Within and cross-generational effects of elevated seawater pCO2 on larval bay scallops Argopecten irradians (L)

Authors: GURR, SAMUEL - National Oceanic & Atmospheric Administration (NOAA); BERNATCHEZ, GENEVIVE - National Oceanic & Atmospheric Administration (NOAA); DIXON, MARK - National Oceanic & Atmospheric Administration (NOAA); KEITH, LISA - National Oceanic & Atmospheric Administration (NOAA); HART, DEBORAH - National Oceanic & Atmospheric Administration (NOAA); MILKE, LISA - National Oceanic & Atmospheric Administration (NOAA); REDMAN, DYLAN - National Oceanic & Atmospheric Administration (NOAA); Plough, Louis; SENNEFELDER, GEORGE - National Oceanic & Atmospheric Administration (NOAA); STILES, SHEILA - National Oceanic & Atmospheric Administration (NOAA); VEILLEUX, DAVID - National Oceanic & Atmospheric Administration (NOAA); WIKFORS, GARY - National Oceanic & Atmospheric Administration (NOAA); MCFARLAND, KATHERINE - National Oceanic & Atmospheric Administration (NOAA); SHANNON, MESECK - National Oceanic & Atmospheric Administration (NOAA); PADILLA, DIANNA - National Oceanic & Atmospheric Administration (NOAA)

Submitted to: Journal of Shellfish Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/26/2025
Publication Date: 8/11/2025
Citation: Gurr, S., Bernatchez, G., Dixon, M., Keith, L., Hart, D., Milke, L., Redman, D.H., Plough, L.V., Sennefelder, G., Stiles, S., Veilleux, D., Wikfors, G.H., Mcfarland, K., Shannon, M.L., Padilla, D.K. 2025. Within and cross-generational effects of elevated seawater pCO2 on larval bay scallops Argopecten irradians (L). Journal of Shellfish Research. 44(2):185-195. https://doi.org/10.2983/035.044.0202.
DOI: https://doi.org/10.2983/035.044.0202

Interpretive Summary: It is well known that bivalve larvae are highly susceptible to ocean acidification but whether or not they can acclimate or adapt across generations to changing ocean conditions is not clear. Multi generation experiments of bivalves under ocean acidification conditions are needed to understand this, and the bay scallop, Argopecten irradians, is a good model for such studies due to its short generation time and commercial relevance. To test the impacts of ocean acidification over multiple generations, bay scallops were exposed across two generations to low, moderate, and high levels of ocean acidification and size and survival were monitored throughout. High ocean acidification resulted in complete mortality in generation one while moderate ocean acidification reduced growth and survivorship relative to low ocean acidification conditions. There was no difference in survival between the moderate and low OA treatments in the 2nd generation, but the difference in size at metamorphosis remained. These results suggest that scallops have some capacity to adapt or acclimate to moderate ocean acidification conditions that may be faced in the near future.

Technical Abstract: Bivalve larvae have been shown to be highly susceptible to ocean acidification (OA), but there is little knowledge of the capacity of bivalve species to acclimate or adapt to changing ocean conditions. It is difficult to predict from short term experiments how populations might respond across generations. The bay scallop, Argopecten irradians, is a good model species for such experiments because of its short generation time and importance commercially and ecologically. Bay scallops were exposed to OA conditions from embryos to metamorphosis across two generations. OA treatment levels included historical or pre-industrial “low” (pCO2 ~450 µatm), current average “moderate” (~800 µatm), and future “high” (~1350 µatm). In the first generation, high OA had negative effects on larval performance with no survival to metamorphosis, preventing its inclusion in the second generation. Moderate OA reduced performance (survivorship and growth) relative to the low OA. In the second generation, however, there was no difference in survival between the moderate and low OA treatments, but the difference in size at metamorphosis remained. These results suggest that over two generations bay scallops either acclimated or adapted to moderate OA. Further work is needed to determine the extent to which long-term, generational adaptation to OA is possible in the bay scallop.