Detachment and motility of surface-associated ciliates at increased flow velocities

Risse‐Buhl, Ute; Scherwaß, Anja; Schlüssel, Annette; Arndt, Hartmut; Kröwer, Sandra; Küsel, Kirsten

doi:10.3354/ame01302

Cited by 12 publications

(8 citation statements)

References 30 publications

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“…Direct observations of ciliates at fast flows revealed a higher displacement rate of motile species indicating that food uptake is inhibited (Risse‐Buhl et al ). On a broader scale, the bentho‐pelagic coupling driven by heterotrophic protists (Weitere and Arndt ; Kathol et al ) might be reduced since sessile ciliates remain longer in a contracted state and their uptake of suspended particles is inhibited (Risse‐Buhl et al ). Hence, bacteria benefitted from grazing release at conditions of increased near bed flow.…”

Section: Discussionmentioning

confidence: 99%

Near streambed flow shapes microbial guilds within and across trophic levels in fluvial biofilms

Risse‐Buhl

Anlanger

Chatzinotas

et al. 2020

Limnology & Oceanography

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Flow is an important physical driver of biofilm communities. Here, we tested the effects of the near bed flows in two mountainous stream reaches on the structure of biofilm microbial guilds (autotrophs, heterotrophic bacteria, and heterotrophic protists) within and across trophic levels. Near bed flow velocity and turbulent kinetic energy were important physical drivers for structuring the communities within and across guilds of the multitrophic fluvial biofilms. The effects of flow were nested in a seasonal and spatial (across-streams) context. Changes in physicochemical factors (temperature, light, dissolved carbon, and nutrients) along the reaches were alike in both streams suggesting that environmental boundary conditions at larger temporal scales were responsible for the seasonal differences of biofilm communities, whereas locally microbial diversity was shaped by near bed flow. Typically, the abundance of autotrophs increased with flow, indicating that biofilms shifted toward increasing autotrophy with increasing shear forces. Filamentous autotrophs seemed to provide protected habitats from the shear forces for smaller sized bacteria. Heterotrophic protist abundance decreased with flow leading to decreasing grazer to prey ratio. Bacteria thus benefitted from a reduction in grazing pressure at faster flowing, more turbulent sites. Our results suggest that near bed flow can impact the magnitude and direction of matter fluxes through the microbial food web and possibly affect ecosystem functioning of fluvial biofilms.

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Section: Discussionmentioning

confidence: 99%

Near streambed flow shapes microbial guilds within and across trophic levels in fluvial biofilms

Risse‐Buhl

Anlanger

Chatzinotas

et al. 2020

Limnology & Oceanography

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“…In contrast, the common but littlestudied protist Chilodonella sp. is a flattened, substrate-crawling raptorial or gulper feeder which preys upon attached cells (8,55). We hypothesized that these ciliates would show different interactions with bacterial biofilms which could be related to their contrasting motility and feeding modes.…”

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confidence: 99%

Preferential Feeding by the Ciliates Chilodonella and Tetrahymena spp. and Effects of These Protozoa on Bacterial Biofilm Structure and Composition

Dopheide

Lear

Stott

et al. 2011

Appl Environ Microbiol

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Protozoa are important components of microbial food webs, but protozoan feeding preferences and their effects in the context of bacterial biofilms are not well understood. The feeding interactions of two contrasting ciliates, the free-swimming filter feeder Tetrahymena sp. and the surface-associated predator Chilodonella sp., were investigated using biofilm-forming bacteria genetically modified to express fluorescent proteins. According to microscopy, both ciliates readily consumed cells from both Pseudomonas costantinii and Serratia plymuthica biofilms. When offered a choice between spatially separated biofilms, each ciliate showed a preference for P. costantinii biofilms. Experiments with bacterial cell extracts indicated that both ciliates used dissolved chemical cues to locate biofilms. Chilodonella sp. evidently used bacterial chemical cues as a basis for preferential feeding decisions, but it was unclear whether Tetrahymena sp. did also. Confocal microscopy of live biofilms revealed that Tetrahymena sp. had a major impact on biofilm morphology, forming holes and channels throughout S. plymuthica biofilms and reducing P. costantinii biofilms to isolated, grazing-resistant microcolonies. Grazing by Chilodonella sp. resulted in the development of less-defined trails through S. plymuthica biofilms and caused P. costantinii biofilms to become homogeneous scatterings of cells. It was not clear whether the observed feeding preferences for spatially separated P. costantinii biofilms over S. plymuthica biofilms resulted in selective targeting of P. costantinii cells in mixed biofilms. Grazing of mixed biofilms resulted in the depletion of both types of bacteria, with Tetrahymena sp. having a larger impact than Chilodonella sp., and effects similar to those seen in grazed single-species biofilms.

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“…Ciliates present in the epilimnetic network cluster are known for their substratum-attached lifestyle, e.g., fine-filter feeding Vorticella sp. [65, 66] that were connected to colonial chrysophytes, or are moderately efficient bacterial grazers such as Rimostrombidium and Strombidimum spp. [62], which were extensively connected to bacterial nodes.…”

Section: Discussionmentioning

confidence: 99%

Depth-dependent dynamics of protist communities as an integral part of spring succession in a freshwater reservoir

Mukherjee,

Grujčić,

Salcher

et al. 2024

Preprint

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Background Protists are essential contributors to eukaryotic diversity and exert profound influence on carbon fluxes and energy transfer in freshwaters. Despite their significance, there is a notable gap in research on protistan dynamics, particularly in the deeper strata of temperate lakes. This study aimed to address this gap by integrating protists into the well-described spring dynamics of Rimov reservoir, Czech Republic. Over a two-month period covering transition from mixing to established stratification, we collected water samples from three reservoir depths (0.5, 10 and 30 m) with a frequency of up to three times per week. Microbial eukaryotic and prokaryotic communities were analysed using SSU rRNA gene amplicon sequencing and dominant protistan groups were enumerated by Catalysed Reporter Deposition-Fluorescence in situ Hybridization (CARD-FISH). Additionally, we collected samples for water chemistry, phyto- and zooplankton composition analyses. Results Following the rapid changes in environmental and biotic parameters during spring, protistan and bacterial communities displayed swift transition from a homogeneous community to distinct strata-specific communities. Epilimnion exhibited the prevalence of auto-, mixotrophic protists dominated by cryptophytes and associated with spring algal bloom-specialized bacteria. In contrast, meta- and hypolimnion showcased the development of protist community dominated by putative parasitic Perkinsozoa, detritus or particle-associated ciliates, cercozoans and excavate protists co-occurring with bacteria associated with lake snow. Conclusions Our high-resolution sampling matching the typical dividing time of microbes along with the combined microscopic and molecular approach and inclusion of all the components of microbial food web allowed us to follow depth-specific populations' successions and interactions in a deep lentic ecosystem.

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Detachment and motility of surface-associated ciliates at increased flow velocities

Cited by 12 publications

References 30 publications

Near streambed flow shapes microbial guilds within and across trophic levels in fluvial biofilms

Near streambed flow shapes microbial guilds within and across trophic levels in fluvial biofilms

Preferential Feeding by the Ciliates Chilodonella and Tetrahymena spp. and Effects of These Protozoa on Bacterial Biofilm Structure and Composition

Depth-dependent dynamics of protist communities as an integral part of spring succession in a freshwater reservoir

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