Invasions of exotic plant species in estuaries have occurred worldwide, and may profoundly affect native biodiversity and estuarine ecosystem functioning. To assess the effect of plant invasions on benthic meiofauna, we compared the nematode communities in marshes dominated, respectively, by invasive Spartina alterniflora and native Scirpus mariqueter and Phragmites australis at 3 local sites over 2 seasons in the Yangtze River estuary, PR China. S. alterniflora stands had generally lower nematode trophic diversity than the stands of the 2 native plants, suggesting that the exotic plant led to a simplified benthic food web. The relative abundance of bacterial-feeding nematodes tended to increase in S. alterniflora marshes compared to P. australis marshes. The increased bacterial-feeding nematodes in S. alterniflora stands are likely to reflect the altered decomposition processes, rates and pathways, which may, in turn, modify belowground nutrient cycling of the estuarine ecosystems. The dissimilarity in nematode community structure between S. alterniflora and S. mariqueter marshes was smaller than that between S. alterniflora and P. australis marshes, and the dissimilarity between Spartina-invaded and native marshes was even smaller than between the 2 native plant marshes. It is suggested that the detection of the ecological consequences of plant invasions depends on which native plant species is considered. Site effects were generally detected in the comparison of sediment properties and nematodes among 3 plant marshes. Sediment water content, electrical conductivity, bacterial biomass and litter biomass were identified as the most important factors in the shaping of the nematode communities.KEY WORDS: Community structure · Cordgrass · C 3 plant · C 4 plant · Diversity · Exotic plant · Nematodes · Wetlands
Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 336: [99][100][101][102][103][104][105][106][107][108][109][110] 2007 Spartina invasions influence benthic communities when compared with unvegetated mudflats (Zipperer 1996, O'Connell 2002, Neira et al. 2005, and several studies have compared benthic macrofaunal communities of the invasive Spartina and those of native vegetated marshes , Chen et al. 2005, Neira et al. 2005, and yielded inconsistent results. In Little Swanport estuary, Tasmania, Hedge & Kriwoken (2000) found that species richness and total abundance of macrofauna in invasive S. anglica and native saltmarshes do not differ significantly. Chen et al. (2005) reported that the replacement of Scirpus mariqueter by S. alterniflora results in reduced macroinvertebrate density and species diversity in salt marshes of Chongming Island in the Yangtze River estuary, China. Neira et al. (2005) found higher macrofaunal species richness in Spartina hybrid-invaded patches relative to native Salicornia marshes in San Francisco Bay, USA, but no differences in total macrofaunal density were found. These studies suggest that the responses of benthic ma...