Using eDNA to assess how estuarine fish communities respond to consecutive extreme events of drought, bushfire, and flood

In the face of climate change, it is vital to gather baseline data to improve our limited understanding of the diversity and distribution of fish community composition in estuaries and how native Australian fishes respond to extreme weather events such as drought, fire, and flood. This project combines the
expertise of an interdisciplinary research team, recreational and First Nations fishers to conduct a pilot study of the largest fish survey in NSW estuaries using environmental DNA (eDNA). Historical eDNA samples were collected weekly by NSW Oyster Farmers over a 24-month period. This project will assess how the diversity and distribution of fish assemblages in three estuaries in NSW were impacted by consecutive extreme weather events of 2018-2020, including the hottest and driest drought on record, the black summer megafires and the first flood pulse of 2020. It will allow us to explore the impact of climate change, where warmer sea surface temperatures extend further south, resulting in the
tropicalisation and latitudinal range-shifts of fishes. Furthermore, recreational and First Nation fishers will conduct present-day follow-up eDNA sampling of fish communities in the three estuaries, and to reflect on observations during these consecutive extreme weather events. This will highlight the importance of involving citizen scientists in collecting samples, integrating their diverse knowledges to create a wholistic understanding, and to inform the expansion and design of long-term biomonitoring programs in estuaries. Findings will shape on ground conservation and management practises for estuarine fish communities in preparation for future extreme weather events.