Herbiciding invasive reed: indirect effects on habitat conditions and snail-algal assemblages one year post-application

  • Published source details Back C.L., Holomuzki J.R., Klarer D.M. & Whyte R.S. (2012) Herbiciding invasive reed: indirect effects on habitat conditions and snail-algal assemblages one year post-application. Wetlands, 20, 419-431.


This study is summarised as evidence for the following.

Action Category

Use herbicide to control problematic plants: freshwater marshes

Action Link
Marsh and Swamp Conservation
  1. Use herbicide to control problematic plants: freshwater marshes

    A replicated, randomized, controlled study in 2007–2008 in a freshwater marsh invaded by common reed Phragmites australis in Ohio, USA (Back et al. 2012) reported that plots sprayed with herbicide were more likely to contain free-growing filamentous algae than unsprayed plots, but found that all plots contained a similar abundance, diversity and community of biofilm algae. After approximately one year, free-growing algae occurred in 13 of 30 samples in sprayed plots (vs 1 of 15 samples in unsprayed plots; statistical significance not assessed). Meanwhile, biofilm algae reached a statistically similar abundance in sprayed and unsprayed plots. This was true for both density (sprayed: 1,700–2,800 cells/cm2; unsprayed: 1,100–1,700 cells/100 cm2) and biomass (sprayed: 5–41 μg chlorophyll/cm2; unsprayed: 5–41 μg chlorophyll/cm2). Sprayed and unsprayed plots also supported a similar diversity of biofilm algae (data reported as a diversity index) and a similar community composition of the most abundant group: diatoms (data reported as a graphical analysis; statistical significance of difference not assessed). Common reed was less abundant in sprayed than unsprayed plots, in terms of both density (sprayed: 2–3 live stems/m2; unsprayed: 36 live stems/m2) and cover (sprayed: 1–3%; unsprayed: 49%). Methods: In June 2007, fifteen contiguous 20 x 20 m plots were established in a reed-invaded, lakeshore marsh. Ten random plots were sprayed once with herbicide (five with glyphosate-based AquaNeat®; five with imazapyr-based Habitat®). The other five plots were not sprayed. Vegetation was surveyed in June–August 2008. Free-growing algae were surveyed in 10 x 10 cm quadrats. Biofilms were surveyed on fallen, submerged reed stems. Reeds were surveyed, in 0.5-m2 quadrats, along a central transect in each plot.

    (Summarised by: Nigel Taylor)

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