Project Number # 4110-17
Project Leader: David Workman
Stable isotope ratios (nitrogen and carbon) can be used to infer the dominant source of nutrients to aquatic systems. Wastewater from the Edgeworth WWTP is distributed locally for commercial use, predominantly in a coal washery and a golf course. Both are adjacent to Cockle Creek, a tributary of Lake Macquarie. A previous study has detected the presence of enriched 15N isotope signature at the mouth of Cockle Creek, suggesting anthropogenic nitrogen in the system. Mangrove leaves, with a leaf tissue turnover rate of 1.5 to 3 years, are to be used to provide a long-term snapshot of dominant nutrient source. Mangrove pneumatophore epiphytes, which cycle nutrients on a temporal scale of days to weeks, will be collected to determine a more short-term picture of nutrient source. Repeated sampling via active deployment of mangrove pneumatophores throughout the year will also provide an idea of seasonal or pulse (eg storm event) impacts. Results will be displayed using maps of spatially interpolated stable isotope data to determine the dominant nutrient sources in Cockle Creek.
Supervisors: Dr Troy Gaston [University of Newcastle] and Dr Louise McKenzie [Hunter Water Corporation]