2021
Hungate, Bruce A.; Marks, Jane C.; Power, Mary E.; Schwartz, Egbert; Groenigen, Kees Jan; Blazewicz, Steven J.; Chuckran, Peter; Dijkstra, Paul; Finley, Brianna K.; Firestone, Mary K.; Foley, Megan; Greenlon, Alex; Hayer, Michaela; Hofmockel, Kirsten S.; Koch, Benjamin J.; Mack, Michelle C.; Mau, Rebecca L.; Miller, Samantha N.; Morrissey, Ember M.; Propster, Jeffrey R.; Purcell, Alicia M.; Sieradzki, Ella; Starr, Evan P.; Stone, Bram W. G.; Terrer, César; Pett-Ridge, Jennifer
The Functional Significance of Bacterial Predators Journal Article
In: mBio, vol. 12, no. e00466-21, 2021.
Abstract | Links | BibTeX | Tags: 18O-H2O, Bdellovibrio, ERCZO, food webs, predator, qSIP, stable isotope probing, top-down control, trophic interactions
@article{Hungate2021,
title = {The Functional Significance of Bacterial Predators},
author = {Bruce A. Hungate and Jane C. Marks and Mary E. Power and Egbert Schwartz and Kees Jan Groenigen and Steven J. Blazewicz and Peter Chuckran and Paul Dijkstra and Brianna K. Finley and Mary K. Firestone and Megan Foley and Alex Greenlon and Michaela Hayer and Kirsten S. Hofmockel and Benjamin J. Koch and Michelle C. Mack and Rebecca L. Mau and Samantha N. Miller and Ember M. Morrissey and Jeffrey R. Propster and Alicia M. Purcell and Ella Sieradzki and Evan P. Starr and Bram W. G. Stone and César Terrer and Jennifer Pett-Ridge},
doi = {10.1128/mBio.00466-21},
year = {2021},
date = {2021-04-27},
urldate = {2021-04-27},
journal = {mBio},
volume = {12},
number = {e00466-21},
abstract = {Predation structures food webs, influences energy flow, and alters rates and pathways of nutrient cycling through ecosystems, effects that are well documented for macroscopic predators. In the microbial world, predatory bacteria are common, yet little is known about their rates of growth and roles in energy flows through microbial food webs, in part because these are difficult to quantify. Here, we show that growth and carbon uptake were higher in predatory bacteria compared to nonpredatory bacteria, a finding across 15 sites, synthesizing 82 experiments and over 100,000 taxon-specific measurements of element flow into newly synthesized bacterial DNA. Obligate predatory bacteria grew 36% faster and assimilated carbon at rates 211% higher than nonpredatory bacteria. These differences were less pronounced for facultative predators (6% higher growth rates, 17% higher carbon assimilation rates), though high growth and carbon assimilation rates were observed for some facultative predators, such as members of the genera Lysobacter and Cytophaga, both capable of gliding motility and wolf-pack hunting behavior. Added carbon substrates disproportionately stimulated growth of obligate predators, with responses 63% higher than those of nonpredators for the Bdellovibrionales and 81% higher for the Vampirovibrionales, whereas responses of facultative predators to substrate addition were no different from those of nonpredators. This finding supports the ecological theory that higher productivity increases predator control of lower trophic levels. These findings also indicate that the functional significance of bacterial predators increases with energy flow and that predatory bacteria influence element flow through microbial food webs.},
keywords = {18O-H2O, Bdellovibrio, ERCZO, food webs, predator, qSIP, stable isotope probing, top-down control, trophic interactions},
pubstate = {published},
tppubtype = {article}
}
Predation structures food webs, influences energy flow, and alters rates and pathways of nutrient cycling through ecosystems, effects that are well documented for macroscopic predators. In the microbial world, predatory bacteria are common, yet little is known about their rates of growth and roles in energy flows through microbial food webs, in part because these are difficult to quantify. Here, we show that growth and carbon uptake were higher in predatory bacteria compared to nonpredatory bacteria, a finding across 15 sites, synthesizing 82 experiments and over 100,000 taxon-specific measurements of element flow into newly synthesized bacterial DNA. Obligate predatory bacteria grew 36% faster and assimilated carbon at rates 211% higher than nonpredatory bacteria. These differences were less pronounced for facultative predators (6% higher growth rates, 17% higher carbon assimilation rates), though high growth and carbon assimilation rates were observed for some facultative predators, such as members of the genera Lysobacter and Cytophaga, both capable of gliding motility and wolf-pack hunting behavior. Added carbon substrates disproportionately stimulated growth of obligate predators, with responses 63% higher than those of nonpredators for the Bdellovibrionales and 81% higher for the Vampirovibrionales, whereas responses of facultative predators to substrate addition were no different from those of nonpredators. This finding supports the ecological theory that higher productivity increases predator control of lower trophic levels. These findings also indicate that the functional significance of bacterial predators increases with energy flow and that predatory bacteria influence element flow through microbial food webs.
2010
Finlay, Jacques C.; Doucett, Richard R.; McNeely, Camille
Tracing energy flow in stream food webs using stable isotopes of hydrogen Journal Article
In: Freshwater Biology, vol. 55, no. 5, pp. 941–951, 2010.
Abstract | Links | BibTeX | Tags: energy flow, food webs, stable isotopes, subsidies, trophic interactions
@article{Finlay2010,
title = {Tracing energy flow in stream food webs using stable isotopes of hydrogen},
author = {Jacques C. Finlay and Richard R. Doucett and Camille McNeely},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Finlay_2010_FreshBio.pdf},
doi = {10.1111/j.1365-2427.2009.02327.x},
year = {2010},
date = {2010-05-01},
journal = {Freshwater Biology},
volume = {55},
number = {5},
pages = {941–951},
abstract = {1. Use of the natural ratios of carbon and nitrogen stable isotopes as tracers of trophic interactions has some clear advantages over alternative methods for food web analyses, yet is limited to situations where organic materials of interest have adequate isotopic separation between potential sources. This constrains the use of natural abundance stable isotope approaches to a subset of ecosystems with biogeochemical conditions favourable to source separation.
2. Recent studies suggest that stable hydrogen isotopes (δD) could provide a robust tracer to distinguish contributions of aquatic and terrestrial production in food webs, but variation in δD of consumers and their organic food sources are poorly known. To explore the utility of the stable hydrogen isotope approach, we examined variation in δD in stream food webs in a forested catchment where variation in δ13C has been described previously.
3. Although algal δD varied by taxa and, to a small degree, between sites, we found consistent and clear separation (by an average of 67‰) from terrestrial carbon sources. Environmental conditions known to affect algal δ13C, such as water velocity and stream productivity did not greatly influence algal δD, and there was no evidence of seasonal variation. In contrast, algal δ13C was strongly affected by environmental factors both within and across sites, was seasonally variable at all sites, and partially overlapped with terrestrial δ13C in all streams with catchment areas larger than 10 km2.
4. While knowledge of isotopic exchange with water and trophic fractionation of δD for aquatic consumers is limited, consistent source separation in streams suggests that δD may provide a complementary food web tracer to δ13C in aquatic food webs. Lack of significant seasonal or spatial variation in δD is a distinct advantage over δ13C for applications in many aquatic ecosystems.},
keywords = {energy flow, food webs, stable isotopes, subsidies, trophic interactions},
pubstate = {published},
tppubtype = {article}
}
1. Use of the natural ratios of carbon and nitrogen stable isotopes as tracers of trophic interactions has some clear advantages over alternative methods for food web analyses, yet is limited to situations where organic materials of interest have adequate isotopic separation between potential sources. This constrains the use of natural abundance stable isotope approaches to a subset of ecosystems with biogeochemical conditions favourable to source separation.
2. Recent studies suggest that stable hydrogen isotopes (δD) could provide a robust tracer to distinguish contributions of aquatic and terrestrial production in food webs, but variation in δD of consumers and their organic food sources are poorly known. To explore the utility of the stable hydrogen isotope approach, we examined variation in δD in stream food webs in a forested catchment where variation in δ13C has been described previously.
3. Although algal δD varied by taxa and, to a small degree, between sites, we found consistent and clear separation (by an average of 67‰) from terrestrial carbon sources. Environmental conditions known to affect algal δ13C, such as water velocity and stream productivity did not greatly influence algal δD, and there was no evidence of seasonal variation. In contrast, algal δ13C was strongly affected by environmental factors both within and across sites, was seasonally variable at all sites, and partially overlapped with terrestrial δ13C in all streams with catchment areas larger than 10 km2.
4. While knowledge of isotopic exchange with water and trophic fractionation of δD for aquatic consumers is limited, consistent source separation in streams suggests that δD may provide a complementary food web tracer to δ13C in aquatic food webs. Lack of significant seasonal or spatial variation in δD is a distinct advantage over δ13C for applications in many aquatic ecosystems.
2. Recent studies suggest that stable hydrogen isotopes (δD) could provide a robust tracer to distinguish contributions of aquatic and terrestrial production in food webs, but variation in δD of consumers and their organic food sources are poorly known. To explore the utility of the stable hydrogen isotope approach, we examined variation in δD in stream food webs in a forested catchment where variation in δ13C has been described previously.
3. Although algal δD varied by taxa and, to a small degree, between sites, we found consistent and clear separation (by an average of 67‰) from terrestrial carbon sources. Environmental conditions known to affect algal δ13C, such as water velocity and stream productivity did not greatly influence algal δD, and there was no evidence of seasonal variation. In contrast, algal δ13C was strongly affected by environmental factors both within and across sites, was seasonally variable at all sites, and partially overlapped with terrestrial δ13C in all streams with catchment areas larger than 10 km2.
4. While knowledge of isotopic exchange with water and trophic fractionation of δD for aquatic consumers is limited, consistent source separation in streams suggests that δD may provide a complementary food web tracer to δ13C in aquatic food webs. Lack of significant seasonal or spatial variation in δD is a distinct advantage over δ13C for applications in many aquatic ecosystems.