Ministère des Pêches et des Océans, Institut Maurice-Lamontagne, C. P. 1000, Mont-Joli, QC G5H 3Z4, Canada.
J Fish Biol. 2013 Mar;82(3):789-805. doi: 10.1111/jfb.12005. Epub 2013 Feb 21.
This study examined the effects of prey exoskeleton characteristics on gastric evacuation patterns in Atlantic cod Gadus morhua. Three distinct stages were highlighted in the gastric evacuation of crustacean prey characterized by a robust exoskeleton. The experiments confirmed that the three shrimp species, Pandalus borealis, Pandalus montagui and Eualus macilentus, and the crab Chionoecetes opilio, were evacuated from the stomach at different rates. The duration of all stages increased with increasing ash (and carbonate) content of the fresh prey. Thickness, chemical composition and morphology of the prey exoskeleton all affected gastric evacuation: duration of initial delay, overall evacuation rate and a decreased evacuation rate at the end of the process. The power exponential function (PEF), with its shape parameter, described the course of evacuation for these prey types well, especially the initial delay. The PEF does not, however, allow describing evacuation by the current stomach content mass independent of meal size, which limits its usefulness in estimating consumption rates of wild G. morhua. To predict and describe gastric evacuation of prey with a robust exoskeleton, it is therefore suggested that the square-root function be expanded with an initial lag phase, coupled to the mechanistically based cylinder model of gastric evacuation.
本研究探讨了猎物外骨骼特征对大西洋鳕鱼（Gadus morhua）胃排空模式的影响。具有坚硬外骨骼的甲壳类猎物的胃排空过程中突出了三个明显的阶段。实验证实，三种虾类（北方长额虾、太平洋鳕和日本囊对虾）和一种蟹类（北方真蟹）的排空速度不同。所有阶段的持续时间随着新鲜猎物灰分（和碳酸盐）含量的增加而增加。猎物外骨骼的厚度、化学成分和形态均影响胃排空：初始延迟时间、整体排空率以及过程结束时排空率降低。幂指数函数（PEF）及其形状参数很好地描述了这些猎物类型的排空过程，尤其是初始延迟时间。然而，PEF 不能描述当前胃内容物质量与餐量无关的排空情况，这限制了其在估计野生 G. morhua 摄食率方面的有用性。因此，建议将平方根函数扩展为具有初始滞后阶段，并与胃排空的基于机制的圆柱模型相结合，以预测和描述具有坚硬外骨骼的猎物的胃排空。
