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May 12, 2021

Oysters to be the natural indicators of our waterways

The world famous Sydney Rock Oysters are considered one of Australia’s best gourmet delicacies. With annual production of over 106 million oysters valued at $35 million.

Now these oysters are the new lab rats in the name of research. Researchers from the University of NSW are using oysters as sensitive indicators of harmful levels of contaminants in water ways and sediments.

Active indicators (or indicator species) is a biological species that defines a trait or characteristic of certain environments.

By assessing the health of the oysters placed in 10 estuaries along the NSW coast for a period of 3 months researchers have been able to determine the health of these waterways. The team placed cages containing 20 oysters at seven sites in each of the 10 estuaries making the study the largest of its kind.

They found that there was a strong association between cell damage in the oysters’ digestive glands and the level of metal contamination in suspended sediments in the water.

emma johnston oysters
Above: Professor Emma Johnston, UNSW dons her wetsuit in Sydney Harbour for oyster research.

Professor Emma Johnston of the UNSW School of Biological, Earth and Environmental Sciences suggests that oysters could be a cost effective and sensitive way of monitoring injury to marine life from environmental contaminants.

Sediment traps were placed in the water near the oysters to collect particles to test the results of the water compared to the health of the oysters.

“Re-suspension of contaminated sediments is a major way that organisms living in the water column become exposed to pollutants, either by eating organic matter attached to the particles or absorbing the contaminants from them,” says lead author, Dr Katelyn Edge.

The 10 waterways used for the research were from Karuah River in the north of NSW to Wagonga Inlet in the south of the state. These estuaries were found to vary in their levels of contamination, with suspended sediments from Port Jackson, Port Kembla and Botany Bay containing the highest levels of metals, including copper, lead and zinc.

The oysters in these estuaries were found to be significantly stressed, with cell damage rates to their digestive glands as high as 70 per cent.

But just because it’s an oyster and not a rat or a bunny rabbit does this make the experiment ok? How does this affect oysters? Do they feel pain? According to The Naked Scientist (http://www.thenakedscientists.com/) a group of media savvy physicians and researchers from Cambridge University have found that oysters have a nervous system and they can respond to different chemicals and other things going on.

Although they don’t have a brain scientists know that they do have two ganglia or masses of nerves around their body. Scientists suggest that oysters don’t have a conscious state like us or some other animals, but does that mean PETA won’t be stepping in for the protection and ethical treatment of these oysters?


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