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Page last updated on 04-08-2025.
Monitoring in Cleveland Bay
Marine Water Monitoring
The Port of Townsville has deployed a number of real-time marine water monitoring buoys in Cleveland Bay. One monitor is located at a navigational channel marker in Cleveland Bay referred to as Pylon S2, and the second is located at Geoffrey Bay, Magnetic Island and was named Beagle by the Port of Townsville’s Community Liaison Group to reflect regional and port history. HMS BEAGLE was a survey ship that surveyed these waters first in 1841 and the naturalist Charles Darwin was aboard on the second voyage of the vessel, and this was his trip of discovery.
Buoy Marine Water Parameters
The marine water monitoring buoys measure marine water quality at approximately 1m below the water surface. Individual water quality sensors measure parameters including temperature, conductivity (EC) and turbidity. Each monitor has a mechanical wiper to prevent biofouling of the sensors. Sensors are calibrated according to manufacturer’s guidelines and changed out regularly to ensure data accuracy.
Temperature – the marine water buoys measure temperature in degrees Celsius (oC). Temperature is affected by ambient temperatures (summer vs winter), riverine inflows and tidal mixing (wave action). Water temperature is important in the functioning of aquatic ecosystems and can affect the diversity and distribution of marine organisms including seagrass, corals and fish.
Conductivity – the marine water buoys measure electrical conductivity, or conductivity for short (a measure of the saltiness of water) in microsiemens per centimetre (µS/cm). Conductivity in the ocean is typically in the range 50-55,000 µS/cm, however conductivity in Cleveland Bay can be affected by freshwater inflows in times of floods and cyclones. Aquatic ecosystems function within a typical conductivity range and changes outside of this can stress organisms.
Turbidity – the marine water buoys measure turbidity in Nephelometric Turbidity Units (NTU). The term Nephelometric refers to the way the instrument estimates how light is scattered by suspended particulate material in the water. The Nephelometer, also called a turbidimeter, has a photocell (similar to the one on your camera or your bathroom nightlight) set at 90 degrees to the direction of the light beam to estimate scattered rather than absorbed light. This measurement generally provides a very good correlation with the concentration of particles in the water that affect clarity.
Turbidity is caused by particles suspended or dissolved in water that scatter light making the water appear cloudy or murky. Increased turbidity in water decreases the amount of light that can penetrate below the surface. Light penetration is important for the health of ocean plants (like seagrass) and algae that live on some corals to make food (photosynthesis). Historical records show that turbidity occurs on average 220 days of the year for water depths up to 5 metres due to wind and current resuspension. This means the shallow areas of Cleveland Bay are naturally turbid for about two thirds of the year.
Raw data from the sensors is collected every 15 minutes via a data logger on the buoy and transmitted by mobile network to a data server. Data is then averaged over the hour and made available on the website. Raw data is reviewed for quality control purposes to flag data points that are related to faulty sensors, outside calibration ranges or outside of ranges compared to other nearby buoys/stations.
Marine water monitoring plans and the data from Cleveland Bay can be downloaded below.
Disclaimer: Whilst Port of Townsville Limited (Port) has taken care in the preparation of all information, neither the Port, any related body corporate of the Port nor any of their officers, employees, consultants, officers, advisors or agents gives any warranty, nor makes any representations (express or implied) as to the completeness, adequacy, suitability, quality or accuracy of this information. Users of this information do so at their own risk and are responsible for ensuring that the information meets their requirements for any proposed usage.
Seagrass Monitoring
Seagrasses are a key marine habitat species, and as plants are sensitive to water quality changes that reduce underwater light, it makes them ideal to monitor and understand the overall health of the marine environment in Townsville.
The Port of Townsville and James Cook University’s TropWATER team have partnered to survey seagrass in Cleveland Bay annually since 2007.
The annual boat and helicopter surveys assess the condition and species of more than 25,000 hectares of seagrass meadows in the Townsville region and track changes over time.
The 2024 annual seagrass survey results for Townsville and Cleveland Bay showed:
- The overall condition of seagrass across Cleveland Bay was ’poor’ at the end of 2024.
- Four of the 10 long-term monitoring meadows were in a satisfactory or better condition, while six were in poor or very poor condition.
- While an extensive seagrass footprint remained at the end of 2024, declines in the seagrass meadows above-ground biomass and/or area between October 2023 to October 2024 were recorded across most meadows and are explained by local environmental conditions.
- The observed decline in most seagrass meadows in recent years is attributable to a combination of simultaneous and successive system-wide meteorological influences including Tropical Cyclones (Jasper, December 2023 and Kirrily, January 2024), above average rainfall and river discharges, extreme temperatures/marine heatwaves and prolonged low light conditions.
- The fact seagrasses in Townsville still had satisfactory spatial coverage, good species composition and the presence of higher light requiring species in subtidal meadows provides a good foundation for future recovery.
Healthy Waters Partnership for the Dry Tropics has recently developed a StoryMap on the seagrasses of Cleveland Bay.
Healthy Waters Partnership for the Dry Tropics
Launched in 2019, the Healthy Waters Partnership for the Dry Tropics is an initiative made up of stakeholders from community, industry, education, science and government organisations. The Partnership produces an annual, independent regional report card on the status of our region’s waterways and associated habitats, as well as the social and economic benefits our waterways and Reef provides to the Townsville community.
Hosted by Port of Townsville, the Healthy Waters Partnership for the Dry Tropics is funded by the Australian and Queensland Governments and collaborating partners. The Partnership is independently chaired and supported by a management committee and two staff who oversee day-to-day operations.
The Report Card focusses on the health of the Townsville region’s freshwater, estuary and coastal waters that lead to the outer Greater Barrier Reef. The catchment area covers a land area of about 134,000km2 and 12,000km2 of sea area. It includes the greater Townsville area and extends north to Crystal Creek and south to Crocodile Creek (near Cape Cleveland). The marine area includes Cleveland Bay and Halifax Bay, Magnetic Island, the Palm Island Group, and offshore to the outer boundary of the Great Barrier Reef Marine Park.
The term “dry tropics” refers to the region which has an average rainfall range of 500 mm to 1000 mm per year. Most rainfall occurs over a few weeks during the summer months. The Dry Tropics region in Queensland is typically defined by the Burdekin River watershed and waterways north and south of Townsville.
Understanding the condition of our waterways and catchments is important for identifying which areas are healthy and others which may need improving. It is also important to determine and understand the potential impacts affecting our waterways. This information will help us track improvements over time and help decision-makers target investment where it is needed most.
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Useful Links:
- Healthy Waters Partnership for Dry Tropics https://drytropicshealthywaters.org/
- National Environmental Science Programme Tropical Water Quality Hub https://nesptropical.edu.au/
- Marine Monitoring Program https://www2.gbrmpa.gov.au/our-work/programs-and-projects/marine-monitoring-program
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Make Eye on the Reef https://www2.gbrmpa.gov.au/help/eye-on-the-reef
- AIMS Weather Observations for Cleveland Bay http://weather.aims.gov.au/#/station/3
- Seabreeze – weather and tide in Townsville https://www.seabreeze.com.au/weather/wind-forecast/qld-far-north#F3TOWN
- Tide Tables https://www.msq.qld.gov.au/Tides/Tide-tables.aspx
- WillyWeather – weather and tide in Townsville https://tides.willyweather.com.au/qld/northern/townsville.html
- Wave monitoring https://www.qld.gov.au/environment/coasts-waterways/beach/waves-sites/townsville
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