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Anoxygenic phototrophic bacteria and aerobic phototrophs in Normans Lagoon, a ‘billabong’ adjacent to the Murray River, south‐eastern Australia
Author(s) -
Gribben Deborah L.,
Rees Gavin N.,
Croome Roger L.
Publication year - 2003
Publication title -
lakes and reservoirs: research and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.296
H-Index - 39
eISSN - 1440-1770
pISSN - 1320-5331
DOI - 10.1046/j.1320-5331.2003.00219.x
Subject(s) - anoxygenic photosynthesis , phototroph , algae , chemocline , biogeochemistry , oceanography , plankton , bacteria , ecology , biology , anoxic waters , botany , geology , paleontology
The development and demise of substantial populations of bacteriochlorophyll (BChl) a and d containing phototrophs are documented within the bottom waters of a billabong (oxbow lake) in south‐eastern Australia. The observation of such populations within a freshwater body is unusual, illustrating an unexpected source of organic carbon within the floodplain ecosystem of one of Australia's principal rivers. Values of up to 1086 µg L −1 BChl a and 490 µg L −1 BChl d were recorded during an 11 month study of physico‐chemical parameters, algae and bacteria. An unusual density stratification was observed within the billabong, fostered by an increase in bivalent ions at depth, and leading to persistent anoxia below 0.75 m depth over summer. A marked vertical distribution was observed for both algae and bacteria, that for the bacteria being lost with a mixing event in late March. The presence of up to 74 µg L −1 BChl a at the surface of the billabong during the summer months is ascribed to entrainment of bacteria within bubble plumes rising from the sediments.