Long-term changes in salt marsh extent affected by channel deepening in a modified estuary

Cox, R.; Wadsworth, Richard A.; Thomson, A. G.

doi:10.1016/j.csr.2003.08.002

Cited by 67 publications

(48 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For example, studies in the Westerschelde have related erosion to increases in the tidal prism induced by dredging operations and to westerly winds (Cox et al 2003). At a macrotidal salt marsh in the Bay of Fundy, van Proosdij et al (2000, 2006 showed that deposition on the marsh (using sediment traps) is primarily related to periods of high SSC and low wave activity, when vegetation height was a small proportion of water depth (i.e.…”

Section: Discussionmentioning

confidence: 99%

Effect of Spartina anglica stems on near-bed hydrodynamics, sediment erodability and morphological changes on an intertidal mudflat

Widdows¹,

Pope²,

Brinsley³

2008

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

Our main objective was to investigate the effect of Spartina anglica stems on hydrodynamics, sediment dynamics and their influence on seasonal morphological changes on the upper shore and salt marsh of an intertidal mudflat in the Tavy estuary (southwest England). On an intertidal transect, the greatest seasonal changes in sediment levels occurred at the seaward edge and lower part of the salt marsh, and on the lower shore mudflat, while the smallest changes occurred on the mid-and upper-shore mudflat. Flume studies demonstrated flow attenuation with increasing Spartina stem density, but this was accompanied by an increase in turbulent kinetic energy and bed shear stress (τ 0 ). The critical erosion threshold (τ e ), however, remained relatively constant at 0.12 Pa. Field measurements showed that τ 0 was well below τ e under calm conditions. During periods of windwave activity, when daily mean wind speeds were > 8 m s -1 , τ 0 was greater than τ e in the lower salt marsh for brief periods at the beginning and end of tidal inundation. At the seaward edge of the salt marsh, τ 0 increased to 1.0 Pa and τ 0 was greater than τ e throughout the inundation period, causing significant sediment erosion. Wind-induced wave activity was the major driver of sediment erosion on soft muddy shores and this was enhanced by the interaction with S. anglica stems. The number of days per month with mean daily wind speeds > 8 m s -1 was inversely related to changes in sediment levels at the seaward edge of the salt marsh. During the summer, winds were below this threshold, and there was gradual accretion. Results are discussed in the context of climate changes involving increased storminess leading to increased erosion. We show that the S. anglica salt marsh should not be considered a 'bio-stabiliser' of fine muddy sediment.

show abstract

Section: Discussionmentioning

confidence: 99%

Effect of Spartina anglica stems on near-bed hydrodynamics, sediment erodability and morphological changes on an intertidal mudflat

Widdows¹,

Pope²,

Brinsley³

2008

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

show abstract

“…Land reclamation over the last 2000 years in estuaries such as Southampton Water, the Humber and Fenland in the UK seems to have caused a major change in tidal range within these estuaries and which are manifested in the stratigraphy (Long et al, 2000;Shennan et al, 2003). Over shorter timescales, instrumental tide gauges reveal the effects of dredging estuaries (Cox et al, 2003;Wang et al, 2002).…”

Section: Additional Vertical Uncertaintymentioning

confidence: 99%

Salt marshes as late Holocene tide gauges

Barlow

Shennan

Long

et al. 2013

Global and Planetary Change

107

101

View full text Add to dashboard Cite

. (2013) 'Salt marshes as late Holocene tide gauges. ', Global and planetary change.,[106][107][108][109][110] Further information on publisher's website:http://dx.doi.org/10.1016/j.gloplacha.2013.03.003Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in Global and planetary change. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reected in this document. Changes may have been made to this work since it was submitted for publication. A denitive version was subsequently published in Global and planetary change, 106, 2013Global and planetary change, 106, , 10.1016Global and planetary change, 106, /j.gloplacha.2013 Additional information:The north west Scotland modern diatom dataset presented in the paper is available for download from: http://www.dur.ac.uk/geography/qec/researchgroups/slru/sea l evel d ata/ Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Keywords:Relative sea-level change; salt marsh; transfer function; diatoms; foraminifera; reconstruction; trends; Holocene; errors 2 AbstractUnderstanding late Holocene to present relative sea-level changes at centennial or sub-centennial scales requires geological records that dovetail with the instrumental era. Salt marsh sediments are one of the most reliable geological tide gauges.In this paper we review the methodological and technical advances that promoted research on 'high resolution' late Holocene sea-level change. We work through an example to demonstrate different pathways to quantitative reconstructions of relative sea level based on salt marsh sediments. We demonstrate that any reconstruction is in part a result of the environment from which the record is taken, the modern dataset used to calibrate the fossil changes, statistical assumptions behind calibrating microfossil assemblages and choices made by the researchers. With the error term of typical transfer function models ~10-15% of the tidal range, micro-tidal environments should produce the most precise sea-level reconstructions. Sampled elevation range of the modern dataset also has a strong influence on model predictive ability. Model-specific errors may under represent total uncertainty which comes from field practices, sedimentary environment, palaeo-tidal changes and sediment compaction as well as statistical uncertainties. Geological tide gauges require a detailed chronology but we must be certain that apparent relative s...

show abstract

“…We tested our idea on mudflats on the coasts of both Florida and The Netherlands and did so for the following reasons. First, in both locations, salt marshes once dominated protected shorelines but have recently experienced intense die-off due to human-induced stressors (36,37). Second, salt marsh restoration is a primary focus of nongovernmental and governmental organizations in both locations, so experiments can inform local efforts for coastal conservation.…”

Section: Significancementioning

confidence: 99%

Facilitation shifts paradigms and can amplify coastal restoration efforts

Silliman

Schrack

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

226

300

View full text Add to dashboard Cite

Restoration has been elevated as an important strategy to reverse the decline of coastal wetlands worldwide. Current practice in restoration science emphasizes minimizing competition between outplanted propagules to maximize planting success. This paradigm persists despite the fact that foundational theory in ecology demonstrates that positive species interactions are key to organism success under high physical stress, such as recolonization of bare substrate. As evidence of how entrenched this restoration paradigm is, our survey of 25 restoration organizations in 14 states in the United States revealed that >95% of these agencies assume minimizing negative interactions (i.e., competition) between outplants will maximize propagule growth. Restoration experiments in both Western and Eastern Atlantic salt marshes demonstrate, however, that a simple change in planting configuration (placing propagules next to, rather than at a distance from, each other) results in harnessing facilitation and increased yields by 107% on average. Thus, small adjustments in restoration design may catalyze untapped positive species interactions, resulting in significantly higher restoration success with no added cost. As positive interactions between organisms commonly occur in coastal ecosystems (especially in more physically stressful areas like uncolonized substrate) and conservation resources are limited, transformation of the coastal restoration paradigm to incorporate facilitation theory may enhance conservation efforts, shoreline defense, and provisioning of ecosystem services such as fisheries production.shoreline defense | facilitation | coastal wetlands | wetland restoration D egradation of coastal ecosystems is occurring worldwide (1).Human-generated threats such as overharvesting, eutrophication, climate change, habitat destruction, and pollution have threatened these valuable ecosystems at local, regional and global scales (2-6). As these threats have intensified and combined, substantial declines in overall habitat coverage have occurred in almost all major coastal ecosystems, including those generated by key habitat-forming foundation species. For example, oyster reefs have declined by at least ∼85% (7), coral reefs by ∼19% (8), seagrasses by ∼29% (9), North American salt marshes by ∼42% (10), and mangroves by ∼35% (1). Because these ecosystems generate some of the richest biodiversity hotspots on Earth (11, 12), and provide critical services for human populations, including storm protection (13), fisheries production (2, 14, 15), and carbon storage (16, 17), conservation resources totaling over 1 billion US dollars have been spent globally in an attempt to halt and reverse the decline of foundation species in the coastal realm (18,19).A number of strategies have been used to conserve coastal ecosystems, including threat reduction, marine protected areas, buffer establishment, and international treaties. Habitat restoration, although in existence for many decades, has only recently been elevated as a global strategy for ...

show abstract

Long-term changes in salt marsh extent affected by channel deepening in a modified estuary

Cited by 67 publications

References 12 publications

Effect of Spartina anglica stems on near-bed hydrodynamics, sediment erodability and morphological changes on an intertidal mudflat

Effect of Spartina anglica stems on near-bed hydrodynamics, sediment erodability and morphological changes on an intertidal mudflat

Salt marshes as late Holocene tide gauges

Facilitation shifts paradigms and can amplify coastal restoration efforts

Contact Info

Product

Resources

About