Habitat heterogeneity determining the macrobenthic infaunal community in a mangrove swamp in South China: implication for plantation and plant invasion

Abstract

Leung, J.Y.S., 2015. Habitat heterogeneity determining the macrobenthic infaunal community in a mangrove swamp in South China: Implication for plantation and plant invasion. Mangroves have been severely disturbed by human exploitation over the last few decades, and mangrove plantation programs have been launched to restore degraded mangroves worldwide. However, mangrove plantations can change habitat heterogeneity, potentially altering the macrobenthic infaunal community, an important constituent in mangrove ecosystems. The Tai O mangrove swamp in Hong Kong was chosen as the study site for evaluation of the significance of habitat heterogeneity on the macrobenthic infaunal community by interpreting infaunal and environmental data through univariate and multivariate analyses. Infauna and sediment samples were collected by sediment cores in habitats with an increasing order of habitat heterogeneity (mudflat < seedling < Kandelia < Kandelia with algal mats < pneumatophore). Compared with other areas, a higher Shannon-Weaver index was found in the seedling area and higher abundance was found in the mudflat area. Spearman correlation analysis revealed that abundance, Margalef's species richness, and the Shannon-Weaver index were negatively correlated with root biomass, particle size in phi value, and redox potential. Analysis of similarities revealed that different habitats had different macrobenthic infaunal communities. Biota–environment analysis and a distance-based linear model both showed unequivocally that root biomass was the paramount factor in determining the macrobenthic infaunal community. The findings signified the importance of habitat heterogeneity, largely depending on root biomass, in determining the macrobenthic infaunal community and implied that plantation or plant invasion in open areas poses far-reaching consequences in mangrove ecosystems.