Geographically widespread 13 C-depletion of grazing caddis larvae: A third way of fuelling stream food webs?
Geographically widespread 13 C-depletion of grazing caddis larvae: A third way of fuelling stream food webs?
复制标题
放牧石蚕幼虫在地理上广泛存在的 13 C 消耗：为溪流食物网提供燃料的第三种方式？
DOI：
10.1111/fwb.13262
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发表时间：
2019
影响因子：
2.7
通讯作者：
Sampson A
中科院分区：
文献类型：
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作者：
Sampson A
河流生态系统是由绿色和（即基于放牧）和棕色（即碎屑）食物网，而甲烷衍生的碳一般不被认为是重要的;在这里，we add添加circumstantial间接evidence证据for this potential潜在third第三way.（毛翅目）幼虫在科Glossosomatidae可以非常丰富的泉水和水源，往往有低得多的稳定碳同位素比值（即，它们在同位素13 C稳定同位素中被耗尽）比它们所生活的石头的上表面上的生物膜（表石）更少，并且这是它们的假定饮食。在其他lotic无脊椎动物类似的同位素耗尽的证据目前是有限的，但是，即使是glossosomatids，它已被观察到目前为止，只有在一些流排水南部的英国白垩纪白垩和在北方加州的几个源头。如果这种现象被证明是更普遍的，在溪流或类群中，它可能意味着一个更普遍的河流食物网的基础，来自甲烷的同位素轻碳，并通过消费者喂养甲烷营养细菌获得。在这里，我们采样了58个溪流站点，以检查石蛾幼虫是否也在其他地质的溪流中耗尽13 C。我们主要关注石炭纪石灰岩和砂岩，以及代表大部分英国白垩含水层的其他白垩流：这些新地点的总面积接近90，000平方公里，大约是以前调查的面积的三倍。在所有58个地点，甲烷气体相对于大气平衡都过饱和，其中49只幼虫相对于大量表石（我们知道其中的成分可以氧化甲烷）明显缺乏13 C-（从-17.5 ‰到-3.6 ‰）。虽然这种现象在白垩上仍然最明显，但在地理和地质上比以前显示的要普遍得多，并表明甲烷衍生的碳确实可以在河流食物网中发挥突出作用（即第三种方式）。
Stream ecosystems are supported by bothgreen(i.e. based on grazing) andbrown(i.e. detritus) food webs, whereas methane‐derived carbon is not considered generally to be important; here, we add circumstantial evidence for this potentialthird way.Grazing cased‐caddis (Trichoptera) larvae in the family Glossosomatidae can be very abundant in springs and headwaters and frequently have much lower stable carbon isotope ratios (i.e. they are depleted in the heavier13C stable isotope) than the biofilm (epilithon) on the upper surfaces of the stones on which they live, and which is their presumed diet. Evidence for similar isotopic depletion in other lotic invertebrates is currently limited, however; even for glossosomatids it has been observed so far only in some streams draining the southern English cretaceous chalk and in a few headwaters in northern California. If this phenomenon proves to be more widespread, among streams or taxa, it could imply a more general underpinning of stream food webs byisotopically lightcarbon derived from methane and accessed via consumers feeding on methanotrophic bacteria.Here, we sampled 58 stream sites to examine whether caddis larvae are also13C‐depleted in streams draining other geologies. We focused mainly on carboniferous limestone and sandstone, as well as on further chalk streams representative of most of the British chalk aquifer: together, these new sites covered an area of almost 90,000 km2, around three times greater than that surveyed previously.At all 58 sites methane gas was supersaturated relative to the atmospheric equilibrium, and at 49 of them larvae were conspicuously13C‐depleted (from −17.5‰ to −3.6‰) relative to the bulk epilithon (components of which we know can oxidise methane). Although still most pronounced on chalk, this phenomenon was geographically and geologically much more widespread than shown previously and suggests methane‐derived carbon could indeed play a prominent role in stream food webs (i.e. thethird way).