"When you start messing around with a complex ecosystem it is impossible to tell what will happen."
The Ischia site does not present a perfect experiment for future oceans because levels of acidity shift regularly as the currents change, whereas future oceanic pH levels will be more stable.
But the site does show clear winners and losers: the lush seagrass, hyper-fertilised by CO2, may be the tallest in the world.
The extra acidity will suit some creatures, but Dr Hall-Spencer argues that the diversity of the site is reduced and therefore it is likely that productivity of valuable species will diminish in future acidified oceans.
Ocean acidification is increasingly known as "the other CO2 problem".
It is a new branch of science and researchers were initially uncertain how seriously to take the threat.
"In 2004, I did a Google search for ocean acidification and got 17 hits," says Dr Turley.
"Now you get hundreds of thousands. There is much more evidence to show this will be a problem for the future - indeed it may even be a problem for now."
For many people it will strike a sobering note that humans appear to be changing the chemistry of the mighty oceans.
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