Environmental effects on bacterial diversity in the surface mucus layer of the reef coral Montastraea faveolata

Abstract

Spatial and temporal variation in bacterial 16S rDNA diversity from healthy coral Montastraea faveolata (Ellis & Solander, 1786) was investigated using denaturing gradient gel electrophoresis (DGGE). The microbial communities of the surface mucus layer (SML) were investigated at 5 sites in Tobago of varying water quality and proximity to the mainland. Presence/absence and band intensity data from DGGE profiles were used as a relative measure of diversity of the microbial community structure. Multivariate analyses using PRIMER software Version 6.1.5 (multidimensional scaling and analysis of similarity) showed that microbial communities associated with corals from within the same reef area were very similar (p = 0.093), that there were significant differences between sites (p = 0.001), and that SML communities were significantly different from the microbial community within the water column (p = 0.001). No strong correlations between the SML bacterial community structure and measured water quality parameters were observed using a biota-environment matching routine within PRIMER (BIOENV). Strong seasonal effects were observed on tagged corals from sites that were re-sampled 6 times covering the wet and dry seasons. Although the SML of M. faveolata appears to support a distinct microbial community, this study shows that intraspecific temporal and spatial variation also exists, and reasons for these differences are explored. © Inter-Research 2006.