Land loss by pond expansion on the Mississippi River Delta Plain

Ortiz, Alejandra C.; Roy, Samapriya; Edmonds, Douglas A.

doi:10.1002/2017gl073079

Cited by 51 publications

(50 citation statements)

References 51 publications

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“…Algal and microbial (PUFA, SCFA) contributions to SOM were higher in ponds than marshes, but lower than tidal creeks (Pascal et al 2013;Spivak and Reeve 2015;Spivak and Ossolinski 2016). Bacterial lipids (BrFA, 10-methyl C16) made up a similar fraction of total PLFAs in pond and tidal creek sediments, but were relatively more abundant in marsh sediments (Pascal et al 2013;Spivak and Reeve 2015;Spivak and Ossolinski 2016). Unlike many shallow systems, pond surface SOM composition and fluxes were similar in summer and fall (Figs.…”

Section: Ponds Are Heterogeneous and Biogeochemically Distinct Habitamentioning

confidence: 92%

“…Pond sediments had a higher %TOC and lower C : N than tidal creeks and vegetated marshes (Wang et al 2003;Deegan et al 2012;Spivak and Ossolinski 2016). Algal and microbial (PUFA, SCFA) contributions to SOM were higher in ponds than marshes, but lower than tidal creeks (Pascal et al 2013;Spivak and Reeve 2015;Spivak and Ossolinski 2016). Bacterial lipids (BrFA, 10-methyl C16) made up a similar fraction of total PLFAs in pond and tidal creek sediments, but were relatively more abundant in marsh sediments (Pascal et al 2013;Spivak and Reeve 2015;Spivak and Ossolinski 2016).…”

Section: Ponds Are Heterogeneous and Biogeochemically Distinct Habitamentioning

confidence: 97%

“…This can facilitate re‐establishment of emergent grasses and rapid vertical accretion of organic matter (OM), so that the elevation of the former pond may eventually become level with the surrounding marsh platform (Wilson et al ; Wilson et al ; Mariotti ). However, ponds can contribute to permanent marsh loss when disturbances that waterlog soils and reduce drainage accelerate rates of formation and expansion (Reed ; Kennish ; Hartig et al ; Kearney et al ; Ortiz et al ; Raposa et al ). Over time, pond expansion may create landscape mosaics that represent the gradual conversion of vegetated marshes into open water environments (Turner and Rao ; Fagherazzi et al ; Marani et al ; Wang and Temmerman ).…”

mentioning

confidence: 99%

“…This can facilitate re-establishment of emergent grasses and rapid vertical accretion of organic matter (OM), so that the elevation of the former pond may eventually become level with the surrounding marsh platform (Wilson et al 2010;Wilson et al 2014;Mariotti 2016). However, ponds can contribute to permanent marsh loss when disturbances that waterlog soils and reduce drainage accelerate rates of formation and expansion (Reed 1995;Kennish 2001;Hartig et al 2002;Kearney et al 2002;Ortiz et al 2017;*Correspondence: aspivak@whoi.edu Additional Supporting Information may be found in the online version of this article. Raposa et al 2017).…”

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confidence: 99%

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Shallow ponds are biogeochemically distinct habitats in salt marsh ecosystems

Spivak

Gosselin

Sylva

2018

Limnology & Oceanography

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Runaway expansion of shallow ponds can catalyze the conversion of vegetated marshes into open water environments. Predicting how this transition affects ecosystem functioning is difficult because little is known about pond biogeochemistry. We characterized sediment organic matter sources and transformations in three ponds with different plant communities, over alternating periods of tidal isolation and flushing, during summer and fall, using a combination of stable isotopes, lipid biomarkers, and benthic fluxes. Sediment respiration rates (1.66 ± 0.09 mmol C m−2 d−1 to 28.53 ± 7.76 mmol C m−2 d−1) were comparable to shallow estuaries and driven by sulfate reduction. Rates varied across ponds, reflecting differences in summertime Ruppia maritima and macroalgae abundances, but were similar between seasons. Interactions between aboveground plant and sediment bacterial communities translated into distinct biogeochemical processes across the three ponds. Tidal isolation and summer weather intensified plant and bacterial community effects on pond carbon dynamics, resulting in algal biomass and lipid δ13C values that were 3–12‰ enriched, compared to nearby habitats. Surface sediment organic matter mainly derived from pond microalgae and was compositionally distinct from tidal creeks and marshes. Surprisingly, sediment bacteria were not tightly coupled to benthic microalgae but decomposed multiple carbon sources in surface sediments and became increasingly reliant on buried peat at deeper horizons. Pond development over time could largely be explained by sediment respiration and the simultaneous accretion of the surrounding marsh platform. The role of decomposition in pond expansion is consistent with previous assessments based on whole‐pond metabolism rates. Consequently, future pond expansion could alter ecosystem biogeochemistry and reduce carbon storage.

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Section: Ponds Are Heterogeneous and Biogeochemically Distinct Habitamentioning

confidence: 92%

Section: Ponds Are Heterogeneous and Biogeochemically Distinct Habitamentioning

confidence: 97%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Shallow ponds are biogeochemically distinct habitats in salt marsh ecosystems

Spivak

Gosselin

Sylva

2018

Limnology & Oceanography

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“…The CRMS stations measure V a change to wetland platforms and are not designed to measure any lateral erosion of wetland edges. Over 34 years, there has been 250 km 2 of marsh edge erosion (Ortiz et al, 2017). If the depth of this marsh erosion is 2 m (Wilson & Allison, 2008) and the sediment has an average ρ of 1.15 g/cm 3 (Bomer et al, 2019), this would result in about 17 MT/year of edge erosion over the 34-year period, which is small in relation to mass accumulation on the wetland platform.…”

Section: Limitationsmentioning

confidence: 99%

Field‐Based Estimate of the Sediment Deficit in Coastal Louisiana

2020

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Coastal and deltaic sediment balances are crucial for a region's sustainability. However, such balances remain difficult to quantify accurately, particularly for large regions. We calculate organic and mineral sediment mass and volume balances using field measurements from 273 Coastwide Reference Monitoring System sites across the Louisiana Coast between 2006 and 2015. The rapid relative sea level rise rate (average 13.4 mm/year) is offset by the small dry bulk densities observed (average 0.3 g/cm3) to produce a 16.2 ± 41.1% mass deficit and 24.1 ± 14.0% volume deficit, significantly smaller than recent predictions for 2000–2100 (73–79% mass deficit). Geostatisical estimates show that this deficit is primarily located in areas not directly nourished by major rivers, yet these regions still accumulate ~24 MT/year of mineral sediment. A fluvial sediment discharge of 113.8 MT/year suggests a coast‐wide trapping efficiency of 31.5 ± 15.8% of the riverine sediment, excluding subaqueous deposition. Organic accumulation accounts for 25% of all mass accumulation during our study period, and total organic mass accumulation per unit area is relatively constant in both directly and indirectly nourished regions. Sediment characteristics in the modern coastal wetlands differ from the Holocene deposit, suggesting secular changes within the system that will likely continue to influence coastal dynamics over the coming decades. Our results suggest that the gap between accommodation and accumulation (mass or volume) during this decade was not as large as the previously predicted century average.

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