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Ecology and physiology of bacterial activity in a temperate saltmarsh lagoon, with an emphasis on nitrogen fixation
Heterotrophic bacterial activity and nitrogen fixation are fundamental to nutrient regeneration and nitrogen cycling in saltmarsh ecosystems. Ecological and physiological aspects of bacterial production and nitrogenase activity in marine sediments and water were examined in Langebaan Lagoon, a tempe...
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| Format: | Thesis |
| Language: | English |
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Department of Biological Sciences
2016
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| _version_ | 1867614458523680768 |
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| access_status_str | Open Access |
| author | Tibbles, Brian Jonathan |
| author2 | Lucas, Michael I |
| author_browse | Lucas, Michael I Tibbles, Brian Jonathan |
| author_facet | Lucas, Michael I Tibbles, Brian Jonathan |
| author_sort | Tibbles, Brian Jonathan |
| collection | Thesis |
| description | Heterotrophic bacterial activity and nitrogen fixation are fundamental to nutrient regeneration and nitrogen cycling in saltmarsh ecosystems. Ecological and physiological aspects of bacterial production and nitrogenase activity in marine sediments and water were examined in Langebaan Lagoon, a temperate saltmarsh ecosystem. Emphasis was placed on factors modulating rates and patterns of nitrogen fixation. Nitrogen fixation appeared to be dominated by heterotrophic bacteria. Rates of nitrogen fixation (estimated by the acetylene reduction technique), and bacterial production (estimated by tritiated thymidine incorporation, Tri) were higher in fine, muddy sediments near the head of the lagoon (Geelbek) than in coarser, sandy sediments near the mouth of the lagoon (Oesterwal). These comparisons (between sites) reflected the higher bacterial abundance and organic content of sediments from Geelbek. Examinations of five sedimentary microhabitats at each site (including those associated with beds of the seagrass Zostera capensis, burrows of the sandprawn Callianassa kraussi at Oesterwal, and burrows of the mudprawn Upogebia africana at Geelbek) showed that bacterial activity was higher in surface sediments than in subsurface sediments. Highest rates of nitrogen fixation (annual mean, 0.28 + 0.07 nmol C2H4 g-1 dry sediment h-1) were measured in Zostera bed sediments at Geelbek. Thymidine incorporation activity and nitrogenase activity were higher in burrow linings than in adjacent subsurface sediments, suggesting that burrow linings provided an improved subsurface environment for bacterial activity. Burrow linings also had a higher organic content than subsurface sediments away from burrows. Nitrogenase activity was not detected in lagoon water. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/21512 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:52:22.043Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2016 |
| publishDateRange | 2016 |
| publishDateSort | 2016 |
| publisher | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/21512 Ecology and physiology of bacterial activity in a temperate saltmarsh lagoon, with an emphasis on nitrogen fixation Tibbles, Brian Jonathan Lucas, Michael I Rawlings , Douglas E Branch, George M Zoology Heterotrophic bacterial activity and nitrogen fixation are fundamental to nutrient regeneration and nitrogen cycling in saltmarsh ecosystems. Ecological and physiological aspects of bacterial production and nitrogenase activity in marine sediments and water were examined in Langebaan Lagoon, a temperate saltmarsh ecosystem. Emphasis was placed on factors modulating rates and patterns of nitrogen fixation. Nitrogen fixation appeared to be dominated by heterotrophic bacteria. Rates of nitrogen fixation (estimated by the acetylene reduction technique), and bacterial production (estimated by tritiated thymidine incorporation, Tri) were higher in fine, muddy sediments near the head of the lagoon (Geelbek) than in coarser, sandy sediments near the mouth of the lagoon (Oesterwal). These comparisons (between sites) reflected the higher bacterial abundance and organic content of sediments from Geelbek. Examinations of five sedimentary microhabitats at each site (including those associated with beds of the seagrass Zostera capensis, burrows of the sandprawn Callianassa kraussi at Oesterwal, and burrows of the mudprawn Upogebia africana at Geelbek) showed that bacterial activity was higher in surface sediments than in subsurface sediments. Highest rates of nitrogen fixation (annual mean, 0.28 + 0.07 nmol C2H4 g-1 dry sediment h-1) were measured in Zostera bed sediments at Geelbek. Thymidine incorporation activity and nitrogenase activity were higher in burrow linings than in adjacent subsurface sediments, suggesting that burrow linings provided an improved subsurface environment for bacterial activity. Burrow linings also had a higher organic content than subsurface sediments away from burrows. Nitrogenase activity was not detected in lagoon water. 2016-08-24T12:59:20Z 2016-08-24T12:59:20Z 1994 Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/21512 eng application/pdf Department of Biological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Zoology Tibbles, Brian Jonathan Ecology and physiology of bacterial activity in a temperate saltmarsh lagoon, with an emphasis on nitrogen fixation |
| thesis_degree_str | Doctoral |
| title | Ecology and physiology of bacterial activity in a temperate saltmarsh lagoon, with an emphasis on nitrogen fixation |
| title_full | Ecology and physiology of bacterial activity in a temperate saltmarsh lagoon, with an emphasis on nitrogen fixation |
| title_fullStr | Ecology and physiology of bacterial activity in a temperate saltmarsh lagoon, with an emphasis on nitrogen fixation |
| title_full_unstemmed | Ecology and physiology of bacterial activity in a temperate saltmarsh lagoon, with an emphasis on nitrogen fixation |
| title_short | Ecology and physiology of bacterial activity in a temperate saltmarsh lagoon, with an emphasis on nitrogen fixation |
| title_sort | ecology and physiology of bacterial activity in a temperate saltmarsh lagoon with an emphasis on nitrogen fixation |
| topic | Zoology |
| url | http://hdl.handle.net/11427/21512 |
| work_keys_str_mv | AT tibblesbrianjonathan ecologyandphysiologyofbacterialactivityinatemperatesaltmarshlagoonwithanemphasisonnitrogenfixation |