates of three marshes using radiocarbon dating methods and analyze loss on ignition (LOI) data to understand the physical properties of the sedimentary record in the three marshes. Average net accretion rates for Tijuana Estuary are 1.0 ± 0.94 mm yr¬-1, for Upper Newport Bay are 1.0 ± 0.4 mm yr-1, and for Morro Bay are 8.0 ± 8.3 mm yr-1. Over the past 2000 cal YBP, all net accretion rates kept pace or exceed rates of SLR (when compared to historic SLR of 0.6 to 2 mm yr-1); however, only Morro Bay exhibits historic net accretion rates high enough to compare to possible rates of SLR associated with projected sea level gains of 0.3 to 1.6 m on the Pacific coast through 2100. Core stratigraphies indicate marsh conditions change frequently and the current Spartina spp. and Salicornia spp. marsh vegetation communities are geologically recent features in their present locations, existing from 700 to 1000 cal YBP. The future under continued human modification of coastal systems, climate change, and accelerated SLR merit continued research into the dynamics of coastal salt marsh systems on the California coast.
Author: Lauren Nicole Brown
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
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Book Description
Coastal marshes are complex ecogeomorphic feedback systems that require further investigation on the Southern California coast to understand potential responses to sea level rise (SLR). Long-term accretion rates - deposition and erosion of mineral and organic matter - form a basis of understanding processes in the marsh related to SLR responses. From sediment cores, I reconstruct the net accretion rates of three marshes using radiocarbon dating methods and analyze loss on ignition (LOI) data to understand the physical properties of the sedimentary record in the three marshes. Average net accretion rates for Tijuana Estuary are 1.0 ± 0.94 mm yr¬-1, for Upper Newport Bay are 1.0 ± 0.4 mm yr-1, and for Morro Bay are 8.0 ± 8.3 mm yr-1. Over the past 2000 cal YBP, all net accretion rates kept pace or exceed rates of SLR (when compared to historic SLR of 0.6 to 2 mm yr-1); however, only Morro Bay exhibits historic net accretion rates high enough to compare to possible rates of SLR associated with projected sea level gains of 0.3 to 1.6 m on the Pacific coast through 2100. Core stratigraphies indicate marsh conditions change frequently and the current Spartina spp. and Salicornia spp. marsh vegetation communities are geologically recent features in their present locations, existing from 700 to 1000 cal YBP. The future under continued human modification of coastal systems, climate change, and accelerated SLR merit continued research into the dynamics of coastal salt marsh systems on the California coast.
Author: Lauren Brown
Publisher:
ISBN:
Category :
Languages : en
Pages : 240
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Book Description
Coastal salt marsh ecosystems in California are at risk from projected rates of sea-level rise (SLR) of up to an order of magnitude higher than rates seen over the past 6,000 years of stable sea levels (Griggs, Cayan, Tebaldi, Fricker, & rvai, 2017). With rates of this magnitude, salt marsh area, already limited by land use changes in the 19th and 20th centuries, could be completely lost by 2100 (Thorne et al., 2018). To better understand how California salt marshes are adapting to modern acceleration of SLR, over 100 sediment cores were collected from 13 salt marsh sites, ranging from Humboldt Bay to Tijuana River Estuary. Sediment accretion rates over the past several hundred years were measured using radiocesium, radiolead, and radiocarbon dating on 32 cores. Valuation of the carbon storage, an ecosystem service known as blue carbon provided by salt marshes, presents an opportunity to help preserve and restore sites threatened by SLR through carbon credits (Bear, 2017; Callaway, Borgnis, Turner, & Milan, 2012; Mcleod et al., 2011), but there are many questions which much be addressed before this can become a reality for the state of California (Macreadie et al., 2019). A standardized protocol for estimation of carbon content from loss-on-ignition (LOI) was developed with an emphasis on quantifying error and uncertainty in carbon measurements for blue carbon purposes. Using a conversion between soil organic matter and soil organic carbon shown to be effective for California salt marshes, carbon content was estimated through LOI analysis of 61 sediment cores. The impact of climate change in these ecosystems was further explored in the first documented record of a fire in a Pacific coast salt marsh at Mugu Lagoon. California salt marsh sediment accretion averages at 2.93 1.9 mm yr-1, which is lower than average rates from regions such as the US Gulf and East coasts. Rates of accretion and relative SLR (RSLR) show a non-linear relationship with highest accretion occurring at rates of RSLR from 2 - 6 mm yr-1. Linear relationships between SLR and accretion are comparatively weak, but are stronger in the low elevations of salt marsh habitat. Salt marshes in the state annually sequester about 0.08% of state-wide annual greenhouse gas emissions and store about 23% of one year's emissions in their soils (as compared to 2016 emissions). Because of limited area, these habitats will not serve as an effective mitigation strategy at the state level, but loss of this habitat may release up to 27 0.3 Tg stored carbon, potentially valued at about $1.4 billion (using an estimate of $15/tonne CO2 equivalent). Preservation of current habitat through facilitation of sediment accretion will have the largest positive impact on carbon storage and sequestration, as well as protect salt marsh habitat from being lost to SLR. Analysis of the persistent effects of a recent marsh fire at Mugu Lagoon demonstrates that drought-stress may slow California salt marsh response to disturbance by one or more growing seasons and highlights the uncertain impacts of climate change on system function. This dissertation provides important baseline data for salt marsh sediment accretion, salt marsh carbon stocks and sequestrations rates, recommends best practices for use of LOI as a measure of soil organic carbon, and examines ecosystem recovery under multiple stressors. This work can be used in vulnerability assessments, ecosystem models, and valuation of ecosystem services for California salt marshes.
Author: H. Peter Eilers
Publisher:
ISBN:
Category : Marsh ecology
Languages : en
Pages : 8
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Author: Chad James Pritchard
Publisher:
ISBN:
Category : Arcata Bay (Calif.)
Languages : en
Pages : 112
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Author: Joy B Zedler
Publisher:
ISBN:
Category : Halophytes
Languages : en
Pages : 258
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Author: Jessica Kegel
Publisher:
ISBN:
Category : Cedar Island (Carteret County, N.C. : Island)
Languages : en
Pages : 83
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Book Description
Future sea-level rise will dramatically affect coastal landscapes and populations. The coast of North Carolina (USA) is particularly vulnerable to sea-level rise because its low-lying coastal plain is expansive, has a low gradient, provides significant ecosystem services and is economically important. In order to understand how future sea-level rise may affect the coast, it is necessary to study past sea-level rise. Widespread salt-marshes compose much of North Carolina's coastal system, providing an excellent environment from which to produce relative sea-level reconstructions using salt-marsh foraminifera, whose distribution is controlled by tidal elevation. Distinctive assemblage zones related to different tidal ranges can be recognized in salt-marsh foraminiferal assemblages, allowing them to be used as a proxy for reconstructing sea level as sea-level indicators. Foraminiferal assemblages from surface samples along two transects at Sand Hill Point on Cedar Island, North Carolina added to an existing modern training set of paired observations of foraminiferal assemblages and tidal elevation; these data provide local analogues for interpreting fossil assemblages using a locally weighted-weighted average (LWWA) regression model. Foraminiferal assemblages preserved in a radiocarbon-dated core of salt-marsh peat from Sand Hill Point were used to produce a continuous, high-resolution late Holocene relative sea-level reconstruction. The existing late Holocene RSL reconstruction from North Carolina is based on two sites: Sand Point on Roanoke Island and Tump Point on Cedar Island. The Sand Point record spans the last ~2200 years, but the Tump Point record spans only the last ~1000 years. Therefore, the sea-level history described from 200 BC to 1000 AD is based on only one site. The new sea-level reconstruction from Sand Hill Point extends the existing record from nearby Tump Point, NC by 1400 years, producing a high resolution, continuous record of sea-level change spanning 1500 BC - 1915 AD. This new record tests whether patterns and rates of late Holocene sea-level changes reconstructed elsewhere in North Carolina are consistent throughout the region. The calculated average rate of relative sea-level rise for Sand Hill Point of 0.7 mm/year is consistent with patterns of regional rates along the US Atlantic coast, which may be partly attributed to isostatic response to deglaciation of the Laurentide Ice Sheet.
Author: Intergovernmental Panel on Climate Change (IPCC)
Publisher: Cambridge University Press
ISBN: 9781009157971
Category : Science
Languages : en
Pages : 755
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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.
Author: C. D. Woodroffe
Publisher: Cambridge University Press
ISBN: 9780521011839
Category : Nature
Languages : en
Pages : 640
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Book Description
Coasts are some of the most rapidly changing places on earth. Understanding the natural adjustments that occur between coastal landforms and the processes that influence them is essential for the better management of coastal resources. Coasts provides a necessary background in geomorphology for those studying coastal systems. It describes the landforms that occur on the coast, their responses to the processes that shape them, and the pattern of evolution that can be determined for different types of coast over thousands of years. Numerous examples from around the world are used to illustrate the variety of environments. Particular attention is paid to coastal morphodynamics, the co-adjustment of process and form, on rocky, reef, sandy, deltaic-estuarine and muddy coasts. This valuable text for advanced undergraduate and graduate students is well illustrated and contains an extensive reference section. It will also be of great interest to environmental scientists, geologists, coastal managers and planners.
Author: Brian R. Silliman
Publisher: Univ of California Press
ISBN: 9780520258921
Category : Nature
Languages : en
Pages : 440
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"Human Impacts on Salt Marshes provides an excellent global synthesis of an important, underappreciated environmental problem and suggests solutions to the diverse threats affecting salt marshes."—Peter B. Moyle, University of California, Davis
Author: Elizabeth Burke Watson
Publisher:
ISBN:
Category : Paleoecology
Languages : en
Pages : 178
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