Original Articles: Sources of Dissolved Organic Carbon Supporting Planktonic Bacterial Production in the Tidal Freshwater Hudson River

Findlay, Stuart E. G.; Sinsabaugh, Robert L.; Fischer, David; Franchini, Paula

doi:10.1007/s100219900018

Cited by 73 publications

(45 citation statements)

References 33 publications

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“…This assumption overestimates the actual bacterial respiration and thus provides a conservative estimate of the BGE (Table 5). In the literature, the fraction of the community respiration that bacteria contribute ranges from 11% to 100% (Findlay et al 1992; del Giorgio and Cole 2000; Warkentin et al 2007). Our measurements and assumptions yielded BGE values of 0.60 and 0.46 for the dry and wet seasons, respectively (Table 3).…”

Section: Discussionmentioning

confidence: 99%

“…These declines are a function of dilution, residence time, and the supply of DOC; and they are linked to variations in microbial metabolism, at least in temperate studies (Sobczak and Findlay 2002). Terrestrial DOC entering an aquatic freshwater ecosystem can be rapidly respired, with most of the water column respiration associated with aerobic heterotrophic bacterial metabolism (Findlay et al 1998) even if the DOC has persisted in the terrestrial environment for many years (Cole and Caraco 2001). As the DOC moves downstream it supports bacterial respiration, growth, and production, connecting the river with a reservoir of DOC and generating CO 2 to become an active part of the global carbon cycle ).…”

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confidence: 99%

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Ultrahigh bacterial production in a eutrophic subtropical Australian river: Does viral lysis short‐circuit the microbial loop?

Pollard

Ducklow

2011

Limnology & Oceanography

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We studied trophic dynamics in a warm eutrophic subtropical river (Bremer River, Australia) to determine potential sources of dissolved organic carbon (DOC) and the fate of heterotrophic bacterial production. Sustained high rates of bacterial production suggested that the exogenous DOC was accessible (labile). Bacterial specific growth rates (0.2 h 21 to 1.8 h 21 ) were some of the highest measured for natural aquatic ecosystems, which is consistent with high respiration rates. Bacteria consumed 10 times more organic carbon than that supplied by the daily algal production, a result that implies that terrestrial sources of organic carbon were driving the high rates of bacterial production. Viruses (10 11 L 21 ) were 10 times more abundant than bacteria; the viral to bacterial ratio ranged from 3.5 to 12 in the wet summer and 11 to 35 in the dry spring weather typical of eutrophic environments. Through a combination of high bacterial respiration and phage lysis, a continuous supply of terrestrial DOC was lost from the aquatic ecosystem in a CO 2 -vented bacterial-viral loop. Bacterial processing of DOC in subtropical rivers may be contributing disproportionately large amounts of CO 2 to the global carbon cycle compared to temperate freshwater ecosystems.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Ultrahigh bacterial production in a eutrophic subtropical Australian river: Does viral lysis short‐circuit the microbial loop?

Pollard

Ducklow

2011

Limnology & Oceanography

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“…Terrestrial ecosystems export large quantities of DOM to inland, estuarine and coastal marine waterbodies (Goni et al 1997, Findlay et al 1998, Neff & Asner 2001. However, terrestrial-derived DOM has traditionally been considered a poor-quality resource for aquatic bacteria because it is relatively old (Raymond & Bauer 2001) and comprises humic compounds with low nutritional content (McKnight & Aiken 1998).…”

Section: Introductionmentioning

confidence: 99%

Source and supply of terrestrial organic matter affects aquatic microbial metabolism

Lennon

Pfaff²

2005

Aquat. Microb. Ecol.

134

118

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Aquatic ecosystems are connected to their surrounding watersheds through inputs of terrestrial-derived dissolved organic matter (DOM). The assimilation of this allochthonous resource by recipient bacterioplankton has consequences for food webs and the biogeochemistry of aquatic ecosystems. We used laboratory batch experiments to examine how variation in the source and supply (i.e. concentration) of DOM affects the productivity, respiration and growth efficiency of heterotrophic lake bacterioplankton. We created 6 different DOM sources from soils beneath nearmonotypic tree stands in a temperate deciduous-coniferous forest. We then exposed freshwater microcosms containing a natural microbial community to a 1100 µM supply gradient of each DOM source. Bacterial productivity (BP) and bacterial respiration (BR) increased linearly over the broad gradient, on average consuming 7% of the standing pool of dissolved organic carbon (DOC). Bacterial metabolism was also influenced by the chemical composition of the DOM source. Carbon-specific productivity declined exponentially with an increase in the carbon:phosphorus (C:P) ratio of the different DOM sources, consistent with the predictions of ecological stoichiometry. Together, our shortterm laboratory experiments quantitatively describe the metabolic responses of freshwater bacterioplankton to variation in the supply of terrestrial-derived DOM. Furthermore, our results suggest that dissolved organic phosphorus (DOP) content, which may be linked to the identity of terrestrial vegetation, is indicative of DOM quality and influences the productivity of freshwater bacterioplankton.KEY WORDS: Allochthonous · Bacteria · DOC · DOM · Ecosystem · Plankton · Stoichiometry · Subsidy Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 39: [107][108][109][110][111][112][113][114][115][116][117][118][119] 2005 decoupled from local primary productivity. One potential explanation for this decoupling is that bacterial carbon demand is subsidized by terrestrial-derived DOM.Terrestrial ecosystems export large quantities of DOM to inland, estuarine and coastal marine waterbodies (Goni et al. 1997, Findlay et al. 1998, Neff & Asner 2001. However, terrestrial-derived DOM has traditionally been considered a poor-quality resource for aquatic bacteria because it is relatively old (Raymond & Bauer 2001) and comprises humic compounds with low nutritional content (McKnight & Aiken 1998). Nevertheless, a few lines of evidence indicate that bacterial metabolism may be supported to varying degrees by inputs of terrestrial DOM. First, numerous laboratory studies have directly demonstrated that aquatic bacteria grow on terrestrial fractions of DOM (Tranvik 1988, Bano et al. 1997, Moran & Hodson 1994. Second, as lake DOM concentrations increase, community respiration tends to exceed local primary productivity (Hanson et al. 2003), suggesting that allochthonous carbon may be consumed by heterotrophic bacteria. Third, experimental isotope-enrichment of...

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“…Most of the CO2 emitted from freshwaters in temperate regions due to respiration is the result of heterotrophic bacterial metabolism (Findlay et al 1998) and recent studies have demonstrated the importance of DOC source and quality for influencing rates of bacterial metabolism (Berggren & del Giorgio, 2015). DOC is also consumed by biofilms (Meyer et al 1987), which are a complex mixture of algae, bacteria, micro-fauna and exopolysaccharides that reside on bed sediments.…”

Section: Introductionmentioning

confidence: 99%

Transformations in DOC along a source to sea continuum; impacts of photo-degradation, biological processes and mixing

Jones¹,

Evans

Jones³

et al. 2015

Aquat Sci

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Original Articles: Sources of Dissolved Organic Carbon Supporting Planktonic Bacterial Production in the Tidal Freshwater Hudson River

Cited by 73 publications

References 33 publications

Ultrahigh bacterial production in a eutrophic subtropical Australian river: Does viral lysis short‐circuit the microbial loop?

Ultrahigh bacterial production in a eutrophic subtropical Australian river: Does viral lysis short‐circuit the microbial loop?

Source and supply of terrestrial organic matter affects aquatic microbial metabolism

Transformations in DOC along a source to sea continuum; impacts of photo-degradation, biological processes and mixing

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