Stress and plasma corticosterone levels in the american alligator—relationships with stocking density and nesting success

Elsey, Ruth M.; Joanen, Ted; McNease, Larry; Lance, Valentine A.

doi:10.1016/0300-9629(90)90009-h

Cited by 89 publications

(51 citation statements)

References 24 publications

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“…Although published data are scarce, previous studies on reptiles generally have reported the opposite situation: higher plasma corticosterone levels in males than in females (Elsey et al, 1990;Lance et al, 2001;Mathies et al, 2001). Higher levels of plasma corticosterone may enhance organismal fitness by facilitating access to energy stores, and thus enhance the animal's ability to escape rapidly from a predator, battle with conspecifics, etc.…”

Section: Degree Of Stress Induced By Alternative Methodsmentioning

confidence: 91%

How much stress do researchers inflict on their study animals? A case study using a scincid lizard, Eulamprus heatwolei

Langkilde

Shine

2006

Journal of Experimental Biology

214

140

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SUMMARY Research on live vertebrates is regulated by ethics committees, who prohibit `excessively stressful' procedures. That judgment is based on intuition – a notoriously unreliable criterion when dealing with animals phylogenetically distant from humans. To objectively evaluate the stress imposed by research practices, we measured plasma corticosterone levels in lizards (Eulamprus heatwolei Wells & Wellington, Scincidae). Some procedures (handling and measuring, toe-clipping for identification, exposure to predator scent) did not induce significant increases in corticosterone levels, suggesting that these stimuli generated relatively little stress. However, other stimuli (testing locomotor speed, microchip implantation, blood sampling, an unfamiliar enclosure, tail autotomy, exposure to a heterospecific lizard) were more stressful, with corticosterone levels increasing only transiently in some treatments (<2 h for tail autotomy), but persisting much longer in others (14 days for microchip implantation). Overall, our data suggest that the levels of stress induced by routine laboratory procedures are no greater than those often experienced by lizards in nature; but that intuition provides a poor basis for evaluating the levels of stress induced by research. For example, toe-clipping is often criticized and sometimes banned;but our data suggest that this method is actually less stressful than the technique frequently recommended to replace it on ethical grounds (microchip implantation). Toe-clipping also was less stressful than superficially trivial manipulations such as housing the animal in an unfamiliar enclosure. More generally, we urge researchers to seek objective information on the effects of their activities on research subjects, rather than relying upon subjectivity and anthropomorphism in making these evaluations.

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Section: Degree Of Stress Induced By Alternative Methodsmentioning

confidence: 91%

How much stress do researchers inflict on their study animals? A case study using a scincid lizard, Eulamprus heatwolei

Langkilde

Shine

2006

Journal of Experimental Biology

214

140

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“…The available data suggest that the sex of the individual can influence the stress response. Adult male alligators (Alligator mississippiensis) had significantly higher corticosterone levels than adult female alligators in captive and wild populations (Elsey et al, 1990b). A difference in plasma corticosterone concentration is also apparent between the sexes in turtles.…”

Section: Sex and Stress Hormonesmentioning

confidence: 97%

“…The only available data set supporting a chronic effect comes from a captive study. Captive adult alligators maintained at high stocking densities had plasma corticosterone concentrations significantly higher than those maintained at lower stocking densities (Elsey et al, 1990b) and elevated plasma corticosterone was correlated with decreased growth in juvenile alligators (Elsey et al, 1990a). Managers of crocodile farms have observed poor reproductive activity following the transport of animals from one pond to another or after extensive modification of a pond (J.…”

Section: Ctenophorus Ornatusmentioning

confidence: 98%

Biology of stress: interactions with reproduction, immunology and intermediary metabolism

GuilletteJr.¹,

Cree²,

Rooney³

1995

Health and Welfare of Captive Reptiles

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Animals must maintain a steady physiological state, homeostasis, in response to a changing environment. An understanding of the stress response is essential if one is to appreciate the complex physiological mechanisms maintaining homeostasis in vertebrates. Moreover, a comprehensive understanding of the biology of stress is essential if we are to reduce stress in the care of any vertebrate species, induding those that are not domesticated and traditional laboratory animals.The goals of this chapter are to review our knowledge of the phenomenon of the physiological stress response in vertebrates generally, and then to describe in detail the limited information available on the biology of stress in reptiles. We shall not deal with psychic or emotional considerations of stress in reptiles. Specifically, we focus on the interactions between the physiological stress response and reproduction, immune function and intermediary metabolism. These three areas are critical to any husbandry and captive management programme. If not prevented or countermanded, the detrimental aspects of the stress response mounted by, for example,

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“…52,66,68 Likewise, in crocodilians, limited studies suggest that high plasma corticosterone in females may result in relatively poor egg quality and decreased hatchling survival. 14,61 The clutch effect in crocodile runting 26,33,48,58 suggests that crocodiles in specific clutches are hatched with a tendency to become runts, although more research needs to be done on the degree of clutch effect and variation within a clutch. A clutch effect could be due to genetics, maternal circumstances, egg incubation conditions, or, where members of a clutch are reared together in some degree of isolation from other clutches, their rearing environment.…”

Section: Discussionmentioning

confidence: 99%

Pathology of Runting in Farmed Saltwater Crocodiles (Crocodylus porosus) in Australia

et al. 2014

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Extremely poor growth of some individuals within a birth cohort (runting) is a significant problem in crocodile farming. We conducted a pathological investigation to determine if infectious disease is associated with runting in farmed saltwater crocodiles (Crocodylus porosus) and to look for evidence of other etiologies. In each of 2005 and 2007, 10 normal and 10 runt crocodiles, with an average age of 5.5 months and reared under identical conditions, were sampled. Laboratory testing included postmortem; histological examination of a wide variety of tissues (with quantitation of features that were noted subjectively to be different between groups); hematology; serum biochemistry (total protein, albumin, globulins, total calcium, phosphorus, and iron); bacterial culture of liver and spleen (2005 only); viral culture of liver, thymus, tonsil, and spleen using primary crocodile cell lines (2007 only); and serum corticosterone (2007 only). The only evidence of infectious disease was mild cutaneous poxvirus infection in 45% of normal and 40% of runt crocodiles and rare intestinal coccidia in 5% of normal and 15% of runt crocodiles. Bacterial and viral culture did not reveal significant differences between the 2 groups. However, runt crocodiles exhibited significant (P < .05) increases in adrenocortical cell cytoplasmic vacuolation and serum corticosterone, decreased production of bone (osteoporosis), and reduced lymphoid populations in the spleen, tonsil, and thymus. Runts also exhibited moderate anemia, hypoalbuminemia, and mild hypophosphatemia. Taken together, these findings suggest an association between runting and a chronic stress response (hyperactivity of the hypothalamic-pituitary-adrenal axis).Keywords adrenocortical hyperplasia, crocodile, farmed, histopathology, inanition, lymphoid atrophy, runting, stressIn the crocodilian farming industry, extremely poor growth of some hatchlings compared with their birth cohort (runting) is a major problem worldwide, affecting up to 30% of animals. 3,21,32,33,48,49,55,58 Runting is a cause of major economic loss, in an industry where juvenile growth and survival are important economic factors. 33The cause of runting in farmed crocodiles is unknown. Although various possibilities have been proposed, none have been thoroughly investigated. Proposed factors associated with runting include egg incubation conditions; 38,69 poor yolk absorption posthatching; 22,32 inappropriate diet or problems with diet assimilation; 11,22,26,55 posthatching environment, including temperature, stocking density, and behavior of conspecifics; 26,32,39,48,58 and failure to adapt to the captive environment.3,64 Poor growth has been found to be clutch related in that some clutches produce relatively high numbers of runts. 26,33,48,58 However, future crocodile runts are not identifiable at hatching, since body size at hatching is a poor predictor of posthatching growth. 26,34,38,69 There is limited information on diseases and pathology exhibited by runt crocodiles. A few studies mention b...

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Stress and plasma corticosterone levels in the american alligator—relationships with stocking density and nesting success

Cited by 89 publications

References 24 publications

How much stress do researchers inflict on their study animals? A case study using a scincid lizard, Eulamprus heatwolei

How much stress do researchers inflict on their study animals? A case study using a scincid lizard, Eulamprus heatwolei

Biology of stress: interactions with reproduction, immunology and intermediary metabolism

Pathology of Runting in Farmed Saltwater Crocodiles (Crocodylus porosus) in Australia

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