Protists have divergent effects on bacterial diversity along a productivity gradient

Bell, Thomas; Bonsall, Michael B.; Buckling, Angus; Whiteley, Andrew S.; Goodall, Tim; Griffiths, Robert I.

doi:10.1098/rsbl.2010.0027

Cited by 68 publications

(55 citation statements)

References 26 publications

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“…Although differing feeding strategies and food preferences between protists species are known (Jezbera et al, 2005;Bell et al, 2010), predation may be influenced not only by various prey characteristics but also by the environmental or experimental context (Bruno and O'Connor, 2005). Overall, the positive bottom-up effect of prey richness on predator production is in line with the balanced diet hypothesis, which assumes that predators benefit nutritionally from a diverse resource pool as prey mixtures better satisfy the nutritional requirements of predators than individual prey species (DeMott, 1998;Gamfeldt et al, 2005).…”

Section: Discussionsupporting

confidence: 53%

“…Finally, we estimated the feeding preferences (specialist vs generalist) of the investigated predators ( Figure 5). For this, we regressed relative abundance of bacteria in the presence vs absence of different predators in microcosms ( Figure 5; Bell et al, 2010). We took a diagonal with slope of 1 and intercept zero as a reference (no-effect model).…”

Section: Statistical Analysesmentioning

confidence: 99%

“…Similar to food web modules composed of larger organisms, topdown control by protistan predators regulates bacterial abundance, community composition and, consequently, has an influence on many microbial ecosystem processes (Simek et al, 1997;Pernthaler, 2005;Corno and Jü rgens, 2008;Rosenberg et al, 2009;Bell et al, 2010;Glü cksman et al, 2010). Although direct influences of top-down control of bacterial communities by protists have been studied earlier (for example, Bell et al, 2010;Roberts et al, 2011;Martinez-Garcia et al, 2012), relatively little is known about direct mutual effects of species richness on community structures and performances of the prey or predator communities, respectively. Ecological theory has long predicted that prey richness determines the performance of consumer species and affects the strength of top-down control (DeMott, 1998;Gamfeldt et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Diversity of protists and bacteria determines predation performance and stability

et al. 2013

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Predation influences prey diversity and productivity while it effectuates the flux and reallocation of organic nutrients into biomass at higher trophic levels. However, it is unknown how bacterivorous protists are influenced by the diversity of their bacterial prey. Using 456 microcosms, in which different bacterial mixtures with equal initial cell numbers were exposed to single or multiple predators (Tetrahymena sp., Poterioochromonas sp. and Acanthamoeba sp.), we showed that increasing prey richness enhanced production of single predators. The extent of the response depended, however, on predator identity. Bacterial prey richness had a stabilizing effect on predator performance in that it reduced variability in predator production. Further, prey richness tended to enhance predator evenness in the predation experiment including all three protists predators (multiple predation experiment). However, we also observed a negative relationship between prey richness and predator production in multiple predation experiments. Mathematical analysis of potential ecological mechanisms of positive predator diversity-functioning relationships revealed predator complementarity as a factor responsible for both enhanced predator production and prey reduction. We suggest that the diversity at both trophic levels interactively determines protistan performance and might have implications in microbial ecosystem processes and services.

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Section: Discussionsupporting

confidence: 53%

Section: Statistical Analysesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Diversity of protists and bacteria determines predation performance and stability

et al. 2013

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“…The significance of predation on bacterial activity and community structure in natural aquatic systems has been demonstrated (10,(37)(38)(39)(40). Consequently, effort is currently placed on understanding the details and dynamics of grazing by protists (11).…”

Section: Discussionmentioning

confidence: 99%

Some Mixotrophic Flagellate Species Selectively Graze on Archaea

Ballen-Segura

Felip

Catalan

2017

Appl Environ Microbiol

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Many phototrophic flagellates ingest prokaryotes. This mixotrophic trait becomes a critical aspect of the microbial loop in planktonic food webs because of the typical high abundance of these flagellates. Our knowledge of their selective feeding upon different groups of prokaryotes, particularly under field conditions, is still quite limited. In this study, we investigated the feeding behavior of three species (Rhodomonas sp., Cryptomonas ovata, and Dinobryon cylindricum) via their food vacuole content in field populations of a high mountain lake. We used the catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH) protocol with probes specific for the domain Archaea and three groups of Eubacteria: Betaproteobacteria, Actinobacteria, and Cytophaga-Flavobacteria of Bacteroidetes. Our results provide field evidence that contrasting selective feeding exists between coexisting mixotrophic flagellates under the same environmental conditions and that some prokaryotic groups may be preferentially impacted by phagotrophic pressure in aquatic microbial food webs. In our study, Archaea were the preferred prey, chiefly in the case of Rhodomonas sp., which rarely fed on any other prokaryotic group. In general, prey selection did not relate to prey size among the grazed groups. However, Actinobacteria, which were clearly avoided, mostly showed a size of Ͻ0.5 m, markedly smaller than cells from the other groups.IMPORTANCE That mixotrophic flagellates are not randomly feeding in the main prokaryotic groups under field conditions is a pioneer finding in species-specific behavior that paves the way for future studies according to this new paradigm. The particular case that Archaea were preferentially affected in the situation studied shows that phagotrophic pressure cannot be disregarded when considering the distribution of this group in freshwater oligotrophic systems.KEYWORDS Archaea, mixotrophic protist, selective feeding M ixotrophic behavior, the combination of phototrophic and phagotrophic nutritional modes within a single cell, has been increasingly documented in aquatic systems (1, 2). Phagotrophy occurs in a variety of phytoplankton flagellate groups, including Chrysophyceae, dinoflagellates, prymnesiophytes, and cryptophytes, which comprise some picoeukaryotes (3-5). Currently, there is no doubt of the ubiquity of mixotrophy and its significance in the functioning of planktonic systems. Under oligotrophic conditions, phototrophic flagellates can account for up to 80% of total bacterial grazing (4,6,7).Predation by protists is among the primary mortality factors of prokaryotes in planktonic communities and thus is an important selective pressure. It becomes a structuring factor of the abundance, morphology, composition, and activity of bacterial assemblages (8, 9). The impact of protist predation appears to be modulated by the characteristics of the system (e.g., productivity) and predator and prey traits (10). Over

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“…Several studies have recognised that protozoan grazing is an important controlling and modifier factor of bacterial populations and communities, capable of causing direct impacts on their production and biomass, as well as changes on their structure, morphology, physiology, taxonomy (e.g. Corno et al, 2008) and diversity (Bell et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

The importance of protozoan bacterivory in a subtropical environment (Lobo-Broa Reservoir, SP, Brazil)

et al. 2014

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This study evaluated the importance of heterotrophic nanoflagellates (HNF) and ciliates bacterivory in a mesotrophic subtropical environment (Lobo-Broa Reservoir, Brazil) by the quantification of their ingestion rates. The in situ experiments using fluorescently labelled bacteria (FLB) were carried out bimonthly over one year (three surveys in the dry season and three in the rainy one) at the sub-surface of two sampling points that have different trophic degrees. The ingestion rates for both ciliates and HNF were higher in the meso-eutrophic region (point 2) due to the higher water temperatures, which accelerate the metabolism of protozoans and the higher bacteria densities. Concerning total protozoan bacterivory, the HNF had the greatest grazing impact on bacterial community, especially the HNF <5µm. The data showed that HNF grazing, in addition to regulating the bacteria abundance, also induced changes to the bacterial community structure, such as increasing size and numbers of bacterial filaments. The ciliates were also important to the system bacterivory, especially in point 2, where there were high densities and ingestion rates. The protozoan bottom-up control was more important in the dry season and the top-down control was more important in the rainy season, so, these two forces are equally important to the bacterial abundance regulation in this reservoir in an annual basis.Keywords: grazing, bacteria, nanoflagellates, ciliates, mesotrophic.A importância da bacterivoria por protozoários em um ambiente subtropical (Reservatório do Lobo-Broa, SP, Brasil) ResumoEste estudo avaliou a importância da bacterivoria por nanoflagelados heterotróficos (NFH) e ciliados em um ambiente subtropical mesotrófico (Reservatório do Lobo-Broa, Brasil) pela quantificação de suas taxas de ingestão. Os experimentos in situ utilizando bactérias marcadas por fluorescência (FLB) foram realizados bimestralmente durante um ano (três estudos no período seco e três no período chuvoso) na superfície de dois pontos de coleta que apresentam graus de trofia diferentes. As taxas de ingestão, tanto para os ciliados quanto para os NHF, foram maiores no ponto 2 (P2) devido provavelmente as maiores temperaturas da água, que aceleram o metabolismo dos protozoários, e as maiores densidades de bactérias. Em relação à bacterivoria total por protozoários, as populações de NFH causaram maior impacto de predação sobre a comunidade bacteriana do reservatório, principalmente os NFH menores que 5µm. Os dados indicaram que a predação por NFH, além de regular a abundância de bactérias, provavelmente também induziu modificações na estrutura da comunidade bacteriana, como o aumento do tamanho e da quantidade de filamentos bacterianos. Os ciliados também contribuíram significativamente para a bacterivoria no sistema, principalmente no P2, onde apresentaram altas densidades e taxas de ingestão. O controle bottom-up teve maior importância no período seco e o controle top-down maior importância no período chuvoso, assim, estas duas forças são igualmente...

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Protists have divergent effects on bacterial diversity along a productivity gradient

Cited by 68 publications

References 26 publications

Diversity of protists and bacteria determines predation performance and stability

Diversity of protists and bacteria determines predation performance and stability

Some Mixotrophic Flagellate Species Selectively Graze on Archaea

The importance of protozoan bacterivory in a subtropical environment (Lobo-Broa Reservoir, SP, Brazil)

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