ZONE 5 Inner Harbour
This pilot report card will report on a sub-set of indicators for water quality only. The grades for future report cards will also include indicators for sediment quality, habitats, connectivity and fish & crabs indicators.
The water quality score for the Inner Harbour was 0.74 and based on physical, chemical, metal and nutrient related parameters.
Zone 5 Inner Harbour
(Two monitoring sites)
The Inner Harbour is located immediately to the east of the Western Basin and is bounded by a mangrove dominated intertidal system on Curtis Island and the town of Gladstone on the southern edge.
Taking all of the measured indicators into account, the Inner Harbour received a score for water quality of 0.74, which was the highest water quality score for Gladstone Harbour in 2013-’14 and gave this zone an overall environmental grade of B. The Inner Harbour received very good scores for dissolved oxygen, copper and aluminium, a good score for turbidity, a moderate score for phosphorus and a poor score for nitrogen.
Water Quality: Inner Harbour
Why were these indicators measured?
Dissolved oxygen was measured as it is an important indicator of potential problems in aquatic environments. Low levels of dissolved oxygen can occur as the result of high levels of organic matter in the water, and can lead to severe problems including mortality of aquatic organisms (e.g. fish kills).
Turbidity was measured as it is an important indicator of potential problems in aquatic environments. High turbidity can occur due to high levels of sediment or other undissolved solid particles being present in the water. This can reduce light levels reaching the seabed leading to reduced health and photosynthesis, and increased mortality of algae and plants. High turbidity can also damage the gills of many marine animals.
Total Nitrogen & Total Phosphorus were measured as they are good general indicators of water quality. However it is important to understand the processes through which these nutrients enter the environment, and how they are cycled through the environment.
Dissolved aluminium & copper were measured as they are relevant as constituents of effluent that may potentially be released into the harbour. High levels of aluminium and copper in aquatic systems can be toxic for algae, invertebrates, fish and other animals. It has yet to be determined whether aluminium in Gladstone Harbour is anthropogenic or naturally occurring.
These six indicators were measured to assess water quality within Gladstone Harbour to be used in the Pilot Report Card.