Vermetids form reefs in sub-tropical and warm-temperate waters that protect coasts from erosion, regulate sediment transport and accumulation, serve as carbon sinks and provide habitat for other species. The gastropods that form these reefs brood encapsulated larvae; they are threatened by rapid environmental changes since their ability to disperse is very limited. We used transplant experiments along a natural CO2 gradient to assess ocean acidification effects on the reef-building gastropod Dendropoma petraeum. We found that although D. petraeum were able to reproduce and brood at elevated levels of CO2, recruitment success was adversely affected. Long-term exposure to acidified conditions predicted for the year 2100 and beyond caused shell dissolution and a significant increase in shell Mg content. Unless CO2 emissions are reduced and conservation measures taken, our results suggest these reefs are in danger of extinction within this century, with significant ecological and socioeconomic ramifications for coastal systems.
(A) A pristine vermetid reef at low tide in NW Sicily, Italy. (B) Collection of a vermetid core in the outer rim of a vermetid reef; black spots are the shell openings of Dendropoma petraeum cemented by the coralline alga Neogoniolithon brassica-florida. (C) A vermetid core transplanted in the intertidal off Vulcano Island. (D) A recruit newly settled on the coralline alga (top left) and the shell opening with the operculum of a D. petraeum adult (below). Photo credits: R.C. (A); M.M. (B,C); M.M. and M.F. (D)
ScienceDaily (Apr. 11, 2012) — Researchers at Oregon State University have definitively linked an increase in ocean acidification to the collapse of oyster seed production at a commercial oyster hatchery in Oregon, where larval growth had declined to a level considered by the owners to be “non-economically viable.”
A study by the researchers found that elevated seawater carbon dioxide (CO2) levels, resulting in more corrosive ocean water, inhibited the larval oysters from developing their shells and growing at a pace that would make commercial production cost-effective. As atmospheric CO2 levels continue to rise, this may serve as the proverbial canary in the coal mine for other ocean acidification impacts on shellfish, the scientists say.
A screen covered with oyster larvae, taken in 2007 at the Whiskey Creek Shellfish Hatchery near Netarts Bay, Ore. A 2012 study has found that Increasingly acidic ocean water is preventing larvae from developing shells. (Credit: Lynn Ketchum, Oregon State University)