Benthic sediment surveys of inner Darwin Harbour (GA0358) and shallow water areas in and around Bynoe Harbour (GA0359) in 2017: Sediment oxygen demand measurements on seabed sediments.

Brief description

Benthic sediment sampling of Inner Darwin Harbour (GA0358) and shallow water areas in and around Bynoe Harbour (GA0359) was undertaken between May 29 and June 19, 2017. Partners involved in the surveys included Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS) and the Department of Environment and Natural Resources within the Northern Territory Government (NT DENR) (formerly the Department of Land and Resource Management (DLRM)). These surveys form part of a four year (2014-2018) science program aimed at improving knowledge about the marine environments in the regions around Darwin and Bynoe Harbour’s through the collection and collation of baseline data that will enable the creation of thematic habitat maps to underpin marine resource management decisions. This project is being led by the Northern Territory Government and is supported by the INPEX-led Ichthys LNG Project, in collaboration with - and co-investment from GA and AIMS. This dataset comprises sediment oxygen demand measurements made on seabed sediments.

Lineage

Maintenance and Update Frequency: asNeeded

Statement: Bottom sediments were collected using a Shipek Grab or a Box Core. Bulk sub-samples (6.5 ml) of surface sediment (0-2 cm) were incubated in biological oxygen demand bottles filled with filtered seawater (0.4 um) for ~24 hrs in the dark at sea surface temperatures. Dissolved oxygen concentrations (and saturation values) were measured at the start and finish of each incubation (after a ~30 minute pre-incubation period). Results were expressed on a per gram dry weight (dwt) basis utilising a separate volumetric sample to measure sediment water content. Three blank samples of filtered and uv-treated seawater sediment oxygen demands of 0.0 +/- 0.2 mg L-1 and 3.95 +/- 4.88%. The accuracies of the O2 measurements were +/- 1 mg/L. The accuracy of the scale used to measure wet/dry weights was better than 1%.