Department of Ocean Sciences, Memorial University, 0 Marine Lab Road, St John's, NL, A1C 5S7, Canada; Bamfield Marine Sciences Centre, Bamfield, BC, VOR 1BO, Canada.
Comp Biochem Physiol A Mol Integr Physiol. 2013 Nov;166(3):414-25. doi: 10.1016/j.cbpa.2013.07.023. Epub 2013 Aug 1.
Meal size and animal size are important factors affecting the characteristics of the specific dynamic action (SDA) response across a variety of taxa. The effects of these two variables on the SDA of decapod crustaceans are based on just a couple of articles, and are not wholly consistent with the responses reported for other aquatic ectotherms. Therefore, the effects of meal size and animal size on the characteristics of SDA response were investigated in a variety of decapod crustaceans from different families. A 6 fold increase in meal size (0.5%-3% body mass) resulted a pronounced increase in the duration of increased oxygen consumption, resulting in an increase in the SDA of Callinectes sapidus, Cancer gracilis, Hemigrapsus nudus, Homarus americanus, Pugettia producta and Procambarus clarkii. Unlike many other aquatic ectotherms a substantial increase between meal sizes was required, with meal size close to their upper feeding limit (3% body mass), before changes were evident. In many organisms increases in both duration and scope contribute to the overall SDA, here changes in scope as a function of meal size were weak, suggesting that a similar amount of energy is required to upregulate gastric processes, regardless of meal size. The SDA characteristics were less likely to be influenced by the size of the animal, and there was no difference in the SDA (kJ) as a function of size in H. americanus or Cancer irroratus when analysed as mass specific values. In several fish species characteristics of the SDA response are more closely related to the transit times of food, rather than the size of a meal. To determine if a similar trend occurred in crustaceans, the transit rates of different sized meals were followed through the digestive system using a fluoroscope. Although there was a trend towards larger meals taking longer to pass through the gut, this was only statistically significant for P. clarkii. There were some changes in transit times as a function of animal size. The foregut clearance times for Cancer magister increased with increasing body size, while smaller Carcinus maenas cleared the hindgut region at a faster rate than larger individuals. Unlike fish there was no clear relationship between transit rates and any of the SDA characteristics. While the fluoroscopy method is useful for assessing foregut activity and food passage, it is limited when inferring connections between nutrient assimilation and post-absorptive processes in crustaceans. Therefore, at least with respect to meal size, transit rates do not make a good proxy for determining the SDA characteristics in crustaceans.
饮食大小和动物大小是影响各种分类群特定动力作用（SDA）反应特征的重要因素。这两个变量对十足目甲壳动物 SDA 的影响仅基于几篇文章，并且与其他水生变温动物报告的反应不完全一致。因此，研究了不同科的各种十足目甲壳动物的饮食大小和动物大小对 SDA 反应特征的影响。饮食大小增加 6 倍（0.5%-3% 体重）导致耗氧量增加的持续时间明显延长，从而导致美味可口的蟹、拟穴青蟹、脊尾白虾、美洲螯龙虾、太平洋潜泥蛤和红螯螯虾的 SDA 增加。与许多其他水生变温动物不同，需要大量增加饮食大小，当饮食大小接近其上限（3% 体重）时，才会出现变化。在许多生物体中，持续时间和范围的增加都会导致整体 SDA 增加，而这里饮食大小与范围的变化较弱，这表明无论饮食大小如何，上调胃过程都需要相同数量的能量。动物大小对 SDA 特征的影响较小，并且当以质量特异性值分析时，美洲螯龙虾或拟穴青蟹的 SDA（kJ）大小与大小无关。在几种鱼类中，SDA 反应的特征与食物的通过时间更密切相关，而不是与饮食的大小有关。为了确定甲壳类动物是否也存在类似的趋势，使用荧光透视法跟踪不同大小饮食在消化系统中的通过速度。虽然较大的饮食通过肠道的时间有延长的趋势，但这仅在红螯螯虾中具有统计学意义。动物大小对通过时间有一些影响。随着身体大小的增加，赤拟谷盗的前肠清除时间增加，而较小的三疣梭子蟹清除后肠区域的速度比个体大的速度快。与鱼类不同，通过速率与任何 SDA 特征之间都没有明确的关系。虽然荧光透视法方法对于评估前肠活动和食物通过是有用的，但它在推断甲壳类动物中营养吸收和吸收后过程之间的联系时受到限制。因此，至少就饮食大小而言，通过速率不能很好地替代确定甲壳类动物 SDA 特征的指标。
