Journal
JOURNAL OF EXPERIMENTAL ZOOLOGY PART A-ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY
Volume 337, Issue 4, Pages 282-292Publisher
WILEY
DOI: 10.1002/jez.2565
Keywords
Amazon ecotourism; Caiman crocodilus; corticosterone; crocodilian conservation; Melanosuchus niger; plasma biochemistry; stress monitoring
Categories
Funding
- Fundacao de Amparo a Pesquisa do Estado do Amazonas (FAPEAM) [POSGRAD 2017-2018]
- Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)
Ask authors/readers for more resources
The study found that stressed caimans exhibit increased plasma corticosterone levels, as well as elevated lactate and glucose levels. There are differences in recovery time and lactate clearance between the two caiman species, indicating potential variations in sensitivity to acute stress. These findings have implications for management and conservation programs, as well as assessing the impact of tourism and recreational capture on caimans in the Amazon.
When captured, free-living crocodilians respond by hyperstimulation of the hypothalamic-pituitary-adrenal (HPA) axis, which triggers a cascade of downstream events of physiological stress. We examined these responses in two unstressed, and stressed Amazonian caimans, Caiman crocodilus and Melanosuchus niger. Plasma corticosterone levels increased in both stressed caiman species. In M. niger, the levels of this hormone increased 5.2-fold compared with the basal range values, while in C. crocodilus this was only 1.7-fold. After stress, M. niger needed more than 6 h to return its corticosterone levels to basal range values, whereas in C. crocodilus just 0.5 h was enough. Downstream events were characterized by an increase in glucose levels, which is associated with corticosterone increments. Excessive muscle activity resulted in increased plasma lactate content in both species. Lactate levels were also related to plasma calcium concentration, possibly due to the buffering capacity for preventing lactic acidosis. Clearance of excessive lactate load was faster in M. niger (0.5 h) than in C. crocodilus (more than 6 h). Although both caiman species respond in the same way to capture, the amplitude and duration of activation of the HPA axis are different. M. niger may be potentially more sensitive to acute stress than C. crocodilus. On the other hand, C. crocodilus needs more time to recover from the lactic acid load. Our experiment provides a useful diagnostic tool for management and conservation programs, as well as evaluating the impacts of tourism and recreational capture on caimans in the Amazon.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available