Atlantic Salmon Aquaculture Subprogram: characterising benthic pelagic interactions in Macquarie Harbour - organic matter processing in sediments and the importance for nutrient dynamics
University of Tasmania (UTAS)
Strategic growth for the Tasmanian Salmonid Industry over the next decade is contingent upon ecologically sustainable development in Macquarie Harbour. In coastal bays and estuaries, it is well known that sediment water column interactions are a major driver of ecosystem condition and health. A key knowledge gap in Macquarie Harbour is a lack of ecological data on the capacity of sediments to process organic matter and nutrients and the influence on bottom waters, particularly in response to increased loads associated with expanded farming. This was acknowledged in the EIS for industry expansion in Macquarie Harbour prepared by the Proponent (the three companies growing salmonids in Macquarie Harbour; Tassal, Huon Aquaculture and Petuna Aquaculture). The work proposed in this study feeds directly into the adaptive monitoring and modelling approach adopted to support decision making for marine farming expansion in Macquarie Harbour, reducing the uncertainty in the environmental model, particularly with respect to bottom water predictions. This will be achieved via the collection of empirical process data and re-calibration and validation of sediment water column interactions in the environmental model. A limited understanding of sediment-water column processes is often lamented in other regions where ecosystem/biogeochemical model outputs are used to help guide environmental management decisions (e.g. trigger levels in the Channel/Huon), and as such, this research is likely to have much broader R & D applications.
1. Quantify sediment water column nutrient fluxes at both the farm (local) and harbour (regional) scales
2. Generate sediment nutrient and dissolved oxygen respiration maps of Macquarie Harbour, including the release of nutrients from deposited farm waste
3. Calibration of sediment water column interactions in the Macquarie Harbour environmental model using process information from 1 and 2 above
4. Identify ecologically relevant and practical indicators of key ecosystem processes