Understanding patterns of connectivity among populations of marine organisms is essential for the development of realistic, spatially explicit models of population dynamics. Two approaches, empirical genetic patterns and oceanographic dispersal modelling, have been used to estimate levels of evolutionary connectivity among marine populations but rarely have their potentially complementary insights been combined. Here, a spatially realistic Lagrangian model of larval dispersal and a theoretical genetic model are integrated with the most extensive study of gene flow in a Caribbean marine organism. The 871 genets collected from 26 sites spread over the wider Caribbean subsampled 45.8% of the 1900 potential unique genets in the model. At a coarse scale, significant consensus between modelled estimates of genetic structure and empirical genetic data for populations of the reef-building coral Montastraea annularis is observed. However, modelled and empirical data differ in their estimates of connectivity among northern Mesoamerican reefs indicating that processes other than dispersal may dominate here. Further, the geographic location and porosity of the previously described east-west barrier to gene flow in the Caribbean is refined. A multi-prong approach, integrating genetic data and spatially realistic models of larval dispersal and genetic projection, provides complementary insights into the processes underpinning population connectivity in marine invertebrates on evolutionary timescales.
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.
The gel-forming properties of mucus are closely related to its functioning; although there is limited information available relating to coral mucus gels. The present study investigates coral mucus glycoprotein using rheological methods. We demonstrate the presence of a high-molecular-weight polymeric glycoprotein similar to that found in vertebrates, capable of forming a gel. The milked mucus exuded mostly from the oral cavity of corals is not a gel; however, it does show a tendency to form a gel upon concentration. Such results indicate the potential for corals to produce two different kinds of mucus, each potentially capable of performing different functions.
Sea surface temperature (SST) plays a key role in regulating ocean-atmosphere interactions and modulating climate variability (Deser et al., 2010;Folland et al., 1986). Our knowledge of the natural drivers of long-term SST changes and our ability to constrain past climate variability is often restricted by temporally short and spatially sparse instrumental and historical climate records (Gagan et al., 2000;Lough, 2010). Expanding the number of paleoclimate proxy records to increase geographical and temporal coverage of SST reconstructions will improve our understanding of future changes.Massive and long-lived scleractinian corals provide high temporal (sub-seasonal) resolution, long term climate and environmental records that have been used to reconstruct Earth's past climate on interannual to millennial timescales (e.g.,
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