The scaling of parasite biomass with host biomass in lake ecosystems: are parasites limited by host resources?

The standing crop biomass of different populations or trophic levels reflects patterns of energy flow through an ecosystem. The contribution of parasites to total biomass is often considered negligible; recent evidence suggests otherwise, although it comes from a narrow range of natural systems. Quantifying how local parasite biomass, whether that of a single species or an assemblage of species sharing the same host, varies across localities with host population biomass, is critical to determine what constrains parasite populations. We use an extensive dataset on all free-living and parasitic metazoan species from multiple sites in New Zealand lakes to measure parasite biomass and test how it covaries with host biomass. In all lakes, trematodes had the highest combined biomass among parasite taxa, ranging from about 0.01 to 0.25 g m−2, surpassing the biomass of minor free-living taxa. Unlike findings from other studies, the life stage contributing the most to total trematode biomass was...

不同种群或营养级的现存量生物量（standing crop biomass）可反映生态系统的能量流动模式。寄生虫对总生物量的贡献常被视为微不足道；尽管相关新近证据仅来自有限的自然生态系统类型，但已有研究表明实际情况并非如此。量化局部区域内寄生虫生物量——无论是单一物种还是共享同一宿主的物种组合——随宿主种群生物量在不同地点间的变化规律，是明确制约寄生虫种群的关键因素的核心前提。本研究依托新西兰多个湖泊站点采集的涵盖所有自由生活与寄生后生动物（metazoan）的大型数据集，对寄生虫生物量进行测算，并检验其与宿主生物量的协变关系。在所有调研湖泊中，吸虫类（trematodes）在寄生虫类群中总生物量最高，范围约为0.01至0.25克每平方米，其生物量超过了小型自由生活类群。与其他研究的结论不同，对吸虫总生物量贡献最大的生活史阶段为……