How nitrogen and phosphorus supply to nutrient-limited autotroph communities affects herbivore growth: testing stoichiometric and co-limitation theory across trophic levels

Primary producer communities are often growth-limited by essential nutrients such as nitrogen (N) and phosphorus (P). The magnitude of limitation and whether N, P, or both elements are limiting autotroph growth depends on the supply and ratios of these essential nutrients. Previous studies identified single, serial or co-limitation as predominant limitation outcomes in autotroph communities by factorial nutrient additions. Little is known about potential consequences of such scenarios for herbivores and whether their growth is primarily affected by changes in autotroph quantity or nutritional quality. We grew a community of phytoplankton species differing in various food quality aspects in experimental microcosms at varying N and P concentrations resulting in three different N:P ratios. At carrying capacity, N, P, both nutrients or none were added to reveal which nutrients were limiting. The nutrient supplied communities were fed to the generalist herbivorous rotifer Brachionus calycifl...

初级生产者群落通常会受到氮（N）、磷（P）等必需营养元素的生长限制。此类限制的强度，以及氮、磷单独还是共同限制自养生物生长，均取决于这些必需营养元素的供给量及其比值。过往研究通过因子式营养添加实验，确定了单营养限制、连续营养限制或共同营养限制是自养生物群落中占主导的限制类型。目前对于此类限制情形对植食动物的潜在影响，以及植食动物的生长是否主要受自养生物生物量或营养品质变化的影响，仍知之甚少。我们在不同氮、磷浓度的实验微宇宙（experimental microcosms）中培养了一批在多种食物品质维度上存在差异的浮游植物（phytoplankton）群落，最终得到三种不同的氮磷比。在达到环境容纳量（carrying capacity）后，我们分别添加氮、磷、双营养元素或不添加营养，以明确哪种营养元素构成了生长限制。随后将这些经营养供给调控的浮游植物群落投喂给广食性植食性轮虫——萼花臂尾轮虫（Brachionus calycifl...）