Comprehensive health assessment of green turtles Chelonia mydas nesting in southeastern Florida, USA

Abstract

Important indicators of population health needed for large-scale sea turtle population recovery efforts include demographics, disease and mortality trends, condition indices, and baseline blood data. With this comprehensive health assessment of adult female green sea turtles Chelonia mydas nesting on Juno Beach, Florida, USA, we (1) established comprehensive baseline health indices; (2) identified individuals with evidence of infection by chelonid alphaherpesviruses 5 and 6 (ChHV5, ChHV6), which are implicated in fibropapillomatosis and respiratory and skin disease, respectively; and (3) compared measured health indices between turtles that did versus those that did not test positive for ChHV5 and/or ChHV6. All 60 turtles included in the study were in good body condition with no external fibropapillomatosis tumors. Hematological and biochemical reference intervals were established. Via quantitative PCR (qPCR), 5/60 turtles (8%) tested positive for ChHV5, and all turtles were negative for ChHV6. Of 41 turtles tested for antibodies to ChHV5 and ChHV6, 29% and 15% tested positive, respectively, and 10% tested positive for antibodies to both viruses. Notably, there were no statistically significant differences between health variables for nesting turtles that tested positive for ChHV5 DNA versus those that tested negative; and also no differences between turtles that tested positive for ChHV5 or ChHV6 antibodies and those that did not. This suggests that these viruses are enzootically stable in Florida’s adult green turtles. This study provides a health profile of nesting green turtles in southeastern Florida applicable to temporal and spatial investigations of this and other populations.

Blood analytes of immature Kemp’s ridley sea turtles (Lepidochelys kempii) from Georgia, USA: reference intervals and body size correlations

“…Conservation physiology projects like these seek to explore wildlife populations and provide a baseline for future studies investigating their responses to physiological changes, environmental disturbances or disease, so that we may better understand reasons for population declines or changes in population dynamics ( Wikelski and Cooke, 2006 , Cooke and O’Connor, 2010 ). The RIs established here, in due consideration of capture technique in this study, provide valuable information for individuals that strand and enter rehabilitation facilities, in addition to future health assessment studies that may be conducted for population monitoring or in response to environmental changes or disturbances ( Deem et al ., 2001 ; Aguirre and Lutz, 2004 ; Osborne et al , 2010 ; Flint et al ., 2015 ; Kelly et al ., 2015 ; Page-Karjian et al ., 2015 , 2020 ; Villa et al , 2017 ; Stacy et al , 2017 , 2018a ). We identified a number of physiological changes in these organisms considered in ‘good health’ that are likely associated with dietary/habitat shifts, somatic growth and/or other physiological alterations.…”

“…Therefore, RI establishment in wildlife populations is a developing field of study. RIs have been established in some sea turtle species and populations [leatherback sea turtles ( Dermochelys coriacea ); hereafter, leatherbacks; loggerhead sea turtles ( Caretta caretta ); hereafter, loggerheads; green turtles ( Chelonia mydas )] ( Aguirre and Balazs, 2000 ; Flint et al , 2010a , b ; Osborne et al , 2010 ; Kelly et al , 2015 ; Page-Karjian et al , 2015 , 2020 ; Stacy et al , 2018a , 2019 ; Fleming et al , 2020 ), yet no RIs exist for critically endangered Kemp’s ridley sea turtles [ Lepidochelys kempii ; hereafter, Kemp’s ridleys] ( Wibbels and Bevan, 2019 ). Understanding baseline health of this sea turtle species is critical, as several on-going threats to their population recovery still exist ( Wibbels and Bevan, 2019 ).…”

Trace Element Concentrations in Blood and Scute Tissues from Wild and Captive Hawaiian Green Sea Turtles (Chelonia mydas)

“…In the wild, female turtles are capital breeders and in general do not feed during the nesting season, though opportunistic feeding can occur. Instead, their energy is supplied from fat stores (Bjorndal 1985; Hays et al 2002; Tucker and Read 2017; Page‐Karjian et al 2020). One hypothesis to explain the greater scute Pb concentrations in these captive female turtles is that as Ca, and hence Pb as a Ca mimic, was mobilized from bones during egg vitellogenesis/egg production, blood Pb concentrations increased.…”

Insights on Immune Function in Free-Ranging Green Sea Turtles (Chelonia mydas) with and without Fibropapillomatosis

“…Green sea turtles ( Chelonia mydas ) are considered indicators of marine ecosystem health [ 1 , 2 , 3 , 4 ]. They play important roles in seagrass bed resiliency by preventing overgrowth and reducing nutrient input into these areas [ 5 ].…”

“…ChHV5 nucleic acids can be detected in biological samples using polymerase chain reaction (PCR). Previous exposure to, and presumptive infection with ChHV5 can be identified via detection of circulating antibodies in sea turtle blood samples using enzyme-linked immunosorbent assays (ELISA) [ 4 , 44 ]. Changes in blood-based indicators of health have been observed in turtles with FP, including anemia, hypoproteinemia, leukopenia/immunosuppression, and other biochemical alterations [ 15 , 17 , 29 , 45 , 46 , 47 , 48 , 49 , 50 , 51 ].…”