Coast & Estuaries
Page 208
Sample Location: POR020, Mangrove Cove
Impacts on Marine Ecologies
The EPA has noted a serious and continuing decline in the extent and quality of
marine ecosystems in the region, particularly in the loss of seagrass and
mangroves. High nutrient levels especially nitrogen, are considered to be a
principal factor in the ecosystem changes. In general, urban and coastal
development and industrial land use are important contributing factors in
changes to the distribution of biological communities in the Port waterways.
Mangroves, Seagrass and Saltmarsh
Development and subsequent pollution that has occurred throughout the history
of South Australia has resulted in a decline in the ecosystem health of its
waterways. This is apparent to the community through the large-scale loss of
intertidal and sub-tidal seagrasses and the occurrence of algal blooms including
toxic species. Studies into the environmental status of the waterways
consistently report this situation.
Despite efforts since the early 1990s by a range of agencies with responsibility
for water quality management, particularly since the early 1990s, the area is
characterised by problems that stem from poor water quality and concerns
remain for its future ability to support a sustainable ecosystem (EPA, 2008).
It has shown that the discharges from Penrice and Bolivar interact in the
waterways even though they are over 10 km apart. The combined effect of the
two discharges is likely to be the cause of the seagrass loss that has occurred
in parts of Barker Inlet, although the Bolivar discharge is probably the dominant
cause of the loss along the coast north of Barker Inlet (WQIP EPA, 2008).
Ambient water quality data concentrations of nutrients as a measure of
ecosystem health is a useful indicator. Offshore from the Bolivar Waste Water
Treatment Plant (WWTP) discharge, for example, one major effect contributing
to the seagrass decline is prolific growth of algae covering the seagrass blades.
This blanket cover of sea grasses by algae acts as a nutrient sink, whilst also
