Invertebrate food webs along a stream resource gradient
Invertebrate food webs along a stream resource gradient
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沿溪流资源梯度的无脊椎动物食物网
DOI：
10.1046/j.1365-2427.2002.00786.x
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发表时间：
2002
影响因子：
2.7
通讯作者：
Wallace
中科院分区：
文献类型：
--
作者：
E. Rosi;J. Bruce;Wallace
总结1。在相似物种的食物网中，能量的流动可以随时间和空间的变化而变化。河流连续统概念（RCC）为预测河流生物区系和食物供应的变化提供了一个有用的框架。我们估计了有机物质通过食物网的流量（g ~2“1”），这些食物网沿河流排列，具有不同的资源投入。沿着美国北卡罗来纳州的小田纳西河选取了四个地点：两个五阶地点，一个六阶地点和一个七阶地点。优势资源为上游河段（上游第5级）的叶片碎屑、中游河段（下游第5级和第6级）的藻类和下游（第7级）的悬浮物。2. 研究了11个属，占各样地大型无脊椎动物次生产量的50% ~ 66%。我们通过结合以前测量的无脊椎动物次生产物率和肠道含量分析和同化效率来估计从资源到消费者的有机物流量。3. 在食物网结构保持不变的情况下，有机质在食物网中的流动向下游方向增加。所分析的类群的总食物消耗量从上游站点的34 g m~2 year”1增加到最下游站点的730 g m~2 year”1。我们估计整个大型无脊椎动物群落消耗的有机质在66 ~ 1164 g m~2年之间。这些结果表明，沿着这条河流连续体的食物网，有机物流量的大小是有变化的。4. 优势食物资源的消耗也随梯度变化。叶片碎屑的消耗从上游总消耗的58%下降到下游总消耗的6%，而无定形碎屑的消耗从18%上升到64%。动物性材料的消耗比例也从3%增加到27%。本地资源（硅藻和丝状藻类）的总消耗量随时间的增加而增加（从6.41 g ~2 g ~ 1）。我们认为，这些结果与资源可利用性、饮食变化和无脊椎动物次生产量的变化有关。这些结果将资源可用性与能量流联系起来，这是RCC最初提出的关系。
SUMMARY 1. The flow of energy through food webs with similar species can vary with both space and time. The river continuum concept (RCC) provides a useful framework for predicting variability in the biota and food availability along streams. We estimated the flow of organic matter (g m~2 year"1) through food webs, arrayed along a stream, that had different resource inputs. Four sites were sampled along the Little Tennessee River, North Carolina, U.S.A.: two fifth order sites, one sixth and one seventh order site. The dominant resource is leaf detritus in the upstream reach (the upstream fifth order site), algae in the mid-reaches (the downstream fifth and sixth order sites), and suspended material downstream (seventh order site). 2. Eleven genera, contributing from 50 to 66% of the total macroinvertebrate secondary production of each site, were studied. We estimated organic matter flow from resource to consumer by combining previously measured rates of invertebrate secondary production with gut content analyses and assimilation efficiencies. 3. Organic matter flow through food webs increased in a downstream direction, while the structure of the food webs remained constant. The total food consumed by the taxa analysed increased from 34 g m~2 year"1 at the upstream site to 730 g m~2 year"1 at the most downstream site. We estimate that the organic matter consumed by the entire macroinvertebrate community ranged from 66 to 1164 g m~2 year"1. These results indicate that there is variation in the magnitude of organic matter flow through the food webs along this river continuum. 4. The dominant food resource consumed also changed along the gradient. Leaf detritus consumption decreased from 58% of the total consumption upstream to 6% downstream, whereas consumption of amorphous detritus increased from 18 to 64%. The proportion of animal material consumed also increased from 3 to 27%. The total consumption of autochthonous resources (diatoms and filamentous algae) increased along the continuum (from 6.41 to 34.05 g m~2 year"1). We conclude that these results are related to variation in resource availability, dietary shifts and invertebrate secondary production. These results link resource availability to energy flow, a relationship originally suggested by the RCC.