A new study of coral reefs in Papua New Guinea shows ocean acidification simplifies coral structure, making crucial habitat less appealing to certain fish species.
While much media attention has focused on heat stress-induced coral bleaching, this finding, by a University of Adelaide research team led by Professor Ivan Nagelkerken, adds nuance to concerns about how global warming affects coral reefs.
Ocean acidification is caused by an increase in the level of carbon dioxide in oceanwater, leading to a reduction in pH. This makes calcium carbonate less available in the ocean, which corals use to build and repair their skeleton.
Professor Nagelkerken and his team show that, while ocean acidification in some instances does not reduce overall coral cover on a reef, the structures are less branched and therefore less appealing as habitat to some fish species.
Researchers observed two reefs in Upa-Upasina, Papua New Guinea: one located next to a volcanic seep releasing a steady stream of carbon dioxide, causing natural acidification, and another located 500 metres away unaffected by the volcanic gases.
…
“Ocean acidification has the potential to reshuffle ecological communities globally, lead to the loss of key habitats and biodiversity, reduce fisheries’ productivity, and have negative physiological impacts on many marine animals and plants,” says Professor Nagelkerken, from the University of Adelaide’s School of Biological Sciences.
“It might also lead to a reduction in populations of various fish species, which could create novel species community structures that might have lower biodiversity and not be as resilient as present-day communities. It could also clearly distinguish winner species from loser species. And if this ocean acidification affects fisheries species, some species that recreational and commercial fishers target might become less abundant.”
The acidification conditions observed in the research, which was published in the Journal of Animal Ecology, at the reef beside the volcanic seep are expected to occur in the ocean more broadly as the increasing level of human-caused carbon emissions in Earth’s atmosphere are absorbed by the ocean.
…
University of Adelaide (via ScienceDaily), 1 July 2024. Press release.
