成人大片

While much media attention has focused on heat stress-induced coral bleaching, this finding, by a 成人大片 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.

鈥淎quarium experiments are rather simplistic and cannot adequately mimic the complex species interactions that commonly occur in nature,鈥� says Professor Nagelkerken.

鈥淭hese reefs presented an incredible opportunity to directly compare current and future-analogous conditions side-by-side, with a full suite of ecological interactions in place.鈥�

Of the five damselfish species Professor Nagelkerken鈥檚 research team observed, two displayed a preference for complex, branched structures; while two others were not disinclined to interact with simplified coral structures but still sought out complex habitats even as they became scarce. A fifth rubble-specialist species associated most strongly with rubble.

鈥淥cean acidification has the potential to reshuffle ecological communities globally, lead to the loss of key habitats and biodiversity, reduce fisheries鈥� productivity, and have negative physiological impacts on many marine animals and plants,鈥� says Professor Nagelkerken, from the 成人大片鈥檚 School of Biological Sciences.

鈥淚t 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.鈥�

The acidification conditions observed in the research, which was , 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鈥檚 atmosphere are absorbed by the ocean.

鈥淚f we continue to emit carbon dioxide unabated, at some point in the future we could see such levels of ocean acidification in Australia,鈥� says Professor Nagelkerken, who worked alongside colleagues from James Cook University as part of an international team that included researchers from New Caledonia, Hong Kong and Japan.

鈥淭he effects observed in our study would be similar in Australian ecosystems, because many of the coral and fish species that we studied in Papua New Guinea also occur on the Great Barrier Reef.

鈥淏ut temperate reefs might also be affected, with ocean acidification having negative effects on cold-water reef builders such as oysters, mussels and calcareous algae, among others.鈥�

The way to avoid this looming future, according to Professor Nagelkerken, is simple. 鈥淲e should increase our efforts to reduce CO2 emissions globally,鈥� he says.