Microbial communities of wild-captured Kemp’s ridley (Lepidochelys kempii) and green sea turtles (Chelonia mydas)

Abstract

Conservation efforts for endangered sea turtle species, such as Kemp’s ridley turtles Lepidochelys kempii and green turtles Chelonia mydas, may benefit from information on the microbial communities that contribute to host health. Previous studies examining host-associated microbiomes of these species have been limited in geographic region, life stage, and/or health. Here, we characterized the microbiome of the oral cavity and cloaca from wild-captured Kemp’s ridley and green turtles off the west coast of Florida, USA, by using Illumina sequencing to analyze the 16S rRNA gene. Microbial communities were distinct between body sites as well as between turtle species, suggesting that the turtle species is more important than the local environment in determining the microbiome of sea turtles. We identified the core microbiome for each species at each body site and determined that there were very few bacteria shared among the oral samples of both species, and no taxa co-occurred in the cloaca samples among both species. The core microbiome of the green turtle cloaca was primarily from the order Clostridiales, which plays an important role in digestion for other herbivorous species. Due to high prevalence of fibropapillomatosis in the green turtles (90%), we also investigated the correlation between the microbiome and the severity of fibropapillomatosis, and we identified changes in beta diversity associated with the total number of tumors. This study provides the first glimpse of the microbiome in 2 sympatric species of sea turtle and sheds an important species-specific light on the microbiome of these endangered species.

Characterization of oral and cloacal microbial communities in cold-stunned Kemp’s ridley sea turtles (Lepidochelys kempii) during the time course of rehabilitation

“…Compared to wild healthy Kemp’s ridley turtles from the Gulf of Mexico, the oral microbiome of cold-stunned turtles at intake shared similar predominant bacterial families, including Flavobacteraceae and Rhodobacteraceae [ 64 ]. The cloacal samples, by contrast, were different between the healthy wild Kemp’s ridley turtles and the cold-stunned stranded turtles with no shared dominant families between the two groups [ 64 ].…”

“…Compared to wild healthy Kemp’s ridley turtles from the Gulf of Mexico, the oral microbiome of cold-stunned turtles at intake shared similar predominant bacterial families, including Flavobacteraceae and Rhodobacteraceae [ 64 ]. The cloacal samples, by contrast, were different between the healthy wild Kemp’s ridley turtles and the cold-stunned stranded turtles with no shared dominant families between the two groups [ 64 ]. Cardiobacteraceae, Flavobacteraceae, and Neisseriaceae were most prevalent in the wild healthy turtles, while Vibrionaceae, Arcobacteraceae, Shewanellaceae, and Rhodobacteraceae were prevalent from the intake cloacal samples of cold-stunned turtles.…”

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

“…Twenty wild caught green sea turtles were caught off the coast of Florida adjacent to the St. Martins Marsh Aquatic Preserve of Crystal River. Among all 20 samples the families Neisseriaceae and Arcobacteraceae were found to have the highest percent mean abundance (MA) at 29.2% and 14.7% respectively [56]. These findings are more comparable to samples obtained from stranded and hospitalized green sea turtles [32,38] and brings forth the question, what external factors may be affecting the cloacal microbiota?…”

“…In direct contrast to the two other studies on wild caught green sea turtles [38,51], McNally et al 2021 found an abundance of microbial families within the Proteobacteria phylum in wild caught green sea turtles [56]. Twenty wild caught green sea turtles were caught off the coast of Florida adjacent to the St. Martins Marsh Aquatic Preserve of Crystal River.…”

“…In addition to the previously mentioned studies utilizing traditional culture techniques, there are also an array of studies that have used high throughput sequencing to identify the microbiota on the cloacal surface of sea turtles. Three of these studies collected cloacal samples from wild captured green sea turtles [38,51,56]; two of which found similar profiles with Firmicutes and Bacteroidetes as the dominant phyla [38,51]. Price et al investigated the cloacal microbiota in wild caught juvenile green turtles from three different habitats (pelagic, beachfront, bay) in the Northern Gulf of Mexico [51].…”