Restoring marsh elevation in a rapidly subsiding salt marsh by thin-layer deposition of dredged material

  • Published source details Ford M.A., Cahoon D.R. & Lynch J.C. (1999) Restoring marsh elevation in a rapidly subsiding salt marsh by thin-layer deposition of dredged material. Ecological Engineering, 12, 189-205.


This study is summarised as evidence for the following.

Action Category

Add sediment: brackish/salt marshes

Action Link
Marsh and Swamp Conservation
  1. Add sediment: brackish/salt marshes

    A before-and-after, site comparison study in 1996–1997 of two coastal marshes in Louisiana, USA (Ford et al. 1999) reported that one year after spraying dredged sediment onto a marsh, cover of three of four plant species was greater than before spraying. Statistical significance was not assessed. One year after spraying, the marsh had 66% cover of smooth cordgrass Spartina alterniflora (before: 19%), 35% cover of hairy cowpea Vigna luteloa (before: 1%), 16% cover of three-square bulrush Scirpus americanus (before: 7%) and 0% cover of saltmeadow cordgrass Spartina patens (before: 11%). Meanwhile, cover of the first three species was stable over time in a nearby unsprayed marsh (smooth cordgrass: 54–55%; cowpea: 8–12%; bulrush: 7–9%) whilst cover of saltmeadow cordgrass declined (from 6% to 0%). Methods: In July 1996, dredged canal sediment was sprayed in a high-pressure jet onto an area of subsided marsh in the Mississippi Delta. This increased the marsh surface elevation by approximately 2 cm. Cover of each plant species was surveyed in the sprayed marsh and a nearby reference marsh (not subsided, not sprayed), five weeks before spraying (June 1996) and for up to one year after (July 1997).

    (Summarised by: Nigel Taylor)

Output references
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust