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Primary producer response to dredging


Defining thresholds and indicators of primary producer response to dredging related pressures

Other Details: 

Dredging Science Program: Theme 5
Location:  Pilbara and Kimberley
Project Leader: Paul Lavery, ECU
Telephone: 6304 5687


Effects of dredging on seagrass_Review_WAMSI DSN Report 5.1.1_McMahon et al 2017_FINAL

Seagrass Biogeography_WAMSI DSN Report 5.1.2_McMahon et al 2017_FINAL

Seagrass Genetics_WAMSI DSN Report  5.2_McMahon et al 2017_FINAL

Seagrass Natural Dynamics_WAMSI DSN Report 5.3_Vanderklift et al 2017_Final

Seagrass Recovery Mechanisms_WAMSI DSN Report 5.4_Vanderklift et al 2017_FINAL

Determining light stress thresholds for seagrass_WAMSI DSN Project 5.5.1_Statton et al 2017_FINAL

Seagrass sediment burial_WAMSI DSN Project 5.5.2_Statton et al 2017_FINAL

Seagrass Light Frequency Reduction Experiment_WAMSI DSN Project 5.5.3_Statton et al 2017_FINAL

Seagrass burial by organic and inoganic sediments under low light_WAMSI Project 5.5.4_Statton et al 2017_FINAL



This project meets the needs of the State Government and industry to improve their understanding of how key primary producers are affected by dredging-related pressures.

There is almost no knowledge of how primary producers in the NW of Australia will respond to the environmental changes produced by dredging. Consequently, it is difficult to predict and then manage the impacts of dredging on these critical habitats with an acceptable level of certainty.

This project will improve our understanding of how seagrasses are affected by dredging activities, and will apply that understanding to better prediction of impacts and management of dredging.

A combination of laboratory and field experiments and field surveys will determine the levels of dredging-related pressures (or ‘thresholds’) that produce the earliest observable effects, sub-lethal effects and lethal effects on two species of seagrasses considered most ecologically important in the NW. The research will also determine the capacity of those seagrasses to recover from dredging-related stress.

The research will focus on two of the most significant stresses produced by dredging: the reduction in light availability to plants; and the smothering of seagrass and algae as suspended sediments settle.

The responses of seagrasses to dredging-related pressures will be characterised in order to identify plant or meadow features that can indicate the duration and the intensity of dredging-related stress that seagrasses have suffered. These indicators can be applied in monitoring programmes to identify stress and trigger management responses.

The research will enhance the capacity of government and industry to predict the impacts on dredging on key benthic primary producer ecosystems and, in so doing, improve the certainty and timeliness of key approvals and regulatory processes. It will also improve the capacity to manage the impacts of dredging through improved design of monitoring and management frameworks.


McMahon K et al. Genetic variability within seagrass and implications for recovery potential 2017 WAMSI Research Conference (audioPresentation slides

Kendrick G et al. Thresholds and indicators of seagrass response to dredge pressures 2017 WAMSI Research Conference (audioPresentation slides

Strydom S et al. The influence of light quality on seagrasses 2017 WAMSI Research Conference (audioPresentation slides


Wu P, Mengersen K, McMahon K, Kendrick G, Chartrand K, York P, Rasheed M, Caley J (2017) Timing anthropogenic stressors to mitigate their impact on marine ecosystem resilience. Nature Communication doi:10.1038/s41467-017-01306-9

Wu P, McMahon K,  Rasheed M, Kendrick G, York P, Chartrand K,  Caley J,  Mengersen K (2017) Managing seagrass resilience under cumulative dredging affecting light: Predicting risk using dynamic Bayesian networks. Journal of Applied Ecology DOI: 10.1111/1365-2664.13037

Strydom S, McMahon K, Kendrick G, Statton J, Lavery P.(2017) Seagrass Halophila ovalis is affected by light quality across different life history stages. Marine Ecology Progress Series DOI: 10.3354/meps12105

Strydom S, McMahon K, Lavery P. (2017) Response of the seagrass Halophila ovalis to altered light quality in a simulated dredge plume. Marine Pollution Bulletin


Saving seagrasses from dredging - new research finds solutions (UQ 6/11/17)