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Rock glaciers and paraglacial features influence stream invertebrates in a deglaciating Alpine area
Freshwater Biology ( IF 2.7 ) Pub Date : 2020-12-07 , DOI: 10.1111/fwb.13658
Stefano Brighenti 1, 2, 3, 4 , Monica Tolotti 3 , Walter Bertoldi 2 , Geraldene Wharton 4 , Maria Cristina Bruno 3
Affiliation  

  1. Climate change and progressive glacier loss are leading to rapid ecological shifts in alpine aquatic systems. Rock glaciers and paraglacial features such as proglacial lakes, moraines, and taluses can alter the gradients of glacial influence along alpine river networks, but the ecological responses are still understudied.
  2. We investigated benthic invertebrate communities of different stream types (upper kryal, lower kryal, glacio‐rhithral, krenal, and rock glacial) within a deglaciating area of the Italian Alps (Solda and Zay sub‐catchments). Alpha‐ (Shannon index and taxa richness) and β‐diversity (i.e. nestedness and turnover), production (abundance, biomass), average body mass of invertebrate taxa, and functional feeding groups were used to analyse the influence of habitat conditions on invertebrate communities in different microhabitats (mineral substrates, bryophytes, Hydrurus foetidus). We defined an index of habitat mildness based on water temperature, channel stability, turbidity, and organic detritus, to measure the difference in community metrics over a gradient of habitat amelioration, driven by the mixing of distinct stream types and their interactions with paraglacial features.
  3. While diversity proxies showed an asymptotic behaviour along the gradient, the quantitative metrics peaked at intermediate mildness. Peaks of invertebrate biomass/abundance were recorded at the glacio‐rhithral station below the talus. Highest average body mass occurred at Zay, specifically at the rock glacial stream, and at the lower kryal stations influenced by the lake/moraine and the rock glacier. The moraine outflow showed unexpected high biomass/abundance values of shredders and grazers, that were supported by a high epilithic production. Bryophytes acted as local scale multipliers of mildness as they stored more detritus, and hosted higher biomass/abundance of invertebrates and, in particular, of gatherer–collectors.
  4. Beta‐diversity, driven by the turnover component, was positively related to different habitat mildness of the sampling stations. Although influenced by distinct lentic/lotic conditions, rock glacial streams hosted several taxa typical of glacio‐rhithral and krenal stations, alongside large numbers of Diamesa (Chironomidae), a genus typical of kryal habitats.
  5. Under progressive deglaciation, rock glaciers and paraglacial features influence the invertebrate communities of alpine river networks. As they host a high number of taxa dwelling in non‐glacial locations, rock glacial streams may act as stepping stones facilitating invertebrate colonisation following glacier retreat. After glacier loss, rock glacial streams may represent climate refugia for cold adapted taxa and/or kryal specialists, because the slow thawing of their ice might sustain cold water conditions for a longer period of time.


中文翻译:

冰川和副冰川特征影响着一个高山冰川地区的河流无脊椎动物

  1. 气候变化和渐进的冰川损失正在导致高山水生系统的快速生态转变。岩石冰川和冰川前特征(如冰川湖,莫兰河和距骨)可以改变沿高山河网的冰川影响的梯度,但生态响应仍未得到充分研究。
  2. 我们调查了意大利阿尔卑斯山(Solda和Zay子汇水区)的一个冰河地区不同河流类型的底栖无脊椎动物群落(上部kryal,下部kryal,冰川-斜纹岩,krenal和岩石冰川)。Alpha(香农指数和分类单元的丰富度)和β-多样性(即嵌套和周转),产量(丰度,生物量),无脊椎动物分类单元的平均体重和功能性摄食组用于分析生境条件对无脊椎动物群落的影响在不同的微生境中(矿物质,苔藓植物,Hydrurus foetidus)。我们基于水温,河道稳定性,浊度和有机碎屑定义了栖息地温和度指数,以测量在不同生境类型的河水混合以及它们与副冰川特征的相互作用驱动下,栖息地改善梯度上社区指标的差异。
  3. 虽然多样性代理表现出沿梯度的渐近行为,但定量指标在中等温和度时达到顶峰。在距骨下方的冰川-根脉站记录了无脊椎动物生物量/丰度的峰值。最高的平均体重发生在Zay,特别是在岩石冰川流以及受湖泊/冰a和冰川影响的较低kryal测站。ora冰流出显示出切碎机和放牧机出乎意料的高生物量/丰度值,这由较高的上石片产量支持。苔藓植物作为本地规模的温和倍增器,因为它们储存了更多的碎屑,并且拥有更高的生物量/无脊椎动物,特别是采集者-采集者的丰度。
  4. β多样性是由更新率驱动的,与采样站不同的栖息地温和度呈正相关。尽管受到不同的透镜/地势条件的影响,但岩石冰川流却拥有几个典型的冰川-上肢和肾科站类群,以及大量的迪亚美萨犬科(Chironomidae),这是一种典型的Kryal生境。
  5. 在渐进的冰消作用下,冰川和副冰川特征影响着高山河网的无脊椎动物群落。由于它们在非冰川地区拥有大量的分类单元,因此冰川退缩后,岩石冰川流可能充当垫脚石,促进无脊椎动物的定居。在冰川损失之后,岩石冰川流可能代表适应寒冷的生物分类群和/或kryal专家的气候避难所,因为它们的冰缓慢解冻可能会维持较长时间的冷水条件。
更新日期:2021-02-09
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