Sestonic bacterial nutrient limitation in a northern temperate river and the impact of pulp-mill effluents

Mohamed, Mohamed N.; Robarts, Richard D.

doi:10.3354/ame033019

Cited by 7 publications

(2 citation statements)

References 28 publications

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“…Bacterial production was also synchronous between the two rivers, probably as a result of synchrony in the environmental factors thought to influence aquatic bacterial growth. Across a range of systems, bacterial production can be predicted with measurements of organic carbon supply or concentration (Cole et al 1988) and is influenced by phytoplankton production, allochthonous organic matter (Findlay et al 1991), temperature (Findlay et al 1991), and nutrient concentration (Mohamed and Robarts 2003). In our study, temperature and all measurements of organic matter and nutrients were correlated between the two rivers, and bacterial production responded to these factors in the same way in both systems.…”

Section: Discussionmentioning

confidence: 61%

Synchrony and seasonality in bacterioplankton communities of two temperate rivers

2005

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The bacterioplankton community composition (measured with denaturing gradient gel electrophoresis of 16S ribosomal DNA [rDNA]) of two nonintersecting temperate rivers was nearly identical and changed synchronously over 2.5 yr, suggesting that intrinsic controls on bacteria were similar in the two rivers and that seasonal changes were driven by extrinsic factors such as climate. Most potential controls on community composition also exhibited synchrony; these included bacterial production rate (leucine incorporation), water temperature, river flow rate, and a suite of chemical measurements. Temperature and river flow rate were the best predictors of temporal patterns in diversity. However, diversity patterns also correlated with bacterial production and concentrations of dissolved organic nitrogen and nitrate, suggesting that diversity is directly or indirectly influenced by complex seasonal shifts in environmental conditions. Winter and summer communities were somewhat predictable over 3 yr, although these communities were not identical. Two polymerase chain reaction (PCR)-amplified clone libraries of 16S rDNA, constructed with summer samples from each river, were not significantly different and contained typical freshwater bacterioplankton of the beta-Proteobacteria, Bacteroidetes, and Actinobacteria, including members of five new freshwater bacterioplankton clusters. However, libraries also included several phylotypes related to bacteria from soil and sediment, indicating the potential importance of allochthonous organisms in river diversity.

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Section: Discussionmentioning

confidence: 61%

Synchrony and seasonality in bacterioplankton communities of two temperate rivers

2005

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“…Different bacterial species have different cellular stoichiometric needs (Makino et al 2003), and many bacteria are phosphorus limited due to their low C:P and N:P cellular ratios and the abundance of large carbon compounds in many freshwater environments (Mohamed and Robarts 2003;Cross et al 2005). This suggests that bacterial community structure may shift in ways that allow for the most efficient use of the nutrient supply, i.e., bacteria whose cellular needs match the nutrient supply may become more abundant while other species are reduced in number.…”

Section: Introductionmentioning

confidence: 98%

Planktonic Bacterial Responses to Nutrient Amendments in Wetland Mesocosms

Barlett

Leff

2010

Wetlands

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Although bacteria are important in the processing of anthropogenic nutrient inputs to wetlands, the effects of nutrient type and stoichiometry on bacterial communities have rarely been studied in natural systems. In this study, mesocosm enclosures were constructed in wetland pools at the Herrick Aquatic Ecology Research Facility at Kent State University (Kent, OH, USA) and amended with nutrients. Several experiments were conducted using various inorganic and organic nutrient sources (nitrate, ammonium, amino acids, phosphate, glucose-6-phosphate) as well as low, medium, and high N:P molar ratios. Structure of planktonic bacterial communities was determined using fluorescent in situ hybridization and denaturing gradient gel electrophoresis (DGGE) targeting Domain Bacteria and beta-proteobacteria. Abundances of Domain Bacteria, as well as other taxa examined (alpha-, beta-, and gamma-proteobacteria and the Cytophaga-Flavobacteria cluster), did not change in response to N:P ratios or nutrient amendments. However, Domain Bacteria, alphaproteobacteria, and Cytophaga-Flavobacteria abundances varied among dates. DGGE clusters also contained communities collected on the same date, suggesting that temporal changes rather than nutrient amendments were the most important factor determining community composition. Overall, although some community changes appeared to be related to the nutrient amendments, temporal factors were a more important mediator of community structure.

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Nutrients and Other Abiotic Factors Affecting Bacterial Communities in an Ohio River (USA)

Rubin

Leff

2007

Microb Ecol

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Nitrogen and phosphorus additions from anthropogenic sources can alter the nutrient pool of aquatic systems, both through increased nutrient concentrations and changes in stoichiometry. Because bacteria are important in nutrient cycling and aquatic food webs, information about how nutrients affect bacterial communities enhances our understanding of how changes in nutrient concentrations and stoichiometry potentially affect aquatic ecosystems as a whole. In this study, bacterial communities were examined in biofilms from cobbles collected across seasons at three sites along the Mahoning River (Ohio) with differing levels of inorganic nutrient inputs. Members of the alpha-, beta-, and gamma-proteobacteria, the Cytophaga-Flavobacteria cluster, and the Domain Bacteria were enumerated using fluorescent in situ hybridization. Detrended canonical correspondence analysis (DCCA) revealed that stoichiometric ratios, especially the dissolved inorganic nitrogen (DIN):soluble reactive phosphorus (SRP) molar ratio (NO(2)/NO(3) + NH(4):soluble reactive phosphorus), were correlated with abundance of the various bacterial taxa. However, the patterns were complicated by correlations with single nutrient concentrations and seasonal changes in temperature. Seasonal cycles appeared to play an important role in structuring the community, as there were distinct winter communities and temperature was negatively correlated with abundance of both alpha-proteobacteria and Cytophaga-Flavobacteria. However, nutrients and stoichiometry also appeared to affect the community. Numbers of cells hybridizing the Domain Bacteria probe were correlated with the DOC:DIN ratio, the beta-proteobacteria had a negative correlation with soluble reactive phosphorus concentrations and a positive correlation with the DIN:SRP ratio, and the Cytophaga-Flavobacteria had a significant negative partial correlation with the DIN:SRP ratio. Abundances of the alpha- or gamma-proteobacteria were not directly correlated to nutrient concentrations or stoichiometry. It appears that nutrient stoichiometry may be an important factor structuring bacterial communities; however, it is one of many factors, such as temperature, that are interlinked and must be considered together when studying environmental bacteria.

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Sestonic bacterial nutrient limitation in a northern temperate river and the impact of pulp-mill effluents

Cited by 7 publications

References 28 publications

Synchrony and seasonality in bacterioplankton communities of two temperate rivers

Synchrony and seasonality in bacterioplankton communities of two temperate rivers

Planktonic Bacterial Responses to Nutrient Amendments in Wetland Mesocosms

Nutrients and Other Abiotic Factors Affecting Bacterial Communities in an Ohio River (USA)

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