ENVIRONMENTAL
RESULTS
AREA: 1.33 km2
ABOUT THE ZONE
Auckland Inlet is a tidal inlet that connects to the Inner Harbour through a complex of small streams meandering through mangrove-lined mudflats that are often inundated at high tide. Seawater extracted from Auckland Creek is used to cool the Gladstone Power Station. Stormwater run-off outlets are located along Auckland Creek.
This zone has five water and sediment monitoring sites, one fish monitoring site, one mud crab monitoring site and one mangrove monitoring sub-zone.
WATER & SEDIMENT
Auckland Inlet received an overall water quality score of 0.77 (B).
Sediment quality of Auckland Inlet was very good with an overall score of 0.97 (A).
The following graphs compare the Water and Sediment scores reported for 2023 (top line) to those from the previous year.
WATER
SEDIMENT
Very good (0.85-1.00)
Poor (0.25-0.49)
Good (0.65-0.84)
Satisfactory (0.5-0.64)
Very Poor (0.00-0.24)
No data available
Overall, Water quality in Auckland Inlet scored 0.77 and received a good grade (B), very similar to the 2022 report card. This score was calculated by aggregating the three sub-indicator and associated measure scores (Physiochemical – pH and turbidity, Nutrients – total nitrogen, total phosphorus and dissolved metals, and dissolved metals – aluminum, copper, lead, manganese, nickel and zinc).
Within the Physiochemical sub-indicator, Auckland Inlet received a score of 1.00 and a very good grade (A) for pH indicating that the average pH was well below the guideline value range. This zone received a score of 0.52 and satisfactory grade (C) for turbidity indicating that average turbidity was within the guideline value.
Within the Nutrient sub-indicator group, total nitrogen (0.47) received a poor grade (D) indicating concentrations for this measure were above guideline values. In contrast, total phosphorus (0.56) received a satisfactory grade (C) and chlorophyll-a (0.77) a good grade (B), indicating that average concentrations for these measures were within or below the guideline values.
Five of the six Dissolved metals received high scores (0.87–1.00) and very good grades (A) and one measure –copper – received a score of 0.79 and a good grade (B). These results indicate that average concentrations were well below the guideline values.
For Sediment quality, Auckland Inlet received an overall score of 0.97 and a very good grade (A), also a similar result to the previous year. This score was calculated by aggregating one sub-indicator and associated measure scores (Metal and metalloids – arsenic, cadmium, copper, lead, mercury, nickel and zinc).
In 2023, all seven Metal and metalloid sub-indicator measures received very high scores (0.90–1.00) and very good grades (A), indicating that average concentrations were well below the guideline values for this zone.
HABITATS
MANGROVE RESULTS
No mangrove assessment was conducted in 2023, results are from monitoring conducted in 2019. The overall zone score for Auckland Inlet was 0.65 (B) indicating a good condition for mangroves in this zone. This score was similar to the score of 0.68 recorded in 2018.
Mangrove extent (0.76) was good and canopy condition (0.57) and shoreline condition (0.62) were satisfactory.
FISH & CRABS
FISH RECRUITMENT RESULTS
Fish recruitment was assessed for two species: Yellowfin bream Acanthopagrus australis and Pikey bream Acanthopagrus pacificus. The overall score for 2023 was lower than the previous year (2022: 0.60, 2023: 0.36) and declined one grade to
poor (D). This decline in score is a result of a decrease in number of bream caught during the 2022–23 reporting period
(2022 report card: 38 fish, 2023 report card: 23 fish).
Fish health is assessed though two sub-indicators, Fish condition and Fish Health Assessment Index (HAI).
The overall score for Fish health in 2023 was 0.81 and received a good grade (B). The 2023 results were calculated by the average of the Fish HAI score (0.90; results carried over from 2021) and new assessment of Fish condition which scored similar to the previous year (2022: 0.74, 2023: 0.73).
MUD CRAB RESULTS
For the first time since 2017, the number of crabs caught in Auckland Inlet were sufficient to calculate scores for this zone. Abundance and sex ratio scores were both very low (0.00) similar to the results from the last calculations. In contrast, there was no prevalence of rust legions resulting in a high score (1.00) an improvement from the last calculation of this sub-indicator in 2017 (0.63).