The absorption of rising atmospheric carbon dioxide (CO2) into the oceans has caused ocean acidification and associated shifts in marine carbonate chemistry. In coastal waters, excessive nutrient runoff can also create regions of low oxygen, high CO2, and acidification. These conditions have been shown to be detrimental to growth and survival of larval and juvenile shellfish such as oysters, clams and scallops in laboratory studies, but the consequences of these effects on wild populations have been unknown.
Now, a new publication shows that the levels of impairment observed in laboratory experiments have the potential to cause increased risk to wild populations of marine bivalves in the northeastern USA. For this study, results from a project supported by NCCOS and the NOAA Ocean Acidification Program were used in new field-based population models of northern quahog (hard clam) and bay scallop to estimate the risk of population declines under scenarios of current and increased atmospheric CO2.
For scallops, the risk of losing one-half the population in 5 years increased from 56 percent in present-day conditions (400 μatm to 99 percent when daytime CO2 levels doubled (800 μatm), and greater than 99 percent when tripled (1200 μatm). For hard clams, the risk was 25 percent under present conditions, 79 percent when CO2 was doubled and 97 percent when tripled. These CO2 exposure levels are less extreme than ones often used in stress response experiments, so the risk to field populations may be even greater.
Citation: Grear, J. S., C. A. O’Leary, J. A. Nye, S. T. Tettelbach, and C. J. Gobler. 2020. Effects of coastal acidification on North Atlantic bivalves: interpreting laboratory responses in the context of in situ populations. Marine Ecology Progress Series 633: 89-104. DOI: https://doi.org/10.3354/meps13140
For more information, contact Elizabeth.Turner@noaa.gov.