Epibiotic bacteria on the carapace of hawksbill and green sea turtles

In this study, epibiotic bacteria on the carapace of sea turtles at three different sites in the Persian Gulf were studied. Bacterial density counted using a Scanning Electron Microscope showed that the highest (9.4 × 10⁶ ± 0.8 × 10⁶ cm^-2) and lowest (5.3 × 10⁶ ± 0.4 × 10⁶ cm^-2) average bacterial densities were found on the green and hawksbill sea turtles, respectively. Bacterial community analysis using Illumina 16S rRNA gene sequencing showed that Gamma- and Alpha-proteobacteria were the dominant classes on all substrates. Some genera, such as Anaerolinea, were site- and substrate-specific. In general, bacterial communities on sea turtles differed from those on the non-living substrate, stones, and exhibited lower species richness and diversity compared to the latter. Despite some similarities, the majority of bacterial communities on the two sea turtles were different. This study provides baseline information about the epibiotic bacteria of sea turtles of different species.