Indian Journal of Animal Research

  • Chief EditorK.M.L. Pathak

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Blood gases and biochemistry of stranded endangered green turtles (Chelonia Mydas) in Taiwan

Hwee-Peng Ong1, Po-Yu Wu2, Tsung-Hsien Li2,*
1National University of Singapore, 21 Lower Kent Ridge Road, Singapore 119077, Singapore.
2Department of Biology, National Museum of Marine Biology and Aquarium, Pingtung, 94450, Taiwan.
Blood characteristics provide a useful tool to evaluate the health status of animals, especially when animals are during the convalescence period. In this study, we observed that the mean lactate level in non-surviving sea turtles was higher than that in surviving ones. Furthermore, non-surviving sea turtles had significantly higher levels of potassium than surviving sea turtles. The data in our report could be helpful in the evaluation of physiological and pathological changes in critically ill juvenile green turtles.
Green turtles (Chelonia mydas) are native to Taiwan (King et al., 2013). It is the most abundant sea turtle species in Taiwan (Kuo et al., 2017) and is classified as globally endangered (IUCN, 2016). Blood characteristics provide a useful tool to evaluate the animal health status (Casal et al., 2009; Barkakati et al., 2015; Ramulu et al., 2015; Espinoza-Romo et al., 2018; Mohammed Muayad et al., 2018; Stacy et al., 2018). Reference in hematological and plasma biochemical intervals of sea turtles discovered in Taiwan have been reported previously (Fong et al., 2010; Li et al., 2015). These data are important in the clinical evaluation of the health of free-ranging and captive sea turtles. Variations of the blood gas and biochemical analyte combinations of green turtles due to stranding and survival outcome (survival and non-survival) have not been reported in Taiwan. This study compared the blood gas and biochemistry profiles between stranded sea turtles. The different values parameters were compared according to the cause of stranding and survival outcome of sea turtles.

Sea turtle rehabilitation at the National Museum of Marine Biology and Aquarium (NMMBA) was conducted with authorization of the Forestry Bureau, Council of Agriculture, Executive Yuan, Taiwan (Li et al., 2015). This study included a total of 15 green turtles (Chelonia mydas) in the rehabilitation facility. Mass (in kg) and curved carapace lengths (CCL) (in cm) were recorded from each turtle. Medical and stranding records of unhealthy green turtles brought into the NMMBA over the span of year 2017 were assessed. In this study, blood samples of the sea turtles used were first samples collected upon sea turtles arrival at rehabilitation facility. During routine medical procedures, blood samples (maximum volume <0.8 mL/kg) (Campbell and Ellis, 2007; Mitchell, 2009) were extracted from an external jugular vein (Day et al., 2010; Li et al., 2015) using a 12 ml syringe fitted with a 23 gauge needle after using 70% alcohol solution to disinfect the skin of puncture site by a certified veterinarian.
Blood analysis
Blood samples collected were analysed using an iSTAT analyser to obtain blood gas, electrolyte and biochemical analyte combinations, including pondus hydrogenii (pH), partial pressure of carbon dioxide (pCO2), base excess in extracellular fluid (BEecf), bicarbonate (HCO3), total carbon dioxide (TCO2), blood urea nitrogen (BUN), potassium (K), chloride (Cl), sodium (Na), glucose, haemoglobin (Hb), haematocrit (Hct), Anion Gap (AnGap) and creatinine. Blood lactate was assayed using an EDGE Lactate Analyser.
Statistical analysis
Turtles were categorised into their cause of stranding, whether they were live bycatch or live-stranded. Live bycatch included accidental capture by fishermen or nets, while live stranded included those found alive stranded on land or floating on open waters. Outcomes of the green turtles were grouped into surviving and non-surviving. Surviving turtles defined live turtles still in rehabilitation care or were healthy and released after clinical care, while non-surviving turtles were dead after clinical care in rehabilitation facility. To determine if there were differences in blood gas and biochemistry values within turtle outcome (surviving and non-surviving) and cause of stranding (live-bycatch and live stranded), each parameter was compared within respective groups using a non-parametric Mann-Whitney U-test. For all tests, p values lesser than 0.05 obtained were recognised as statistically significant. Any turtle with parameters absent from the data were omitted only for that particular parameter during analysis. All statistical analysis was done using SPSS 18.0.
Ethics statement
All samples were collected under humane procedures from an external jugular vein as described by Day et al., (2010). The collection of specimens for blood test was conducted during routine medical procedures because we need to have the relevant information to offer effective treatments for the clinical case. Therefore, the specific approval of the Institutional Animal Ethics Committee is not required and we did not apply for it.
The mean (sd) curved carapace length and weight of the turtles was 47.35 (6.97) cm and the mean (sd) bodyweight was 12.23 (6.15) kg. The comparison results of blood gas and biochemistry values between bycatch and live-stranded sea turtles were shown in Table 1. Various blood gas and biochemistry profiles were similar between bycatch and live-stranded sea turtles. Table 2 shows the comparison results of blood gas and biochemistry values between surviving and non-surviving turtles. Non-surviving turtles were observed to have significantly higher lactate and K levels as compared to surviving turtles.

Table 1: Comparison of lactate and blood gas profiles between bycatch and live-stranded sea turtles using Mann-Whitney U-test.

Table 2: Comparison of lactate and blood gas profiles between surviving and non-surviving sea turtles using Mann-Whitney U test.

In this study, we observed that the mean lactate concentration in non-surviving sea turtles was higher than that in surviving ones and also higher than that in wild Galápagos hawksbill turtles (Eretmochelys imbricata) reported by Munoz-Perez et al., (2017). It is also notable that the lactate levels we observed in non-surviving turtles was higher than that of the wild Galapagos green turtles which appeared clinically healthy as previously reported (Lewbart et al., 2014). It is well known that blood lactate levels increase when there is a lack in tissue perfusion and oxygen delivery (Mader and Rudloff, 2006). Higher lactate concentrations have also been reported in gillnet trapped green turtles (Snoddy et al., 2009) and loggerhead turtles (Caretta caretta) captured in trawlers (Harms et al., 2003). Moreover, one green sea turtle entangled in a large mesh gillnet had an exertional myopathy with hyperlactatemia (Phillips et al., 2015). AlKindi et al., (2001) reported that nesting green turtles with high concentrations of lactate are related to higher stressful conditions during nesting (AlKindi et al., 2001). The previous study also found that the increased lactate levels were related to morbidity in cold-stunned Kemp’s ridley turtles (Keller et al., 2012).

In the present study it was, we found that the K level in non-surviving sea turtles was higher than that in surviving ones, and also higher than that in wild green turtles (Chelonia mydas) which appeared clinically healthy reported by Lewbart et al., (2014). In previous research on clinical pathology of Kemp’s Ridley sea turtles (Lepidochelys kempii) suffering from cold stunning, K level in the non-surviving group was significantly higher than that in the surviving group (Keller et al., 2012). It was also found that K derangements in cold-stunned Kemp’s Ridley sea turtles that died were almost always reflected by hyperkalemia (Stacy et al., 2013). Hyperkalemia can also result from dehydration, impaired renal function (Innis et al., 2009) and a compensatory response to acidosis (Lutz et al., 1989; Campbell, 2006). Innis et al., (2014) further documented that increased K values can be associated with exertional events in leatherback turtles (Dermochelys coriacea). Moreover, higher K values were also reported in a juvenile green sea turtle with exertional myopathy (Phillips et al., 2015).

The present study identified significant differences of blood lactate concentration and K level between surviving and non-surviving green turtles. The data in this report could be helpful in the evaluation of physiological and pathological changes in critically ill juvenile green turtles.
Sea turtles discussed in this study were rescued and rehabilitated at the NMMBA with authorization from the Forestry Bureau (FOREST), Council of Agriculture, Executive Yuan, Taiwan. Authors gratefully acknowledge the funding support provided for sea turtle rehabilitation and treatment by the forest.

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