Influence of plantation of an exotic mangrove species, Sonneratia caseolaris (L.) Engl., on macrobenthic infaunal community in Futian Mangrove National Nature Reserve, China

Sonneratia caseolaris, a superior mangrove species characterized by rapid growth and proliferation, has been introduced to Futian Mangrove National Nature Reserve, Shenzhen, China for mangrove restoration since 1993. However, the effect of Sonneratia plantation on the macrobenthic infaunal community, a vital component of energy flow and nutrient recycling in mangrove ecosystems, remains obscure. The present study aimed to answer this question by determining the macrobenthic infaunal community, habitat characteristics and physico-chemical properties of sediment in the vegetated sites, dominated by different mangrove species (Kandelia obovata, Avicennia marina and S. caseolaris), and un-vegetated mudflat at four sampling times from August 2008 to September 2009. Results showed that the presence of Sonneratia can enhance the biodiversity of macrobenthic infauna in terms of Shannon-Weaver index (H'), compared to the mudflat, since August 2008 onwards. Multivariate analyses (CLUSTER and SIMPER) showed that the macrobenthic infaunal community in the Sonneratia site was different from all the other sites due to higher abundance of deposit and filter feeders, including Limnodriloides sp., Capitella capitata, Potamilla acuminata, Tharyx sp. and Ampharete arctica. The presence of Sonneratia, however, could not significantly alter the sediment properties. Spearman correlation analysis revealed that H' was negatively correlated with cadmium concentration whereas distance-based linear model (DistLM) suggested that cadmium was a significant predictor variable correlating with the macrobenthic infaunal community. The higher cadmium concentration in August 2008 explained why H' was lower and different macrobenthic infaunal communities were observed compared to the other sampling times. However, cadmium was the only significant predictor variable explaining 14.9% total variation, suggesting that the macrobenthic infaunal community was generally not affected by the sediment properties. Therefore, we concluded that Sonneratia plantation in the open mudflat can enhance the biodiversity of macrobenthic infauna in view of higher habitat complexity (e.g. presence of pneumatophores, below-ground vegetation and litter) on condition that the cadmium concentration was below the harmful level. (C) 2013 Elsevier B.V. All rights reserved.