Effects of non-native Spartina patens on plant and sediment organic matter carbon incorporation into the local invertebrate community

Abstract

The cycling of organic matter through food webs is a fundamental process that may be altered by the invasion of non-indigenous plants. We explored consequences of the invasion of non-indigenous Spartina patens to the composition of soil organic matter (SOM) and to detritivore and herbivore diets in the upper salt marsh within Corrubedo National Park, northwest Spain. We tested for the incorporation of S. patens carbon (C) into SOM and by detritivores and herbivores using stable isotope analysis, focusing primarily on detritivorous enchytraeid oligochaetes and herbivorous insects. Stable isotope results indicated that C derived from S. patens has been incorporated into SOM. Elevated densities of enchytraeids in stands of S. patens, and their incorporation of C derived from this plant, suggested that dense patches of S. patens may facilitate detritivore populations. In contrast, although insect herbivores used S. patens as habitat, there was little isotopic evidence for the widespread incorporation of S. patens-derived C by these consumers. The population and dietary response of enchytraeids to S. patens suggests that S. patens invasion could indirectly influence soil processes and pathways mediated by detritivore activity (e.g., soil respiration rates, nutrient retention and transformation, energy flow). The loss of food resources to insect herbivores alters local food webs. However, insect herbivores may move and feed on native plants elsewhere. As a result, insect populations may be less immediately impacted than soil detritivore populations by S. patens. Our study suggests that the influences of S. patens invasion extend beyond the more obvious changes in native plant abundance, to include differing responses in the cycling of organic matter between detritivore and insect herbivore food web pathways.

Effects of Spartina alterniflora invasion on the communities of methanogens and sulfate-reducing bacteria in estuarine marsh sediments

“…The extensive expansion of S. alterniflora is recognized as one of the major threats to the natural ecology of salt marshes, because the plant can alter the carbon and nitrogen contents of sediments (Turner, 1993; Liao et al, 2007; Page et al, 2010). This, in turn, may influence the carbon and nitrogen cycles in the sediments and the microbes that provide these functions.…”

Restoration of native mangrove wetlands can reverse diet shifts of benthic macrofauna caused by invasive cordgrass

“…Biological invasions pose a significant threat to local community structure and ecosystem function world‐wide (Levin, Neira, & Grosholz, ; Page, Lastra, Rodil, Briones, & Garrido, ; Simberloff, ; Vitousek, D'Antonio, Loope, Rejmanek, & Westbrooks, ). Although mangrove forests are relatively resistant to invasion (Lugo, ), mangrove stands in southeastern China have been invaded by Spartina alterniflora over the last several decades (An et al., ; Zhang, Huang, Wang, Chen, & Lin, ).…”

Systematics and management of natural resources: the case of Spartina species on European shores

“…Besides, the presence of S. patens on the Iberian coasts is fully accepted (e.g. Ainouche et al 2003;Ayres et al 2004;Page et al 2010), and consequently, it has already been included in numerous catalogues of invasive plants of the Iberian Peninsula coast (e.g. Sanz Elorza et al 2004;Campos & Herrera 2009a, 2009b.…”

“…Within this assumption, the management of European coastal natural resources should consider that Spartina patens strongly modifies and disturbs such habitats (Sanz Elorza et al 2004;Campos & Herrera 2009a;Page et al 2010). The goals of the management of S. patens on European shores should target to prevent the establishment and spread of any Spartina populations.…”