Marsh Vertical Accretion in a Southern California Estuary, U.S.A.

Cahoon, Donald R.; Lynch, James C.; Powell, Abby N.

doi:10.1006/ecss.1996.0055

Cited by 110 publications

(55 citation statements)

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“…At Mugu over longer time scales, combined impacts of infrequent storms and organic accretion yielded a slightly higher rate of 1-2 mm/year between 1995and 2009(Chan and Ambrose, unpublished, 2010. While likely site-specific and not necessarily applicable to Mugu and/or Seal Beach, in cordgrass-dominated portions of Tijuana Estuary, Cahoon et al (1996) found higher rates of accretion compared to pickleweed-dominated portions which are likely related to an increase in inundation frequency and duration in lower elevations. In comparison to the relatively low rate of SLR in Los Angeles (0.82 mm/year), Seal Beach1 and Seal Beach2, with an annual dry period net flux of 16,000 and 150,000 kg/year, would have deficits of 260,000 and 250,000 kg/year, based on their current rate of dry period import.…”

Section: Future Stability Of Southern California Marshes In the Face mentioning

confidence: 78%

“…Episodic import of sediment during more powerful storms has been documented in marshes with less urbanized basins; for example, open water areas near Mugu and Tijuana Estuary have been partially filled by intense, isolated storms during El Niño events (Onuf 1987;Cahoon et al 1996). Warrick and Farnsworth (2009b) found that most sediment transport occurred during El Niño or at intervals greater than 10 years.…”

Section: Discussion Atmospheric and Tidal Controls On Sediment Transportmentioning

confidence: 99%

“…Tidal energy appeared to be driving the magnitude of the flux within the tidal channels in these salt marshes. In other marshes, storm-driven surge has accounted for a large percent of sediment fluxes over time (Cahoon et al 1996;Turner et al 2006;Fagherazzi et al 2013b). However, not all of our sites responded to tidal energy; the discrepancy is likely a result of the lower range of velocities observed in Seal Beach2.…”

Section: Discussion Atmospheric and Tidal Controls On Sediment Transportmentioning

confidence: 99%

“…Corners of the plots were marked with a gray polyvinyl chloride pipe. In September, we used a plug extraction method suitable for drier soils (Cahoon et al 1996). The sampling method consisted of visually surveying the plot to see if any feldspar was exposed.…”

Section: Suspended Sediment Concentration and Vertical Accretion On Tmentioning

confidence: 99%

“…Salt marsh loss has been shown to result from past alterations to rivers and sediment delivery (Day et al 2000(Day et al , 2011Mudd 2011). In Mediterranean-climate regions such as southern California, USA, the long-term effects of sediment alterations on salt marshes are poorly understood, with a few notable exceptions including the sediment-rich Tijuana Estuary (Cahoon et al 1996;Wallace et al 2005) and Mugu Lagoon (Onuf 1987). Over the past 200 years, sedimentation rates have increased in some southern California marshes (Mudie and Byrne 1980;Davis 1992) that have imported the majority of sediment during El Niño events when coastal zone sediment loads are typically high (Warrick and Farnsworth 2009b).…”

Section: Introductionmentioning

confidence: 99%

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Balanced Sediment Fluxes in Southern California’s Mediterranean-Climate Zone Salt Marshes

Rosencranz

Ganju

Ambrose

et al. 2015

Estuaries and Coasts

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Salt marsh elevation and geomorphic stability depends on mineral sedimentation. Many Mediterraneanclimate salt marshes along southern California, USA coast import sediment during El Niño storm events, but sediment fluxes and mechanisms during dry weather are potentially important for marsh stability. We calculated tidal creek sediment fluxes within a highly modified, sediment-starved, 1.5-km 2 salt marsh (Seal Beach) and a less modified 1-km 2 marsh (Mugu) with fluvial sediment supply. We measured salt marsh plain suspended sediment concentration and vertical accretion using single stage samplers and marker horizons. At Seal Beach, a 2014 storm yielded 39 and 28 g/s mean sediment fluxes and imported 12,000 and 8800 kg in a western and eastern channel. Western channel storm imports offset 8700 kg exported during 2 months of dry weather, while eastern channel storm imports augmented 9200 kg imported during dry weather. During the storm at Mugu, suspended sediment concentrations on the marsh plain increased by a factor of four; accretion was 1-2 mm near creek levees. An exceptionally high tide sequence yielded 4.4 g/s mean sediment flux, importing 1700 kg: 20 % of Mugu's dry weather fluxes. Overall, low sediment fluxes were observed, suggesting that these salt marshes are geomorphically stable during dry weather conditions. Results suggest storms and high lunar tides may play large roles, importing sediment and maintaining dry weather sediment flux balances for southern California salt marshes. However, under future climate change and sea level rise scenarios, results suggest that balanced sediment fluxes lead to marsh elevational instability based on estimated mineral sediment deficits.

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Section: Future Stability Of Southern California Marshes In the Face mentioning

confidence: 78%

Section: Discussion Atmospheric and Tidal Controls On Sediment Transportmentioning

confidence: 99%

Section: Discussion Atmospheric and Tidal Controls On Sediment Transportmentioning

confidence: 99%

Section: Suspended Sediment Concentration and Vertical Accretion On Tmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Balanced Sediment Fluxes in Southern California’s Mediterranean-Climate Zone Salt Marshes

Rosencranz

Ganju

Ambrose

et al. 2015

Estuaries and Coasts

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A global analysis of the seaward salt marsh extent: The importance of tidal range

Balke

Stöck

Jensen

et al. 2016

Water Resources Research

108

102

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Despite the growing interest in ecosystem services provided by intertidal wetlands, we lack sufficient understanding of the processes that determine the seaward extent of salt marsh vegetation on tidal flats. With the present study, we aim to establish a globally valid demarcation between tidal flats and salt marsh vegetation in relation to tidal range. By comparing results from a regional GIS study with a global literature search on the salt marsh-tidal flat border, we are able to define the global critical elevation, above which salt marsh plants can grow in the intertidal zone. Moreover, we calculate inundation characteristics from global tide gauge records to determine inundation duration and frequency at this predicted salt marsh-tidal flat border depending on tidal range. Our study shows that the height difference between the lowest elevation of salt marsh pioneer vegetation and mean high water increases logarithmically with tidal range when including macrotidal salt marshes. Hence, the potentially vegetated section of the tidal frame below mean high water does not proportionally increase with tidal range. The data analysis suggests that inundation frequency rather than duration defines the global lower elevational limit of vascular salt marsh plants on tidal flats. This is critical information to better estimate sea level rise and coastal change effects on lateral marsh development.

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Buried hurricane legacies: increased nutrient limitation and decreased root biomass in coastal wetlands

et al. 2021

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Plant identity and cover in coastal wetlands is changing in worldwide, and many subtropical salt marshes dominated by low-stature herbaceous species are becoming woody mangroves. Yet, how changes affect coastal soil biogeochemical processes and belowground biomass before and after storms is uncertain. We experimentally manipulated the percent mangrove cover (Avicennia germinans) in 3 × 3 m cells embedded in 10 plots (24 × 42 m) comprising a gradient of marsh (e.g., Spartina alterniflora, Batis maritima) and mangrove cover in Texas, USA. Hurricane Harvey made direct landfall over our site on 25 August 2017, providing a unique opportunity to test how plant composition mitigates hurricane effects on surface sediment accretion, soil chemistry (carbon, C; nitrogen, N; phosphorus, P; and sulfur, S), and root biomass. Data were collected before (2013 and 2016), one-month after (2017), and one-year after (2018) Hurricane Harvey crossed the area, allowing us to measure stocks before and after the hurricane. The accretion depth was higher in fringe compared with interior cells of plots, more variable in cells dominated by marsh than mangrove, and declined with increasing plot-scale mangrove cover. The concentrations of P and δ 34 S in storm-driven accreted surface sediments, and the concentrations of N, P, S, and δ 34 S in underlying soils (0-30 cm), decreased post-hurricane, whereas the C concentrations in both compartments were unchanged. Root biomass in both marsh and mangrove cells was reduced by 80% in 2017 compared with previous dates and remained reduced in 2018. Post-hurricane loss of root biomass in plots correlated with enhanced nutrient limitation. Total sulfide accumulation as indicated by δ 34 S, increased nutrient limitation, and decreased root biomass of both marshes and mangroves after hurricanes may affect ecosystem function and increase vulnerability in coastal wetlands to subsequent disturbances. Understanding how changes in plant composition in coastal ecosystems affects responses to hurricane disturbances is needed to assess coastal vulnerability.

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Marsh Vertical Accretion in a Southern California Estuary, U.S.A.

Cited by 110 publications

References 0 publications

Balanced Sediment Fluxes in Southern California’s Mediterranean-Climate Zone Salt Marshes

Balanced Sediment Fluxes in Southern California’s Mediterranean-Climate Zone Salt Marshes

A global analysis of the seaward salt marsh extent: The importance of tidal range

Buried hurricane legacies: increased nutrient limitation and decreased root biomass in coastal wetlands

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