Implications of rapid sediment accumulation in a small New England salt marsh

1992 ◽  
Vol 29 (9) ◽  
pp. 2013-2017 ◽  
Author(s):  
R. Scott Anderson ◽  
H. W. Borns Jr. ◽  
D. C. Smith ◽  
C. Race
Keyword(s):  
Salt Marsh ◽  
New England ◽  
Sea Level ◽  
Accumulation Rate ◽  
Sediment Accumulation ◽  
Sediment Supply ◽  
Greenhouse Warming ◽  
Accumulation Rates ◽  
Marsh Sediment ◽  
England Salt Marsh

The sediment accumulation rate within a small Spartina alterniflora marsh in Maine has been determined by measuring the amount of peat accretion on top of human-produced boards protruding from an exposed face of the marsh. Boards are at depths of 50–140 cm, suggesting sediment accumulation rates of 6.2–7.0 mm/year. Based on these data and a review of other relevant studies, aggradation in small marshes such as Shipyard Cove should be able to keep pace marginally with the anticipated sea-level rise due to "greenhouse" warming, given sufficient sediment supply. Local 19th century land clearance and subsequent erosion, activities that are greatly reduced today, probably supplied the bulk of the inorganic marsh sediment.

The Cenomanian-Turonian Boundary Event in northern Spain

1994 ◽  
Vol 131 (6) ◽  
pp. 801-817 ◽  
Author(s):  
C. R. C. Paul ◽  
S. Mitchell ◽  
M. Lamolda ◽  
A. Gorostidi
Keyword(s):  
Sea Level ◽  
Carbon Isotopes ◽  
Accumulation Rate ◽  
Sediment Accumulation ◽  
Insoluble Residue ◽  
Accumulation Rates ◽  
Northern Spain ◽  
Local Effects ◽  
Total Carbonate ◽  
Straight Line

AbstractA sparse but moderately diverse nannoflora is recorded through the Cenomanian-Turonian Boundary Event (CTBE) at Menoyo, Spain and allows recognition of the late Cenomanian Eiffellithus turriseiffelii Zone and the early Turonian Quadrum gartneri Zone, as well as five significant nannofossil bioevents associated with the CTBE. Carbon isotopes record a modest excursion which lasted 250–270 thousand years (ka) in three phases, buildup (105 ka), plateau (126 ka) and recovery (42 ka). Acid insoluble residue values imply that sea level rose through the buildup phase, indicated by a reduction in the accumulation rate of siliciclastic sediment. However, oceanic productivity apparently declined through the CTBE, indicated by reduction in accumulation rates of total carbonate and intact coccoliths to less than a quarter of their initial values. These patterns are very similar to those found through the CTBE at Dover, England and reflect widespread not local effects. A combination of lithological changes, seven key bioevents, and details of the δ13C curve, allows us to suggest a bed-by-bed correlation through the CTBE between Dover and Menoyo, demonstrating the practicality of cyclostratigraphy for international correlation at a precision of ± 10 ka. Graphic correlation produces a straight line fit despite wide fluctuations in sediment accumulation rates at both localities. This can only occur if changes were in phase and of similar magnitudes at both localities, again suggesting widespread, perhaps global, control.

scholarly journals Top-down and bottom-up controls on southern New England salt marsh crab populations

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4876 ◽  
Author(s):  
Kenneth B. Raposa ◽  
Richard A. McKinney ◽  
Cathleen Wigand ◽  
Jeffrey W. Hollister ◽  
Cassie Lovall ◽  
...  
Keyword(s):  
Salt Marsh ◽  
New England ◽  
Sea Level Rise ◽  
Sea Level ◽  
Salt Marshes ◽  
Fiddler Crab ◽  
Water Levels ◽  
Southern New England ◽  
England Salt Marsh ◽  
Crab Abundance

Southern New England salt marsh vegetation and habitats are changing rapidly in response to sea-level rise. At the same time, fiddler crab (Uca spp.) distributions have expanded and purple marsh crab (Sesarma reticulatum) grazing on creekbank vegetation has increased. Sea-level rise and reduced predation pressure drive these changing crab populations but most studies focus on one species; there is a need for community-level assessments of impacts from multiple crab species. There is also a need to identify additional factors that can affect crab populations. We sampled crabs and environmental parameters in four Rhode Island salt marshes in 2014 and compiled existing data to quantify trends in crab abundance and multiple factors that potentially affect crabs. Crab communities were dominated by fiddler and green crabs (Carcinus maenas); S. reticulatum was much less abundant. Burrow sizes suggest that Uca is responsible for most burrows. On the marsh platform, burrows and Carcinus abundance were negatively correlated with elevation, soil moisture, and soil percent organic matter and positively correlated with soil bulk density. Uca abundance was negatively correlated with Spartina patens cover and height and positively correlated with Spartina alterniflora cover and soil shear strength. Creekbank burrow density increased dramatically between 1998 and 2016. During the same time, fishing effort and the abundance of birds that prey on crabs decreased, and water levels increased. Unlike in other southern New England marshes where recreational overfishing is hypothesized to drive increasing marsh crab abundance, we propose that changes in crab abundance were likely unrelated to recreational finfish over-harvest; instead, they better track sea-level rise and changing abundances of alternate predators, such as birds. We predict that marsh crab abundance will continue to expand with ongoing sea-level rise, at least until inundation thresholds for crab survival are exceeded.

Nutrients, competition and plant zonation in a New England salt marsh

1998 ◽  
Vol 86 (2) ◽  
pp. 285-292 ◽  
Author(s):  
Jonathan M. Levine ◽  
J. Stephen Brewer ◽  
Mark D. Bertness
Keyword(s):  
Salt Marsh ◽  
New England ◽  
Plant Zonation ◽  
England Salt Marsh

Linked variations in sediment accumulation rates and sea-level in Guanabara Bay, Brazil, over the last 6000years

2014 ◽  
Vol 415 ◽  
pp. 83-90 ◽  
Author(s):  
Alberto G. Figueiredo ◽  
Mauro B. de Toledo ◽  
Renato C. Cordeiro ◽  
José M.O. Godoy ◽  
Fabiano T. da Silva ◽  
...  
Keyword(s):  
Sea Level ◽  
Sediment Accumulation ◽  
Guanabara Bay ◽  
Accumulation Rates ◽  
And Sea Level

scholarly journals Holocene sea level and climate interactions on wet dune slack evolution in SW Portugal: A model for future scenarios?

The Holocene ◽  
2018 ◽  
Vol 29 (1) ◽  
pp. 26-44 ◽  
Author(s):  
Manel Leira ◽  
Maria C Freitas ◽  
Tania Ferreira ◽  
Anabela Cruces ◽  
Simon Connor ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Environmental Changes ◽  
Sediment Accumulation ◽  
High Energy ◽  
Sediment Supply ◽  
Dune Slack ◽  
Ecological Stability ◽  
The Holocene ◽  
Climate Interactions

We examine the Holocene environmental changes in a wet dune slack of the Portuguese coast, Poço do Barbarroxa de Baixo. Lithology, organic matter, biological proxies and high-resolution chronology provide estimations of sediment accumulation rates and changes in environmental conditions in relation to sea-level change and climate variability during the Holocene. Results show that the wet dune slack was formed 7.5 cal. ka BP, contemporaneous with the last stages of the rapid sea-level rise. This depositional environment formed under frequent freshwater flooding and water ponding that allowed the development and post-mortem accumulation of abundant plant remains. The wetland evolved into mostly palustrine conditions over the next 2000 years, until a phase of stabilization in relative sea-level rise, when sedimentation rates slowed down to 0.04 mm yr−1, between 5.3 and 2.5 cal. ka BP. Later, about 0.8 cal. ka BP, high-energy events, likely due to enhanced storminess and more frequent onshore winds, caused the collapse of the foredune above the wetlands’ seaward margin. The delicate balance between hydrology (controlled by sea-level rise and climate change), sediment supply and storminess modulates the habitat’s resilience and ecological stability. This underpins the relevance of integrating past records in coastal wet dune slacks management in a scenario of constant adaptation processes.

scholarly journals High-resolution magnetostratigraphy of the upper Nacimiento Formation, San Juan Basin, New Mexico, USA: implications for basin evolution and mammalian turnover

2017 ◽  
Author(s):  
Caitlin Leslie ◽  
Daniel J. Peppe ◽  
Thomas E. Williamson ◽  
Dario Bilardello ◽  
Matthew Heizler ◽  
...  
Keyword(s):  
New Mexico ◽  
North America ◽  
Accumulation Rate ◽  
Global Climate ◽  
Sediment Accumulation ◽  
San Juan ◽  
Accumulation Rates ◽  
Fluvial System ◽  
San Juan Basin ◽  
Geomagnetic Polarity

Lower Paleocene deposits in the San Juan Basin document one of the best records of mammalian change and turnover following the Cretaceous-Paleogene extinctions and are the type section for the Puercan (Pu) and Torrejonian (To) North America Land Mammal age biozones (NALMA). One of the largest mammalian turnover events in the early Paleocene occurs between the Torrejonian 2 (To2) and Torrejonian 3 (To3) NALMA biozones. The Nacimiento Formation are the only deposits in North America where the To2-To3 mammalian turnover can be constrained, however the precise age and duration of the turnover is poorly understood due to the lack of a precise chronostratigraphic framework. We analyzed paleomagnetic samples, produced a 40Ar/39Ar detrital sanidine age, and developed a detailed lithostratigraphy for four sections of the upper Nacimiento Formation in the San Juan Basin, New Mexico (Kutz Canyon, Escavada Wash, Torreon West and East) to constrain the age and duration of the deposits and the To2-To3 turnover. The polarity stratigraphy for the four sections can be correlated to chrons C27r-C26r of the geomagnetic polarity time scale (GPTS). Using the local polarity stratigraphy for each section, we calculated a mean sediment accumulation rate and developed a precise age model, which allows us to determine the age of important late Torrejonian mammalian localities. Using the assigned ages, we estimate the To2-To3 turnover was relatively rapid and occurred over ~120 kyr (-60/+50 kyr) between 62.59 and 62.47 Ma. This rapid duration of the mammalian turnover suggests that it was driven by external forcing factors, such as environmental change driven by the progradation of the distributive fluvial system across the basin and/or changes in regional or global climate. Additionally, comparisons of the mean sediment accumulation rates between the sections that span from the basin margin to the basin center indicate that sediment accumulation rates equalized across the basin from the end of C27r through the start of C26r, suggesting an accommodation minima in the basin associated with the progradation of a distributive fluvial system into the basin. This accommodation minimum also likely led to the long hiatus of deposition between the Paleocene Nacimiento Formation and the overlying Eocene San Jose Formation.

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