Fish and other ocean life may face risks associated with coal seam gas (CSG) mining, say scientists exploring the link between groundwater and coastal life.
Ten years after they discovered groundwater on the Australian mainland was seeping into the ocean, water scientists are trying to understand what it means for coastal ecosystems.
Professor Craig Simmons from the National Centre for Groundwater Research and Training, says it is possible contaminated groundwater could get into oceans.
The water flows into the ocean underground through old river channels that have since been buried, known as "wonky holes".
"If there's any contamination in the groundwater on the mainland and they intersect with one of these wonky holes, they're definitely going to take out the chemistry as well as the water," Prof Simmons said.
"It's certainly not impossible that something like that could happen. I've not heard of it yet but there's certainly nutrients that are taken into the ocean so there is that possibility."
During coal seam gas extraction, water, sand and chemicals are injected into the ground at high pressures.
The Commonwealth Scientific and Industrial Research Organisation has stated that fracking poses a low risk to groundwater quality through contamination and predicts groundwater levels will fall in some places.
Prof Simmons said his research colleague was convinced coastal ecosystems in some areas were strongly dependent on freshwater seepage but more work needed to be done. AAP