Aquatic protists modulate the microbial activity associated with mineral surfaces and leaf litter

Risse‐Buhl, Ute; Karsubke, Martina; Schlief, Jeanette; Baschien, Christiane; Weitere, Markus; Mutz, Michael

doi:10.3354/ame01564

Cited by 20 publications

(18 citation statements)

References 76 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, both protists and benthic algae can stimulate fungal growth and activity (Risse-Buhl et al, 2012;Danger et al, 2013b) but the role of ES in mediating this stimulation is currently unknown. How does resource stoichiometry affect fungal physiology, and, as a result, the production of secondary metabolites, essential fatty acids and other compounds by aquatic fungi, and what are the effects on detritivorous consumers?…”

Section: Discussionmentioning

confidence: 99%

Ecological stoichiometry of aquatic fungi: current knowledge and perspectives

2016

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 99%

Ecological stoichiometry of aquatic fungi: current knowledge and perspectives

2016

View full text Add to dashboard Cite

“…Yet, some studies report that protists significantly stimulate the efficiency of leaf processing by the microbial communities (fungi, bacteria) associated with decaying leaves (e.g. Ribblett, Palmer & Wayne Coats, ; Risse‐Buhl et al ., ; Risse‐Buhl, Schlief & Mutz, ). In their study, Risse‐Buhl et al .…”

Section: Discussionmentioning

confidence: 99%

Two microcrustaceans affect microbial and macroinvertebrate‐driven litter breakdown

et al. 2017

View full text Add to dashboard Cite

Summary Leaf litter degradation in fresh waters is a fundamental ecosystem process performed by a wide array of decomposers. The meiofauna is an important component of aquatic heterotrophic assemblages, which can provide a trophic link between plant detritus and associated microbial and macroinvertebrate communities, but their contribution to leaf breakdown remains poorly understood. We hypothesised that, through their feeding activity, microcrustaceans influence the structure of fungal assemblages and consequently microbially mediated litter breakdown. Litter‐associated microcrustaceans were predicted to change the pathways of energy transfer in the food web according to the positive (e.g. complementarity) or negative (e.g. predation) interactions with macroinvertebrate detritivore taxa. We evaluated experimentally in the laboratory, over 6 and 13 days, the potential contribution of two freshwater microcrustaceans (a cladoceran and a copepod) to litter breakdown in the presence of microfungi (aquatic hyphomycetes), with and without macroinvertebrate detritivores (a trichopteran and a gammarid amphipod). The presence of microcrustaceans enhanced leaf mass loss by 62 and 22% in treatments with fungi or trichopteran alone, respectively, while no significant effect was observed for treatments with the amphipod. Microcrustaceans strongly increased the production of fine particulate organic matter, particularly in treatments with fungi alone (+637%). The leaf consumption rate by the amphipod significantly decreased (−61%) at 13 days in the presence of microcrustaceans, likely due to predation on cladocerans. Our study supports the potential role of microcrustaceans in the detrital food web of streams and rivers. Interestingly, microcrustaceans may interact with microbial and macroinvertebrate decomposers in either positive or negative ways. Therefore, microcrustaceans add complexity to detrital food webs by increasing vertical diversity and modulating biotic interactions with important consequences for carbon and energy transfers in stream ecosystems.

show abstract

“…(Bengtsson, ; Gulis & Suberkropp, ). The lower abundance of suspended bacteria in the presence of both bacterivorous suspension feeders, Tetrahymena (Risse‐Buhl et al ., ) and Glaucoma (present microcosm experiment), indicates that they partly relied on suspended bacteria.…”

Section: Discussionmentioning

confidence: 99%

“…Risse‐Buhl et al . () found similar results in microcosm incubations. In our experimental microcosms, leaf‐associated respiration rates were not affected by the microbial community in low oxic treatments.…”

Section: Discussionmentioning

confidence: 99%

“…Several phagotrophic protist species either tolerate or are adapted to low oxic environments (Fenchel, Finlay & Gianní, ; Finlay & Esteban, ). Under such conditions, ventilating protists were found to stimulate microbial respiration during the initial phase of leaf litter processing, possibly by increasing oxygen supply to leaf‐associated cells (Glud & Fenchel, ; Risse‐Buhl et al ., ). Leaf mass loss was not affected during a 21‐day microcosm incubation (Risse‐Buhl et al ., ).…”

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Phagotrophic protists are a key component of microbial communities processing leaf litter under contrasting oxic conditions

2015

View full text Add to dashboard Cite

Summary The transformation of leaf litter, a key process in aquatic systems, is known to be reduced with decreasing oxygen concentrations, mainly due to lower abundance of and/or less active shredding macroinvertebrates. Aquatic fungi and phagotrophic protists involved in leaf litter processing can tolerate low oxygen, but little is known about their role in leaf litter processing under these conditions. We aimed to unravel the importance of phagotrophic protists within microbially mediated leaf litter processing under contrasting oxic conditions. We hypothesised that respiration, abundance of aquatic bacteria and biomass of aquatic fungi, and thus leaf litter processing, are enhanced in the presence of phagotrophic protists, both under normoxic and low oxic conditions. Lower leaf processing was expected under low oxic than under normoxic conditions. In microcosms, oxygen concentration was adjusted to either normoxic or low. For a total of 105 days, leaf litter was cocultivated with three microbial communities: (i) a multispecies bacterial community enriched from stream leaf litter, (ii) the aquatic fungus Heliscus lugdunensis added to the bacterial community and (iii) the phagotrophic protist Glaucoma scintillans added to the bacteria–fungi community. Oxic condition had no significant effect on microbially mediated leaf mass loss. The leaf mass loss was faster in the presence of the aquatic fungus and further accelerated by adding the phagotrophic protist. After 105 days, leaf mass remaining approximated 64–79%, 57–68% and 55–61% of initial leaf mass in the bacteria, bacteria–fungi, and bacteria–fungi–phagotrophic protist communities, respectively. Under both oxic conditions, the lower leaf toughness indicated that the aquatic fungus had the potential to process leaf structural components more efficiently than bacteria alone. The combination of lower ergosterol concentrations and enhanced leaf mass loss indicated that phagotrophic protists stimulated the efficiency of leaf processing by the microbial community. Under normoxic conditions, leaf‐associated respiration increased when successively adding an aquatic fungus and a phagotrophic protist to bacterial communities, which matches the faster leaf litter processing in these treatments. Under low oxic conditions, respiration of all three microbial communities was comparable. Thus, enhanced leaf litter processing in treatments with aquatic bacteria, fungi and phagotrophic protists was presumably caused either by other metabolic pathways such as fermentation and anaerobic respiration, or by changes in community composition and growth efficiency of the microbial community. Microbial communities composed of aquatic bacteria, fungi and phagotrophic protists play a crucial role in leaf litter processing under a range of oxic conditions. Although processing of leaf litter by microbial communities alone is slower than in the presence of shredding invertebrates, the interaction of aquatic bacteria, fungi and phagotrophic protists can modulate leaf quality and subsequen...

show abstract

Aquatic protists modulate the microbial activity associated with mineral surfaces and leaf litter

Cited by 20 publications

References 76 publications

Ecological stoichiometry of aquatic fungi: current knowledge and perspectives

Ecological stoichiometry of aquatic fungi: current knowledge and perspectives

Two microcrustaceans affect microbial and macroinvertebrate‐driven litter breakdown

Phagotrophic protists are a key component of microbial communities processing leaf litter under contrasting oxic conditions

Contact Info

Product

Resources

About