Gladstone Ports Corporation is supporting and assisting the development of a world leading seagrass health assessment monitoring program to protect seagrass in the Gladstone harbour.
Western Basin Dredging and Disposal Project (WBDDP) Marine Scientist Dr Daniel Spooner said as part of conditioned requirements of the Queensland Coordinator General, research to reveal light requirements for seagrass species in the Western Basin should be part of the future water quality monitoring program.
The Department of Agriculture, Fisheries and Forestry (DAFF) and their research partners at the University of Technology Sydney (UTS) have been actively undertaking seagrass related research in the Gladstone harbour to address seagrass health during the (WBDDP).
“While initial experiments assessed three of the species found in Port Curtis, efforts were focused on Zostera capricorni, the dominant species in distribution, biomass and density in the Gladstone port and the species with the highest light requirement,” Dr Spooner said.
“In May 2012, DAFF delivered a report that documented a light-based management approach to protect Gladstone seagrasses from dredging impacts associated with the WBDDP.”
Studies were conducted by DAFF from November 2009 to December 2010 to simulate the effects of a dredge-related reduction in light from increased turbidity over a seagrass meadow and to establish an initial range of light required for local seagrass survival.
“The management plan and trigger levels were based on findings from two years of seagrass research in the Gladstone harbour directed at establishing the required light levels for local seagrass survival,” Dr Spooner explained.
Dr Spooner said results of these studies established initial light requirements during the growing season (1July to 31 January) for Zostera capricorni,were somewhere in the range from 4.5 to 12 mol/m2/day.
“Further investigations led to refining this light trigger value to 6 mol/m2/day over a rolling two week average, under which management actions and alerts are proposed to ensure appropriate steps are taken to mitigate seagrass declines.”
This requirement of light is based on measuring the total amount of light reaching the seagrasses and averaging the last 14 days.
DAFF and experts from UTS have also been working towards delivering outputs that will help satisfy the Queensland Coordinator General’s condition for the use of sub-lethal indicators (detecting stress before actual declines occur) of seagrass light stress to assess seagrass condition should seagrass light requirement triggers be exceeded.
Dr Spooner said the current focus is on developing a genetic technique that is capable of rapidly assessing seagrass health to regulate a response to light stress.
“Early signs for this work are positive and GPC has recently agreed to continue supporting this work in the hope of developing a world leading rapid seagrass health assessment tool.” Dr Spooner said.
“GPC will now undertake a six week trial of this approach. If successful this light based approach will be integrated into the current turbidity management plan to become a dual water quality management approach.”
Dredging Today Staff, June 27, 2012; Image: westernbasinportdevelopment