ENVIRONMENTAL
RESULTS
AREA: 33.68 km2
ABOUT THE ZONE
The Inner Harbour is located immediately to the east of the Western Basin and is bounded by mangroves on Curtis Island and the town of Gladstone on the southern edge. Coral reefs have been recorded at Turtle, Quoin and Diamantina islands although there is little evidence that these areas have recently supported viable coral communities. There are several seagrass meadows, including one monitored seagrass meadow in the north of this zone. The Quoin Island Turtle Rehabilitation Centre is located in the centre of this zone and the Barney Point Coal Terminal is located on the south-east banks of the zone.
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This zone has three water and sediment monitoring sites, one seagrass monitoring meadow, two fish monitoring sites, one mud crab monitoring site and two mangrove monitoring sub-zones.
WATER & SEDIMENT
WATER
SEDIMENT
The Inner Harbour received an overall water quality score of 0.84 (B). This score was based on the scores for physicochemical (0.84), nutrients (0.68) and dissolved metals (1.00).
Sediment quality of the Inner Harbour was very good with an overall score of 0.94 (A).
MEASURES RESULTS
WATER
SEDIMENT
pH = acidity TN = Total nitrogen TP = Total phosphorus Chl-a = Chlorophyll-a Al = Aluminum Cu = Copper Pb = Lead Mn = Magnesium Ni = Nickel Zn = Zinc
As = Arsenic Cd = Cadmium Cu = Copper Hg = Mercury Pb = Lead Ni = Nickel Zn = Zinc
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
The Inner Harbour received a very good score of 1.00 for pH indicating that the average pH was well within the guideline value range. This zone received a good score for turbidity (0.69) indicating that average turbidity was below the guideline value.
All six dissolved metals received very good scores (0.98-1.00) indicating that average concentrations were well below the water quality guideline values.
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The Inner Harbour received a good overall score for nutrients (0.68). Total phosphorus had a very good score (0.95) while total nitrogen (0.56) and chlorophyll-a (0.51) had satisfactory scores, indicating that average concentrations for these measures were below the guideline values for this zone.
HABITATS
SEAGRASS (MEADOW 58)
The Inner Harbour has one monitored, intertidal meadow in the south-east corner of the zone near South Trees Inlet.
In 2022 the Inner Harbour was in poor condition (0.39, C)—a continued decline since the Meadow 58 score peaked at 0.70 (B) in 2020. The continued decrease in zone/meadow score was driven by changes in the meadow species composition, with no dominant species recorded in the meadow. Conversely, meadow area was very good (0.89, A) and meadow biomass was good (0.77, B).
MANGROVE RESULTS
Very good (0.85-1.00)
Good (0.65-0.84)
Satisfactory (0.5-0.64)
Poor (0.25-0.49)
Very Poor (0.00-0.24)
No data available
The overall mangrove score for the Inner Harbour was 0.55 (C) indicating a satisfactory condition for mangroves in this zone. Mangrove extent (0.62), canopy condition (0.51) and shoreline condition (0.52) were all satisfactory.
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The overall score improved from 0.43 in 2018 to 0.55 in 2019. This was one of three zones where an improved overall score was recorded.
FISH & CRABS
FISH HEALTH RESULTS
HARBOUR SCORE
OVERALL VISUAL FISH CONDITION: HARBOUR SCORE
VISUAL FISH CONDITION: HARBOUR SCORE
FISH HEALTH ASSESSMENT INDEX: HARBOUR SCORE
Very good (0.85-1.00)
Good (0.65-0.84)
Satisfactory (0.5-0.64)
Poor (0.25-0.49)
Very Poor (0.00-0.24)
No data available
Fish Health (Overall)
The overall score calculated for fish health in 2022 was 0.80 (B), which is an average of the scores for Fish Condition 0.72 (B) and the Health Assessment Index 0.90 (A).
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Visual Fish Condition:
The overall score for Fish Condition (0.72) is an average of 0.97 (A) for Fish Visual Condition (FVC) and 0.47 (D) for Fish Body Condition (FBC).
The high scores for FVC are a result of a low incidence of poor visual health. All fish species assessed for this metric received very good scores ranging from 0.90 (A) to 0.98 (A). This result was similar to the HAI scores for external measures where a very low number of external health issues were recorded.
The poor score for FBC in 2022 was a result of poor scores for yellow-finned bream (0.43), pikey bream (0.46) dusky flathead (0.43), and barred javelin (0.44). Almost all species assessed had a mean body condition below the long-term average (2003 – 2021). However, the remaining species assessed, mangrove jack, had a satisfactory score of 0.50.
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Fish Health Assessment Index (HAI):
The overall HAI score for Gladstone Harbour was 0.90 (A), as data from the 2021 Gladstone Harbour Report Card was reused.
This was comprised of scores from five fish species, barramundi 0.98 (A), barred javelin 0.90 (A) and blue catfish 0.81 (B), bream 0.98 (A) and mullet 0.81 (B).
In general, the surveyed fish species showed very few signs of external health issues, a similar result to the Fish Visual Condition sub-indicator. Scores for internal organs were also low indicating good to very good fish health.
FISH RECRUITMENT RESULTS
Fish recruitment was assessed for two species: yellow-finned bream Acanthopagrus australis and pikey bream Acanthopagrus pacificus. The overall score for 2022 was 0.57 (C) similar to the 2020 score of 0.62. The final scores were measured against a 2012 to 2021 baseline. The 2022 score for fish recruitment indicates a season with higher recruitment rate (increased catch rate) relative to the mean reference level determined over the baseline period. The total number of bream caught in the 2022 reporting year was 764, 316 yellow-finned bream and 448 pikey bream.
MUD CRAB RESULTS
The Inner Harbour is located immediately to the east of the Western Basin and is bounded by mangroves on Curtis Island and the town of Gladstone on the southern edge.
The overall zone score for the Inner Harbour was 0.14 indicating a very poor condition for mud crabs and a decline from the 2021 score (0.39). Both abundance (0.00) and sex ratio (0.11) received very poor scores while the score for prevalence of rust lesions was poor (0.47).