Papastamatiou Yannis P, Lowe Christopher G
Department of Biological Sciences, California State University-Long Beach, 1250 Bellflower Blvd, Long Beach, CA 90840, USA.
J Exp Biol. 2004 Jan;207(Pt 2):225-32. doi: 10.1242/jeb.00741.
Changes in gastric pH of leopard sharks Triakis semifasciata were quantified as an indicator of feeding frequency and ration size. Continuous in situ measurements of gastric pH were made in captive adult leopard sharks using an autonomous pH/temperature probe for periods ranging from 5-16 days. Instrumented sharks were fed meals of squid at different ration sizes. Gastric fluid samples were also taken from non-instrumented juvenile leopard sharks at different time intervals after feeding, and the pH measured to quantify effects of the pH probe in the stomach. Continuous in situ measurements of pH show that empty stomachs have a low pH of 1.54+/-1.42 (mean +/- S.D.) and that feeding causes a rapid increase in pH to 3.11+/-0.71, followed by a gradual decrease back down to baseline levels. There was a positive relationship between changes in pH and meal size (r(2)=0.72, P=0.001). There were no significant differences in pH between continuous in situ and laboratory serial sample measurements. Together these findings indicate that gastric acid secretion may be continuous in leopard sharks, and that changes in gastric pH may be used to estimate feeding chronology, frequency and ration size of leopard sharks in the field.
对半带皱唇鲨（Triakis semifasciata）胃内pH值的变化进行了量化，以此作为摄食频率和食量大小的指标。使用自主式pH/温度探头，对圈养的成年半带皱唇鲨进行胃内pH值的连续原位测量，测量时间为5至16天。给安装了仪器的鲨鱼投喂不同食量的鱿鱼餐。还在不同的进食时间间隔后，从未安装仪器的幼年半带皱唇鲨身上采集胃液样本，并测量pH值，以量化pH探头在胃内的影响。pH值的连续原位测量表明，空腹时胃内pH值较低，为1.54±1.42（平均值±标准差），进食会使pH值迅速升至3.11±0.71，随后逐渐下降至基线水平。pH值变化与食量大小呈正相关（r² = 0.72，P = 0.001）。连续原位测量和实验室系列样本测量的pH值之间没有显著差异。这些研究结果共同表明，半带皱唇鲨的胃酸分泌可能是持续的，胃内pH值的变化可用于估计野外半带皱唇鲨的摄食时间、频率和食量大小。
