We’ve known about the anthropogenic threats to coral reefs for some time. Eutrophication smothers corals; fishing with cyanide and explosives destroys reefs; and warming oceans spawn coral bleaching events.
Recently, ocean acidification has been added to that list of threats. Corals are not alone, however. Ocean acidification threatens all calcifying marine organism – including shellfish. Increased atmospheric carbon is taken up by ocean water, causing oceans to acidify. More acidic waters are less able to hold carbonate, the compound used by shellfish to produce calcium carbonate in building their shells.
The following article describes research at Stony Brook University in New York. Researchers observed that survival and growth of Northern quahog (hard clams) and Atlantic bay scallops were reduced in larvae exposed to water equilibrated with 390 ppm CO2 in the atmosphere when compared to those exposed to pre-industrial levels (250 ppm). Shell malformations occurred at higher CO2 concentrations, which are projected later this century in some climate models.
International climate negotiations currently espouse 450 ppm as the threshold of atmospheric CO2 that the world should not exceed. Many scientist, however, believe that major consequences are likely above 350 ppm and that we should roll-back greenhouse gas emissions to return to this level (current atmospheric CO2 measured at the NOAA Mauna Loa Observatory reads 389.69 ppm).
All of these levels, it appears, would negatively affect shellfish. The viability of shellfish in a world of increasing atmospheric CO2 and ocean acidification is an important issue for all coastal communities, as we all work to re-establish shellfisheries, both for sustainable food systems and for ecosystem services.
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