Filter-feeders have differential bottom-up impacts on green and brown food webs
Filter-feeders have differential bottom-up impacts on green and brown food webs
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DOI：
10.1007/s00442-020-04821-7
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发表时间：
2021-01-02
期刊：
影响因子：
2.7
通讯作者：
Waters, Matthew N.
中科院分区：
文献类型：
--
作者：
Atkinson, Carla L.;Halvorson, Halvor M.;Waters, Matthew N.
消费者的养分循环会严重影响自养和异养微生物的养分利用率，从而影响初级生产和分解等功能。滤食性淡水贻贝在水生生态系统中形成密集的多物种群落，已被证明在营养循环中发挥关键作用。贻贝排泄物可提高底栖生物初级生产力，影响藻类种类组成。然而，贻贝在棕色或碎屑为基础的食物网中的作用以及物种特有的差异却受到了相当少的关注。在这里，利用中游实验，我们评估了三种淡水贻贝在三个不同的系统发育部落中如何影响底栖藻类的累积量、生态系统新陈代谢、棉条分解、叶凋落物(糖枫)分解以及以麦角甾醇衡量的凋落物相关真菌生物量。此外，我们测量了贻贝的排泄率和生物沉积率，并评估了底栖藻类、棉条和树叶的化学计量比(C：N、C：P和N：P)。与不加贻贝的对照相比，贻贝处理具有更高的底栖藻类生物量，由更多的硅藻组成，更高的总初级生产力和净生态系统生产力，更高的棉条抗张强度损失，但生态系统呼吸速率、叶凋落物分解速率和真菌生物量没有差异。底栖藻在贻贝处理池中C：N较低，N：P较高，棉条C：N在有贻贝的围隔中较低。我们的结果表明，贻贝的营养再生对绿色食物网的调节最强，对棕色食物网也有一些影响，这表明消费者对淡水中的微生物功能有交互作用。
Nutrient recycling by consumers can strongly impact nutrient availability for autotrophic and heterotrophic microbes, thus impacting functions such as primary production and decomposition. Filter-feeding freshwater mussels form dense, multispecies assemblages in aquatic ecosystems and have been shown to play a critical role in nutrient cycling. Mussel excretion can enhance benthic primary production and influence algal species composition. However, the role of mussels in brown or detritus-based food webs and species-specific differences has received considerably less attention. Here, using mesocosm experiments, we assessed how three species of freshwater mussels that occupy three different phylogenetic tribes influenced benthic algal accrual, ecosystem metabolism, cotton strip decomposition, leaf litter (Acer saccharum) decomposition, and litter-associated fungal biomass measured as ergosterol. Additionally, we measured mussel excretion and biodeposition rates and assessed the stoichiometry (C:N, C:P, and N:P) of the benthic algae, cotton strips, and leaf litter. In comparison to controls without mussels, generally, mussel treatments had higher benthic algal biomass composed of more diatoms, higher gross primary productivity and net ecosystem production rates, and higher cotton strip tensile strength loss, but there was not a difference in ecosystem respiration rates, leaf litter decomposition rates, or fungal biomass. Benthic algae had lower C:N and higher N:P in mussel treatment tanks and cotton strip C:N was lower in mesocosms with mussels. Our results suggest that nutrient regeneration by mussels most strongly regulates green food webs, with some impacts to brown food webs, suggesting that consumers have interactive effects on microbial functioning in freshwaters.