Santonja Mathieu, Pellan Laura, Piscart Christophe
Université Rennes 1 - UMR CNRS 6553 ECOBIO Rennes France.
Ecol Evol. 2018 Feb 4;8(5):2542-2553. doi: 10.1002/ece3.3790. eCollection 2018 Mar.
Plant litter decomposition is an essential ecosystem function that contributes to carbon and nutrient cycling in streams. Aquatic shredders, mainly macroinvertebrates, can affect this process in various ways; they consume leaf litter, breaking it down into fragments and creating suitable habitats or resources for other organisms through the production of fine particulate organic matter (FPOM). However, measures of litter-feeding traits across a wide range of aquatic macroinvertebrates are still rare. Here, we assessed the contributions of 11 species of freshwater macroinvertebrates to litter decomposition, by measuring consumption rate, FPOM production, and assimilation rate of highly decomposable () or poorly decomposable () leaf litter types. In general, an increase in the quality of litter improved the litter consumption rate, and fungal conditioning of the leaf litter increased both the litter consumption rate and FPOM production. Macroinvertebrates specializing in leaf litter consumption also appeared to be the most sensitive to shifts in litter quality and the conditioning process. Contrary to expectations, the conditioning process did not increase the assimilation of low-quality litter. There was a strong correlation between the relative consumption rate (RCR) of the two litter types, and the relative FPOM production (RFP) was strongly correlated to the RCR. These findings suggest a consistent relationship between RCR and macroinvertebrate identity that is not affected by litter quality, and that the RFP could be inferred from the RCR. The varying responses of the macroinvertebrate feeding traits to litter quality and the conditioning process suggest that the replacement of a shredder invertebrate species by another species could have major consequences for the decomposition process and the detritus-based food web in streams. Further studies onto the importance of invertebrate identity and the effects of litter quality in a variety of freshwater ecosystems are needed to understand the whole ecosystem functioning and to predict its response to environmental changes.
植物凋落物分解是一项重要的生态系统功能，有助于溪流中的碳和养分循环。水生碎食者，主要是大型无脊椎动物，可以通过多种方式影响这一过程；它们消耗落叶，将其分解成碎片，并通过产生细颗粒有机物质（FPOM）为其他生物创造适宜的栖息地或资源。然而，对广泛的水生大型无脊椎动物的落叶取食特性进行测量的研究仍然很少。在这里，我们通过测量11种淡水大型无脊椎动物对高分解性（）或低分解性（）落叶类型的消耗率、FPOM产量和同化率，评估了它们对落叶分解的贡献。一般来说，落叶质量的提高会提高落叶消耗率，而落叶的真菌预处理会同时提高落叶消耗率和FPOM产量。专门以落叶为食的大型无脊椎动物似乎对落叶质量的变化和预处理过程也最为敏感。与预期相反，预处理过程并没有增加低质量落叶的同化。两种落叶类型的相对消耗率（RCR）之间存在很强的相关性，相对FPOM产量（RFP）与RCR也密切相关。这些发现表明，RCR与大型无脊椎动物种类之间存在一致的关系，且不受落叶质量影响，并且可以从RCR推断出RFP。大型无脊椎动物取食特性对落叶质量和预处理过程的不同反应表明，一种碎食性无脊椎动物物种被另一种物种取代可能会对溪流中的分解过程和碎屑基食物网产生重大影响。需要进一步研究无脊椎动物种类的重要性以及落叶质量在各种淡水生态系统中的影响，以了解整个生态系统的功能并预测其对环境变化的反应。
