Bacterial structures and ecosystem functions in glaciated floodplains: contemporary states and potential future shifts

Freimann, Remo; Bürgmann, Helmut; Findlay, Stuart E. G.; Robinson, Christopher T.

doi:10.1038/ismej.2013.114

Cited by 47 publications

(75 citation statements)

References 72 publications

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“…For example, complementarity among algal species has been shown to increase the uptake of nitrate by stream biofilms 75 but, although it is plausible that this may also occur among bacteria in biofilms, we are not aware of any such study. Studies on the activities of extracellular enzymes increasingly suggest that functional plasticity and functional redundancy may blur the relationship between microbial diversity and function in complex biofilm communities [76][77][78] . For instance, one study described biofilm communities with functional plasticity in groundwater-fed streams that may resist environmental fluctuations by adapting their enzymatic machinery, whereas biofilms in glacier-fed streams lacked this plasticity and were instead characterized by specialists able to express specific extracellular enzymes under given conditions 76 .…”

Section: Diversity and Functionmentioning

confidence: 99%

“…Studies on the activities of extracellular enzymes increasingly suggest that functional plasticity and functional redundancy may blur the relationship between microbial diversity and function in complex biofilm communities [76][77][78] . For instance, one study described biofilm communities with functional plasticity in groundwater-fed streams that may resist environmental fluctuations by adapting their enzymatic machinery, whereas biofilms in glacier-fed streams lacked this plasticity and were instead characterized by specialists able to express specific extracellular enzymes under given conditions 76 . Most of these studies have focused on the function of a single extracellular enzyme at a time.…”

Section: Diversity and Functionmentioning

confidence: 99%

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The ecology and biogeochemistry of stream biofilms

et al. 2016

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The perception that most microorganisms live as complex communities that are attached to surfaces has profoundly changed microbiology over the past decades. Most, if not all, bacteria can form biofilms, which are communities of cells embedded in a porous extracellular matrix.Dental plaque, the microorganisms on catheters and implants that cause persistent infections and the fouling of ship hulls and pipework are all examples of biofilms with important implications for public health and industrial processes. Most contemporary biofilm research rests on the discovery made more than 35 years ago by Maurice Lock, Gill Geesey and Bill Costerton: bacteria attached to surfaces dominate microbial life in streams [1][2][3] . These microbiologists pioneered research into stream biofilms, also termed periphyton or epilithon, and described them as complex aggregates of bacteria, algae, protozoa, fungi and meiobenthos. The early study of stream biofilms also highlighted the relevance of interactions between microbial phototrophs and heterotrophs for energy fluxes and the role of the biofilm matrix as the site of extracellular enzyme activity and adsorption of dissolved organic matter (DOM) 3,4 .Since these early days, the study of the ecology and biogeochemistry of stream biofilms has slowly developed in the wake of thriving research on bacterial biofilms -often comprising 3 only a single strain, of interest to medical microbiology, rather than the polymicrobial communities found in stream biofilms -and on the microbial ecology of marine and lake planktonic communities 5 . Unlike bacterial biofilms grown in the laboratory, biofilms in streams are continuously exposed to a diverse inoculum that includes bacteria, archaea, algae, fungi, protozoa and even metazoa. These diverse biological 'building blocks', when combined with the dynamic flow of streamwater, generate biofilms with inherently complex and varying physical structures that have implications for microbial functioning and ecosystem processes 6 . In streams, biofilms are key sites of enzymatic activity 7 , including organic matter cycling, ecosystem respiration and primary production and, as such, form the basis of the food web.Why should we study the ecology and biogeochemistry of stream biofilms? Streams sculpt the continental surface, forming dense and conspicuous channel networks that can be thought of as ecological arteries that perfuse the landscape. Streams are connected to their catchments through various surface and subsurface flow paths and notably through the hyporheic zone in the streambed at the interface between groundwater and streamwater 8 . Microbial cells, solutes and particles enter streams through these flow paths and, en route to downstream ecosystems and ultimately to the oceans, they may interact with the biofilms that colonize the large surface area provided by the streambed as a 'microbial skin' (BOX 1). As a result, the streambed and its biofilm microbiome contribute to biogeochemical fluxes 8 . Indeed, stream biofilms are now recognized as su...

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Section: Diversity and Functionmentioning

confidence: 99%

Section: Diversity and Functionmentioning

confidence: 99%

The ecology and biogeochemistry of stream biofilms

et al. 2016

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“…In some cases, streams will cease to flow or transition to intermittency (Haldorsen & Heim, 1999). Such dramatic habitat alterations are expected to shift the microbial community, with glacier-fed stream specialists (e.g., family Exiguobacteriaceae) being lost as more generalist or groundwater-associated taxa become more prevalent (Freimann et al, 2013a).…”

Section: The Future Of Microbial Diversity In Alpine Headwatersmentioning

confidence: 99%

Microbial assemblages reflect environmental heterogeneity in alpine streams

Hotaling

Foley

Zeglin

et al. 2019

Global Change Biology

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Alpine streams are dynamic habitats harboring substantial biodiversity across small spatial extents. The diversity of alpine stream biota is largely reflective of environmental heterogeneity stemming from varying hydrological sources. Globally, alpine stream diversity is under threat as meltwater sources recede and stream conditions become increasingly homogeneous. Much attention has been devoted to macroinvertebrate diversity in alpine headwaters, yet to fully understand the breadth of climate change threats, a more thorough accounting of microbial diversity is needed. We characterized microbial diversity (specifically Bacteria and Archaea) of 13 streams in two disjunct Rocky Mountain subranges through 16S rRNA gene sequencing. Our study encompassed the spectrum of alpine stream sources (glaciers, snowfields, subterranean ice, and groundwater) and three microhabitats (ice, biofilms, and streamwater). We observed no difference in regional (γ) diversity between subranges but substantial differences in diversity among (β) stream types and microhabitats. Within‐stream (α) diversity was highest in groundwater‐fed springs, lowest in glacier‐fed streams, and positively correlated with water temperature for both streamwater and biofilm assemblages. We identified an underappreciated alpine stream type—the icy seep—that are fed by subterranean ice, exhibit cold temperatures (summer mean <2°C), moderate bed stability, and relatively high conductivity. Icy seeps will likely be important for combatting biodiversity losses as they contain similar microbial assemblages to streams fed by surface ice yet may be buffered against climate change by insulating debris cover. Our results show that the patterns of microbial diversity support an ominous trend for alpine stream biodiversity; as meltwater sources decline, stream communities will become more diverse locally, but regional diversity will be lost. Icy seeps, however, represent a source of optimism for the future of biodiversity in these imperiled ecosystems.

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“…This sensitivity will be exacerbated by future decreases in glacial influence and increasing fragmentation of the alpine stream landscape, which will expose more stretches of streams to flowing over bedrock (and associated solar radiation). In glacial floodplains, structure and function of microbial communities is again linked to ecosystem physicochemistry, with a prevalence of specialist taxa in harsh glacier-fed streams versus a greater abundance of generalists in more stable, warmer groundwater-fed springs (Freimann et al, 2013;.…”

Section: Proglacial Streamsmentioning

confidence: 99%

Microbial ecology of mountain glacier ecosystems: biodiversity, ecological connections and implications of a warming climate

Hotaling

Hood

Hamilton

2017

Environmental Microbiology

139

133

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Summary Glacier ecosystems are teeming with life on, beneath, and to a lesser degree, within their icy masses. This conclusion largely stems from polar research, with less attention paid to mountain glaciers that overlap environmentally and ecologically with their polar counterparts in some ways, but diverge in others. One difference lies in the susceptibility of mountain glaciers to the near‐term threat of climate change, as they tend to be much smaller in both area and volume. Moreover, mountain glaciers are typically steeper, more dependent upon basal sliding for movement, and experience higher seasonal precipitation. Here, we provide a modern synthesis of the microbial ecology of mountain glacier ecosystems, and particularly those at low‐ to mid‐latitudes. We focus on five ecological zones: the supraglacial surface, englacial interior, subglacial bedrock–ice interface, proglacial streams and glacier forefields. For each, we discuss the role of microbiota in biogeochemical cycling and outline ecological and hydrological connections among zones, underscoring the interconnected nature of these ecosystems. Collectively, we highlight the need to: better document the biodiversity and functional roles of mountain glacier microbiota; describe the ecological implications of rapid glacial retreat under climate change and resolve the relative contributions of ecological zones to broader ecosystem function.

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Bacterial structures and ecosystem functions in glaciated floodplains: contemporary states and potential future shifts

Cited by 47 publications

References 72 publications

The ecology and biogeochemistry of stream biofilms

The ecology and biogeochemistry of stream biofilms

Microbial assemblages reflect environmental heterogeneity in alpine streams

Microbial ecology of mountain glacier ecosystems: biodiversity, ecological connections and implications of a warming climate

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