5.5.4 Seagrass burial by organic and inorganic sediments under low light

Description

Seagrasses can be negatively affected by dredging-associated deterioration in water clarity due to suspended sediments and burial by the subsequent deposition of those sediments. The majority of studies investigating these impacts of dredging have focussed on each factor in isolation. Furthermore, past studies examining the effects of burial have not examined whether the nature of the sediment can affect the plant response, despite knowledge that organic-rich sediments can produce conditions unfavourable to seagrasses. This report presents findings from a controlled sediment burial experiment.

Aims

• To determine the effects of sediment burial using inorganic and organic-rich sediments under dredge-simulated conditions of severe light reduction on the growth and health of two seagrass species found in the northwest of Western Australia.
• Provide guidance and protocols for the application of the research outputs (e.g. influence of burial sediments on seagrass response relationships, sub-lethal and lethal bio-indicators and thresholds) to the prediction, assessment, monitoring and management of dredging programs in northwest Western Australia.