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The Pimpama estuary received a “C” in the 2009
Report Card, a deterioration in ecosystem health from the previous year
(“C+”). This slight reduction in grade was due mainly to an increase in
phytoplankton abundance (49% compliance compared with 84% in 2007/2008)
and deterioration in turbidity levels (47% compliance compared to 60% in
2007/2008). Despite a drop in report card grade, there were slight
improvements in dissolved oxygen concentrations in the upper reaches and
the BHR also improved slightly with sewage nitrogen levels
(δ15N) slightly reduced from the previous reporting
period. TN concentrations did not comply with QWQ guidelines throughout
the year (previously 9% compliance in 2007/2008).
Water quality patterns in the estuary are
strongly partitioned and influenced by the weir which restricts tidal
flushing of the upper estuary. As a result, water quality is poor in
the upper reaches and is characterised by high nutrient and low DO
concentrations.
Overall, 68% of the riparian habitat of the
Pimpama estuary is unmodified with the majority of that found in the
reaches beneath the weir where the system passes through conservation
area and National Park. Much of the habitat in the reaches above the
weir and behind the intertidal zone has been removed for agricultural
purposes.
Abbreviations glossary |
Indicators and methods
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