Fish and aquatic species play a vital role in global food security by providing nearly 17% of animal protein eaten by people. However, freshwater and marine aquatic ecosystems that sustain aquaculture and fisheries are undergoing significant changes as a result of global warming of our atmosphere and oceans with projections suggesting that these changes will be heightened in the future (Bahri et al., 2018). It is estimated that global marine primary production (ie phytoplankton) which underpins the health and sustainability of all marine ecosystems will decline by 6 +/- 3% by 2100 (Bahri et al., 2018). This decline in primary productivity will result in key vulnerabilities in aquatic food production that contribute to global food security. Climate-driven changes in temperature, precipitation, ocean acidification, incidence and extent of hypoxia and sea level rise, amongst others, are expected to have long-term impacts in the aquaculture and fisheries sectors at multiple scales (Bahri et al., 2018, Fulton et al., 2020).

Australia’s marine environment is changing faster than at any other period in recorded history (Fulton et al., 2020). In the last 100 years, Australia's oceans have warmed by 1C and there are identified hotspots located in southeast and southwest Australia which have warmed by 2C (Hobday et al., 2018). The surface sea temperatures around Australia are expected to increase by another 1 to 2C in the north and 2 to 5C in the south over the next 100 years (Hobday et al., 2018). While the warming is predicted to continue, the specific mixes of atmospheric and ocean current patterns around Australia mean the magnitude of climate change will differ place-to-place, and different aquaculture and fisheries and sectors will face different challenges (Fulton et al., 2020).

Biological and ecological impacts of climate change on aquatic ecosystems include shifts in food resources, habitat availability and fluctuations in species distributions (Bahri et al., 2018, Fulton et al., 2020). The FAO (Bahri et al., 2018) have identified that climate change may also bring increased risks for aquatic animal health (e.g., by changing the abundance and virulence of pathogens or the susceptibility of the host to pathogens and infections) and food safety concerns (e.g., faster growth rates of pathogenic marine bacteria, or the incidence of parasites and food-borne viruses).

The project proposed will use a risk analysis framework applied at the sector-level to address the change in the risks of infectious diseases in Australian aquaculture and fisheries industries due to climate change. The project outcomes will identify and prioritize the risks from infectious diseases under the future climate scenarios. This project falls under the research priority to address sector-level mitigation strategies to support strategies for disease preparedness, biosecurity, and border protection. The project outcomes will assist industries in preparing risk mitigation strategies to build resilience and sustain productivity in Australia’s aquaculture and fishery industries.

References
Bahri, T., Barange, M., Moustahfid, H. 2018. Chapter 1: Climate change and aquatic systems. In Barange, M., Bahri, T., Beveridge, M.C.M., Cochrane, K.L., Funge-Smith, S., Poulain, F. (Eds), Impacts of climate change on fisheries and aquaculture: synthesis of current knowledge, adaptation and mitigation options. FAO Fisheries and Aquaculture Technical Paper No. 627. Rome, FAO, pp. 1-18.

Fulton EA, van Putten EI, Dutra LXC, Melbourne-Thomas J, Ogier E, Thomas L, Murphy RP, Butler I, Ghebrezgabhier D, Hobday AJ, Rayns N (2020) Adaptation of fisheries management to climate change Handbook, CSIRO, Australia.

Hobday, A.J., Pecl, G.T., Fulton, B., Pethybridge, H., Bulman, C., Villanueva, C. 2018. Chapter 16: Climate change impacts, vulnerabilities and adaptions: Australian marine fisheries. In Barange, M., Bahri, T., Beveridge, M.C.M., Cochrane, K.L., Funge-Smith, S., Poulain, F. (Eds), Impacts of climate change on fisheries and aquaculture: synthesis of current knowledge, adaptation and mitigation options. FAO Fisheries and Aquaculture Technical Paper No. 627. Rome, FAO, pp. 347-362.

Vibrio parahaemolyticus can live in sediments and waters year-round and generally proliferates in the water column when water temperatures are greater than 14degC. V. parahaemolyticus are rarely isolated from seawaters below 10degC, though some cold-tolerant strains have been isolated overseas. The concentration of V. parahaemolyticus in the water column increases as the water temperature increases. Oysters naturally accumulate and depurate V. parahaemolyticus through filter-feeding, but once oysters are no longer underwater depuration can no longer occur and V. parahaemolyticus levels increase quickly unless the oysters are less than 10degC. Recent outbreaks in South Australia have been very unusual in that they have occurred in winter-spring. Other environmental factors including salinity, chlorophyll and turbidity have also been linked to vibrio prevalence, but relationships are inconsistent. Internationally some growing areas have established relationships between V. parahaemolyticus and other environmental parameters such as suspended matter, chlorophyll a and dissolved organic carbon, although this varies between areas and is not consistent.

Little is known around why outbreaks have begun occurring in Australia and Vibrios are an increasing risk to commercially produced oysters in Australia. The prevalence of vibriosis is globally linked to the effects of climate change, aging populations, dietary changes and improved detection methods. It is vital that all available relevant environmental data associated with these recent outbreaks is recorded and made available for future interrogations. The identification of data gaps and tools that could be used to identify and assess potential vibrio risk factors may help guide where additional effort is required to assist future understanding of this complex and emerging food safety issue in Australia. This project is important to help defend current demand, consumer trust and safety in oysters.