Wastewater Treatment Plant Effluents Change Abundance and Composition of Ammonia-Oxidizing Microorganisms in Mediterranean Urban Stream Biofilms

Merbt, Stephanie N.; Auguet, Jean‐Christophe; Blesa, Alba; Martı́, Eugènia; Casamayor, Emilio O.

doi:10.1007/s00248-014-0464-8

Cited by 48 publications

(48 citation statements)

References 36 publications

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“…An alternative explanation is that the enrichment of NH 4 ? can favor the development of nitrifiers, which is supported by results from previous studies (Bernhardt and Likens 2004;Merbt et al 2015). Nitrifying microorganisms have lower growth efficiencies compared to other microbial components of the biofilms (Risgaard-Petersen et al 2004) and they also have a preferential demand for NH 4…”

supporting

confidence: 74%

Biofilm growth and nitrogen uptake responses to increases in nitrate and ammonium availability

et al. 2015

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Nitrate (NO 3 -) and ammonium (NH 4 ? ) are the two major dissolved inorganic nitrogen (DIN) species available in streams. Human activities increase stream DIN concentrations and modify the NO 3 -:NH 4 ? ratio. However, few studies have examined biofilm responses to enrichment of both DIN species. We examined biofilm responses to variation in ambient concentrations and enrichments in either NO 3 -or NH 4 ? . We incubated nutrient diffusing substrata (NDS) bioassays with three treatments (DIN-free, ?NO 3 -and ?NH 4 ? ) in five streams. Biomass-specific uptake rates (U spec ) of NO 3 -and NH 4? were then measured using in situ additions of 15 N-labeled NO 3 -and NH 4 ? . Biomass (estimated from changes in carbon content) and algal accrual rates, as well as U spec -NO 3 -of biofilms in DIN-free treatments varied among the streams in which the NDS had been incubated. Higher ambient DIN concentrations were only correlated with enhanced biofilm growth rates. U spec -NO 3 -was one order of magnitude greater and more variable than U spec -NH 4 ? , however similar relative preference index (RPI) suggested that biofilms did not show a clear preference for either DIN species. Biofilm growth and DIN uptake in DIN-amended NDS (i.e., ?NO 3 -and ?NH 4 ? ) were consistently lower than in DIN-free NDS (i.e., control). Lower values in controls with respect to amended NDS were consistently more pronounced for algal accrual rates and U spec -NO 3 -and for the ?NH 4? than for the ?NO 3 -treatments. In particular, enrichment with NH 4 ? reduced biofilm U spec -NO 3 -uptake, which has important implications for N cycling in high NH 4 ? streams.

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confidence: 74%

Biofilm growth and nitrogen uptake responses to increases in nitrate and ammonium availability

et al. 2015

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“…In fact, a similar mechanism has been proposed to explain sustained photoautotrophic activity under high irradiance in streams (Boston and Hill ; Guasch and Sabater ). In this line of thought, previous investigations carried out in the same stream sites showed Nitrosotalea devanaterra ‐like as dominant AOA in both, light‐side and dark‐side biofilms (Merbt et al ), a species strongly inhibited by light in experiments carried out in cultures (Merbt et al ). This fact suggests that light avoidance was the most likely strategy to overcome photoinhibition in natural biofilms.…”

Section: Discussionmentioning

confidence: 63%

“…). However, despite large differences in light availability and abundance of photoautotrophs, light‐side and dark‐side biofilms from a given location hosted similar AOA community composition (Merbt et al ). Based on these findings, we assumed that differences observed during incubation experiments between biofilms from the two sides of the cobbles for a given location were related to their physiological response to light conditions rather than to differences in the composition of AO communities.…”

Section: Methodsmentioning

confidence: 99%

Photoinhibition on natural ammonia oxidizers biofilm populations and implications for nitrogen uptake in stream biofilms

Merbt

Bernal

Proia

et al. 2016

Limnology & Oceanography

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We investigated photoinhibition on natural communities of ammonia oxidizing (AO) archaea (AOA) and bacteria (AOB) embedded in complex stream biofilms, and its implications on nitrogen uptake at biofilm scale. Based on the strong photoinhibition previously exhibited by free living and cultured AOA and AOB, we expected AO activity to decrease in biofilms experimentally exposed to light, reducing the contribution of microbial nitrification to ammonium uptake. To test it, we conducted light manipulation experiments in mesocosms using biofilms naturally developed on stream cobbles sides both exposed to light (light‐side) and facing the sediment (dark‐side). We observed a strong AO photoinhibition in dark‐side biofilms, accompanied by either biofilm‐scale decreases in nitrification or increases in nitrogen uptake likely by heterotrophic activity. Conversely, in light‐side biofilms photoinhibition was not observed suggesting that photoautotrophic layers may protect AO in situ by a sunshade effect. Experimental light and dark alternation cycles stimulated AO, enhancing both nitrification and ammonium uptake. These results support photoinhibition effects on natural AO communities, especially in biofilms developed under ambient dark conditions, whereas this effect seems to be buffered in biofilms developed under light conditions. Therefore, the contribution of nitrification to ammonium uptake at biofilm scale should consider not only the physiological study of AOA and AOB, but also the environmental conditions and community structure at the habitat microscale, since they may counterbalance, among others, the damaging light effects under natural conditions.

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“…Studies addressing the effect of flow intermittency on archaeal communities are scarce compared to those with bacteria, and this can be taken as an indication that Archaea constitute a minor component of streambed microbial communities. Even in permanent rivers and streams Bacteria outnumber Archaea in all streambed compartments (Battin et al, 2001;Herrmann et al, 2011;Merbt et al, 2011Merbt et al, , 2015Buriánková et al, 2013), but is also true that Archaea occur in arid soils, microbial mats and freshwater sediments exposed to desiccation (Rothrock and (Rothrock and Garcia-Pichel, 2005;Soule et al, 2009;Timonen and Bomberg, 2009;Conrad et al, 2014). Despite this information, no conclusive data on the ecological function of the Archaea in streambeds are available.…”

Section: Structural Changes and Adaptations Of Biofilms To Dry And Wementioning

confidence: 88%

“…Despite this information, no conclusive data on the ecological function of the Archaea in streambeds are available. Some studies have identified either methanogenic groups (Buriánková et al, 2013;Mach et al, 2015) or molecular signatures of ammonia oxidizing archaea (AOA; Merbt et al, 2011Merbt et al, , 2015 suggesting a relevant but not yet resolved contribution to C and N cycles, respectively. AOA are abundant in soils, where they play an outstanding role in nitrification (Stahl and de la Torre, 2012), but are less resistant to desiccation than ammonia oxidizing bacteria and less resilient to flow return, when ammonium concentrations are high (Thion and Prosser, 2014).…”

Section: Structural Changes and Adaptations Of Biofilms To Dry And Wementioning

confidence: 99%

Stream Biofilm Responses to Flow Intermittency: From Cells to Ecosystems

Sabater

Timoner

Borrego

et al. 2016

Front. Environ. Sci.

107

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Temporary streams are characterized by the alternation of dry and wet hydrological phases, creating both a harsh environment for the biota as well as a high diversity of opportunities for adaptation. These systems are mainly microbial-based during several of these hydrological phases, and those growing on all solid substrata (biofilms) accordingly change their physical structure and community composition. Biofilms experience large decreases in cell densities and biomass, both of bacteria and algae, during dryness. Algal and bacterial communities show remarkable decreases in their diversity, at least locally (at the habitat scale). Biofilms also respond with significant physiological plasticity to each of the hydrological changes. The decreasing humidity of the substrata through the drying process, and the changing quantity and quality of organic matter and nutrients available in the stream during that process, causes unequal responses on the biofilm bacteria and algae. Biofilm algae are affected faster than bacteria by the hydric stress, and as a result the ecosystem respiration resists longer than gross primary production to the increasing duration of flow intermittency. This response implies enhancing ecosystem heterotrophy, a pattern that can be exacerbated in temporary streams suffering of longer dry periods under global change.Keywords: biofilm, dry-rewetting cycle, temporary, intermittency, bacteria, algae, Mediterranean THE RELEVANCE OF TEMPORARY STREAMS IN THE WORLDFlow intermittency is part of the natural hydrology for streams and rivers, especially in arid and semi-arid landscapes. Temporary streams, or those that cease to flow at some points in space and time along their course, are a large fraction of many river networks, basically in tributaries of small order, but also in segments in the middle and lower parts of river networks. The number of temporary streams has been probably underestimated , as it appears from the application of novel on-site sensors, advances in remote sensing, and new modeling approaches. Flow intermittency has been estimated to account for 69% of first-order streams below 60 • , and up to 34% of larger order rivers (Raymond et al., 2013). Flow intermittency produces periodic or eventrelated loss of hydrologic connectivity between stream compartments, with consequences for all the processes ongoing in a waterway. Thus, flow intermittency triggers a chain of cascading effects eventually affecting water chemistry and biogeochemistry, as well as biodiversity, and ultimately community structure and ecosystem functioning.The direct implications of climate change and anomalous climatic events on flow regime are behind of the increasing temporality of many streams and rivers. Complex planetary scale processes, as well as local processes, may justify these situations. Anomalies such as the El Niño

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Wastewater Treatment Plant Effluents Change Abundance and Composition of Ammonia-Oxidizing Microorganisms in Mediterranean Urban Stream Biofilms

Cited by 48 publications

References 36 publications

Biofilm growth and nitrogen uptake responses to increases in nitrate and ammonium availability

Biofilm growth and nitrogen uptake responses to increases in nitrate and ammonium availability

Photoinhibition on natural ammonia oxidizers biofilm populations and implications for nitrogen uptake in stream biofilms

Stream Biofilm Responses to Flow Intermittency: From Cells to Ecosystems

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