The Soft-Shell Clam Mya arenaria: Biology, Fisheries, and Mariculture

Chapter 11: Effects of Ocean Warming and Acidification on the Soft-Shell Clam Mya arenaria

Jeff C. Clements and Heather L. Hunt


Since the onset of the Industrial Revolution and large-scale burning of fossil fuels, global climate change has driven rapid and unprecedented changes to our planet. The world’s oceans are no exception. Alongside the burning of fossil fuels, increasing human activity and development in coastal regions have further contributed to biological, physical, and chemical changes in coastal marine systems (Cloern et al. 2016). Given these widespread and rapid changes occurring in coastal oceans globally, marine global change has become an important issue of concern.

Two global change stressors of current concern in marine science are ocean acidification and warming. The oceans absorb a considerable amount (>90%) of excess heat trapped by greenhouse gases (Levitus et al. 2012). This heat absorption has resulted in large-scale ocean warming (Cheng et al. 2017; Yao et al. 2017), which is projected to continue into the future (Fox-Kemper et al. 2021). Oceans also serve as the planet’s largest carbon sink, absorbing approximately 25% to 30% of excess anthropogenic carbon dioxide from the atmosphere (Doney et al. 2009). Consequently, oceanic pH has dropped by approximately 0.1 pH units since the Industrial Revolution and is projected to drop another 0.44 units by the end of this century (based on latest Intergovernmental Panel on Climate Change projections under the SSP5-8.5 defined in their sixth assessment report; Canadell et al. 2021) in a process coined “ocean acidification” (Caldeira and Wickett 2003; Doney et al. 2009; Brewer 2013). Given the widespread and rapid change currently occurring in marine systems globally, understanding how acidification and warming might affect marine life has become a cornerstone of contemporary marine research.

Since soft-shell clams Mya arenaria are important to coastal regions both ecologically and economically (e.g., Seitz and Hines 2023; Beal 2023a, 2023b; Kennedy 2023, all this volume), it is critical to understand how this species may be affected by global change stressors such as acidification and warming. In this chapter, we review some of the potential independent and interactive effects of these stressors on soft-shell clams at the organismal, population, and community levels of biological organization. We draw on experimental studies conducted with M. arenaria, as well as other clam species with similar biological and/or ecological attributes, to synthesize the ways in which the stressors might affect soft-shell clams. We also discuss nuances of such effects on M. arenaria, including the mediating roles of environmental variability, habitat complexity, and acclimation and adaptation.