Department of Civil and Environment Engineering, University of Washington, Seattle, Washington, United States of America.
PLoS One. 2012;7(6):e39508. doi: 10.1371/journal.pone.0039508. Epub 2012 Jun 26.
Many studies have concluded terrestrial carbon inputs contribute 20-70% of the carbon supporting zooplankton and fish production in lakes. Conversely, it is also known that terrestrial carbon inputs are of very low nutritional quality and phytoplankton are strongly preferentially utilized by zooplankton. Because of its low quality, substantial terrestrial support of zooplankton production in lakes is only conceivable when terrigenous organic matter inputs are much larger than algal production. We conducted a quantitative analysis of terrestrial carbon mass influx and algal primary production estimates for oligo/mesotrophic lakes (i.e., TP ≤ 20 µg L(-1)). In keeping with the principle of mass conservation, only the flux of terrestrial carbon retained within lakes can be utilized by zooplankton. Our field data compilation showed the median (inter-quartile range) terrestrial particulate organic carbon (t-POC), available dissolved organic carbon (t-DOC) inputs, and in-lake bacterial and algal production were 11 (8-17), 34 (11-78), 74 (37-165), and 253 (115-546) mg C m(-2) d(-1), respectively. Despite the widespread view that terrestrial inputs dominate the carbon flux of many lakes, our analysis indicates algal production is a factor 4-7 greater than the available flux of allochthonous basal resources in low productivity lakes. Lakes with high loading of t-DOC also have high hydraulic flushing rates. Because t-DOC is processed, i.e., mineralized or lost to the sediments, in lakes at ≈ 0.1% d(-1), in systems with the highest t-DOC inputs (i.e., 1000 mg m(-2) d(-1)) a median of 98% of the t-DOC flux is advected and therefore is not available to support zooplankton production. Further, advection is the primary fate of t-DOC in lakes with hydraulic retention times <3 years. When taking into account the availability and quality of terrestrial and autochthonous fluxes, this analysis indicates ≈ 95-99% of aquatic herbivore production is supported by in-lake primary production.
许多研究得出结论，陆源碳输入为湖泊中浮游动物和鱼类提供了 20-70%的碳。相反，人们也知道陆源碳输入的营养质量非常低，浮游植物也被浮游动物强烈优先利用。由于其质量低，只有当陆源有机物质输入远远大于藻类生产时，湖泊中浮游动物的大量陆地支持才是可以想象的。我们对寡营养/中营养湖泊（即 TP≤20µg L(-1)）的陆地碳质量流入和藻类初级生产力估算进行了定量分析。根据质量守恒原理，只有滞留在湖泊内的陆地碳通量才能被浮游动物利用。我们的实地数据汇编显示，中位数（四分位距）陆地颗粒有机碳（t-POC）、可用溶解有机碳（t-DOC）输入以及湖泊内细菌和藻类的生产力分别为 11（8-17）、34（11-78）、74（37-165）和 253（115-546）mg C m(-2) d(-1)。尽管人们普遍认为陆地输入主导着许多湖泊的碳通量，但我们的分析表明，藻类生产力是低生产力湖泊中所有异源基础资源可用通量的 4-7 倍。高 t-DOC 负荷的湖泊也具有较高的水力冲刷率。由于 t-DOC 在湖泊中以≈0.1% d(-1)的速度被处理，即矿化或流失到沉积物中，在 t-DOC 输入最高的系统（即 1000mg m(-2) d(-1))中，t-DOC 通量的中位数有 98%被平流输送，因此无法用于支持浮游动物的生产。此外，在水力停留时间<3 年的湖泊中，平流是 t-DOC 的主要归宿。当考虑到陆地和自生通量的可用性和质量时，这项分析表明，大约 95-99%的水生食草动物的生产力是由湖泊内的初级生产力来支持的。
