Further evidence of elemental composition as an indicator of the bioavailability of humic substances to bacteria

Hunt, A. P.; Parry, Jacqueline D.; Hamilton−Taylor, John

doi:10.4319/lo.2000.45.1.0237

Cited by 81 publications

(59 citation statements)

References 16 publications

(38 reference statements)

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“…The ratio of DOC:DON in soil solution DOM proved to be a good predictor of biodegradable DOM supporting the idea that microbes grow more eYciently on DOM with low C:N ratios (Hunt et al 2000;Wiegner and Seitzinger 2004). We also found a strong negative correlation between BDOC and SUVA 254 , consistent with other studies showing a relationship between aromatic C content and BDOC (Kalbitz et al 2003a;Marschner and Kalbitz 2003;Saadi et al 2006).…”

Section: Indicators Of Biodegradable Docsupporting

confidence: 81%

“…One common approach is to use elemental ratios, such as C:N, H:C or O:C, as an indicator of the biodegradability of DOM (Meyer et al 1987;Hunt et al 2000). Another approach is the use of speciWc UV absorbance (SUVA 254 ), an indicator of aromatic C content, which has been shown to be negatively correlated with BDOC (Kalbitz et al 2003a;Saadi et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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Fluorescence characteristics and biodegradability of dissolved organic matter in forest and wetland soils from coastal temperate watersheds in southeast Alaska

et al. 2008

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Understanding how the concentration and chemical quality of dissolved organic matter (DOM) varies in soils is critical because DOM inXuences an array of biological, chemical, and physical processes. We used PARAFAC modeling of excitation-emission Xuorescence spectroscopy, speciWc UV absorbance (SUVA 254 ) and biodegradable dissolved organic carbon (BDOC) incubations to investigate the chemical quality of DOM in soil water collected from 25 cm piezometers in four diVerent wetland and forest soils: bog, forested wetland, fen and upland forest. There were signiWcant diVerences in soil solution concentrations of dissolved organic C, N, and P, DOC:DON ratios, SUVA 254 and BDOC among the four soil types. Throughout the sampling period, average DOC concentrations in the four soil types ranged from 9-32 mg C l ¡1 and between 23-42% of the DOC was biodegradable. Seasonal patterns in dissolved nutrient concentrations and BDOC were observed in the three wetland types suggesting strong biotic controls over DOM concentrations in wetland soils. PARAFAC modeling of excitation-emission Xuorescence spectroscopy showed that protein-like Xuorescence was positively correlated (r 2 = 0.82; P < 0.001) with BDOC for all soil types taken together. This Wnding indicates that PARAFAC modeling may substantially improve the ability to predict BDOC in natural environments. Coincident measurements of DOM concentrations, BDOC and PARA-FAC modeling conWrmed that the four soil types contain DOM with distinct chemical properties and have unique Xuorescent Wngerprints. DOM inputs to streams from the four soil types therefore have the potential to alter stream biogeochemical processes diVerently by inXuencing temporal patterns in stream heterotrophic productivity.

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Section: Indicators Of Biodegradable Docsupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Fluorescence characteristics and biodegradability of dissolved organic matter in forest and wetland soils from coastal temperate watersheds in southeast Alaska

et al. 2008

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“…Aquatic bacterial metabolism is also affected by the chemical attributes of different DOM sources, including its oxidation state (Vallino et al 1996), molecular weight (Weiss & Simon 1999), humic content (Moran & Hodson 1990), percentage of aliphatic compounds (Sun et al 1997) and the stoichiometric ratios of growth-limiting nutrients (Hunt et al 2000, Castillo et al 2003. Most of the DOM in freshwater and coastal ecosystems originates from DOM in the soils of nearby terrestrial ecosystems (Thurman 1985).…”

Section: Introductionmentioning

confidence: 99%

“…In freshwater ecosystems, bulk DOM concentrations range over 2 orders of magnitude (Mulholland 2003) and can be explained in part by watershed attributes including wetland cover (Engstrom 1987, Gergel et al 1999, soil properties (Nelson et al 1993, McClain et al 1997, drainage area (Rasmussen et al 1989), forest cover (Goodale et al 2000, Canham et al 2004) and hydrology (Hinton et al 1997, Boyer et al 2000. Given the high demand for organic carbon by heterotrophic bacteria (Kirchman & Rich 1997), BP and BR may be expected to increase along increasing DOM concentration gradients.Aquatic bacterial metabolism is also affected by the chemical attributes of different DOM sources, including its oxidation state (Vallino et al 1996), molecular weight (Weiss & Simon 1999), humic content (Moran & Hodson 1990), percentage of aliphatic compounds (Sun et al 1997) and the stoichiometric ratios of growth-limiting nutrients (Hunt et al 2000, Castillo et al 2003. Most of the DOM in freshwater and coastal ecosystems originates from DOM in the soils of nearby terrestrial ecosystems (Thurman 1985).…”

mentioning

confidence: 99%

Source and supply of terrestrial organic matter affects aquatic microbial metabolism

Lennon

Pfaff²

2005

Aquat. Microb. Ecol.

130

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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“…N-fixing plants were chosen because their foliar C:N tends to be low compared with non-N-fixing plants found in Hawai'i (Scowcroft 1997, Hughes andDenslow 2005), and higher bioavailability has been observed for DOC with lower C:N (Sun et al 1997, Hunt et al 2000. Psidium cattleianum fruit was also used to make DOC because they contain simple sugars (Baker et al 1998), which are thought to provide a readily labile source of energy and C to aquatic bacteria (Carlson 1993).…”

Section: Dissolved Organic Carbon Preparationmentioning

confidence: 99%

Comparison of Dissolved Organic Carbon Bioavailability from Native and Invasive Vegetation along a Hawaiian River

Wiegner

Tubal

2010

Pacific Science

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Riparian litter fall is an important source of organic matter to rivers and accounts for a large fraction of their dissolved organic carbon (DOC) load. DOC is metabolically important in rivers, and therefore changes in riparian vegetation species composition should affect riverine DOC bioavailability. Worldwide, invasive vegetation composes a large percentage of riparian vegetation. In Hawai'i, riparian vegetation changes from native to invasive species with decreasing elevation. To assess how changes in riparian vegetation affect riverine DOC dynamics, we compared DOC bioavailability from native (Acacia koa and Metrosideros polymorpha) and invasive (Falcataria moluccana and Psidium cattleianum) riparian trees to freshwater and estuarine bacteria from the Wailuku River on Hawai'i Island through dark bioassays. DOC bioavailabilities in riverine and estuarine waters were similar among all riparian vegetation types. In contrast, vegetation-derived DOC was more bioavailable (52% e 4%) than the riverine and estuarine DOC (14% e 3%). Combining DOC bioavailability and leaf litter input data from our native and invaded riparian sites suggests that a shift in leaf litter inputs from native to invasive species may increase the amount of bioavailable DOC entering Hawaiian rivers and streams. This DOC input has the potential to impact the metabolism and food webs of downstream ecosystems.

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Further evidence of elemental composition as an indicator of the bioavailability of humic substances to bacteria

Cited by 81 publications

References 16 publications

Fluorescence characteristics and biodegradability of dissolved organic matter in forest and wetland soils from coastal temperate watersheds in southeast Alaska

Fluorescence characteristics and biodegradability of dissolved organic matter in forest and wetland soils from coastal temperate watersheds in southeast Alaska

Source and supply of terrestrial organic matter affects aquatic microbial metabolism

Comparison of Dissolved Organic Carbon Bioavailability from Native and Invasive Vegetation along a Hawaiian River

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