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.

The overall grade for the South zone in 2023-24 remained ‘moderate’ and the score decreased from 55 to 47 since the previous year.

Key results

• The water quality grade in 2023-24 for the South inshore zone remained ‘good’ whilst the score decreased from 75 to 63 since the previous year.
• Total suspended solids (TSS) declined in grade from ‘good’ to ‘poor’ and turbidity declined in grade from ‘good’ to ‘moderate’ since the previous year.
• Particulate nitrogen (PN) declined from ‘poor’ to ‘very poor’ and particulate phosphorus (PP) declined from ‘good’ to ‘poor’ since the previous year.
• For the South zone sites, higher concentrations of NOx, PN and PP typically occurred during wet season months and peak concentrations occurred in the December sampling occasions that coincided with the high discharge from the Tully River that followed Tropical Cyclone Jasper.
• During the wet season, nutrient concentrations were highest at sites closer to the Tully River mouth.
• The coral condition index remained ‘moderate’ whilst the score decreased from 56 to 50 since the previous year.
• Coral cover remained ‘moderate’ with only a marginal decrease in score. Some decline in coral cover was attributed to thermal bleaching.
• Cover change decreased from 49 to 41 with decreased growth and higher mortality linked to increased levels of disease.
• Macroalgae scores differed widely across sites with macroalgae cover ranging between ‘very good’ to ‘very poor’.
• South zone inshore seagrass remained in ‘poor’ condition. Declines in score occurred at most sites and were evident for both the abundance and resilience indicators.

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