Differential Salinity Response between Two Mississippi River Subdeltas: Implications for Changes in Plant Composition

Holm, Guerry O.; Sasser, Charles E.

doi:10.2307/1352815

Cited by 49 publications

(27 citation statements)

References 26 publications

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“…The plant community is in a dynamic early successional phase, and its composition is mainly determined by fluvial discharge, elevation, disturbance, salinity, organic content of sediment, and nutrient availability (Rejmanek et al, 1987; Shaffer et al, 1992;Holm and Sasser, 2001). …”

Section: Wax Lake Delta (Wld)mentioning

confidence: 99%

Morphological responses of the Wax Lake Delta, Louisiana, to Hurricanes Rita

Xing

Syvitski

Kettner

et al. 2017

Elementa: Science of the Anthropocene

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This study examines the morphodynamic response of a deltaic system to extreme weather events. The Wax Lake Delta (WLD) in Louisiana, USA, is used to illustrate the impact of extreme events (hurricanes) on a river-dominated deltaic system. Simulations using the open source Delft3D model reveal that Hurricane Rita, which made landfall 120 km to the west of WLD as a Category 3 storm in 2005, caused erosion on the right side and deposition on the left side of the hurricane eye track on the continental shelf line (water depth 10 m to 50 m). Erosion over a wide area occurred both on the continental shelf line and in coastal areas when the hurricane moved onshore, while deposition occurred along the Gulf coastline (water depth < 5 m) when storm surge water moved back offshore. The numerical model estimated that Hurricane Rita's storm surge reached 2.5 m, with maximum currents of 2.0 m s -1 , and wave heights of 1.4 m on the WLD. The northwestern-directed flow and waves induced shear stresses, caused erosion on the eastern banks of the deltaic islands and deposition in channels located west of these islands. In total, Hurricane Rita eroded more than 500,000 m 3 of sediments on the WLD area. Including waves in the analysis resulted in doubling the amount of erosion in the study area, comparing to the wave-excluding scenario. The exclusion of fluvial input caused minor changes in deltaic morphology during the event. Vegetation cover was represented as rigid rods in the model which add extra source terms for drag and turbulence to influence the momentum and turbulence equations. Vegetation slowed down the floodwater propagation and decreased flow velocity on the islands, leading to a 47% reduction in the total amount of erosion. Morphodynamic impact of the hurricane track relative to the delta was explored. Simulations indicate that the original track of Hurricane Rita (landfall 120 km west of the WLD) produced twice as much erosion and deposition at the delta compared to a hurricane of a similar intensity that made landfall directly on the delta. This demonstrates that the wetlands located on the right side of a hurricane track experience more significant morphological changes than areas located directly on the hurricane track.Keywords: sediment balance; hurricanes; vegetation; hurricane track; waves; Wax Lake Delta . Applying numerical experiments, marsh morphology (e.g., horizontal extent of marsh, marsh vertical elevation, frictional characteristics, and degree of segmentation) has shown to significantly influence the surge height during hurricanes (Loder et al., 2009;Wamsley et al., 2009). On the other hand, the impact of hurricanes on morphological changes of wetlands is less well studied, although hurricanes-driven wetland changes could have important ecological consequences (Cahoon, 2006). Most previous studies are based on field observations and analysis of satellite images before and after hurricane passages (Barras, 2006;Kiage et al., 2005;Howes et al., 2010). Barras (2006), by comparing Landsat images befo...

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Section: Wax Lake Delta (Wld)mentioning

confidence: 99%

Morphological responses of the Wax Lake Delta, Louisiana, to Hurricanes Rita

Xing

Syvitski

Kettner

et al. 2017

Elementa: Science of the Anthropocene

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“…Salinity is a growing threat to natural ecosystems ( Yeo, 1999;Rogers & McCarty, 2000 ) because it disrupts the physiological processes of terrestrial plants ( Levitt, 1980;Yeo, 1983;Hasegawa et al ., 2000 ), increases mortality of wetland populations ( Krauss et al ., 2000 ), and reduces the diversity of ecological communities ( Flynn et al ., 1995;Holm & Sasser, 2001 ). Water-deficit stress also has strong effects on plants and a rich history in the ecological literature ( White, 1976;Mattson, 1980;Larsson, 1989;Waring & Cobb, 1992;Schowalter et al ., 1999;Inbar et al ., 2001;Awmack & Leather, 2002 ).…”

Section: Introductionmentioning

confidence: 99%

The deleterious effects of salinity stress on leafminers and their freshwater host

Schile

Mopper

2006

Ecological Entomology

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1. Salinity is an important cause of abiotic stress in wetland communities yet little is known about its consequences for freshwater plants and their insect herbivores. The goal of this study was to test the effect of salinity on a leafmining insect, Cerodontha iridiphora , and its herbaceous host plant, Iris hexagona .2. Leafminer performance was evaluated on irises grown in control and saline treatments, and the effects of salinity and herbivory on leaf quality and mortality was measured.3. Leafminer density and size were significantly lower on irises grown in saline water compared with freshwater.4. Both salinity and herbivory accelerated leaf senescence and mortality, and their combined effects increased tissue loss by an order of magnitude compared with controls.5. Leafminers acted as nutrient sinks. The undamaged regions of mined leaves contained 40% less nitrogen than unmined leaves, providing a mechanism for the premature leaf mortality.6. Salinity was detrimental to the performance and survival of both the iris leafminer and its host plant. We propose that glycophytic host plants and their insect herbivores will suffer more than halophytic communities from environmental salinity because they lack the adaptive mechanisms to tolerate this potent physiological stress.

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“…Our cursory analysis suggests that streaklines form mostly on 20 deltas with established marshes that flow into freshwater basins or river discharge is enough to make the proximal receiving basin fresh. The latter condition characterizes the Wax Lake Delta and Atchafalaya Bay (Holm and Sasser, 2001;Li et al, 2011).…”

Section: Bathymetry and Flow Patterns On River-dominated Deltasmentioning

confidence: 99%

Measuring Subaqueous Progradation of the Wax Lake Delta with a Model of Flow Direction Divergence

Shaw¹,

Estep²,

Whaling³

et al. 2018

Preprint

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Abstract.Remotely sensed flow patterns can reveal the location of the subaqueous distal tip of a distributary channel on a prograding river delta. Morphodynamic feedbacks produce distributary channel tips that become shallower over their final reaches before becoming deeper over the unchannelized foreset. The flow direction field over this morphology tends to diverge 10 and then converge providing a diagnostic signature that can be captured in flow or remote sensing data. Twenty-one measurements from the Wax Lake Delta (WLD) in coastal Louisiana, and 317 measurements from numerically simulated deltas show that the transition from divergence to convergence occurs in a distribution that is centered just downstream of the channel tip, on average 132 m in the case of the WLD. With these data we validate the Flow Direction to Channel tips (FD2C) inverse model for remotely estimating subaqueous channel tip location. We apply this model to 33 remotely sensed images of 15 the WLD between its initiation in 1974 and 2016. We find that the distributaries grew unevenly, 6 of the primary channels grew at rates of 60-80 m/yr while one grew at 116 m/yr. We also estimate the growth rate of the total area enclosed by the subaqueous delta platform to be 1.83 km 2 /yr with no obvious rate changes over time.

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Differential Salinity Response between Two Mississippi River Subdeltas: Implications for Changes in Plant Composition

Cited by 49 publications

References 26 publications

Morphological responses of the Wax Lake Delta, Louisiana, to Hurricanes Rita

Morphological responses of the Wax Lake Delta, Louisiana, to Hurricanes Rita

The deleterious effects of salinity stress on leafminers and their freshwater host

Measuring Subaqueous Progradation of the Wax Lake Delta with a Model of Flow Direction Divergence

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