TWQ dredging impact surveys dredging research helps set environmental trigger levels at Port of Townsville expansion project

Cutting-edge underwater monitoring technology has enabled NESP TWQ Hub researchers to develop models to help decision-makers assess the risk posed to inshore corals by port dredging.

The project team, led by Dr Ross Jones at the Australian Institute of Marine Science (AIMS), collected a wide variety of water condition data in close proximity to a working suction-hopper dredge at Cleveland Bay near Townsville.

Light is essential for corals and the researchers used a variety of methods including multi- and hyper-spectral light sensors to describe how water cloudiness (turbidity) caused by dredging and storms changes the quantity and the quality of underwater light.

The data was then used to develop highly accurate simulations at the Australian Institute of Marine Science’s SeaSim aquarium facility, and the responses of several species of inshore coral and sponges examined over extended periods.

The results and analyses in the project’s recent final report have provided a means of assessing whether the changes in underwater light associated with dredging could have biological effects – and hence to reactively manage the dredging activity.

Melinda Louden at Port of Townsville said the recommendations from Dr Jones and his team would be implemented as the Port of Townsville Expansion Project proceeded.

“Port of Townsville has adopted the findings from the report produced by Ross Jones and the NESP TWQ Hub,” she said.

The following have been incorporated into the current monitoring program for the Port of Townsville capital dredging project which is at Stage 1 of the long-term 30 year Townsville Port Expansion Project:

  • Measurement of light and use of multispectral submersible PAR sensors have been incorporated into all sites and will form the basis of trigger levels.
  • Surface light based monitoring in proximity to the underwater monitoring sites has been implemented; and
  • We have incorporated the re-designed deposition sensors in our monitoring program as well.

“A range of further recommendations will be incorporated into the development of relevant site specific trigger levels and early warning indicators for this project over the next 12 months. Development of these will have input and oversight from the project Independent Technical Advisory Committee and be submitted to regulatory agencies as part of Port of Townsville’s approval conditions.

Recommendations from this work will be considered and incorporated into future programs and monitoring undertaken by the Port of Townsville and will be incorporated into risk assessments and scheduling for our routine dredging.”


Photo: Ross Jones


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