Université de La Rochelle-CNRS, UMR 6250 Littoral Environnement et Sociétés (LIENSs), La Rochelle, France.
PLoS One. 2011;6(8):e23273. doi: 10.1371/journal.pone.0023273. Epub 2011 Aug 22.
This study is the first assessment of the quantitative impact of parasitic chytrids on a planktonic food web. We used a carbon-based food web model of Lake Pavin (Massif Central, France) to investigate the effects of chytrids during the spring diatom bloom by developing models with and without chytrids. Linear inverse modelling procedures were employed to estimate undetermined flows in the lake. The Monte Carlo Markov chain linear inverse modelling procedure provided estimates of the ranges of model-derived fluxes. Model results support recent theories on the probable impact of parasites on food web function. In the lake, during spring, when 'inedible' algae (unexploited by planktonic herbivores) were the dominant primary producers, the epidemic growth of chytrids significantly reduced the sedimentation loss of algal carbon to the detritus pool through the production of grazer-exploitable zoospores. We also review some theories about the potential influence of parasites on ecological network properties and argue that parasitism contributes to longer carbon path lengths, higher levels of activity and specialization, and lower recycling. Considering the "structural asymmetry" hypothesis as a stabilizing pattern, chytrids should contribute to the stability of aquatic food webs.
这项研究首次评估了寄生水霉对浮游食物网的定量影响。我们使用法国中央高原帕文湖（Lake Pavin）的基于碳的食物网模型，通过开发有和没有水霉的模型，研究水霉在春季硅藻水华期间的影响。线性反演建模程序用于估计湖中未确定的流量。蒙特卡罗马尔可夫链线性反演建模程序提供了模型衍生通量的范围估计。模型结果支持寄生虫对食物网功能可能产生影响的最新理论。在湖中，春季时，当“不可食用”的藻类（浮游食草动物无法利用）成为主要的初级生产者时，水霉的流行生长通过产生可被食草动物利用的游动孢子，显著减少了藻类碳向碎屑库的沉降损失。我们还回顾了一些关于寄生虫对生态网络特性潜在影响的理论，并认为寄生作用导致更长的碳路径长度、更高的活动和专业化水平以及更低的再循环。考虑到“结构不对称”假说作为一种稳定模式，水霉应该有助于水生食物网的稳定。
