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 increased from ‘poor’ to ‘moderate’ with the score increasing from 37 in 2016-17 to 41 in 2017-18.
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 2017-18 for the South inshore zone remained ‘moderate’ and scored 47.
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 31 (‘poor’) in the South zone is comprised of total suspended solids (‘very poor’) and turbidity (‘moderate’).
Nutrients scored 34 (‘poor’) in the South zone, comprising of ‘very poor’ for oxidised nitrogen (NOx), a ‘moderate’ for particulate nitrogen (PN) and a ‘good’ for particulate phosphorus (PP).
The chlorophyll a score in the South zone was 36 (‘poor’).
Using the pesticide risk metric pesticides were graded “very good” and scored 88, equating to 99.4 percent of species protected.
The South zone has consistently scored lowest of the four inshore zones over the last three years with continuing low scores for TSS and NOx.
The overall coral grade in 2017-18 for the South inshore zone was 55 (‘moderate’). Since 2014-15 the coral index in the South zone has remained as a ‘moderate’ grade.
The coral grade is comprised of the density of juvenile hard corals score of 81 (‘very good’), the macroalgae cover score of 40 (‘moderate’), the coral cover score of 34 (‘poor’), the change in coral cover score of 66 (‘good’), and the coral community composition score of 58 (‘moderate’).
In the South zone there was a slightly poorer coral condition score due to lower coral cover change, a decline of juvenile density and high macroalgae cover predominantly at shallow depths. The South zone condition is limited in particular at Bedarra and Dunk South sites where low macroalgae and coral cover indicator scores persist.
More information on recent changes in coral indicators and the relationships with environmental conditions are provided in the latest Marine Monitoring Program coral report Thompson et al. (2019).
The overall seagrass grade in 2017-18 for the South zone increased from ’very poor’ in 2015-16 to ‘poor’ with the score improving from 6 to 23.
The seagrass grade is comprised of the percent cover score of 19 (‘very poor’), the tissue nutrient score of 39 (‘moderate’), and reproductive effort score of 0 (‘very poor’) from the Marine Monitoring Program.
Key messages of seagrass condition in 2017-18 for the South zone include the following.
- All seagrass monitoring in this zone is limited to smaller scale transect monitoring sites, with no larger scale meadow monitoring conducted in this zone.
- The poor overall condition in 2017-2018, was an improvement from very poor condition for the 3 years prior.
- Percent cover improved from very poor condition in 2016-2017.
- Tissue nutrient condition decreased to ‘poor’ and reproductive effort remained ‘very poor’.
More information on seagrass condition in the South zone is available from the Marine Monitoring Program reports available 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.