Biochemical Parameter Analysis of Rescued Olive Ridley Sea Turtles (Lepidochelys olivacea)

The Olive ridley turtle (Lepidochelys olivacea) is one of the smallest species of sea turtle in the world (80 cm) and they are the most numerous and widely distributed turtles species in the Indian sub-continent (IUCN 2008). The first reptiles probably appeared in the Permian period, about 250 million years ago. There are about 3000 lizard species, 2700 snakes, 200 turtles, 140 worm lizards, 20 crocodilians and one tuatara. Turtles are the most ancient living reptiles and fossil turtles, several of which antedate the dinosaurs, are found throughout the world (WWF 2006; Fowler 2008). Blood characteristics provide a useful tool to evaluate the animal health status (Ramulu et al., 2015; Mohammed Muayad et al., 2018). A major part of the unusual anatomy and physiology of the turtles and tortoises is hardly identified and regular routine clinical examination usually applied to domestic animals provides little information about their health status (McArthur et al., 2004). The mortalities in sea turtles population by commercial fisheries vessels hinder their role in maintaining health of world’s oceans (Chandrasekar and Srinivasan, 2013). While, injured sea turtles usually displays reduced signs of clinical illness in addition to that disease diagnosis methods of sea turtles is relatively poor. The purpose of the study is to obtain biochemical data on L. olivacea as to depict a quantitative comparison with other studies on sea turtles and to provide process for sampling and analyses of data which will be comparable for further studies. The circulatory biochemical parameters serve as a useful diagnostic tool in animal health management as published data on sea turtle is limited.

The research work was carried out on stranded Olive Ridley Sea Turtles (Lepidochelys olivacea) of various age groups that were rescued at different period of time and maintained at the rescue center of Trust for Environmental and Education (TREE) foundation Tree Foundation, Vettuvankeni, Chennai, Tamil Nadu. While the examination for venipuncture was done by placing a clean moist cloth on the carapace of turtle as well as holding neck of turtle. In sea turtles venipuncture is a demanding technique because blood vessels are not palpable easily. The common blood collection site for venipuncture applied was dorsal cervical sinus vessels and turtle was restrained in a sternal recumbency with its head over the edge of a table. The head was held extended from the body and tipped in slight ventroflexion and then, the needle was inserted behind the occipital, in a caudal direction, at an angle of 30o and then blood was collected (Bolten et al., 1992; Faizo et al., 2012 and Pinto et al., 2015). The collection was at the rate of 1 ml of blood per 100 grams of body weight (1 per cent of total body weight) with needle size of 22G was used for blood collection (Lloyd and Morris, 1999). Biochemical analyses were performed in serum with help of automated analyzer (Bio-Rad) and were analyzed for glucose, cholesterol, total protein, albumin and globulin, blood urea nitrogen (BUN), creatinine, alanine aminotransferase (ALT), calcium and phosphorus. While all the samples were identified and deep frozen until time of analysis.

The observed mean (S.D) values of glucose (mg/dl), cholesterol (mg/dl) are 108.85 (10.526) and 88.57 (5.763), respectively. The recorded mean (S.D) values of blood urea nitrogen (BUN) (mg/dl) and creatinine (mg/dl) are 35.15 (2.918) and 0.64 (0.127), respectively. The observed mean (S.D) values total protein (g/dl), albumin (g/dl), globulin (g/dl), A: G, ALT Alanine Aminotransferase (U/L) are 5.21 (1.190), 2.14 (0.761), 3.02 (1.606), 1.19 (1.27) and 16.28 (2.690), respectively. The recorded mean (S.D) values of calcium (mg/dl) and phosphorus (mg/dl) are 2.88 (1.372) and 2.71 (0.77), respectively. The median values along with minimum and maximum values are presented in Table 1.
 

       
The result was similar to reports published by juvenile Hawksbill sea turtles rescue and rehabilitation center. The observed biochemistry value glucose, ALT (Alanine aminotrasnferase), creatinine, calcium, phosphorus, total protein, albumin and globulin was similar with the findings of previous studies in other species of sea turtles (Aguirre et al., 2000; Anderson et al., 2011; Bolten and Bjorndal 1992; Bradley et al., 1998; Caliendro et al., 2010; Kelly et al., 2015 and Lara et al., 2016).
       
Blood glucose was found within normal level which may be indicative to the lower stress levels in rescue and rehabilitation centers which are in comparable to reports as suggested by McArthur et al., 2004.
       
Ramsay and Dotson (1995) suggested that ALT (Alanine aminotrasnferase) was rarely raised in sea turtles even in the presence of glomerulonephritis which correlates with our study, while also indicated that ALT (Alanine aminotrasnferase) may be artificially low in samples taken from tail puncture.
       
Campbell (2004) reported that creatinine is a muscle specific enzyme which is suggestive for muscle cell damage, trauma and systemic infections which is increased during handling and intravenous puncture as creatinine levels in our study sea turtles is within normal levels, they have better prognosis in clinically healthy parameters.
       
There were variations found in some parameters such as albumin, cholesterol, blood urea nitrogen (BUN), calcium which may be influenced by the different methods of analysis of samples, geospatial distribution, seasonal factors, age, size and diet (Casal et al., 2007 and Wilkinson 2004). Lawrence (1987) reported that albumin levels in female is found to be increased on average of about 30% than males in summer season which is in concurrence with the research findings as the some sample was collected during summer season. Whitaker and Krum (1999) suggested that albumin of immature chelonians varied with adult chelonian of other species supports the research findings.
       
In our study the cholesterol variation would have been due to pre-ovulatory follicle of female during clinical sample collection as well as temperature variation but a larger survey of samples would give more conclusive results (Delgado et al., 2011). These results were similar to study in which cholesterol variation have been attributed to be increased during reproductive period and lower values were observed in temperate species (Derickson 1976) and various other researchers reported that they were higher in sick desert tortoises.
       
The urea variation would have been attributed the seasonal variation in chelonians which were similar to the findings of the study in which the urea level rise was not noticed much in dry months while hibernating animals experienced difference in values (Bolten and Bjorndal 1992; Santaro and Meneses 2008).

Dessauer (1970) reported that serum calcium may be raised by 2-400% prior to egg laying and breeding seasons. The sea turtles in our study shows normal have calcium: phosphorous ratio which could attribute to better captive management and diet. This may be attributed to the fact that sea turtles in rehabilitation centers stays for a longer period of time in with specific diet (Stringer et al., 2010).
       
Hwee-PengOng et al., (2019) suggested that samples collected for blood value was different for the stranded and non-stranded (By catch) green sea turtles which could be due to handling and restraining them. The difference between other studies may result from values depends upon the geospatial distribution such as species, sex, season, sample site, nutrition and management condition and moreover sea turtles examined which we examined were from rehabilitation centre that were stranded off (Caliendo et al., 2010; Wilkinson 2004).

The biochemical parameters measured in the study are influenced by various factors which have been attributed the difference among other species of sea turtles. The biochemical parameters could be highly useful in assessing the health of rescued sea turtles in rehabilitation centers. In addition, providing health screening for free ranging populations is recommended to establish baseline levels of individual health parameters and group exposure to diseases. Although we suggest that the present results can be used as a baseline reference data for evaluation of health status of olive ridley sea turtles in India, further studies are required to identify whether other factors - age, life stage, seasonal variations and captivity - statistically affect the biochemical parameters. These values could be used as working intervals for the free ranging foraging and captive breed olive ridley sea turtles. Further longitudinal studies of olive ridley turtles with larger sample may provide an indication for long-term health of these endangered chelonian populations.