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News no tags 29 Jan 2020

Statement on Australia's Bushfire crisis

Potential impacts of bushfires on our Marine Environment

 

For specific enquiries or interview requests on bushfire impacts relating to marine ecosystems and environment please contact media@sims.org.au

Contaminants and Toxic Effects of Ash to Marine Ecosystems

 

Dr Katherine Dafforn, Senior Lecturer in Environmental Science at the Macquarie University Marine Research Centre, and Deputy Director of SIMS’ Sydney Harbour Research Program:

 

“Bushfire ash contains a number of different constituents including carbon and essential nutrients, but depending on the location of the fires can also contain high concentrations of contaminants such as metals. At low levels these can be beneficial to an ecosystem by stimulating growth, but if levels are too high then there might be toxic effects.”

“Most research has focused on the impact of bushfires on land and so we actually don’t know a lot about the impacts of bushfire ash on waterways. Certainly bushfires remove vegetation which increases soil mobilisation and so we’d expect more soil runoff into waterways resulting in murkier waters. This increased sediment load and reduced light in the water column could have impacts on productivity. Similarly metals in high concentrations can impact on marine life by causing death through toxicity or affecting reproduction and growth rates.”

“Some research has also shown that fire mobilises mercury in runoff and the fluctuating temperatures in fires can cause methylation - higher concentrations of mercury have been found in fish from lakes in burned catchments compared to reference catchments.”

 

Potential Impacts of Bushfire Smoke and Ash to Sydney and Surrounds

 

Assoc. Prof Shauna Murray, core member of the Climate Change Cluster, leader of the Seafood Safety: Marine Algal Biotoxins research program at UTS, and team leader of the Marine Microbial Biotoxins Facility at SIMS:

 

“An ash layer might shade the water column, and lead to an inability of phytoplankton to access sunlight. This might lead to die offs of phytoplankton, which in turn might lead to a low level of oxygen in the water. A low level of oxygen can lead to the deaths of marine life, ie fish, as they basically suffocate.”

“The addition of ash might be lead to a large nutrient input to the water column. This could lead to greatly increased growth of certain ‘weed’ microalgal species. This is called a “harmful algal bloom” (HAB), and they are increasingly common around the world. Some HABs are directly caused by nutrient inputs, ie fertilisers. An addition of ash might have this same effect.”

 

Drought and Fire Impacts in Estuaries

 

Associate Professor William Glamore, Water Research Laboratory, School of Civil and Environmental Engineering, UNSW Sydney. Member of SIMS Scientific Advisory Committee.

 

“The bushfires are a symptom of the prolonged drought impacting our coastal communities. In addition to the fire impacts, the drought has also generated a number of additional effects. While the issues of turbidity, ash and water scarcity have been well covered, the coastal drought has helped generate an unprecedented volume of acidic groundwater.

Initially created by the drainage of coastal floodplains, via Commonwealth supported programs in the 1960-70s, these acidic sediments are prevalent throughout coastal NSW. If left unmanaged, the large volume of acidic groundwater will leach into coastal ecosystems across our marine estate. Once released, the acidic groundwater, with high concentrations of heavy metals, becomes a toxic plume that is transported with the tide throughout an estuary. Previous large events have followed floodplain rainfall and resulted in major fish kills over entire estuaries, such as the Richmond River in 2001 and 2008. Other impacted systems include the Tweed, Clarence, Macleay, Manning, Hastings, Hunter, Shoalhaven and indeed every large coastal floodplain in NSW.

Due to the prolonged drought and the likelihood of future rains, it is anticipated that a major acid event is imminent. The acidic plumes are typically associated with ‘black water’, (i.e. very low dissolved oxygen levels), which can lead to marine animals dying from asphyxiation. This is likely to be exacerbated by large volumes of ash that will consume oxygen in the water. In combination, the toxic metals, acidic water, ash load, drought stressed ecosystem and high turbidity present significant risks to our marine/estuarine estate.

Urgent action is required to restore high priority acidic sites to reduce acid generation, limit acid discharges and recreate intertidal ecosystems that sequester carbon.”

 
Unprecedented Fires require Crucial Research for Future Monitoring of Coastal Environments

 

Combined statement from SIMS’ Postdoctoral Group, including Dr Paloma Matis, Dr Maria Vozzo, Dr Fabrice Jaine, Dr Michael Doane, Dr Hayden Schilling & Dr Nina Schaefer.


“The impacts of these fires will likely be far reaching and influence all levels of the coastal marine ecosystem. Erosion and subsequent run-off of burned land-based material will result in massive inputs of carbon and other nutrients into the marine environment. This will likely ramp up productivity, including microalgal and cyanobacterial blooms. In the event of blooms, oxygen levels will be reduced and this will affect all levels of life, ranging from bacteria through to fish communities. In addition, large amounts of run-off will likely carry heavy metals, which are naturally occurring in the sediments, but can become toxic when shuttled into the food web through mobilization by microbial organisms (i.e. bacterial metabolism). High inputs of ash into the surrounding environment could shade some areas of the coastal region (some beaches already have 'black' waves due to enormous amount of ash in the water), reducing sunlight into the water column.

Should this reduced light availability be prolonged this could impact important sub-tidal habitats including seagrass and kelp beds, which provide refuge and nursery habitats for commercially and recreationally important species, improve water quality and provide protection to coastal zones from erosion.

The extent of these fires is unprecedented and therefore our predictions may in fact underrepresent the extent to which coastal ecosystems will be affected in NSW. Furthermore, research into the impacts and continued monitoring of coastal environments is crucial going forward.”