ENVIRONMENTAL
RESULTS
ABOUT THE ZONE
Rodds Bay is located to the south-east of the Outer Harbour zone. The eastern side of Rodds Bay includes a number of mangrove islands. The creeks that flow into the bay are mangrove-lined and contain large areas of salt pans.
WATER & SEDIMENT
Rodds Bay received an overall water quality score of 0.79 (B).
Sediment quality of Rodds Bay was very good with an overall score of 0.96 (A).
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The following graphs compare the Water and Sediment scores reported for 2025 (top line) to those from 2024.
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 Rodds Bay scored 0.79 and received a Good (B) grade, a decline to the 2024 Report Card (0.87, Very Good, A). This score was calculated by aggregating the three sub-indicator and associated measure scores (Physicochemical – pH and turbidity, Nutrients – total nitrogen, total phosphorus and chlorophyll-a, and dissolved metals – aluminium, copper, lead, manganese, nickel and zinc).
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Rodds Bay received a Very Good (A) grade for pH (1.00), a Good (B) grade for total phosphorus (0.76), and a Satisfactory (C) grade for turbidity (0.59), total nitrogen (0.56), and chlorophyll-a (0.50). All six of the dissolved metals received a Very Good (A) grade, indicating that average concentrations for these measures were within the guideline values for this zone.
For Sediment quality, Rodds Bay received an overall score of 0.96 and a Very Good grade (A), 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). The results reflect that all concentrations were below the guideline values for this zone. Arsenic (0.75) received a Good (B) grade, reflecting its natural occurrence within the harbour and may not be associated with anthropogenic inputs.
HABITATS
SEAGRASS RESULTS
Meadow 94
Meadow 96
Meadow 104
There are three intertidal monitoring meadows in Rodds Bay: Meadows 94, 96 and 104.
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Recent improvements in overall seagrass health in Gladstone Harbour were largely driven by an increase in these meadows’ biomass and area scores (2023: 0.30–0.84, 2024: 0.71–1.00). In 2025, meadows in Rodds Bay continued to improve in biomass and area, with Meadows 96 and 104 improving to a Very Good (A) grade for biomass.
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Between 2009 and 2010, Rodds Bay meadows experienced major declines, culminating in the complete loss of seagrass from 2011 to 2013. However, biomass and area scores peaked between 2019 and 2020, reaching a Very Good condition after nine to 10 years of being rated Satisfactory. Although the meadows fell to poor conditions in 2023, their recovery to Good or Very Good conditions in 2024 and 2025 across all indicators suggests that favourable climate conditions have helped improve their resilience and support another season of growth.
MANGROVE RESULTS
The 2025 Gladstone Harbour Report Card incorporates the 2024 Mangroves results. Mangrove condition has historically remained stable due to strong buffering capacity, and since 2019, monitoring has been undertaken every five years. In 2024, the overall grade for Mangroves in Rodds Bay improved from Satisfactory (C) in 2019 to Good (B).
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The mangrove extent sub-indicator, which measures changes in canopy cover relative to saltmarsh and saltpan areas, retained a Good (B) grade. The canopy condition indicator, based on remote sensing of canopy density and health, also remained stable at a Satisfactory (C) grade. Shoreline condition, assessed through aerial surveys of mangroves bordering Gladstone Harbour’s water quality zones, retained a Good (B) grade across years.
FISH & CRABS
FISH RECRUITMENT RESULTS
Fish recruitment was assessed for two species: Yellowfin bream Acanthopagrus australis and Pikey bream A. pacificus. The overall score for 2025 was higher than the previous year (2024: 0.60, 2025; 0.73) and improved from a Satisfactory (C) to a Good (B) grade. This is a result of increased catch numbers of Yellowfin bream (2024: 63, 2025: 86) and Pikey bream (2024: 43, 2025: 48).
MUD CRAB RESULTS
The overall zone score for Mud crabs for Rodds Bay was 0.44 and graded Poor (D), a increase in score to 2024 (0.35, Poor, D). At the sub-indicator level, abundance remained at a Very Poor (E), reflecting a low catch per unit effort. Mud crab populations may be influenced by both human activities and natural factors, including habitat, reproductive cycles, and environmental conditions like temperature and water movement.
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In Queensland, it is illegal to take female crabs, hence changes in the ratio of male to female crabs can indicate changes in fishing pressures. Sex ratio for Rodds Bay improved from a Very Poor (E) grade in 2024 to Very Good (A), indicating a balance of males and females. The prevalence of rust lesions declined from a Very Good (A) grade to a Poor (D), with the percentage influenced by small capture numbers despite low incidence of rust lesions.