Serious health concerns over Gladstone oysters

By John Mikkelsen – Saturday 19th January, 2012

IGNORANCE is said to be bliss, but  medical and science experts have pointed out it could have serious consequences when it comes to contaminated seafood, including oysters.

Gladstone residents and tourists remain largely unaware of dangers from potentially contaminated oysters and shellfish following toxic algae blooms and the presence of heavy metals detected last year. However, in NSW authorities were quick to issue an official warning about contaminated Sydney oysters in the lead up to the Christmas holidays..

Toxic lyngbya majuscula algae was positively identified in Gladstone Harbour last year following the hospitalisation of two Turkey Beach fishers, and poisonous diatoms, another form of marine algae, were also detected, but no health warnings were issued.

The risks of consuming possibly contaminated local shellfish including oysters were recently highlighted by aquatic disease specialist Dr Matt Landos following extensive research in Gladstone waters.

Dr Landos told the Queensland Telegraph that shellfish populations exposed to the increased sediment load generated by dredging were likely to have been significantly impacted.

“The timing of mortality of oysters (and other aquatic biota) suggests that sediment re-suspension and associated increased metal exposures from the dredging and disposal project has contributed to oyster mortalities.

“Rio Tinto hired a private ecotoxicology firm to undertake oyster testing in Gladstone harbour in 2012, but the results which were very clearly not good for the oysters remained suppressed,” Dr Landos claimed.

He explained that oysters are routinely used to assess toxicity of water and as “sentinels for accumulation of metals”.

While Queensland health authorities have failed to act, their NSW counterparts issued an immediate health alert  following the discovery of contaminated oysters in Botany Bay after the toxic algae outbreak there.

They warned against eating oysters, clam, crabs and abalone, and an environmental medicine specialist, Dr Andrew Jeremijenko, believes similar warnings should have been issued previously at Gladstone.

 Dr Jeremijenko has also called for the monitoring of oysters in Gladstone waters following the continuing controversy over the health of local seafood and other marine animals.

Dredging has been blamed as the most likely cause of the fish disease by Dr Landos, but this has been denied by Gladstone Ports Corporation and Fisheries Queensland which both blame the floods two years ago.

Dr Jeremijenko also believes the dredging and the disturbance of toxic compounds in the silt is responsible, and he has also warned that extreme cases of toxic algae poisoning could result in human fatality.

He told The Telegraph yesterday that monitoring should be conducted for dangerous algae, including the type which produces paralytic shellfish poisoning (PSP) as found in Botany Bay.

“There should be a program of monitoring the Gladstone oysters for toxins such as heavy metals and PSP toxins, but currently this is either not being done or the data is not being made public.

“ In Gladstone Harbour, despite far greater environmental pollution and industrial activity than Botany Bay, there are no warnings about the oysters and whether they are safe to eat.

“What we now know is that an independent scientist has found them to be affected.

“ Gladstone harbour has had multiple toxic algal blooms associated with high turbidity and high nutrient levels, but the algae associated with these blooms has not always been identified.

 “PSP can be fatal in extreme cases and children are more susceptible.

“Despite destruction of oyster habitat, diseased oyster shells and collapse of stock, the State’s willingness to monitor and protect the oysters in the harbour, and the people that eat them, is lacking”.

Dr Jeremijenko said another study in Gladstone Harbour a decade ago during a previous dredging program had also found that oysters were taking up toxins such as heavy metals, arsenic and aluminium and “the closer to the dredging, the worse it was”.

“The authorities should be lobbied now to take appropriate measurements and do this as part of the UNESCO- recommended Gladstone Enquiry,” he said.