Abstract

The effect of increased nutrient loads on biogeochemical processes in macrotidal, mangrove-lined creeks was studied in tropical Darwin Harbour, Australia. Water quality and sediment composition, benthic and pelagic metabolism and benthic nutrient and gas fluxes were studied during three field surveys to compare nutrient transformation and retention processes in three tidal creeks receiving different loads of sewage discharge. There were marked differences in process rates between Buffalo Creek (hypertrophic), which receives the largest sewage loads; Myrmidon Creek (oligotrophic-mesotrophic) which receives smaller sewage inputs; and Reference Creek (oligotrophic) which is comparatively pristine. Net benthic nutrient fluxes in Buffalo Creek were more than an order of magnitude higher than in Myrmidon and Reference Creeks, which have similar and low benthic fluxes during the wet and dry seasons. Similarly, net pelagic primary production rates were much higher in Buffalo Creek and respiration exceeded primary production resulting in severe drawdown of O2 concentrations at night. In Buffalo Creek, anoxic sediments released oxide-bound phosphorus and inhibited coupled nitrification-denitrification, enhancing benthic nitrogen and phosphorus fluxes. Light limitation of primary production resulted in build-up of excess nutrients in the water column, further stimulating primary production. Poor water quality in Buffalo Creek was exacerbated by poor tidal flushing imposed by a narrow meandering channel and sandbar across the mouth. In contrast to Buffalo Creek, the effect of the sewage load in Myrmidon Creek was confined to the water column, and the impact was temporary and highly localized. This study has identified pelagic primary production, benthic nutrient fluxes and denitrification efficiency as the biogeochemical processes most affected by nutrient loading in tidal creek systems. The serious deterioration of water quality impacts on the functioning of the whole ecosystem, with potential for detrimental effects on higher trophic levels.
Google map showing geographic bounding box with values North bound -12.0 East bound 132.0 West bound 130.5 South bound -13.0
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Product Type/Sub Type

dataset - External Publication - Scientific Journal Paper

Constraints

license
Non-Exclusive licence to publish copyright (please provide TRIM link)

IP Owner

Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

2011

Product Type

dataset

Topic Category

geoscientificInformation

Keywords

External Publication
Scientific Journal Paper
geochemistry
marine
Earth Sciences

Resource Language

English

Resource Character Set

utf8

Resource Security Classification

unclassified

Geographic Extent

North bound
-12.0
East bound
132.0
West bound
130.5
South bound
-13.0

Lineage

Unknown

Digital Transfer Options

onLine

Distributor

Role
distributor
Organisation Name
Geoscience Australia
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address

Metadata File Identifier

a05f7892-f6cc-7506-e044-00144fdd4fa6

Metadata Standard Name

ANZLIC Metadata Profile: An Australian/New Zealand Profile of AS/NZS ISO 19115:2005, Geographic information - Metadata

Metadata Standard Version

1.1

Metadata Date Stamp

2010-03-22

METADATA SECURITY CLASSIFICATION

unclassified

Metadata Contact

Role
pointOfContact
Organisation Name
Geoscience Australia
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address
This product is not available for download due to licence restrictions.

For more information, please contact the Geoscience Australia Sales Centre via:

fax:
+61 2 6249 9960; or
phone:
1800 800 173 (within Australia);
 
+61 2 6249 9966 (outside Australia).

Please note that support hours are 9 am to 5 pm weekdays