Long-term stoichiometry and fates highlight animal egestion as nutrient repackaging, not recycling, in aquatic ecosystems
Long-term stoichiometry and fates highlight animal egestion as nutrient repackaging, not recycling, in aquatic ecosystems
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DOI：
10.1111/1365-2435.12875
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发表时间：
2017-09-01
影响因子：
5.2
通讯作者：
Evans-White, Michelle A.
中科院分区：
文献类型：
--
作者：
Halvorson, Halvor M.;Hall, Delaney J.;Evans-White, Michelle A.
1. 动物排便或排泄是许多生态系统中有机物的明显转化。然而，由于 egesta 被认为是顽固的和低营养的，因此它们作为水生环境中动物营养通量的重要性和可变性 - 特别是相对于通过排泄的矿化 - 知之甚少。2。我们比较了水生粉碎机 Allocapnia spp.、Lirceus spp. 中艾斯塔的短期到长期（长达 107 天）微生物分解的碳 (C)、氮 (N) 和磷 (P) 动态。和提普拉属。饲喂低磷或高磷含量悬铃木垫料，研究艾斯塔在水生营养动态中的作用。 3．与 Lirceus 和 Allocapnia 相比，Tipula 产生的 N 和 P 耗尽的麦子具有更高的 N : P，并且与低 P 日粮相比，高磷日粮增加了麦子 P 含量。尽管分解造成了可测量的碳损失，但这些营养成分含量的差异在分解过程中仍然存在，表明饮食和物种控制着排出颗粒的即时和长期特性。4。 Egesta 在分解过程中在溶解磷和铵的吸收和释放之间切换，并以硝酸盐-亚硝酸盐的形式表现出一致的净氮吸收。在不同物种和饮食中，较低的 N : P gesta 往往会表现出更多的溶解无机 N 吸收，这表明 gesta 的 P 富集会驱动分解微生物更强的溶解氮需求。5。粉碎机显示出长期稳定的养分含量，并且与它们是可忽略不计或次要净来源的假设相反，它们可以是溶解的无机养分的强大的、扩展的汇。未来的研究应考虑动物营养通量与排泄之间的对比，排泄通过矿化促进养分循环，而排泄则通过有机养分重新包装减缓养分循环，并可以形成溶解养分的汇。
1. Animal defecation, or egestion, is a pronounced transformation of organic matter in many ecosystems. However, because egesta have been presumed recalcitrant and low nutrient, their significance and variability as an animal nutrient flux in aquatic settings - especially relative to mineralization via excretion - are poorly known.2. We compared carbon (C), nitrogen (N) and phosphorus (P) dynamics over short- to long-term (up to 107 days) microbial decomposition of egesta from the aquatic shredders Allocapnia spp., Lirceus spp. and Tipula spp. fed low- or high-P content Platanus occidentalis litter to investigate roles of egesta in aquatic nutrient dynamics.3. Tipula produced N and P deplete egesta of higher N : P compared to Lirceus and Allocapnia, and high-P diets increased egesta P content compared to low- P diets. Despite measurable C losses to decomposition, these differences in nutrient content persisted through decomposition, showing diet and species control both immediate and long-term properties of egested particles.4. Egesta switched between uptake and release of dissolved phosphorus and ammonium during decomposition, and exhibited consistent net N uptake as nitrate-nitrite. Across species and diets, lower N : P egesta tended to exhibit greater uptake of dissolved inorganic N, suggesting P enrichment of egesta drove stronger dissolved N demand by decomposer microbes.5. Shredder egesta exhibit stable nutrient contents long term and, counter to assumptions that they are negligible or minor net sources, can be strong, extended sinks of dissolved inorganic nutrients. Future studies should consider contrasts between animal nutrient fluxes as excretion, which facilitates nutrient recycling via mineralization, vs. egestion, which slows nutrient recycling via organic nutrient repackaging and can create sinks of dissolved nutrients.