Abstract

The green turtle (Chelonia mydas), also known as the black turtle in the Pacific Ocean, is a marine chelonian inhabiting oceans throughout the world.¹⁷ The green turtle is currently listed as Endangered on the IUCN Red List, and no commercial use is permitted under CITES Appendix I. Major threats to green turtle populations include habitat destruction, pollution, disease, consumption of meat and eggs by local populations, fishing gear entanglement, and consumption of plastics and other anthropogenic materials.^5,12,15-17 Health assessments of green turtles may therefore have implications for wildlife biology and species conservation. Considerable research on natural history has been performed in this species and studies on the health parameters of green turtles, while still relatively limited, have increased dramatically in the last 5 years.^{1-4,6,7,9-11,13,14} A recent review summarizes the health of wild sea turtles and methods of assessment, including blood parameters.⁸

Reference blood parameter intervals have been published for certain chelonian species, including sea turtles, but baseline hematology, biochemical, and blood gas values are lacking from the Galapagos sea turtles. Blood gases, biochemical parameters, and hematology were evaluated in 28 green turtles captured in two foraging locations on San Cristóbal Island (14 from each site). Of these turtles, 20 were immature and of unknown sex; the other eight were males (five mature, three immature). A portable blood analyzer (iSTAT) was used to obtain near immediate field results for pH, lactate, pO₂, pCO₂, BEecf, HCO₃^-, Hct, Hb, Na, K, iCa, and Glu. Parameter values affected by temperature were corrected with standard formulas, and were compared with the iSTAT's internal corrected numbers. Standard laboratory hematology techniques were employed for the red and white blood cell counts and resulting hematocrit was compared to the values generated by the iSTAT. Of all blood analytes, only lactate concentrations were positively correlated with body size. All other values showed no significant difference between the two sample locations nor were they correlated to body size or internal temperature. The iSTAT blood analyzer provided reliable results for hematocrit counts as well as for temperature-corrected pH and pCO₂, compared to the manually obtained values. In contrast, results for HCO₃^-and pO₂ differed significantly between the manual and iSTAT calculations.

Data from this study represent a reference against which future blood gas and biochemistry results in green turtles may be compared, and also demonstrate associations between certain biochemical parameters, size, and health status. All 28 turtles were judged to be clinically healthy and their blood parameters support this assessment. Because green turtles are an endangered species with importance in the wildlife biology research community and the aquarium/zoo industry, health assessments are important from the standpoint of sustainable conservation and management. These results add to a growing database of knowledge about health management in wild chelonian species. Future research should continue to establish reference values in this species and facilitate comparisons of blood values across age groups and disease states.

Acknowledgements

We thank Diana Amoguimba, Eduardo Espinoza, Craig Harms, Tillie Laws, Carlos Mena, Philip Page, Kent Passingham, Carlos Valle-Castillo, Galo Quezada and Stephen Walsh for their support and assistance with this project.

* Presenting author

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