Project

About the project

Description

Through a combination of laboratory and field experiments and field surveys, 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 northwest of Western Australia. The research also determined the capacity of those seagrasses to recover from dredging-related stress.

The focus was 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 has been 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 programs 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.

Aims

  • To improve our understanding of how seagrasses are affected by dredging activities, and apply that understanding to better prediction of impacts and management of dredging.
  • To determine the capacity of seagrasses to recover from dredging-related stress.

Outcomes

Project News 

Research Articles

Hernawan U, Van Dijk K, Kendrick G, Feng M, Biffin E, Lavery P, McMahon KM (2017) Historical processes and contemporary ocean currents drive genetic structure in the seagrass Thalassia hemprichii in the Indo-Australian Archipelago. Molecular Ecology DOI:10.1111/mec.13966

McMahon K, Evans R, van Dijk K, Hernawan U, Kendrick G, Lavery P, Lowe R, Puotinen M, Waycott M (2017) Disturbance Is an Important Driver of Clonal Richness in Tropical Seagrasses  Frontiers in Plant Science doi: 10.3389/fpls.2017.02026

Statton J, McMahon K, Lavery P, Kendrick G.A. (2018) Determining light stress responses for a tropical multi-species seagrass assemblage. Marine Pollution Bulletin 128:508-518 DOI:10.1016/j.marpolbul.2018.01.060

Strydom S, McMahon K, Kendrick GA, Statton J, Lavery PS (2018) Short-term responses of Posidonia australis to changes in light quality. Frontiers in Plant Science. Vol 8 17 Jan 2018 doi:10.3389/fpls.2017.02224

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 doi.org/10.1016/j.marpolbul.2017.05.060

Presentations

Genetic variability within seagrass and implications for recovery potential (2017 WAMSI Research Conference)

Thresholds and indicators of seagrass response to dredge pressures (2017 WAMSI Research Conference)

The influence of light quality on seagrasses (2017 WAMSI Research Conference)

Primary Producer Response to Dredging Related Pressures (Centre for Marine Ecosystems Research Symposium 2017)

The influences of light quality on seagrasses (Centre for Marine Ecosystems Research Symposium 2017 )

Thresholds and indicators of seagrass response to dredging pressures (Centre for Marine Ecosystems Research Symposium 2017 )

Recovery dynamics of northern Australian seagrasses (Centre for Marine Ecosystems Research Symposium 2017)

Details

Program: Dredging Science Program

Completed: March 2019

Location: Pilbara and Kimberley

Project Leader: Prof Paul Lavery (ECU)

Email: p.lavery@ecu.edu.au

Publications

Theme 5 Synthesis Report

Theme 5 Reports Combined