Turner John W, Nemeth Richard, Rogers Caroline
Department of Physiology and Molecular Medicine, Medical College of Ohio, Toledo, OH 43614-5804, USA.
Gen Comp Endocrinol. 2003 Oct 1;133(3):341-52. doi: 10.1016/s0016-6480(03)00196-5.
Coral reefs are in decline worldwide from a combination of natural and human forces. The environmental compromises faced by coral reef habitats and their associated fishes are potentially stressful, and in this study we examined the potential for assessing stress levels in coral reef fish. We determined the feasibility of using fecal casts from parrotfishes for remote assessment of stress-related hormones (cortisol and corticosterone), and the response of these hormones to the stress of restraint and hypoxia. Measurement of these hormones in fecal extracts by high performance liquid chromatography (HPLC) was validated using mass spectrometry, chemical derivitization, and radioactive tracer methods. In aquarium-adapted parrotfish, baseline levels of cortisol and corticosterone averaged 3.4+/-1.1 and 14.8+/-2.8 ng/g feces, respectively, across 32 days. During 13 days of periodic stress these hormones, respectively, average 10.8-fold and 3.2-fold greater than baseline, with a return to near baseline during a 23-day follow-up. Testosterone was also measured as a reference hormone which is not part of the stress-response axis. Levels of this hormone were similar across the study. These fecal hormones were also measured in a field study of parrotfish in 10 fringing coral reef areas around the Caribbean Island of St. John, US Virgin Islands. Extracts of remotely collected fecal casts of three parrotfish species revealed no difference in respective average hormone levels among these species. Also, there was no difference in respective hormone levels between aquarium and field environments. However, levels of both cortisol and corticosterone, but not testosterone, were elevated in two of the 10 reef sites surveyed. This study demonstrates that parrotfish fecals can be collected in aquarium and field conditions and that steroid hormones in these fecals can be extracted and reliably measured. The study also demonstrates that cortisol and corticosterone in parrotfish fecals can be used as an indicator of the stress-response which is unlikely to be masked by intrinsic variability in the sample source, environment or methodology.
由于自然和人为因素的综合影响，全球范围内的珊瑚礁正在衰退。珊瑚礁栖息地及其相关鱼类所面临的环境问题可能会造成压力，在本研究中，我们探讨了评估珊瑚礁鱼类压力水平的可能性。我们确定了利用鹦嘴鱼粪便远程评估与压力相关激素（皮质醇和皮质酮）的可行性，以及这些激素对束缚和缺氧压力的反应。通过高效液相色谱法（HPLC）对粪便提取物中的这些激素进行测量，并采用质谱法、化学衍生化法和放射性示踪法进行验证。在适应水族箱环境的鹦嘴鱼中，在32天的时间里，皮质醇和皮质酮的基线水平分别平均为3.4±1.1和14.8±2.8纳克/克粪便。在为期13天的周期性压力期间，这些激素的水平分别比基线高出10.8倍和3.2倍，在为期23天的随访期间恢复到接近基线水平。睾酮也作为一种参考激素进行了测量，它不属于应激反应轴的一部分。在整个研究过程中，这种激素的水平相似。在美国维尔京群岛圣约翰岛周围10个边缘珊瑚礁区域对鹦嘴鱼进行的实地研究中，也测量了这些粪便激素。对三种鹦嘴鱼物种远程收集的粪便铸型提取物的分析显示，这些物种各自的平均激素水平没有差异。此外，水族箱环境和野外环境中的各自激素水平也没有差异。然而，在调查的10个珊瑚礁地点中的两个地点，皮质醇和皮质酮的水平都有所升高，但睾酮水平没有升高。这项研究表明，鹦嘴鱼粪便可以在水族箱和野外条件下收集，并且这些粪便中的类固醇激素可以被提取并可靠地测量。该研究还表明，鹦嘴鱼粪便中的皮质醇和皮质酮可以用作应激反应的指标，不太可能被样本来源、环境或方法的内在变异性所掩盖。
