2011/772 Impacts and predictive modelling of coastal upwelling on the South Australian oyster industry

By Clinton Wilkinson

Independent collectors have been collecting water samples within harvesting areas for over 10 years. These samples have been provided to the South Australian Seafood Quality Assurance Program for testing and record keeping. The information is primarily used to identify the presence of and levels of toxic dinoflagellates in the water column, which may be filtered by oysters and then cause sickness (or worse) in humans if consumed. The presence of other phytoplankton is also monitored. The data has not been compiled, or studied to determine any correlations with weather patterns, growth / condition / health of oysters or unexplained mortalities.

This project was needed by the South Australian oyster industry, to understand how the presence of phytoplanton (or lack thereof) varied with weather conditions or mortality events. This will then inform growers of best farming times, provide a predictive ability to put product in the water and give some certainty as to mortality events (if in fact presence or lack of dinoflagellates has an impact).

This project's objectives were to:

1. Determine spatial and time patterns of phytoplankton presence (including toxic species) for individual harvesting areas.
2. Determine the relationship between phytoplankton presence with upwelling events and other environmental parameters.
3. Determine the relationship of phytoplankton presence with oyster growth, condition, health and mortalities.
4. Develop a predictive tool / model for oyster farmers to use for management practices and strategies.
5. If appropriate, develop a user guide to using the predictive tool / model, which may form part of the software for the predictive tool.
6. Deliver a workshop for oyster farmers based on regions in which harvesting areas are located.