Limitation of lowland riverine bacterioplankton by dissolved organic carbon and inorganic nutrients

Westhorpe, DP; Mitrovic, SM; Ryan, D; Kobayashi, T

Limitation of lowland riverine bacterioplankton by dissolved organic carbon and inorganic nutrients

Westhorpe, DP Mitrovic, SM

Ryan, D Kobayashi, T

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Publication Type:: Journal Article
Citation:: Hydrobiologia, 2010, 652 (1), pp. 101 - 117
Issue Date:: 2010-07-22

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Field	Value	Language
dc.contributor.author	Westhorpe, DP	en_US
dc.contributor.author	Mitrovic, SM https://orcid.org/0000-0002-5528-2215	en_US
dc.contributor.author	Ryan, D	en_US
dc.contributor.author	Kobayashi, T	en_US
dc.date.issued	2010-07-22	en_US
dc.identifier.citation	Hydrobiologia, 2010, 652 (1), pp. 101 - 117	en_US
dc.identifier.issn	0018-8158	en_US
dc.identifier.uri	http://hdl.handle.net/10453/13151
dc.description.abstract	Flow regulation in lowland rivers has reduced the amount of allochthonous dissolved organic carbon (DOC) entering main channels through less frequent wetting of benches, flood runners and floodplains. The hypothesis tested was that lowland riverine bacterioplankton are DOC limited when flow events are absent and simulating an increase in assimilable DOC similar to that expected during an environmental flow will lead to heterotrophic dominance. Experiments took place in the Namoi River, a highly regulated lowland river in Australia. Specifically, in situ microcosms were used to examine the responses of bacterioplankton and phytoplankton to various additions of DOC as glucose or leaf leachate, with and without additions of inorganic nutrients. The results indicated that ambient DOC availability limited the bacterioplankton for the three seasons over which we conducted the experiments. When DOC was added alone, dissolved oxygen concentrations decreased primarily because of increased bacterial respiration and bacterioplankton growth generally increased relative to controls. Additions of DOC alone led to a pattern of decreased chlorophyll a concentration relative to controls, except for willow leachate. Additions of inorganic nutrients alone increased chlorophyll a concentrations above controls, indicating limitation of phytoplankton. These findings support our hypothesis. Based on the present results, environmental flows should increase the duration of allochthonously driven heterotrophic dominance, thus shifting regulated lowland rivers to more natural (pre-regulation) conditions for greater periods. © 2010 Springer Science+Business Media B.V.	en_US
dc.relation.ispartof	Hydrobiologia	en_US
dc.relation.isbasedon	10.1007/s10750-010-0322-8	en_US
dc.subject.classification	Marine Biology & Hydrobiology	en_US
dc.title	Limitation of lowland riverine bacterioplankton by dissolved organic carbon and inorganic nutrients	en_US
dc.type	Journal Article
utslib.citation.volume	1	en_US
utslib.citation.volume	652	en_US
utslib.for	0699 Other Biological Sciences	en_US
utslib.for	04 Earth Sciences	en_US
utslib.for	05 Environmental Sciences	en_US
utslib.for	06 Biological Sciences	en_US
dc.location.activity	ISI:000280087900009	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
utslib.copyright.status	closed_access
pubs.issue	1	en_US
pubs.publication-status	Published	en_US
pubs.volume	652	en_US

Abstract:

Flow regulation in lowland rivers has reduced the amount of allochthonous dissolved organic carbon (DOC) entering main channels through less frequent wetting of benches, flood runners and floodplains. The hypothesis tested was that lowland riverine bacterioplankton are DOC limited when flow events are absent and simulating an increase in assimilable DOC similar to that expected during an environmental flow will lead to heterotrophic dominance. Experiments took place in the Namoi River, a highly regulated lowland river in Australia. Specifically, in situ microcosms were used to examine the responses of bacterioplankton and phytoplankton to various additions of DOC as glucose or leaf leachate, with and without additions of inorganic nutrients. The results indicated that ambient DOC availability limited the bacterioplankton for the three seasons over which we conducted the experiments. When DOC was added alone, dissolved oxygen concentrations decreased primarily because of increased bacterial respiration and bacterioplankton growth generally increased relative to controls. Additions of DOC alone led to a pattern of decreased chlorophyll a concentration relative to controls, except for willow leachate. Additions of inorganic nutrients alone increased chlorophyll a concentrations above controls, indicating limitation of phytoplankton. These findings support our hypothesis. Based on the present results, environmental flows should increase the duration of allochthonously driven heterotrophic dominance, thus shifting regulated lowland rivers to more natural (pre-regulation) conditions for greater periods. © 2010 Springer Science+Business Media B.V.

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http://hdl.handle.net/10453/13151