Control of invasive Phragmites australis (European common reed) alters macroinvertebrate communities

Abstract

Wetland restoration often involves invasive‐plant suppression to encourage the recovery of native‐dominated vegetation communities. However, assessment of recovery is usually focused only on vegetation, and the response of other critical wetland biota, such as macroinvertebrates, is seldom assessed. We characterized the aquatic, semi‐aquatic, and terrestrial macroinvertebrate communities in remnant, uninvaded marsh to identify restoration targets and compared this to the communities in Phragmites australis‐invaded marsh and in the formerly invaded marsh that was treated with the herbicide glyphosate in 2016 to simultaneously evaluate the effects of invasion and invasive‐species suppression. We sampled invertebrates in 2017 and 2018 to track 2 years following herbicide treatment. The invertebrate community composition was similar between P. australis invaded and remnant marsh, suggesting invasion has little effect on macroinvertebrate community structure. There was also high concordance between the aquatic and emerging‐invertebrate communities in the invaded and uninvaded habitats. In contrast, herbicide‐treated sites had a unique community composition, characterized by very high densities of Chironomidae (Diptera) and low taxa richness and evenness. Herbicide‐treated sites also exhibited low concordance between the aquatic and emerging‐invertebrate communities, potentially attributable to the sparse, emergent‐vegetation cover providing limited substrates for emergence. Herbicide‐based, invasive‐species control resulted in considerable changes to the macroinvertebrate community in freshwater marshes for at least 2 years after treatment, which may have consequences for aquatic food webs and species that rely on macroinvertebrates as prey.

Predicting The Great Lakes Wetlands' Resilience to Climate Change in Response to Phragmites australis subsp. australis Removal

“…Ensuring an ecosystem is balanced in the various aspects examined throughout this paper is an effective strategy in preserving biological communities for the future (Rahel & Olden, 2008). Many published studies have reported overall ecosystem improvement upon Phragmites removal, as well as identified correlations between invasions and decreased ecosystem capacity to buffer other disturbance effects, such as extreme weather influenced by climate change (Rahel & Olden, 2008;Tozer & Mackenzie, 2019;Robichaud et al, 2021;Modzer & Zieman, 2010;Meyerson et al,1999;Borin et al, 2011;Lenters et al, 2011;Bergquist et al, 2007). Other literature has also supported Phragmites invasions within the Great Lakes wetlands to be amplified by climate change.…”

“…Lastly, an investigation monitoring the differences in aquatic, semi-aquatic, and terrestrial invertebrate community compositions showed little distinction between Phragmitesinvaded and uninvaded marshes, suggesting that Phragmites has little affect on macroinvertebrate communities (Robichaud et al, 2021). However, in sites where herbicide was applied for control of Phragmites, aquatic and semi-aquatic invertebrate community composition shifted, as Chironomidae, Leptoceridae, and Caenidae became the dominating invertebrate taxa in the community (Robichaud et al, 2021).…”

“…However, in sites where herbicide was applied for control of Phragmites, aquatic and semi-aquatic invertebrate community composition shifted, as Chironomidae, Leptoceridae, and Caenidae became the dominating invertebrate taxa in the community (Robichaud et al, 2021). Additionally, aquatic and semi-aquatic taxa richness and evenness declined in herbicide-treated sites (Robichaud et al, 2021). In another study, terrestrial invertebrate density, biomass, and species richness in Phragmites-dominated sites compared to mixed vegetation was found to be species-dependent (Meyerson et al, 1999).…”

The effect of Spartina alterniflora eradication on waterbirds and benthic organisms

“…Experiments in northeast England and Washington restored the bare surfaces of silt and sand in areas cleared of Common Cordgrass ( Spartina anglica ) by using herbicide, turning the areas into a habitat suitable for benthic organisms and attracting waterbirds to re‐use these wetlands (Evans 1986; Patten & O'Casey 2007). Therefore, comparing the density and biomass of benthic organisms between S. alterniflora eradicated areas and bare tidal flat areas (where S. alterniflora was absent) can improve our understanding of the effects of S. alterniflora eradication on benthic communities, and it may explain the distribution of waterbirds across these habitats (Robichaud et al 2022).…”