Inshore North

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.

Key results for 2024-25

• The score for the North zone decreased from 59 to 49 and the grade remained ‘moderate’.
  
  
• The water quality grade for the North inshore zone declined from ‘very good’ in 2023-24 to ‘good’, and the score decreased from 83 to 69. Unlike the previous year, water quality monitoring activities were not impeded by severe weather conditions and sampling captured inshore conditions during the larger flooding and river discharge events that occurred during the wet season.
  
  
• Water clarity declined from ‘very good’ to ‘good’ since the previous year, and this was based on total suspended solids (TSS) grab samples alone as there are no turbidity loggers located in the North zone.
  
  
• Nutrients decreased in score whilst the grade remained ‘good’.
  
  
• Oxidised nitrogen (NOx) declined from ‘very good’ to ‘good’, particulate nitrogen (PN) remained ‘moderate’, and particulate phosphorus (PP) declined from ‘good’ to ‘moderate’.
  
  
• Chlorophyll a declined from ‘good’ to ‘moderate’ with a decrease in score from 80 to 54.
  
  
• Coral condition which remained ‘poor’, had a slight decrease in score mainly due to lag effects from impacts associated with Severe Tropical Cyclone (TC) Jasper in 2023-24.
  
  
• The coral cover indicator remained ‘poor’ with a slight improvement at Snapper North since TC Jasper, although this was offset by a decline in cover for the Low Isles which accounted for the impacts from TC Jasper, since the previous survey for the Low Isles occurred before the tropical cyclone.
  
  
• Coral cover for Snapper South sites remained zero, with no improvement since TC Jasper. Recovery of coral cover will depend upon the process of recruitment and growth of juveniles.
  
  
• The cover change indicator has declined to ‘moderate’, reflecting the reduced rates of recovery for Snapper North and the lack of recovery for Snapper South.
  
  
• The Macroalgae indicator was ‘good’ in 2023-24, when high mortality of macroalgae was caused by floodwater inundation, but the grade declined to ‘moderate’ in 2024-25 following an increase in macroalgae cover at Snapper North, and particularly rapid recolonisation of red species at Snapper South 5m.
  
  
• The juvenile coral indicator improved from ‘very poor’ to ‘poor’ due to the increase in juvenile density at the Low Isles, which offset the very low densities at Snapper Island sites.
  
  
• Overall seagrass condition remained in ‘moderate’ condition.
  
  
• Seagrass condition for Cairns Harbour meadows declined from ‘good’ or ‘very good’ condition in 2023-2024 (monitored prior to TC Jasper) to ‘moderate’ condition in 2024-2025. Species composition remained ‘very good’ for these three meadows – moderate scores were driven by declines in biomass or area.
  
  
• Seagrass condition at Green Island improved from ‘moderate’ to ‘good’ at both the intertidal and subtidal sites.
  
  
• Seagrass at the Low Isles sites remained ‘very poor’ for the seventh year, with resilience and % cover indicators ‘very poor’.

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