To understand the tolerance to salinity and osmoregulation of the introduced Trachemys scripta elegans, the salinity stress of four groups(salinity 5‰, 15‰, 25‰ and control group) were conducted. Inorganic ions, osmotic pressure, glucose and aldosterone of blood and urine in T. s. elegans(BW: 125.60 ± 19.84 g) were analyzed at 30 d, 60 d and 90 d stress. The results showed that: 1) inorganic ions concentration of blood and urine increased with ambient salinity, which indicated that high influx of ions was combined with higher outflow when exposed to saline water in T. s. elegans. However, blood aldosterone decreased with increasing salinity, which indicated that an increased sodium intake resulting in a diminished aldosterone production. However, with elapsed time, inorganic ions in urine decreased, which indicated that inorganic ions in blood would be accumulated, and Na+ and Cl– in the plasma inevitably build up to harmful levels, at last death was happening when T. s. elegans was exposed to salinity 25 during 90 d salinity stress; 2) blood osmotic pressure increased as ambient salinity increased, it would reach 400 mOsm/kg in the group of salinity 25, which was about 1.5 fold of the control group. Higher blood osmotic pressure was due to both higher blood ions and urea concentrations. There may be another mechanism to avoid an excess of NaCl together with an important loss of water using one of the end-products of nitrogen metabolism; 3) blood glucose in each group except the group of salinity 5 decreased with time elapsed and with salinity increased. Therefore, we can conclude that T. s. elegans is an osmoregulator that limits the entry of Na+ and Cl–, but can also tolerate certain degrees of increases in plasma Na+ and Cl–. When ambient salinity was lower than 15‰, T. s. elegans can increase blood osmotic pressure by balancing the entry of NaCl with the secretion of aldosterone decreased, and by accumulating blood urea for osmoregulation effectors, and survive for at least three months. These
巢捕食是造成卵生动物繁殖失败的重要因素之一。为了解不同生境中黄额闭壳龟(Cuora galbinifrons)巢捕食者的类型、巢捕食率及对其繁殖成效的影响,我们于2013年3—5月,在海南吊罗山国家级自然保护区黄额闭壳龟栖息地,按照黄额闭壳龟巢址选择特性和巢穴特征,用红耳龟(Trachemys scripta elegans)的卵作为替代,进行模拟黄额闭壳龟巢卵被捕食状况的研究。在人工林、次生林和原生林内共设置人工巢120个,每巢埋卵2枚,同时在巢周围架设自动红外照相机,监测巢捕食者。结果表明:66.7%的人工巢被破坏,小型兽类和蚂蚁为主要捕食者,被小型兽类捕食的巢占51.3%,被蚂蚁捕食的巢占28.8%。次生林和原生林的人工巢被捕食率均为62.5%,人工林中的被捕食率为72.5%,人工林的捕食率高于次生林和原生林但差异不显著(P>0.05,n=40)。同一林型的林缘和林中之间,人工林和原生林中差异不显著,在次生林中巢捕食率明显高于林缘(P<0.05,n=20)。
红耳龟Trachemys scripta elegans是一种入侵到全世界六大洲70多个国家和地区的半水栖杂食性爬行动物,现已广泛分布于我国野外环境。在国外,由于红耳龟潜在的生态危害和对人类健康的影响而受到特别关注,但在我国的重视程度却不够。本文从活动节律、取食行为、晒背行为、迁移行为与恋巢性、通讯行为、攻击行为、求偶与交配行为、筑巢行为等8个方面综述了红耳龟行为生态学的研究成果。期望有助于红耳龟在入侵地的科学研究、防治与管理。
