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Holocene foraminifera as indicators of relative estuarine-lagoonal and oceanic influences in estuarine sediments of the River Murray, South Australia

Journal Article


Abstract


  • In southeastern South Australia, the River Murray debouches through a coastal barrier separating euryhaline estuarine-lagoonal waters from the Southern Ocean. Depending upon the relative freshwater outflow of the river and ingress of the ocean, water salinity varies greatly within the lower estuary. Ammonia beccarii and Elphidium articulatum are euryhaline species of foraminifera that characterize the estuary and back-barrier Coorang Lagoon. The inner-shelf marine environment hosts an assemblage in which Discorbis dimidiatus, E. crispum, E. macelliforme, and various cibicidid species predominate. In cored sediments recovered from the shallow lower estuary, the relative abundance of A. beccarii + E. articulatum was compared with that of D. dimidiatus + E. crispum + E. macelliforme + other species. These data, and AMS radiocarbon ages determined for foraminifera and ostracods, provide evidence of a change from maximum oceanic influence (5255 �� 60 yr B.P.) to maximum estuarine influence (3605 �� 70 yr B.P.). Over this same time interval, sea level fell relatively by about 2 m. However, the event was also contemporaneous with falling water levels in several Victorian lakes, and it is thus attributed to onset of climatic aridity. Reduced precipitation in the River Murray catchment and reduced freshwater outflow enhanced development of the flood-tide delta and constriction of the mouth. (C) 2000 University of Washington.

UOW Authors


  •   Bourman, Bob P. (external author)

Publication Date


  • 2000

Citation


  • Cann, J. H., Bourman, R. P., & Barnett, E. J. (2000). Holocene foraminifera as indicators of relative estuarine-lagoonal and oceanic influences in estuarine sediments of the River Murray, South Australia. Quaternary Research, 53(3), 378-391. doi:10.1006/qres.2000.2129

Scopus Eid


  • 2-s2.0-0034119274

Start Page


  • 378

End Page


  • 391

Volume


  • 53

Issue


  • 3

Place Of Publication


Abstract


  • In southeastern South Australia, the River Murray debouches through a coastal barrier separating euryhaline estuarine-lagoonal waters from the Southern Ocean. Depending upon the relative freshwater outflow of the river and ingress of the ocean, water salinity varies greatly within the lower estuary. Ammonia beccarii and Elphidium articulatum are euryhaline species of foraminifera that characterize the estuary and back-barrier Coorang Lagoon. The inner-shelf marine environment hosts an assemblage in which Discorbis dimidiatus, E. crispum, E. macelliforme, and various cibicidid species predominate. In cored sediments recovered from the shallow lower estuary, the relative abundance of A. beccarii + E. articulatum was compared with that of D. dimidiatus + E. crispum + E. macelliforme + other species. These data, and AMS radiocarbon ages determined for foraminifera and ostracods, provide evidence of a change from maximum oceanic influence (5255 �� 60 yr B.P.) to maximum estuarine influence (3605 �� 70 yr B.P.). Over this same time interval, sea level fell relatively by about 2 m. However, the event was also contemporaneous with falling water levels in several Victorian lakes, and it is thus attributed to onset of climatic aridity. Reduced precipitation in the River Murray catchment and reduced freshwater outflow enhanced development of the flood-tide delta and constriction of the mouth. (C) 2000 University of Washington.

UOW Authors


  •   Bourman, Bob P. (external author)

Publication Date


  • 2000

Citation


  • Cann, J. H., Bourman, R. P., & Barnett, E. J. (2000). Holocene foraminifera as indicators of relative estuarine-lagoonal and oceanic influences in estuarine sediments of the River Murray, South Australia. Quaternary Research, 53(3), 378-391. doi:10.1006/qres.2000.2129

Scopus Eid


  • 2-s2.0-0034119274

Start Page


  • 378

End Page


  • 391

Volume


  • 53

Issue


  • 3

Place Of Publication