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Bacterial communities associated with plant propagules remain understudied, despite the opportunities that propagules represent as dispersal vectors for bacteria to new sites. These communities may be the product of a combination of environmental influence and inheritance from parent to offspring. The relative role of these mechanisms could have significant implications for our understanding of plant–microbe interactions. We studied the correlates of microbiome community similarities across an invasion front of red mangroves (Rhizophora mangle L.) in Florida, where the species is expanding northward. We collected georeferenced propagule samples from 110 individuals of red mangroves across 11 populations in Florida and used 16S rRNA gene (iTag) sequencing to describe their bacterial communities. We found no core community of bacterial amplicon sequence variants (ASVs) across the Florida range of red mangroves, though there were some ASVs shared among individuals within most populations. Populations differed significantly as measured by Bray–Curtis dissimilarity, but not Unifrac distance. We generated data from 6 microsatellite loci from 60 individuals across 9 of the 11 populations. Geographic distance was correlated with beta diversity, but genetic distance was not. We conclude that red mangrove propagule bacterial communities are likely influenced more by local environmental acquisition than by inheritance. [ABSTRACT FROM AUTHOR]

Benthic foraminifera are valuable indicators in environmental studies, including those on marine pollution monitoring. While a great deal of foraminiferal biomonitoring research utilizes abundance and distributional data, further value resides in better understanding the incorporation of heavy metal pollutants in foraminiferal calcite. By experimentally growing assemblages of foraminifera from propagules (small juveniles) gathered from Sapelo Island, Georgia and Little Duck Key, Florida, this study examines foraminiferal incorporation of the heavy metals arsenic, cadmium, nickel, and zinc over a range of concentrations. Surface sediment was collected and sieved to concentrate the propagules. The propagules were then used to experimentally grow assemblages with each exposed to a different heavy metal. After one month, the experimentally grown foraminifera were harvested and samples of the two most common species from each location, Ammonia tepida (Cushman) and Haynesina germanica (Ehrenberg) from Sapelo Island and Quinqueloculina sabulosa (Cushman) and Triloculina oblonga (Montagu) from Little Duck Key, were selected for trace element analysis. Calcite of the tests was analyzed using LA-ICP-MS to quantify the heavy metal incorporation. Rotalid species A. tepida and H. germanica incorporated more cadmium as its concentration in the surrounding water increased, whereas miliolid species Q. sabulosa and T. oblonga incorporated more of the metals zinc and nickel. This study shows that while foraminiferal incorporation of heavy metals has great potential as a biomonitoring tool, multiple factors (especially inter-clade variation) must be considered carefully. In future marine environmental research, these factors may help to create a more targeted assessment of environmental pollution. • Foraminifera grown experimentally from propagules while exposed to heavy metals. • Heavy metals (arsenic, cadmium, nickel, zinc) represent a range of essentiality. • LA-ICP-MS showed clear differences in incorporation between rotalids and miliolids. • Rotalids incorporated more arsenic and cadmium as content in water increased. • Miliolids incorporated more zinc and nickel as content in water increased. [ABSTRACT FROM AUTHOR]