Legacy effects of drought alters the aquatic food web of a northern boreal peatland
Legacy effects of drought alters the aquatic food web of a northern boreal peatland
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干旱的遗留影响改变了北部北方泥炭地的水生食物网
DOI：
10.1111/fwb.12950
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发表时间：
2017
影响因子：
2.7
通讯作者：
Wyatt, Kevin H.
中科院分区：
文献类型：
--
作者：
DeColibus, Dawn T.;Rober, Allison R.;Sampson, Avery M.;Shurzinske, Amanda C.;Walls, Jeremy T.;Turetsky, Merritt R.;Wyatt, Kevin H.
与其他临时水生生态系统相比，我们知道相对较少的淹没频率和持续时间（即水文制度）如何影响水生群落的结构在北方泥炭地。在这项研究中，我们研究了在阿拉斯加沼泽的自然洪水事件中营养物质的可用性和水生群落结构的模式，在过去的几年中，在三个大规模的实验地块中，地下水位的位置被操纵，以模拟干旱（地下水位降低的处理）和洪水（地下水位升高的处理）相对于没有操纵的对照条件。虽然自然洪水破坏了长期的实验操作，但它提供了一个机会来评估过去水文状况的变化如何影响北方北方泥炭地淹没期间的营养动态和水生食物网结构。（即，在所有地块中，水高于泥炭表面），在干旱处理中，水柱养分浓度显著高于（在上一个生长季节地下水位下降的地方）在所有的地下水位处理中，藻类产量随着营养物质有效性的提高而增加，并且在干燥的土壤再润湿后最高。干旱处理中的沉积物。消费者生物量（异养细菌和大型无脊椎动物）随着藻类生产的增加而增加，并且与水位升高的处理和对照相比，干旱处理中的消费者生物量显着更大。由于藻类生产受到养分供应减少的限制，消费者生物量在持续淹没的第二年有所减少。（13 C和15 N）表明，（即完整的生物膜）与提高养分的可利用性相关，促进能量转移到更高的营养水平（食草动物和捕食者）而不是活的或死的苔藓或维管植物材料。食草动物对藻类材料的消耗改变了藻类群落的大小和组成。藻类群落从球形（可食用）丝状（不可食用）的生长形式与增加放牧丰富的干旱处理，可能是由于选择性放牧。相反，有一个类似的比例，可食用和不可食用的类群在控制和提高处理，其中食草动物丰度较低。我们的研究结果表明，干旱的遗产影响可以调节水生群落结构在北方泥炭地。在一个预测的背景下，我们的研究结果表明，气候变化（即干旱频率增加）预计发生在整个北方纬度地区的水文条件将促进能量流到更高的营养水平，通过释放微藻在洪水期间的营养限制。
Compared to other temporary aquatic ecosystems, we know relatively little about how inundation frequency and duration (i.e. hydrologic regime) influences the structure of aquatic communities in northern peatlands. In this study, we examined patterns in nutrient availability and aquatic community structure during a natural flooding event in an Alaskan fen where water‐table position had been manipulated in three large‐scale experimental plots during previous years to simulate both drought (lowered water‐table treatment) and flooding (raised water‐table treatment) conditions relative to a control without manipulation. Although the natural flood disrupted the long‐term experimental manipulation, it provided an opportunity to evaluate how variation in past hydrologic regime influences nutrient dynamics and aquatic food web structure during periods of inundation in a northern boreal peatland.Despite similar water depth among experimental plots during the time of sampling (i.e. water was above the peat surface in all plots), water‐column nutrient concentrations were significantly greater in the drought treatment (where water table had been lowered during the previous growing season) compared to the raised water‐table treatment and the control.Algal production increased with enhanced nutrient availability across all water‐table treatments and was most elevated following the rewetting of dry sediments in the drought treatment. Consumer biomass (heterotrophic bacteria and macroinvertebrates) increased with algal production and was significantly greater in the drought treatment compared to the raised water‐table treatment and the control. Consumer biomass decreased into the second year of constant inundation as algal production was constrained by reduced nutrient availability.Stable isotope analysis (13C and15N) showed that elevated levels of periphyton (i.e. the intact biofilm) associated with enhanced nutrient availability promoted energy transfer to higher trophic levels (grazers and predators) rather than living or dead mosses or vascular plant material.Consumption of algal material by grazers altered the size and composition of the algal community. The algal community shifted from coccoid (edible) to filamentous (inedible) growth forms with increased grazer abundance in the drought treatment, possibly owing to selective grazing. Conversely, there was a similar proportion of edible and inedible taxa in the control and raised treatments where grazers were lower in abundance.Our results show that the legacy effects of drought can regulate aquatic community structure in northern peatlands. Within a predictive context, our findings suggest that conditions of more variable hydrology expected with climate change (i.e. increased frequency of drought) occurring across northern latitudes will promote energy flow to higher trophic levels by releasing nutrient constraints on microalgae during periods of inundation.
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