New study is investigating how bushfires affect estuaries on Kangaroo Island

New research conducted under the Bushfire and Natural Hazards CRC’s funding for quick response program is investigating the effects of the January 2020 bushfires on estuarine ecosystems of Kangaroo Island.

Led by Prof Bronwyn Gillanders and Dr Patrick Reis Santos from the University of Adelaide, Analysis of the effects of the January 2020 bushfires on the estuarine systems of Kangaroo Island is evaluating the immediate and longer term impacts of bushfires on estuarine water quality and its implications to estuarine fish.

The 2020 bushfires on South Australia’s Kangaroo Island were the largest in the island’s recorded history, with over 200,000 hectares and more than 40% of the island burnt. The impacts of these fires are not confined to the terrestrial landscape and have had detrimental impacts on the island’s aquatic systems. Despite the ecological importance of estuaries, including as nursery habitats for juveniles of numerous fish species, impacts of bushfires in estuaries have not previously been explored.

Prof Gillanders and Dr Reis Santos undertook post event field data collection, evaluation and monitoring to follow ecosystem changes and understand the processes that drive resilience and the potential recovery of estuarine ecosystems. The researchers travelled to Kangaroo Island earlier this year to collect water and fish from targeted estuaries: those directly affected by bushfires in surrounding areas and catchments (Western Middle, Stun’Sail Boom, Harriet and Eleanor), those with no direct fire impacts but parts of the catchment burnt (Cygnet), and estuaries with no direct bushfire impacts (Chapman).

The research will continue to assess:

• impacts on fish species diversity, abundance and assemblage structure
• changes in water quality including fire-induced chemical contamination by heavy metals and its effects on fish
• changes in estuarine water quality parameters
• the mobilisation and fluxes of contaminants released from bushfires into aquatic systems and potential long term contamination of hydrological reservoirs
• implications of bushfires to estuarine ecosystem functioning and coastal marine fish populations that depend on estuaries.

Preliminary findings show a range of post-fire conditions, including heavy sedimentation, turbidity and poor water quality will likely compromise survival and fish abundance in estuaries. Further analysis of these results will lead to predicting future impacts of bushfires on Kangaroo Island, and to the development of potential mitigation or adaptation measures.

This research is ongoing and recurring sampling will be essential to assess changes over time and characterise the short and longer term impacts of last season’s bushfires on the estuarine systems of Kangaroo Island. Final results will be used to underpin biodiversity conservation, adaptation and sustainable management strategies to support the governance that lies ahead.

Access the summary of preliminary findings here.