Sydney rock oysters shrinking due to coastal acidification

Australian oyster farm. Credit: Susan Fitzer

Australian oyster farm. Credit: Susan Fitzer

Sydney rock oysters, found in the waters of Australia and New Zealand, are getting smaller due to coastal acidification, according to a joint Scottish/ Australian study.

A Natural Environment Research Council (NERC) study carried out by scientists at two commercial oyster farms in Wallis Lake and Port Stephens, both in the mid-north coast of New South Wales, confirmed that the oysters’ diminishing size and falling population is due to acidification from land and sea sources.

Ocean acidification has been reported globally, while coastal acidification from the land, as freshwater runoff from acid sulfate soils, is driven by rising sea levels and flooding also decreases environmental pH, said NERC.

Susan Fitzer, a NERC independent research fellow at the University of Stirling in Scotland, reported her findings in the journal Ecology and Environment.

While the research project focused on Australian aquaculture, Fitzer warns that seafood lovers around the globe could begin to find smaller and smaller oysters on their plates.

“A lot of work has been done near to Australia’s oyster fisheries to mitigate the impact of sulphate soils causing acidification, and there has been a marked decline in levels. The run-off from sulfate soils aren’t produced by agricultural activity, they occur as a natural result of climate change-driven increases in rainfall and sea-level rise. But the trend persists and small changes in pH are having a huge impact on these molluscs.”

While the Sydney rock oyster is native to Australia and New Zealand, Fitzer has previously linked rising acidification to weaker shells in mussels in Loch Fyne, Scotland, and sees global ramifications for the study.

“The first thing consumers may notice is smaller oysters, mussels and other molluscs on their plates, but if ocean acidification and coastal acidification are exacerbated by future climate change and sea level rise, this could have a huge impact on commercial aquaculture around the world.”

Undercurrent News, 16 August 2018. Article.

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