Consistent patterns in 16S and 18S microbial diversity from the shells of the common and widespread red-eared slider turtle (Trachemys scripta)

Abstract

Microbial communities associated with freshwater aquatic habitats and resident species are both critical to and indicative of ecosystem status and organismal health. External surfaces of turtle shells readily accumulate microbial growth and could carry representation of habitat-wide microbial diversity, since they are in regular contact with multiple elements of freshwater environments. Yet, microbial diversity residing on freshwater turtle shells is poorly understood. We applied 16S and 18S metabarcoding to characterize microbiota associated with external shell surfaces of 20 red-eared slider (Trachemys scripta) turtles collected from varied habitats in central and western Oklahoma, and ranging to southeast Iowa. Shell-associated microbial communities were highly diverse, with samples dominated by Bacteroidia and alpha-/gamma-proteobacteria, and ciliophoran alveolates. Alpha diversity was lower on turtle shells compared to shallow-water-associated environmental samples, likely resulting from basking-drying behavior and seasonal scute shedding, while alpha diversity was higher on carapace than plastron surfaces. Beta diversity of turtle shells was similarly differentiated from environmental samples, although sampling site was consistently a significant factor. Deinococcus-Thermus bacteria and ciliophoran alveolates were recovered with significantly higher abundance on turtle shells versus environmental samples, while bacterial taxa known to include human-pathogenic species were variably more abundant between shell and environmental samples. Microbial communities from a single, shared-site collection of the ecologically similar river cooter (P. concinna) largely overlapped with those of T. scripta. These data add to a foundation for further characterization of turtle shell microbial communities across species and habitats, with implications for freshwater habitat assessment, microbial ecology and wildlife conservation efforts.

Surface microbiota of Mediterranean loggerhead sea turtles unraveled by 16S and 18S amplicon sequencing

“…Compared to the carapace, the skin of the neck and flippers (sampled in this study) is prone to higher mechanical disturbance caused by the turtle's movements. Parks et al (2020) reported a higher diversity and richness of microbial communities on the freshwater turtles' carapace in comparison to the plastron, and provide the movement of the turtles as one of the possible explanations. Furthermore, Blasi et al (2022) reported significant differences between microbial communities of differently positioned carapace scutes.…”

“…However, very little is known about the epimicrobiomes of reptiles, especially turtles, including terrestrial, freshwater, and marine species. Recently, there have been studies on external microbial communities of freshwater turtles (Trachemys scripta, Pseudemys concinna, and Emydura macquarii krefftii) that identified major microbial components of eukaryotic, bacterial and archaeal surface communities and showed that turtles' microbiotas differ between body parts and between animals and their environment (McKnight et al, 2020;Parks et al, 2020). New knowledge about the functional and phylogenetic composition of epimicrobiomes of different species improves our understanding of the relationships between the host, its microbial flora, and the environment.…”

What lives on and in the sea turtle? A literature review of sea turtle bacterial microbiota

“…There is no current literature citing the use of next generation sequencing on skin samples in sea turtles. However, there are studies that investigated the skin and shell microbiota of freshwater turtles such as the red-eared slider (Trachemys scripta) and the Krefft's river turtle (Emydura macquarii krefftii) [57,58]. These studies suggest that there are unique microbiota located on different parts of the skin, such as the head and the shell with and without algae [57,58].…”

“…However, there are studies that investigated the skin and shell microbiota of freshwater turtles such as the red-eared slider (Trachemys scripta) and the Krefft's river turtle (Emydura macquarii krefftii) [57,58]. These studies suggest that there are unique microbiota located on different parts of the skin, such as the head and the shell with and without algae [57,58]. Microbiota located on the skin, plastron, and carapace of sea turtles is an area in need of investigation.…”

Surface microbiota of Mediterranean loggerhead sea turtles unravelled by 16S and 18S amplicon sequencing

“…However, very little is known about the epimicrobiomes of reptiles, especially turtles, including terrestrial, freshwater, and marine species. Recently, there have been studies on external microbial communities of freshwater turtles ( Trachemys scripta, Pseudemys concinna and Emydura macquarii krefftii ) that identified major microbial components of eukaryotic and prokaryotic surface communities and showed that turtles’ microbiotas differ between body parts and between animals and their environment (McKnight et al, 2020; Parks et al, 2020). New knowledge about the functional and phylogenetic composition of epimicrobiomes of different species improves our understanding of the relationships between the host, its microbial flora, and the environment.…”