ABSTRACT
Chen, Q. and Ma, K., 2018. Determining whether exotic cordgrass (Spartina alterniflora) attracts carnivorous macrobenthic fauna within a Zhanjiang (China) mangrove ecosystem.
The last decade witnessed a paradigm shift concerning the impact of functional diversity on ecosystem functioning, and biological invasions have led to profound effects on functional diversity. However, a comprehensive understanding of the effects of exotic plants on macrobenthic functional diversity is not available for mangrove ecosystems. The macrobenthic functional feeding groups were compared in (1) a noninvaded stand vs. an Spartina alterniflora-invaded stand of the mangrove tree Avicennia marina (a mixture of A. marina and S. alterniflora) and (2) a noninvaded unvegetated shoal vs. an invaded shoal (a S. alterniflora monoculture) in Zhanjiang, China. The results indicated that the phytophagous group was the dominant functional feeding group regardless of habitat or macrobenthic parameter (species richness, abundance, and biomass) percentages. For all macrobenthic parameters, the carnivorous percentages were significantly higher in the S. alterniflora and A. marina mixture than in the A. marina monoculture. Except for species richness, the same was true for the S. alterniflora monoculture compared to the unvegetated shoal. The presence of the exotic cordgrass S. alterniflora is likely to attract more carnivorous macrobenthic fauna in a Zhanjiang mangrove ecosystem. Further analysis revealed that the sediment silt and plant density were the principal environmental variables determining the composition proportion of macrobenthic functional feeding groups. The lower sediment silt proportion and higher plant density ascribed to S. alterniflora invasions might be responsible for the changes in the proportion of macrobenthic functional feeding groups. The results aid the understanding of the effects and mechanisms of plant invasions on benthic functional diversity of mangrove ecosystems and yield insights into the links of biological invasions, functional diversity, and ecosystem functioning in coastal ecosystems.
