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Diatoms Control Nutrient Cycles in a Temperate, Wave-dominated Estuary (Southeast Australia)

Created 17/10/2025

Updated 17/10/2025

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Diatoms are important primary producers within pelagic, benthic end epiphytic communities and their siliceous frustule leads to rapid sinking to the sediment. As a consequence, diatoms play a critical role in nutrient and carbon cycles in shallow and deep water environments. In this study, benthic nutrient and gas fluxes, water column and sediment properties were studied in a coastal lagoon of south-eastern Australia to identify control mechanisms coupling benthic and pelagic processes, in particular, how nutrients become fractionated by processes affecting benthic nutrient fluxes. During late spring, the water column of St. Georges Basin was oligotrophic, primary production was likely P limited and the phytoplankton community was dominated by cyanophytes. Molar ratios of TCO2 : Si benthic fluxes, however, were equal to the molar composition of diatoms suggesting that diatoms preferentially sink and deliver the most labile organic matter fraction to the sediment. The congruent release of Si and C implies a coupling of processes mobilizing Si and C. It is argued that extracellular polymeric substances surrounding the silicious frustule are the primary labile organic matter fraction and their rate of mineralization limits the dissolution of the silicious frustule. As decomposing biomass in sediments lead to net N2-production and very efficient burial of P, the fate of diatoms significantly contribute to the removal of bioavailable nutrients. High DIN:DIP benthic flux ratios of 290 to 900 promote P limitation particularly in shallow water bodies with long water residence times.

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Field Value
Title Diatoms Control Nutrient Cycles in a Temperate, Wave-dominated Estuary (Southeast Australia)
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/35663dbe-7c47-492d-847d-d206d683153f
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 22/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
{
  "coordinates": [
    [
      [
        150.53,
        -35.16
      ],
      [
        150.65,
        -35.16
      ],
      [
        150.65,
        -35.08
      ],
      [
        150.53,
        -35.08
      ],
      [
        150.53,
        -35.16
      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "Diatoms Control Nutrient Cycles in a Temperate, Wave-dominated Estuary (Southeast Australia)". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/diatoms-control-nutrient-cycles-in-a-temperate-wave-dominated-estuary-southeast-australia1