Desai Brinky, Bhowmik Tathagata, Srinivasan Rohith, Whitaker Nikhil, Ghosal Ratna
Biological and Life Sciences, School of Arts and Sciences, Ahmedabad University, Commerce Six Roads, Navrangpura, Ahmedabad 380009, Gujarat, India.
Madras Crocodile Bank Trust, Post Bag No 4, Mahabalipuram, Chennai 603104, Tamil Nadu, India.
Conserv Physiol. 2024 Jun 5;12(1):coae035. doi: 10.1093/conphys/coae035. eCollection 2024.
Animals face several challenges in their natural environment, and to cope with such conditions, they may exhibit contrasting physiological responses that directly affect their overall well-being and survival. In this study, we assessed physiological responses via faecal glucocorticoid metabolite (fGCM) measurements in free-ranging mugger crocodiles inhabiting diverse habitats in Gujarat, India. We sampled muggers within Charotar, a rural area (Zone A) with local people having high tolerance towards the presence of muggers, and Vadodara, a region having both urban (Zone B) and rural (Zone C) areas with high levels of human-mugger conflict (HMC). Further, muggers in Vadodara live in water bodies that are mostly polluted due to sewage disposal from adjoining chemical industries. To measure fGCM (mean ± SEM, ng/g dry faeces) levels in muggers, scats were collected during both breeding ( = 107 scats) and non-breeding ( = 22 scats) seasons from all three zones. We used captive muggers (a focal enclosure) to biologically validate (via capture and restraint) the selected fGCM assay (11-oxoetiocholanolone assay). We showed a significant ( < 0.05) 11-fold increase in fGCM levels between pre-capture (540.9 ± 149.2, = 11) and post-capture (6259.7 ± 1150.5, = 11) samples. The validated assay was applied to free-ranging muggers during the breeding season, and Zone A showed significantly ( < 0.05) lower fGCM levels (542.03 ± 71.3) compared to muggers of Zone B (1699.9 ± 180.8) and Zone C (1806.4 ± 243.2), both zones having high levels of HMC with polluted water bodies. A similar contrast in fGCM levels was also observed during the non-breeding season. Overall, the study demonstrated that fGCM levels in muggers varied across habitats, and such variation could be due to a multitude of ecological factors that the species experience in their immediate local environment. Moreover, high fGCM levels in muggers of Vadodara during both breeding and non-breeding seasons may indicate a condition of chronic stress, which could be maladaptive for the species.
动物在其自然环境中面临着诸多挑战，为应对这些状况，它们可能会展现出截然不同的生理反应，而这些反应会直接影响其整体健康和生存。在本研究中，我们通过测量印度古吉拉特邦不同栖息地中自由放养的泽鳄粪便中的糖皮质激素代谢物（fGCM）来评估其生理反应。我们在查洛塔尔（A区，一个农村地区，当地居民对泽鳄的存在具有较高容忍度）以及瓦多达拉（该地区既有城市区域（B区）又有农村区域（C区），人与泽鳄冲突（HMC）程度较高）对泽鳄进行了采样。此外，瓦多达拉的泽鳄生活在因毗邻化学工业排放污水而大多受到污染的水体中。为测量泽鳄的fGCM水平（平均值±标准误，纳克/克干粪便），在繁殖季（n = 107份粪便样本）和非繁殖季（n = 22份粪便样本）从所有三个区域收集粪便。我们使用圈养泽鳄（一个围栏区域）通过捕捉和束缚对选定的fGCM检测方法（11 - 氧代 - 雄烯醇酮检测法）进行生物学验证。我们发现捕捉前（540.9 ± 149.2，n = 11）和捕捉后（6259.7 ± 1150.5，n = 11）样本的fGCM水平显著升高（P < 0.05），升高了11倍。经验证的检测方法应用于繁殖季的自由放养泽鳄，结果显示A区泽鳄的fGCM水平（542.03 ± 71.3）显著低于（P < 0.05）B区（1699.9 ± 180.8）和C区（1806.4 ± 243.2）的泽鳄，后两个区域人与泽鳄冲突程度高且水体受到污染。在非繁殖季也观察到了类似的fGCM水平差异。总体而言，该研究表明泽鳄的fGCM水平因栖息地而异，这种差异可能是由于该物种在其当地直接环境中所经历的多种生态因素所致。此外，瓦多达拉的泽鳄在繁殖季和非繁殖季的fGCM水平都很高，这可能表明其处于慢性应激状态，而这对该物种可能是不利的。
