Inshore South

The northern boundary of the South inshore reporting zone extends due eastward from the mainland just south of the Moresby River at Double Point to the boundary of the offshore waters and includes enclosed coastal, open coastal and mid-shelf waters. The southern boundary of the South zone extends east from the North West bank of the Seaforth Channel mouth, just south of Hinchinbrook Island, to the offshore boundary.

The major rivers discharging into the South zone are the Tully River and the Murray River. The Hull River discharges to the north of the Tully River. Several smaller waterways drain sub catchments that are dominated by agricultural land use, for example Liverpool Creek and Maria Creek, which discharge into the South zone. Numerous smaller creeks discharge to the north of and within Hinchinbrook Channel.

Water quality in the South inshore zone is affected by plumes of sediments, nutrients and pesticides from rivers and creeks discharging directly into the zone but also from the plumes of southern rivers, particularly the Herbert and also the Burdekin located in the Dry Tropics NRM region.

The area includes the Barnard Island group some 7 km east of Cowley Beach, North and South Dunk Island some 7.5 km south east of Mission Beach, and the Bedarra Island group located several kilometres south of the Dunk Island group. The area also includes Hinchinbrook Island. These islands provide fringing shallow water environments that support coral reef ecosystems and intertidal and subtidal reef seagrass meadows. Extensive seagrass meadows fringe the northern and western coastal areas of Hinchinbrook Island. Intertidal coastal seagrass meadows also occur close to the mainland including Lugger Bay approximately 10 km south of Mission Beach.

Key results for 2024-25

• Water quality declined from ‘good’ to ‘moderate’ while the score decreased from 63 to 55.
• Water clarity remained ‘moderate’, with turbidity improving from ‘moderate’ to ‘good’ and total suspended solids (TSS) remaining ‘poor’.
• Nutrients decreased in score for the South zone but remained ‘moderate’ with oxidised nitrogen (NOx) remaining ‘good’, particulate nitrogen (PN) remaining ‘very poor’ and particulate phosphorus (PP) remaining ‘poor’.
• Chlorophyll a declined from ‘good’ to ‘moderate’.
• Coral condition remained ‘moderate’ with the score decreasing from 50 to 43.
• The coral cover indicator decreased substantially in score and declined from ‘moderate’ to ‘poor’. This resulted from exposure to low salinity floodwaters from the heavy rainfall events and high river discharges, including the Tully and Herbert, in February 2025.
• The cover change indicator continued to decrease in score since 2019-20 and declined to ‘poor’. Whilst a high score was recorded at Dunk North, all other sites scored poorly. The decline in score over time is likely linked to disease as a result of stress from exposure to floodwaters and elevated temperatures in recent years.
• The composition indictor remained ‘moderate’ and has declined since 2020-21 when it peaked with a grade of ‘very good’.
• The macroalgae indicator improved substantially from ‘poor’ to ‘moderate’ and scores increased at most sites. However, this improvement was attributed to the impacts of floodwaters which reduced macroalgae cover.
• The juvenile coral indicator declined substantially from ‘good’ to ‘moderate’ since the previous year. Density of juveniles tended to be poorer for coral reefs at 2m depth compared to 5m depth and the increases of juvenile coral in 2023-24 at Dunk South, Dunk North and Bedarra were reversed for 2024-25.
• Seagrass condition remained ‘poor’ and decreased in score since the previous year. Percent cover condition remained ‘very poor’ at both Dunk Island sites. Lugger Bay resilience declined from ‘poor’ to ‘very poor’, and percent cover remained 0%. Missionary Bay seagrass remained in satisfactory condition for the second year.

The diagram below shows the detailed results for each indicator by year. Click on the timeslider to see data from previous years.