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

Authors / CoAuthors

Haese, R.R. | Murray, E.J. | Smith, C.S. | Smith, J. | Clementson, L.

Abstract

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.

Product Type

nonGeographicDataset

eCat Id

64870

Contact for the resource

Custodian

EGD

Owner

Commonwealth of Australia (Geoscience Australia)

Custodian

Commonwealth of Australia (Geoscience Australia)
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia

Keywords

External PublicationScientific Journal Paper

( Theme )

geochemistry

( Theme )

marine

AU-QLD

Australian and New Zealand Standard Research Classification (ANZSRC)

Earth Sciences

Published_External

Publication Date

2007-01-01T00:00:00

Creation Date

Security Constraints

Australian Government Security ClassificationSystem

Classification - unclassified

Legal Constraints

Creative Commons Attribution 4.0 International Licence

Access - license

Use - license

Status

Purpose

Maintenance Information

unknown

Topic Category

geoscientificInformation

Series Information

Lineage

Unknown

Parent Information

Extents

[-35.16, -35.08, 150.53, 150.65]

Reference System

Spatial Resolution

Service Information

Associations

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