Abstract

The Kemp’s ridley turtle (Lepidochelys kempii) is a critically endangered species of sea turtle. Many Kemp’s ridley turtles become stranded annually from cold-stunning, or hypothermia, on Cape Cod, Massachusetts. Pneumonia is one of the major life-threatening complications of cold-stunning, with over 50% of Kemp’s ridley turtles in rehabilitation affected by bacterial and/or fungal pneumonia.^1,2 Diagnosis of pneumonia has historically relied on radiographic evidence of lung abnormalities and culture-dependent methods at veterinary diagnostic labs.² Emerging research on the microbiome of humans and other animals indicates the importance of microbial communities in health and disease, including pneumonia. Microbes play roles in various metabolic processes and regulation of immunity, and alterations in the microbiome are associated with infection, autoimmune disorders, and metabolic derangements.³ Investigation of the relationships between the animal host and the microbiome is leading to improved understanding of various species’ physiology and health,^4,5 but research on sea turtle microbiomes is limited. To understand the role that microbial communities play in health and disease of cold-stunned Kemp’s ridley turtles, the oral, cloacal, and respiratory microbiome was evaluated throughout rehabilitation, with a comparison of animals with and without pneumonia, as well as exposure to different antibiotics. Twenty-six stranded turtles had oral and cloacal swabs collected at up to five time points from admission to convalescence. Fourteen of these turtles also had tracheal washes performed at three of these time points, and the fluid retrieved was evaluated by high throughput sequencing as well as culture for comparison. Samples were also collected at 4 additional sites, (oral, trachea, anterior lung, and posterior lung) of the respiratory tract from 6 deceased turtles at time of necropsy. High-throughput sequencing of the 16S rRNA gene revealed a diverse and distinct microbial community at each of the sample sites. Tracheal wash microbial communities were not consistently similar to other sample sites along the respiratory tract, such as the oral cavity and posterior lung. Evaluation of the oral and cloacal microbiomes revealed alterations in the microbial community as a result of the rehabilitation setting as well as from antibiotic therapies. This study provides the first characterization of microbial communities in the Kemp’s ridley sea turtle and highlights the effects of environment and medication exposure on wild animals. Microbiome results call into question the utility of culture dependent characterization of tracheal washes as a diagnostic tool for pneumonia in cold-stunned turtles. In addition, results emphasize the need for alternative diagnostic measures to more effectively understand the disease process and treatment options for pneumonia in cold-stunned turtles.

Acknowledgements

The authors wish to thank the New England Aquarium Rescue & Rehabilitation Department, the New England Aquarium Animal Health Department, and the Bowen Lab. The authors thank the Dr. Robert W. Spayne Research Grant and the Nancy Goranson Endowment Fund for financial support.

* Presenting author

Literature Cited

1.  Innis CJ, Nyaoke A, Williams CR, Dunnigan B, Merigo C, Woodward DL, Weber ES, Frasca S. 2009. Pathologic and parasitologic findings of cold-stunned Kemps ridley sea turtles (Lepidochelys kempii) stranded on Cape Cod, Massachusetts, 2001–2006. Journal of Wildlife Diseases. 45(3):594–610.

2.  Stockman J, Innis CJ, Solano M, O’Sullivan Brisson J, Kass PH, Tlusty MF, Weber III ES. 2013. Prevalence, distribution, and progression of radiographic abnormalities in the lungs of cold-stunned Kemp’s ridley sea turtles (Lepidochelys kempii): 89 cases (202–2005). J Am Vet Med Assoc. 242:675–681.

3.  Dickson R, Erb-Downward J, Huffnagle GB. 2014. The role of the bacterial microbiome in lung disease. Expert Rev Respir Med. 7(3):245–257.

4.  McFall-Ngai M, Hadfield MG, Bosch TCG, Carey HV, Domazet-Loso T, Douglas AE, Dubilier N, Ebert G, Fukami T, Gilbert SF, Hantschel U, King N, Kjelleberg S, Knoll AH, Kremer N, Mazmanian SK, Metcalf JL, Nealson K, Pierce NE, Rawls JF, Reid A, Ruby EG, Rumpho M, Sanders JG, Tautz D, Wernegreen JJ. 2013. Animals in a bacterial world, a new imperative for the life sciences. PNAS. 110(9):3229–3236.

5.  Apprill A. 2017. Marine animal microbiomes: toward understanding host-microbiome interactions in a changing ocean. Front Mar Sci. 4:222.