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 diagram below shows the detailed results for each indicator by year. Click on the timeslider to see data from previous years.
Water quality for the South inshore zone in 2016-17 is ‘moderate’ with a score of 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 23 (‘poor’) in the South zone is comprised of total suspended solids (‘very poor’) and turbidity (‘good’).
Nutrients scored 26 (‘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 54 (‘moderate’).
Using the Photosystem II herbicide equivalent concentrations method, pesticides received a score of 86 (‘very good’).
The water quality index in the South zone has remained ‘moderate’ but changed in score from 60 to 47 since 2015-16. The largest decreases occurred for total suspended solids, NOx and PN.
The highest concentrations of TSS (306 mg L-1), PN (634 µg L-1) and NOx (182 µg L-1) recorded during 2016-17 were sampled from the enclosed coastal site located near the mouth of the Tully River during January. The maximum daily discharge at Tully River Euramo gauging station during 2016-17 was substantially higher, with a more pronounced spike and shorter period of high flows, than the previous two years. The peak annual flow for 2016-17 at Euramo gauging station coincided with the high TSS, PN and NOx concentrations and demonstrates the influence of river discharge on the inshore water quality.
The overall coral grade for the South inshore zone in 2016-17 is 60 (‘moderate’).
The coral grade is comprised of the density of juvenile hard corals score of 89 (‘very good’), the macroalgae cover score of 46 (‘moderate’), the coral cover score of 32 (‘poor’), the change in coral cover score of 74 (‘good’), and the coral community composition score of 58 (‘moderate’).
Since 2014-15 the coral index in the South zone has remained as a ‘moderate’ grade.
Despite high levels of bleaching in the South zone, the coral index score increased from 55 in 2015-16 to 60. The continued improvements in the coral change, composition and macroalgal cover indicators, associated with rapid recovery of coral in recent years, offset the decline of the juvenile density indicator.
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. (2018).
The fish index is currently under development and will be available in future report cards.
Further information on the methods used to produce the scores and grades and detailed results can be found here.