Tracking the autochthonous carbon transfer in stream biofilm food webs

Risse‐Buhl, Ute; Trefzger, Nicolai; Seifert, Anne-Gret; Schönborn, W.; Gleixner, Gerd; Küsel, Kirsten

doi:10.1111/j.1574-6941.2011.01202.x

Cited by 41 publications

(30 citation statements)

References 72 publications

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“…Fungi are probably also an important component of stream biofilms but remain poorly studied 15,16 . Ciliates, flagellates, nematodes and even young-instar insects (such as midges) are among the top consumers in stream biofilms 17,18 , and their grazing activity can change the physical structure 19,20 , community composition 21 and carbon cycling of biofilms 22 . Furthermore, viruses have an important role in marine ecosystems 23 ; for example, in bacterial biofilms 24 , bacterial viruses (or phages) can infect cells and regulate the dynamics and diversity of bacterial communities.…”

Section: Biodiversity Across Spatial Scalesmentioning

confidence: 99%

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: Biodiversity Across Spatial Scalesmentioning

confidence: 99%

The ecology and biogeochemistry of stream biofilms

et al. 2016

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“…The proportional increased abundances of Fungi, protozoans and photosynthetic taxa in surface sediments also parallels results from other studies in soils and sediments (Strauss and Dodds 1997, Ekelund et al 2001, Taylor et al 2002. This highlights the importance of phototrophic biofilms as primary producers and their role as an organic substrate for food web interactions and nutrient cycling during flow events (Roeselers et al 2008, Risse-Buhl et al 2012). …”

Section: Sediment Depthmentioning

confidence: 91%

“…The eukaryotes include primary producers including diatoms (Stramenopiles) and green algae (Streptophyta) (Paul 2007, Fedonkin 2009). The high abundance of primary producers are likely to play an important role in the nutrient retention, cycling and release in these stream sediments (Thorp and Delong 1994, Bunn et al 2003, Fellows et al 2007, Risse-Buhl et al 2012). …”

Section: Primary Producers and Food Web Interactionsmentioning

confidence: 99%

“…The associated food webs with microbial communities are important in contributing to higher trophic levels as a food source and also the recycling of nutrients (Meyer 1994, Hall and Meyer 1998, Naeem et al 2000, Risse-Buhl et al 2012). …”

Section: Primary Producers and Food Web Interactionsmentioning

confidence: 99%

“…In the dry season, these biofilms may act as a possible source for nutrients and carbon as a result of microbial mortality from drying induced cell lysis. In carbon limited systems, biofilms and their associated food webs can be an important source of carbon and contribute to the cycling of nutrients (Meyer 1994, Strauss and Dodds 1997, Hall and Meyer 1998, Risse-Buhl et al 2012.…”

Section: Surface Watermentioning

confidence: 99%

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Microbial communities in an ephemeral stream system and the implications of saline mine discharge

Beyer-Robson¹

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The Fitzroy River Basin (FRB), Queensland, contains the largest coal reserve in Australia. Driven by an increasing need to conserve fresh water, coal mine operators in the region have placed significant emphasis on reducing freshwater use by implementing water re-use. As a consequence, the salinity of stored water on mine sites has increased due to accumulation of salts through evaporation, groundwater input and mine operations. When excess water is discharged into the environment, this reduced water quality may constitute an environmental risk to the receiving ecosystem. Reports on the impact of mine site discharge highlighted the lack of data on potential impacts of saline discharge on the aquatic environment following flood events in 2007/08.The FRB is a semi-arid region in which the river systems only flow for a few months a year. In such intermittent rivers, major biogeochemical cycling occurs in river sediments and is largely driven by microbial metabolic processes. These microbial processes are of particular importance in maintaining downstream water quality and healthy functioning of the aquatic ecosystem. Current assessment tools do not capture nutrient cycles mediated by microorganisms, but instead focus on the impacts of larger organisms such as fish and macroinvertebrates. There is a need for a combined approach which includes assessing potential impacts on ecosystem processes.Little is known on the effects of salinity on ecosystem processes mediated by microorganisms in freshwater systems and insights have largely been inferred from comparisons with other ecosystems such as estuarine and marine environments. Further, most research has been conducted on perennial streams and little is known on microbial ecology and nutrient cycling in ephemeral streams.The aim of this thesis was to gain insights into microbial communities and ecosystem processes in an ephemeral stream system to guide management decisions in the context of saline water discharge from coal mines. The thesis was guided by two objectives: 1) to examine microbial community distribution in an ephemeral river system; and 2) to investigate the effect of increased salinity on selected ecosystem processes.The first objective, to examine microbial community distribution in an ephemeral river system (The Upper Isaac catchment, located within the FRB), used a field-based approach to build on the conceptual understanding of microbial communities and microbially driven ecosystem processes.To gain an understanding of microbial distribution, the habitats within the Upper Isaac Catchment were characterised. This provided a framework under which microbial community distribution could be examined. Habitat characterisation was based on physical environmental parameters, for which key habitat characteristics were the presence/absence of surface water in relation to seasonal flow, levels of detritus in stream beds and substrate type.Using 16S rRNA pyrosequencing, key microbial groups were identified; such as high abundances of spore forming bacteri...

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