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 2018-19 remained ‘moderate’ with the score increasing from 41 in 2017-18 to 47.
The diagram below shows the detailed results for each indicator by year. Click on the timeslider to see data from previous years.
The water quality grade in 2018-19 for the South inshore zone remained ‘moderate’ and scored 44.
Water quality grades are based on water quality guideline trigger values established for the waters of the Great Barrier Reef Marine Park that, if exceeded, identify the need for management responses. The guidelines are not targets or assessments of pollutant loads entering the marine environment. The results are derived from in-situ water samples taken at ten locations and from water quality loggers at two locations from inshore waters extending from sites to the north of Kurrimine Beach to the south of Tully Heads. In addition, passive pesticide samplers are located at Dunk Island.
The water clarity score of 54 (‘moderate’) increased from 36 (‘poor’) in 2017-18 and is comprised of total suspended solids and turbidity (both ‘moderate’).
Nutrients scored 7 (very poor) decreasing substantially from 34 (‘poor’) in 2017-18.
Nutrients are comprised of oxidised nitrogen (NOx), particulate nitrogen (PN) and particulate phosphorus (PP) and all three indiciates were graded ‘very poor’. NOx, PN and PP concentrations were highest at sites closest to the Tully River mouth. Concentrations of all three nutrient indicators were highest during and following high river discharges between December and February.
The chlorophyll a score in the South zone was 24 (‘poor’) and decreased from 36 (‘poor’) in 2017-18.
Using the pesticide risk metric pesticides were graded ‘very good’ and scored 88, equating to greater than 99 percent of species protected.
The overall coral grade in 2018-19 for the South inshore zone improved from ‘moderate’ to ‘good’ and scored 62.
The coral grade is comprised of the density of juvenile hard corals score of 87 (‘very good’), the macroalgae cover score of 41 (‘moderate’), the coral cover score of 43 (‘moderate’), the change in coral cover score of 61 (‘good’), and the coral community composition score of 67 (‘good’).
The improved score and grade for the South zone was driven by increases for all indicators except for macroalgae cover. The score for species composition had the largest increase, from 58 to 75, and coral cover also improved.
More information on recent changes in coral indicators and the relationships with environmental conditions are provided in the latest Marine Monitoring Program inshore coral report (Thompson et al. 2020).
The overall seagrass grade in for the South zone remained ‘poor’ with the score improving from 23 to 35.
The seagrass grade is comprised of the percent cover score of 28 (‘poor’), the tissue nutrient score of 27 (‘poor’), and reproductive effort score of 17 (‘very poor’) from the Marine Monitoring Program.
Seagrass condition remained poor in 2018-2019, although the score increased mainly due to increase in the score for reproductive effort.
More information on seagrass condition in the South zone is available from the Marine Monitoring Program reports here.
The fish index is currently under development and will be available in future report cards.
Thompson A, Costello P, Davidson J, Logan M, Greg Coleman (2019) Marine Monitoring Program. Annual Report for inshore coral reef monitoring: 2017 to 2018. Australian Institute of Marine Science, Townsville.132 pp.