Boersma Maarten, Elser James J
Alfred-Wegener-Institut für Polar und Meeresforschung, Biologische Anstalt Helgoland, Germany.
Ecology. 2006 May;87(5):1325-30. doi: 10.1890/0012-9658(2006)87[1325:tmoagt]2.0.co;2.
Nutritional imbalances are of great interest in the ecological stoichiometry literature, in which researchers have focused almost exclusively on cases where nutrients are available in low amounts relative to energy (carbon), and animal growth is impaired due to insufficient nutrient intake. Little attention has been given to situations where food elemental content is higher than the level that satisfies animal requirements. However, most animals are strongly homeostatic with respect to the elemental composition of their body; hence they must excrete the excess of elements that are not in short supply. To date, stoichiometric theory has assumed that excretion of superfluous elements does not come with a cost and, thus, that consumption of food with surplus nutrients does not impair performance. Here we challenge this assumption, based on a compilation of several examples involving food phosphorus content that show that the performance of a wide variety of animals decreases when supplied with food containing high concentrations of (potentially) limiting nutrients. We discuss possible mechanisms for this phenomenon, and suggest that animals most vulnerable to effects of high food nutrient content are those that normally feed on low- quality (low-nutrient: C) food, and have a relatively low body nutrient content themselves, such as herbivores and detritivores.
营养失衡在生态化学计量学文献中备受关注，在该领域，研究人员几乎只关注相对于能量（碳）而言营养素含量较低，且动物生长因营养素摄入不足而受损的情况。对于食物元素含量高于满足动物需求水平的情况，人们关注较少。然而，大多数动物在身体元素组成方面具有很强的稳态性；因此，它们必须排出非短缺元素的过量部分。迄今为止，化学计量学理论一直假定排出多余元素不会产生成本，因而，摄入富含过剩营养素的食物不会损害动物的表现。在此，我们基于对几个涉及食物磷含量例子的汇总对这一假定提出质疑，这些例子表明，当为多种动物提供含有高浓度（潜在）限制性营养素的食物时，它们的表现会下降。我们讨论了这一现象可能的机制，并指出最易受高食物营养素含量影响的动物是那些通常以低质量（低营养素：碳）食物为食、自身身体营养素含量相对较低的动物，如食草动物和食腐动物。
