Podcast : Episode 5: Chat about Sea turtle rehabilitation center

Today is a very special episode: my guest is Dr. Terry Norton. Terry is one of my mentors and he has been my inspiration for many years. He is the reason I did a residency in zoological and aquatic medicine; making me understand that everything is possible if you work hard and are passionate. 

Dr. Norton is a wildlife veterinarian. He became a Diplomate of the American College of Zoological Medicine in 1992. Since then, he has provided veterinary care for White Oak Conservation Center, Riverbanks Zoo, North Carolina State Zoo and the Wildlife Conservation Society’s St. Catherines Island Wildlife Survival Center. He founded the Georgia Sea Turtle Center based on Jekyll Island in Georgia. Not only he provides veterinary care for animals of his center but he also provides veterinary care for the Turtle Survival Alliance’s Turtle Survival Center, and St. Catherines Island Foundation programs.  

Dr. Norton has worked around the world on numerous projects including Bali mynah
reintroduction in Indonesia, lemur health assessments in Madagascar, and sea turtle wildlife conservation efforts in Costa Rica. 

In this episode we will talk about The Georgia Sea Turtle Center based in Jeykyll Island (GA). We will discuss this importance of believing in your projects and dreams, of (re)connecting with nature and of course of following your hearts and hard work. 

Hope you enjoy the travel.  

To know more about Dr. Norton. fantastic work, there are few recent selected papers below:

Effects of GnRH agonists on testosterone and testosterone‐stimulated parameters for contraception and aggression reduction in male lion‐tailed Macaques (Macaca silenus)

LM Penfold, T Norton, CS Asa. Zoo Biology. 2021

Managing social groups in zoos requires controlling reproduction in individuals that do not have a current breeding recommendation, while simultaneously maintaining social harmony and animal well-being. Contraceptives, such as gonadotropin releasing-hormone (GnRH) agonists, that suppress testosterone production, offer a potential solution. They achieve infertility by interrupting spermatogenesis and may ameliorate androgen-induced aggression. This study investigated the effects of two GnRH agonists, histrelin and deslorelin, on testosterone, testis size, body weight and sperm production in male lion-tailed macaques, along with subjective observations of aggressive behavior. Five trials at three institutions with 14 males demonstrated that 100 mg histrelin or 9 to 12 mg of deslorelin could at least temporarily reduce testosterone, but a lower 6 mg dose was ineffective. However, ability of deslorelin to produce azoospermia varied among males, even at the highest dose. In general, a higher dose was needed (1) to achieve than to maintain suppression of any measured parameter and (2) to suppress sperm production than testosterone concentration. Testosterone production was also more likely than sperm production to recover, suggesting possible damage to seminiferous tubules but not to Leydig cells. Aggressive behavior was reduced in all but the group receiving the lowest dose. This allowed social groups to be maintained for many years despite recovery of testosterone in some males, suggesting that new social roles had been learned and become independent of androgen influence.
RESEARCH HIGHLIGHTS
Gonadotropin releasing-hormone agonists histrelin and deslorelin reduced testosterone, sperm production and aggression in lion-tailed macaques in a dose-dependent manner.
Testosterone was more likely than spermatogenesis to recover, making return to fertility uncertain.

Health and nutrition of loggerhead sea turtles (Caretta caretta) in the southeastern United States

CM Molter, TM Norton, LA Hoopes, SE Nelson Jr, M Kaylor, A Hupp, et al. Journal of Animal Physiology and Animal Nutrition. 2021

Loggerhead sea turtles (Caretta caretta) are opportunistic carnivores that feed primarily on benthic invertebrates and fish. Sea turtle rehabilitation requires provision of a species-specific, balanced diet that supplies nutrition similar to that of a wild diet; this can be challenging because free-ranging loggerheads’ diets vary depending on their life stage and geographic location, with predominant prey species dictated by local availability. The goal of this study was to better understand the nutritional needs of subadult and adult loggerheads in rehabilitation. This was accomplished by conducting a retrospective survey of stomach contents identified during gross necropsy of 153 deceased loggerheads that stranded in coastal Georgia, USA. A total of 288 different forage items were identified; the most frequently observed prey items belong to the subphylum Crustacea (N = 131), followed by bony fish (Osteichthyes; N = 45), gastropod mollusks (N = 40), bivalve mollusks (N = 23), and Atlantic horseshoe crabs (Limulus polyphemus; N = 15). The proportions of certain prey items differed significantly with turtle size; adult turtles ate proportionately more gastropods (p = 0.001), and subadults ate proportionately more fish (p = 0.01). Stomach contents information was used to determine common local prey items (blue crab, cannonball jellyfish, horseshoe crab, whelk), which were evaluated for nutritional content. Additionally, we compared hematology and plasma biochemistry profiles (including proteins, trace minerals, and vitamins) between four cohorts of loggerhead turtles, including free-ranging subadults and adults, nesting females, and loggerheads undergoing rehabilitation. This information was applied to inform a regionally specific, formulated diet for tube feeding, and a supplement containing vitamins and minerals for captive loggerheads, to more closely approximate the nutritional content of their natural diet. Assessing the regional and temporal variability in loggerhead diets is an important component in their effective conservation because resultant data can be used to help understand the impacts of environmental perturbations on benthic food webs.

BIOMEDICAL EVALUATION OF THE GOLDEN-CROWNED SIFAKA (PROPITHECUS TATTERSALLI) IN DARAINA, MADAGASCAR

A Page-Karjian, TM Norton, EE Louis Jr, RE Junge. J. of Zoo and Wildlife Medicine, 52(2):726-731 (2021)

Complete medical examinations were performed on 25 wild golden-crowned sifaka (Propithecus tattersalli) from northeastern Madagascar. Each animal received a complete physical examination and weight, body temperature, heart rate, and respiratory rate were documented. Blood samples were collected for packed cell volume, estimated total white blood cell count, serum biochemical profile, fat-soluble vitamin analysis, trace mineral analysis, and Toxoplasma gondii serology. All animals examined were adults and determined to be in good health and body condition. No ectoparasites were observed. Fecal samples were collected for endoparasite examination and bacterial culture; while no endoparasites were observed, fecal samples from two females cultured positive for Bacillus cereus. One male lemur had a positive antibody titer to Toxoplasma gondii immunoglobulin G. These baseline health data provide an important foundation for continued monitoring of this critically endangered species.

Survival of immature gopher tortoises recruited into a translocated population

TD Tuberville, RK McKee, HE Gaya, TM Norton. The Journal of Wildlife Management 85 (4), 631-639

Population manipulations such as translocation and head‐starting are increasingly used as recovery tools for chelonians. But evaluating success of individual projects can require decades of monitoring to detect population trends in these long‐lived species. Furthermore, there are often few benchmarks from stable, unmanipulated populations against which to compare demographic rates, particularly for the immature stages. We used 8 years of mark‐recapture data to estimate apparent survival of immature gopher tortoises (Gopherus polyphemus) recruited into an introduced population of gopher tortoises first established on St. Catherines Island, Georgia, USA, in 1987. During 2006-2013, we conducted targeted trapping of immature gopher tortoises and compared survival of the hatchling, juvenile and subadult stages among treatments: individuals released shortly after hatching from eggs obtained from gravid female founders (direct releases), individuals reared in captivity for 6-9 months following hatching (head‐starts), and individuals first encountered as free‐ranging, wild‐recruited offspring (wild recruits). Among the candidate models we examined, the best fit model included additive effects of tortoise stage and treatment; however, overlapping 95% credible intervals among treatments (CrI) suggested that survival did not vary significantly among treatments. Annual apparent survival increased over the immature period, highlighting the importance of calculating separate estimates for the different immature stages. Across all treatments, the additive model estimated annual apparent survival probability to be 0.37 (CrI = 0.25-0.48) for hatchlings, 0.71 (CrI = 0.61-0.81) for juveniles, and 0.83 (CrI = 0.74-0.94) for subadults. Our study, in combination with previous monitoring efforts at St. Catherines Island, provides strong evidence that the translocation and subsequent population augmentation efforts have been successful in establishing a robust population of gopher tortoises. Additionally, our results provide estimates of demographic rates for life stages that are poorly understood but critical to understanding population dynamics of this imperiled species.

Pharmacokinetic behavior of meloxicam in loggerhead (caretta caretta), kemp’s ridley (lepidochelys kempii), and green (chelonia mydas) sea turtles after subcutaneous administration

TM Norton, T Clauss, R Sommer, S Stowell, M Kaylor, C Thistle, S Cox. Journal of Zoo and Wildlife Medicine 52 (1), 295-299

The objective of this study was to determine the pharmacokinetics of a single dose of meloxicam administered subcutaneously (SQ) to three species of sea turtles: loggerheads (Caretta caretta), Kemp’s ridley (Lepidochelys kempii), and greens (Chelonia mydas). A dose of 1 mg/kg was given to the Kemp’s ridleys and greens, whereas the loggerheads received 2 mg/kg. After SQ administration, the half-life (t1/2) of meloxicam administered at 1 mg/kg in the Kemp’s ridleys was 5.51 hr but could not be determined in the greens. The half-life of meloxicam administered at 2 mg/kg in the loggerheads was 2.99 hr. The maximum concentration (Cmax) for meloxicam after SQ administration at 1 mg/kg in the Kemp’s ridleys was 6.76 µg/ml and in the greens was 9.35 µg/ml. The Cmax in loggerheads for meloxicam after SQ administration at 2 mg/kg was 3.63 µg/mL. Meloxicam administered SQ at a dose of 1 mg/kg to the Kemp’s ridley and greens provided measurable plasma concentrations of meloxicam for 48 and 120 hr, respectively, with no adverse side effects. In loggerheads, meloxicam administered SQ at a dose of 2 mg/kg provided measurable plasma levels of meloxicam for only 24 hr. Plasma levels of meloxicam of greater than 0.5 µg/ml are considered to be therapeutic in humans. Results suggested that administration of meloxicam SQ at 1 mg/kg in Kemp’s ridleys and greens would result in plasma concentrations greater than 0.5 µg/ml for 12 and 120 hr, respectively. The administration of 2 mg/kg meloxicam to loggerhead turtles resulted in plasma concentrations greater than 0.5 µg/ml for only 4 hr.

Steatitis in Cold-Stunned Kemp’s Ridley Sea Turtles (Lepidochelys kempii)

RC Turner, CJ Innis, BA Stacy, JA Hernandez, RC Hill, KC Scott, S Frasca, et al. 2021. Animals 11 (3), 898

The pathogenesis of steatitis that infrequently occurs in cold-stunned Kemp’s ridley sea turtles (KRT; Lepidochelys kempii) has been undetermined. The objectives of this study were to investigate the clinical (n = 23) and histologic findings (n = 11) in cold-stunned KRT, and to compare plasma concentrations of α-tocopherol (vitamin E), thiobarbituric acid reactive substances (TBARS), and the TBARS to vitamin E (T/E) ratio (an assessment of oxidative stress) between cold-stunned KRT with clinically and/or histologically confirmed steatitis (n = 10) and free-ranging KRT (n = 9). None of the cold-stunned turtles had clinically detectable steatitis at admission, and the median number of days to diagnosis of steatitis was 71 (range 33-469). Histologic findings of affected adipose tissue included heterophilic (n = 9) and/or histiocytic (n = 5) steatitis, fat necrosis (n = 7), myonecrosis (n = 2), and intralesional bacteria (n = 6). Cold-stunned KRT had significantly lower plasma vitamin E concentrations (median = 3.5 nmol/g), lower plasma TBARS concentrations (median = 1.6 nmol/g), and higher T/E ratios (median = 0.37), than controls (208.8 nmol/g; 2.1 nmol/g; 0.01, respectively). These results suggest a multifactorial etiology for the development of steatitis in KRT during rehabilitation, including tissue injury, septicemia, and various factors resulting in imbalances of anti-/oxidative status. By highlighting the need to provide more effective vitamin E supplementation, and the need to re-assess specific components of the diet, this study may lead to reduced incidence and improved medical management of steatitis in cold-stunned sea turtles.

Pathogen Surveillance and Detection of Ranavirus (Frog virus 3) in Translocated Gopher Tortoises (Gopherus polyphemus)

RA Cozad, TM Norton, MJ Aresco, MC Allender, SM Hernandez. 2020. Journal of wildlife diseases 56 (3), 679-683

Emerging pathogens may pose additional threats to already vulnerable populations of chelonians, such as gopher tortoises (Gopherus polyphemus). In response to a mortality event on a translocation site in northwest Florida, US during 2013-15, 13 gopher tortoises were necropsied and their tissues were screened for 12 pathogens, including Mycoplasma agassizii, Mycoplasma testudineum, and Frog virus 3-like ranavirus (FV3). The DNA of FV3 was detected via quantitative PCR in the gastrointestinal tract of three tortoises. Subsequently, pathogen surveillance was performed on whole blood and oral-cloacal swab samples of live translocated tortoises from two different enclosures within the site (n=68), rehabilitated tortoises from the site (n=18), and tortoises prior to release on site (n=35) during 2015-17. Mycoplasma spp. were present in all groups and years of live tortoises tested. The DNA of FV3 was detected in 15 individuals both with and without clinical signs of disease in 2016. We recaptured 20 tortoises and captured an additional 20 tortoises in 2017 for surveillance, yet FV3 DNA was no longer detected, even in those that had previously tested positive (n=7). The results of this study contribute to the epidemiology of ranavirus in chelonians and suggests that gopher tortoises could be reservoirs for FV3. We recommend that the status of Ranavirus infection should be included for health screens for gopher tortoises in translocation programs.

Diagnosis and management of marine debris ingestion and entanglement by using advanced imaging and endoscopy in sea turtles

D Franzen-Klein, B Burkhalter, R Sommer, M Weber, B Zirkelbach, T Norton. 2020. Journal of Herpetological Medicine and Surgery 30 (2), 74-87

Marine debris ingestion and entanglement have caused morbidity and mortality in multiple marine species, including all seven species of sea turtles. This case series outlines six cases in which advanced imaging modalities were used to diagnose marine debris-induced foreign body obstructions and to aid in the treatment of wounds caused by marine debris entanglement. Prefemoral ultrasonography was used to correctly diagnose a monofilament fishing line linear foreign body obstruction in a juvenile female Kemp’s Ridley sea turtle (Lepidochelys kempii) and a subadult female loggerhead sea turtle (Caretta caretta). Administration of iodinated contrast confirmed a complete upper gastrointestinal obstruction in a juvenile green sea turtle (Chelonia mydas). Traditional radiographs were nondiagnostic in all three animals. Barium-impregnated polyethylene spheres were used to identify a partial gastrointestinal foreign body obstruction in a juvenile green sea turtle. Endoscopy was used in multiple cases as both a diagnostic and a therapeutic tool. This case series demonstrates that contrast radiography, ultrasonography, and endoscopy are accurate diagnostic tools for the identification of marine debris-induced foreign body obstructions in sea turtles.

Epidemiological investigation of a mortality event in a translocated gopher tortoise (Gopherus polyphemus) population in northwest Florida

RA Cozad, SM Hernandez, TM Norton, TD Tuberville, NI Stacy, et al. 2020. Frontiers in veterinary science 7, 120

Nokuse Plantation, a 22,055 ha private conservation preserve in northwest Florida, is a recipient site for gopher tortoises translocated from development sites in Florida. Since 2006, Nokuse has received over 5,000 tortoises from multiple development sites. During 2013-2015, 52 tortoises were found sick (n = 14) or dead (n = 38) in multiple soft-release enclosures in which tortoises consistently exhibited clinical signs, with additional sick (n = 5) and dead (n = 5) tortoises presenting similarly during 2016-2017. When found alive, tortoises behaved abnormally (e.g., frequently out of burrows during cold weather, pacing along enclosure fencing), appeared emaciated, were lethargic, and had developed redness under plastron scutes. Similar numbers of male (n = 28) and female (n = 32) tortoises were recovered along with two of unidentified sex, including mainly adults (n = 59) and three subadults. Physical examination, blood analysis, and other diagnostics were indicative of starvation and dehydration. Most sick tortoises provided with supportive care recovered. Necropsy findings generally confirmed starvation, with no evidence of infectious pathogens or contaminants. There were no apparent differences in quality of habitat, plant community, or soil or water among affected and unaffected enclosures. Botanical surveys indicated adequate forage quality and quantity, with no poisonous exotic or native plants detected. No land management practices changed prior to this event. Analysis of epidemiological data and demographic factors from before and during this mortality event identified initial density of tortoises in the enclosures as exerting the strongest influence on detection of tortoise morbidity and mortality. We believe that the stress associated with mixing tortoises from different populations and at higher densities during translocation impacted an individual tortoise’s ability to obtain or absorb adequate nutrients from foraging, ultimately leading to a wasting condition consistent with starvation. Based on our findings, we recommend a maximum of 3 gopher tortoises per ha in soft-release enclosures for translocation, but further research is warranted to investigate the complexity of stress and social pressures associated with translocation.

Diagnosis and surgical management of a paratesticular cyst in a rehabilitating juvenile male green turtle (Chelonia mydas)

TC Weisbrod, NI Stacy, NL Stedman, TM Norton. 2020. Frontiers in veterinary science 7, 69

A juvenile green turtle (Chelonia mydas) undergoing rehabilitation for cold stunning exhibited an asymmetric bulging of the left caudal plastron and was diagnosed with a large intra-coelomic mass based on radiographical findings. Ultrasonography further identified a fluid-filled structure within the caudal coelom. Cytological evaluation of fluid obtained from the structure was consistent with a transudate, and thus, a cyst of unknown origin was suspected. Computed tomography imaging was pursued to further characterize the extent and location of the mass, which occupied ~50% of the total coelomic cavity volume. Conservative management with monitoring and occasional drainage of the mass did not result in improvements; thus, an exploratory laparoscopy for further investigation and surgical planning was elected. Intra-coelomic surgery was performed to remove a thick-walled cystic mass associated with the left gonad. Histopathology confirmed a paratesticular cyst continuous with, and possibly originating from, the epididymis. Post-surgical recurrence of the cyst was not appreciated, and the animal was successfully released 1 year after admission. Unrelated to the cyst, the turtle developed acute severe anemia on two occasions throughout rehabilitation that responded to modification of antimicrobial treatment and subsequent steroid administration. To the authors’ knowledge, this is the first report of a paratesticular cyst in a reptile.

(A) Dorsoventral projection full-body radiograph of a juvenile green turtle (Chelonia mydas) showing a large rounded well-demarcated mass with soft tissue opacity within the left caudal coelom (white arrows). (B) Coronal mid-coelomic CT section of a green turtle (Chelonia mydas) showing a large rounded soft tissue/fluid opacity mass (white arrows) within the left caudal coelom displacing gastrointestinal contents dorsally and to the right. CT was performed 2 weeks after initial radiographic diagnosis of mass, and no fluid was aspirated during this interval. Progression of gross left-sided plastron distention was noted. (C) Positioning of turtle in right lateral recumbency for left pre-femoral fine-needle fluid aspiration of intra-coelomic cyst. Inset: Representative 60-ml syringe filled with transudate fluid from cyst aspiration. (D) Gross image of cyst in two sections post-surgical removal. Scale bar = 2.5 cm.

Tick paralysis in a free-ranging bobcat (Lynx rufus)

ME Persky, YS Jafarey, SE Christoff, DD Maddox, SA Stowell, TM Norton. 2020. Journal of the American Veterinary Medical Association 256 (3), 362-364

Case description: A free-ranging male bobcat (Lynx rufus) was evaluated because of signs of pelvic limb paralysis. Clinical findings: Physical examination of the anesthetized animal revealed tick infestation, normal mentation, and a lack of evidence of traumatic injuries. Radiography revealed no clinically relevant abnormalities. Hematologic analysis results were generally unremarkable, and serologic tests for exposure to feline coronavirus, FeLV, FIV, and Toxoplasma gondii were negative. Results of PCR assays for flea- and common tick-borne organisms other than Bartonella clarridgeiae were negative. Treatment and outcome: Ticks were manually removed, and the patient received supportive care and fipronil treatment. The bobcat made a full recovery within 72 hours after treatment for ticks, and a presumptive diagnosis of tick paralysis was made. Identified tick species included Dermacenter variabilis, Amblyomma americanum, and Ixodes scapularis. Clinical relevance: To the authors’ knowledge, tick paralysis has not previously been reported in felids outside Australia. This disease should be considered a differential diagnosis in felids, including exotic cats, with signs of neuromuscular disease of unknown etiopathogenesis.

Tumor re-growth, case outcome, and tumor scoring systems in rehabilitated green turtles with fibropapillomatosis

Annie Page-Karjian, Justin R Perrault, Bette Zirkelbach, Jamie Pescatore, Rebecca Riley, Melanie Stadler, Trevor T Zachariah, Wendy Marks, Terry M Norton 2020. Diseases of aquatic organisms 137 (2), 101-108.

Fibropapillomatosis (FP) is an infectious, neoplastic disease of major concern in sea turtle rehabilitation facilities. Rehabilitating sea turtles that undergo tumor removal surgery often have tumor regrowth and may experience mortality. We evaluated tumor score, removal, and regrowth in rehabilitating green sea turtles with FP in 4 rehabilitation facilities in the southeastern USA during 2009-2017. Of 756 cases, 312 (41%) underwent tumor removal surgery, 155 (50%) of those had tumor regrowth within an average of 46 ± 45 d, and 85 (27%) had multiple (>1) regrowth events. Of 756 turtles with FP, 563 (75%) did not survive after admission into a rehabilitation facility, including 283 (37%) that were euthanized and 280 that died without euthanasia (37%), and 193 survived, including 186 (25%) released and 7 (1%) placed in permanent captive care. Tumor removal surgery increased the odds of tumor regrowth but also enhanced survivorship, whereas tumor regrowth was not a significant predictor of case outcome. Three FP tumor scoring systems were used to assign tumor scores to 449 cases, and differing results emphasize that tumor scoring systems should be applied to the situations and/or location(s) for which they were intended. FP tumor score was not a significant predictor for the event or extent of FP tumor regrowth after surgical excision. Under current rehabilitation regimes, outcomes of rehabilitation for tumored turtles have a low probability of success. The results of this study may be used to help guide clinical decision-making and determine prognoses for rehabilitating sea turtles with FP.

The effect of diet on the gastrointestinal microbiome of juvenile rehabilitating green turtles (Chelonia mydas)

JCG Bloodgood, SM Hernandez, A Isaiah, JS Suchodolski, LA Hoopes et al. 2020. PLoS One 15 (1), e0227060

Threatened and endangered green turtles (Chelonia mydas) are unique because as juveniles they recruit from pelagic to near-shore waters and shift from an omnivorous to primarily herbivorous diet (i.e. seagrass and algae). Nevertheless, when injured and ill animals are admitted to rehabilitation, animal protein (e.g. seafood) is often offered to combat poor appetite and emaciation. We examined how the fecal microbiome of juvenile green turtles changed in response to a dietary shift during rehabilitation. We collected fecal samples from January 2014 -January 2016 from turtles (N = 17) in rehabilitation at the Georgia Sea Turtle Center and used next generation sequencing to analyze bacterial community composition. Samples were collected at admission, mid-rehabilitation, and recovery, which entailed a shift from a mixed seafood-vegetable diet at admission to a primarily herbivorous diet at recovery. The dominant phyla changed over time, from primarily Firmicutes (55.0%) with less Bacteroidetes (11.4%) at admission, to primarily Bacteroidetes (38.4%) and less Firmicutes (31.8%) at recovery. While the microbiome likely shifts with the changing health status of individuals, this consistent inversion of Bacteroidetes and Firmicutes among individuals likely reflects the increased need for protein digestion, for which Bacteroidetes are important. Firmicutes are significant in metabolizing plant polysaccharides; thus, fewer Firmicutes may result in underutilization of wild diet items in released individuals. This study demonstrates the importance of transitioning rehabilitating green turtles to an herbivorous diet as soon as possible to afford them the best probability of survival.