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Is ocean acidification affecting quahog abundance in Narragansett Bay?
Citation:
Grear, J. Is ocean acidification affecting quahog abundance in Narragansett Bay? Quahog Commission, Providence, RI, January 23, 2024.
Impact/Purpose:
This presentation will describe results from previous studies of ocean and coastal acidification in US estuaries, including Narragansett Bay, and their potential effects on quahogs (Mercenaria mercenaria).
Description:
Shellfish harvesters have been reporting decadal declines in the landings of quahogs (Mercenaria mercenaria) from Narragansett Bay, but the roles of local, oceanic and climate-related factors is unclear. Ocean and coastal acidification are one piece of this complex puzzle and are the focus of this presentation. Evidence for changes in the pH of Narragansett Bay and other US east coast estuaries over the past two decades will be discussed. This includes a decrease in the seasonal amplitude of the pH fluctuations in Narragansett Bay that coincides with expected effects of decreased nutrient loading. However, recently observed seasonal minima and associated changes in carbonate chemistry cause significant impacts on quahog survival and shell integrity when replicated in laboratory experiments. Field experiments suggest that that these responses are modified by ecological characteristics of the bay’s environment that are difficult to duplicate in the lab. This could include the biomass, community structure, and nutritional quality of the phytoplankton that quahogs feed upon. In addition, nutrient abatement would be expected to partially offset the effects of acidified ocean source waters and climate-related freshwater dilution of pH buffering capacity. Parsing the relative contributions of these drivers is the subject of ongoing collaborations.