The northern boundary of the North Inshore reporting zone extends north-eastward from the mainland just north of the Bloomfield River along the boundary of the Wet Tropics NRM marine region to the boundary of the offshore waters and includes enclosed coastal, open coastal and mid-shelf waters.
The southern boundary of the North zone extends north-east from Cape Grafton just south of Cairns to the offshore boundary. The major rivers discharging into the North zone are the Daintree River, the Mossman River and the Barron River.
The Bloomfield River discharges at the northern most extent and Smiths Creek discharges through Trinity Inlet at the southernmost extent. Numerous smaller waterways draining the catchments of the often steep eastern slopes of the Great Dividing Range also discharge into the North zone.
Water quality in the North zone is affected by plumes of sediments, nutrients and pesticides from rivers discharging directly into the zone but also from the plumes of southern rivers, particularly the Russell/Mulgrave and the Tully/Murray, which are carried north by prevailing currents.
The area includes Snapper Island, some 3.7 km east of the Daintree River mouth, the low Isles 11km south-east of Snapper Island, and Green Island, approximately 27 km north east of Cairns. These islands provide fringing shallow water environments that support coral reef ecosystems and intertidal reef seagrass meadows. Subtidal and intertidal coastal seagrass meadows also occur close to the mainland including Cairns Harbour and Yule Point approximately 10km south of Port Douglas.
The overall grade for the North zone remained ‘moderate’ in 2019-20 with the score unchanged at 60.
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 2019-20 for the North inshore zone remained ‘very good’ and the score increased from 85 to 91.
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 an assessment of pollutant loads entering the marine environment. The results are derived from in-situ water samples taken at six locations from inshore waters extending from sites adjacent to Cape Tribulation in the north to sites adjacent to Cairns in the south.
The water clarity score of 96 in the North zone is comprised of a total suspended solids (TSS) score only. Turbidity was not monitored in the North Zone. Water clarity remained ‘very good’.
Nutrients scored 86 (‘very good’) in the North zone and improved from a score of 80 with a grade of ‘good’ in 2018-19. Nutrients were graded ‘very good’ for oxidised nitrogen (NOx), ‘good’ for particulate nitrogen (PN) and ‘good’ for particulate phosphorus (PP).
The chlorophyll a score in the North zone was 91 (‘very good’) and improved from 75 (‘good’) in 2018-19.
A pesticide score was not available due to the cessation of pesticide logger deployment in the North zone.
The overall coral grade in 2019-20 for the North inshore zone was ‘moderate’ and scored 44. The coral index grade in the north zone has remained ‘moderate’ since 2014-15.
The coral grade is comprised of the density of juvenile hard corals score of 33 (‘poor’), the macroalgae cover score of 42 (‘moderate’), the coral cover score of 44 (‘moderate’), the change in coral cover score of 70 (‘good’), and the coral community composition score of 33 (‘poor’).
The coral condition score was unchanged from 2018-19 when cyclone Owen caused reductions in juvenile density and coral cover indicator scores at the shallow reefs of Snapper South. High macroalgae cover has also persisted on shallow reefs of Snapper North.
More information is available in the latest Marine Monitoring Program inshore coral report.
The overall seagrass grade in 2019-20 for the North inshore zone remained ‘moderate’ with the score decreasing from 53 in 2018-19 to 46.
The seagrass grade is comprised of the seagrass percent cover score of 36 (‘moderate’), the tissue nutrient score of 38 (‘poor’), and reproductive effort score of 20 (‘very poor’) from the Marine Monitoring Program in addition to the seagrass biomass score of 70 (‘good’), the meadow area score of 84 (‘very good’), and seagrass species composition score of 85 (‘very good’) from the Queensland Ports Seagrass Monitoring Program.
Seagrass condition in inshore monitoring meadows that are part of the QPSMP program have improved in recent years. The average grades for all condition indicators (biomass, area, species composition) were all ‘good’ or ‘very good’ in the past 2 years. Overall condition scores declined at all MMP sites in the past year, largely because of zero scores for reproductive effort in 4 of the 5 sites where this is monitored. Percent cover also declined from ‘moderate; to ‘poor’ (averaged across all sites).
More information on seagrass condition in the North 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.