Most studies of the feeding habits of octopuses have focused on the use of a single technique, often selected on the basis of its familiarity or minimal impact on study animals. Although over time new methods have been developed for dietary assessment, no comparative analysis has ever been done. Using Octopus insularis as a model, we examined the results of three methods of diet analysis to understand how these techniques can influence study conclusions. Octopus diets were assessed through the analysis of (1) fresh prey remains deposited in midden piles, (2) digestive contents from the octopus crop and stomach, and (3) stable isotope data on the octopus and its potential food sources. The research was conducted at Rocas Atoll, a pristine oceanic reef off the northeastern coast of Brazil, with data from a coastal environment with substantial human impact (i.e. Rio do Fogo, northeastern Brazil) being evaluated as well. Overall, the three methods differed in the type of data they produced and the timescale represented, reflecting their own biases, the biology and behaviour of the octopus, and even the local oceanographic and other environmental conditions. We therefore provide a conceptual diagram to help researchers to consider the inherent aspects of each method when planning and performing studies of octopus diet, and also when interpreting study results.

中文翻译：

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评估章鱼的饮食：传统技术和稳定同位素方法

关于章鱼的摄食习惯的大多数研究都集中在单一技术的使用上，通常是基于对章鱼的熟悉程度或对研究动物的影响最小而选择的。尽管随着时间的流逝，已经开发出了用于饮食评估的新方法，但是从未进行过比较分析。使用章鱼作为模型，我们检查了三种饮食分析方法的结果，以了解这些技术如何影响研究结论。通过分析（1）堆积在中间堆中的新鲜猎物，（2）章鱼作物和胃的消化成分以及（3）章鱼及其潜在食物来源的稳定同位素数据，对章鱼的饮食进行了评估。这项研究是在巴西东北沿海的原始海洋礁石罗卡斯环礁进行的，同时还评估了来自沿海环境的数据，该数据对人类造成了重大影响（即巴西东北部的Rio do Fogo）。总体而言，这三种方法在产生的数据类型和所表示的时间尺度上有所不同，反映了它们自身的偏见，章鱼的生物学和行为，甚至还包括当地的海洋学和其他环境条件。