Study

Alginate addition influences smooth cordgrass (Spartina alterniflora) growth and macroinvertebrate densities

  • Published source details Cohen R.A. & Kern H. (2012) Alginate addition influences smooth cordgrass (Spartina alterniflora) growth and macroinvertebrate densities. Wetlands, 32, 51-58.

Actions

This study is summarised as evidence for the following.

Action Category

Add below-ground organic matter: brackish/salt marshes

Action Link
Marsh and Swamp Conservation
  1. Add below-ground organic matter: brackish/salt marshes

    A replicated, randomized, controlled, before-and-after study in 2007–2008 in a salt marsh in Georgia, USA (Cohen & Kern 2012) found that adding alginate generally increased the density and height, but not biomass, of smooth cordgrass Spartina alterniflora. Before intervention, plots contained 285–334 smooth cordgrass stems/0.5 m2 and plants were 53–59 cm tall. After 6–16 weeks, smooth cordgrass density was greater in plots amended with alginate (282–367 stems/0.5 m2) than in unamended plots (224–313 stems/0.5 m2). However, smooth cordgrass height did not significantly differ between treatments (amended: 65–68 cm; unamended: 60–63 cm). After 28–52 weeks, smooth cordgrass density remained greater in amended plots (135–213 stems/0.5 m2) than in unamended plots (121–164 stems/0.5 m2). Cordgrass was also significantly taller in amended plots (23–49 cm) than in unamended plots (15–35 cm). Finally, after 52 weeks, above-ground cordgrass biomass did not significantly differ between treatments (amended: 3.4 g/0.25 m2; unamended: 6.3 g/0.25 m2). Methods: In July 2007, ten 0.5-m2 plots were established in a cordgrass-dominated salt marsh. Alginate (a carbon-rich seaweed extract) was added to five plots (80 g/plot, across ten 2-cm diameter x 10-cm deep holes). In the other five plots, holes were dug but alginate was not added. Live stem density and the height of the five tallest plants were recorded immediately before intervention and biweekly afterwards. Smooth cordgrass was cut from plots after one year, then dried and weighed.

    (Summarised by: Nigel Taylor)

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