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Effects of coastal acidification on North Atlantic bivalves: Interpreting laboratory responses in the context of in situ populations
Citation:
Grear, J., C. O'Leary, J. Nye, S. Tettelbach, AND C. Gobler. Effects of coastal acidification on North Atlantic bivalves: Interpreting laboratory responses in the context of in situ populations. MARINE ECOLOGY PROGRESS SERIES. Inter-Research, Luhe, Germany, 633:89-104, (2020). https://doi.org/10.3354/meps13140
Impact/Purpose:
Clams and scallops make shells using the carbonate ions that naturally occur in seawater. The availability of this carbonate decreases when carbon dioxide is added to seawater and acidity is increased, threatening the survival and growth of these important bivalves. In coastal ecosystems where many shellfish thrive, the two main factors causing this change in carbonate chemistry are nutrient enrichment and absorption of carbon dioxide from the atmosphere. Most concern about effects of these water quality changes are based on laboratory studies, but extrapolation of observed effects to wild populations has been a major challenge. We estimated risk to hard clams and bay scallops by combining available data on laboratory effects with available time series data on populations of these species in estuaries of Long Island, New York. Understanding these risks will be critical to stakeholders who enjoy these shellfish or benefit from their harvest.
Description:
Experimental exposure of early life stage bivalves has documented negative effects of elevated pCO2 on survival and growth, but the population consequences of these effects are unknown. Following standard practices from population viability analysis and wildlife risk assessment, we substituted laboratory-derived stress-response relationships into baseline population models of Mercenaria mercenaria and Argopecten irradians. The models were constructed using inverse demographic analyses with time series of size-structured field data in NY, USA, whereas the stress-response relationships were developed using data from a series of previously published laboratory studies. We used stochastic projection methods and diffusion approximations of extinction probability to estimate cumulative risk of 50% population decline during ten-year population projections at 1, 1.5 and 2 times ambient pCO2 levels. Although the A. irradians population exhibited higher growth in the field data (12% per year) than the declining M. mercenaria population (-8% per year), cumulative risk was high for A. irradians in the first ten years due to high variance in the stochastic growth rate estimate (log λs = -0.02, σ2 = 0.24). This ten-year cumulative risk increased from 69% to 94% and >99% at 1.5 and 2 times ambient scenarios. For M. mercenaria (log λs = -0.09, σ2 = 0.01), ten-year risk was 81%, 96% and >99% at 1, 1.5 and 2 times ambient pCO2, respectively. These estimates of risk could be improved with detailed consideration of harvest effects, disease, restocking, compensatory responses, other ecological complexities, and the nature of interactions between these and other effects that are beyond the scope of available data. However, results clearly indicate that early life stage responses to plausible levels of pCO2 enrichment have the potential to cause significant increases in risk to these marine bivalve populations.
URLs/Downloads:
DOI: Effects of coastal acidification on North Atlantic bivalves: Interpreting laboratory responses in the context of in situ populations