Development of a molecular biology toolkit to monitor dredging-related stress in Zostera muelleri ssp. capricorni in the Port of Gladstone: interim report

Schliep, M., Rasheed, M., Bryant, C., Chartrand, K., York, P., Petrou, K., and Ralph, P. (2014) Development of a molecular biology toolkit to monitor dredging-related stress in Zostera muelleri ssp. capricorni in the Port of Gladstone: interim report. Report. James Cook University, Cairns, QLD, Australia.

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[Extract] The Port Curtis Western Basin Dredging and Disposal Project (WBDDP) was identified as posing a high level of environmental risk to marine habitats in the Gladstone area, particularly to seagrass meadows. The process of marine dredging elevates suspended solids within the water column, reducing light availability to marine habitats, and can result in high levels of stress and mortality to benthic primary producers such as seagrasses (Erftemeijer et al. 2006). Minimum light requirements (MLR) for seagrass differ among species and seasons, yet it is well established that changes in the availability of light remains the primary factor affecting seagrass distribution, abundance and productivity (Duarte et al. 1997; Vermaat et al. 1997; Hemminga & Duarte 2000; Erftemeijer et al. 2006; Ralph et al. 2007). Since 2009, James Cook University (JCU and previously the Department of Agriculture, Fisheries and Forestry, DAFF) and the University of Technology Sydney (UTS) have been actively undertaking seagrass research to assess seagrass health during the WBDDP. The primary aim of this research has been to address one of the Queensland Coordinator General's conditions on the project to develop a water quality monitoring program incorporating a) minimum light requirements of local seagrasses and b) the use of sub- lethal indicators of seagrass light stress to assess seagrass condition should seagrass light requirement triggers be exceeded. In May 2012, DAFF (now JCU) delivered a report that documented a light-based management approach to protect Gladstone seagrasses from dredging impacts associated with the WBDDP. Through a multifaceted research program spanning over two years, Chartrand et al. (2012) determined that Z. muelleri the dominant species in Gladstone harbour requires between 4.5 and 12 mol quanta m ̄2 d ̄1 during the growing season over a minimum period of two weeks to survive. Trends in benthic irradiance and seagrass condition at permanent survey sites showed that, in general Z. muelleri consistently received greater than 6 mol m ̄2 d ̄1 over a two week rolling average at most locations in the harbour during the growing season (when seagrass remained stable or increased in abundance). This value was therefore trialled as a trigger for management actions as part of an adaptive light based approach to manage potential impacts on seagrasses during Western Basin developments. While we have empirically established that 6 moles of irradiance per day is required to maintain a seagrass meadow in Gladstone Harbour, we do not have the ability to accurately predict over what period of time this quantity of light energy is required. While photophysiological and stable isotope (13C/15N) studies showed promising results for detecting changes in the seagrass health when exposed to dredging events (Chartrand et al. 2012), these methods lacked the temporal resolution to function as a sub-lethal stress indicator. The current focus of research is on a genetic approach which looks at changes in expression level of genes that respond when light limitations cause a change in the overall health of the plant. The specific aim of this research is to develop a fast and accurate RT-qPCR-based seagrass health monitoring system to provide a sub-lethal indicator for stress linked to managing dredging impacts. This new biomarker can be assessed when light falls below the required value in a light-based approach to dredge management. Such a biomarker will allow for robust and defendable decisions to be made on the health of seagrass potentially impacted by dredging before mortality symptoms become apparent. This interim report outlines progress on the project to date. The report is divided into two sections to describe progress on a) the laboratory development program and b) the field/laboratory validation program.

Item ID: 45752
Item Type: Report (Report)
Keywords: Zostera muelleri; seagrass resilience; sub-lethal indicator; light stress; dredging; molecular toolkit; Port Curtis; Gladstone Harbour
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A Report for Gladstone Ports Corporation Limited (GPCL). Report No. 14/08

Funders: Gladstone Ports Corporation Limited
Date Deposited: 20 Sep 2016 03:32
FoR Codes: 06 BIOLOGICAL SCIENCES > 0604 Genetics > 060405 Gene Expression (incl Microarray and other genome-wide approaches) @ 60%
06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060705 Plant Physiology @ 40%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 100%
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