Effects of Spartina alterniflora invasion on benthic nematode communities in the Yangtze Estuary

Abstract

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...

Spartina alterniflora Invasion Alters Carbon Exchange and Soil Organic Carbon in Eastern Salt Marsh of China

“…Spartina alterniflora, a smooth cordgrass species from North America, has been introduced into China since the 1970s for coastal protection [25]. This exotic plant has great advantages in competing for distribution area with native plants: Phragmites australis, Suaeda salsa, Cyperus malaccensis, and Scirpus mariqueter [26][27][28]. As a successful example of colonization in eastern coast of China, S. alterniflora has been considered as a serious problem to the structure and function of native ecosystems [29][30][31][32][33][34].…”

Ecosystem Engineering Effects of Aster tripolium and Salicornia procumbens Salt Marsh on Macrofaunal Community Structure

“…Indeed, lutein/Chl-a, a proxy for plant detritus, significantly explained the macrobenthic composition in the salt marsh based on species abundance. In fine-grained marsh sediments, Polychaeta, such as N. diversicolor, and to some extent also H. filiformis and P. elegans, had lower biomass and abundance in favor of Oligochaeta, which have a shallower burying depth and a smaller size (and thus higher surface area to body volume), making them better adapted to hypoxic environments (Seys et al 1999;Chen et al 2007). The limited abundance of large bioturbators such as N. diversicolor (perhaps also hindered by the root structure of the marsh) may have caused further changes in the geochemical properties of such salt marsh sediments (Gribsholt and Kristensen 2003;Van Wesenbeeck et al 2007).…”

Distribution and ecological role of the non-native macroalga Gracilaria vermiculophylla in Virginia salt marshes

“…Salt marshes are relatively rarely reported to be dominated by non-native species, and the vast majority of existing studies on non-native species describe a few fast-growing angiosperms, in particular Phragmites australis or various Spartina species (e.g., Daehler and Strong 1996;Benoit and Askins 1999;Amsberry et al 2000;Hedge and Kriwoken 2000;Able and Ragan 2003;Chambers et al 2003;Nieva et al 2003;Silliman and Bertness 2004;Bart et al 2006;Brusati and Grosholz 2006;Neira et al 2006;Brusati and Grosholz 2007;Chen et al 2007;Cottet et al 2007). In contrast, we are not aware of studies that describe non-native macroalgae in marshes.…”