Acid creek eats oysters and profits
A BALLINA oyster grower says the water in North Creek has become so acidic that it is destroying his oysters.
Geoff Lawler from Steinhardt's Oysters has been growing oysters in the creek since 1989, but he said he had recently noticed holes in the shells.
"We went out to do some testing to find out what was going on, and up around Ross Lane we were getting some really low pH readings," he said. The pH is a measure of the acidity - the lower the number the more acidic.
"There's a drain in the Ballina Nature Reserve which was decommissioned, but now it has been vandalised and someone has removed very large rocks from there.
"The pH was at 3.6 during some of our tests."
To give you an idea of how acidic that is, a pH of 3.6 is somewhere between the acidity level of vinegar or Coca-Cola and the level of tomatoes. Fish start dying at pH levels below 4.5.
"The recommended guideline for oyster farming is a pH of 6.75 and no lower," Mr Lawler said.
"There is a constant flow of acid going into North Creek and these drains are a problem.
"They might not be the whole problem, but they are definitely a major contributor. The effect is that our oysters are dying. Oysters are a fantastic indicator of estuarine health.
"One of my leases is 2ha that could make me $20,000 a year, but I can't use it because it's too unpredictable."
Mr Lawler said the acidity in North Creek would also have an impact on small fish, prawns and even plankton, because they all use the creek as a nursery.
"It's frustrating because this is a manageable problem," he said.
Michael Wood from Richmond River County Council said the county council was teaming up with the National Parks and Wildlife Service this week to fix the drain in the Ballina Nature Reserve.
But he said it would not solve the bigger problem.
"The big picture is that this is an acid sulphate soil hot spot and it's no surprise that there is acid," Mr Wood said.
"Oysters are like the canary in the coal mine. Oysters and acid run-off don't mix.
"But we've had development on the Newrybar catchment - cane, rural residential, farms - and it has changed the whole game plan.
"The ideal solution would be to find $30 million and buy all the land."
In the meantime, Mr Wood said it was important to start collating data about North Creek so the problems could be identified.
A data logger is expected to be installed within the next couple of months.