ANSWER 1

Written response:

The South Australian bloom has had a devasting impact on the environment and the marine life in the impacted zones. It is caused by mixed species of harmful algae, including Karenia species, likely to cause harm through multiple mechanisms (e.g. in marine life through gill damage and oxygen depletion, toxic impacts on cells, and in humans through respiratory and eye reactions, or through consumption of neurological toxins). The algal species involved have yet to be confirmed.
At present the bloom is confined to specific zones in South Australia and is being held in these zones by the prevailing winds and currents. The South Australian government website gives the latest updates and predictions related to the positioning of the bloom. The ability to spread outside this area is dependent on a change to the current conditions and whether the causative species will continue to thrive in the ocean between South Australia and Tasmania (largely unknown until the species can be identified).
Some harmful algae are transferred through ship ballast water or in association with fouling organisms. Karenia cells are very fragile, and whilst it is unlikely they could survive long in ballast water, it is possible that they could survive for the short periods that occur in domestic shipping routes (see Burkholder et al. (2007) for survival of HAB in ballast water; Wetsteyn and Vink (2001) for identification of Karenia in ballast water and Rosa et al. (2013) for HAB transfer on biofouling ascidians). Whether they would form a bloom in Tasmanian waters on arrival depends on the state of the cells if they get here, and the whether the Tasmanian seawater conditions at the time of arrival support bloom initiation. Many knowledge gaps prevent a full risk assessment for this transfer.
Most Karenia species are widespread, and many have been found in Tasmania in the past, some of which have been involved in fish-kills. At present there are no mitigation measures for large scale blooms like the one occurring in South Australia, so it is difficult to prevent such events. Monitoring of phytoplankton exists around aquaculture sites in Tasmania and can help with early warning. Preparedness measures also include understanding where expertise and capability exists in the State, identifying government agencies responsible for monitoring and managing large scale events, and developing operating procedures and lines of communication ahead of time. These actions are currently occurring in Tasmania, for Karenia and other potentially harmful species.  

Burkholder, J. M., Hallegraeff, G. M., Melia, G., Cohen, A., Bowers, H. A., Oldach, D. W., Parrow, M. W., Sullivan, M. J., Zimba, P. V., Allen, E. H., Kinder, C. A., & Mallin, M. A. (2007). Phytoplankton and bacterial assemblages in ballast water of U.S. military ships as a function of port of origin, voyage time, and ocean exchange practices. Harmful Algae, 6(4), 486-518. https://doi.org/https://doi.org/10.1016/j.hal.2006.11.006
Rosa, M., Holohan, B. A., Shumway, S. E., Bullard, S. G., Wikfors, G. H., Morton, S., & Getchis, T. (2013). Biofouling ascidians on aquaculture gear as potential vectors of harmful algal introductions. Harmful Algae, 23, 1-7. https://doi.org/https://doi.org/10.1016/j.hal.2012.11.008
Wetsteyn, L. P. M. J., & Vink, M. (2001). An investigation into the presence of plankton organisms in the ballast water of ships arriving in Dutch ports, and the survival of these organisms in Dutch surface and port waters (Report RIKZ/2001.026).