MOLLUSK HARVESTS TODAY, VULNERABILITY TO OCEAN ACIDIFICATION TOMORROW?

Atmospheric carbon dioxide (CO₂) emissions from human industrial activities are causing a progressive alteration of seawater chemistry, termed ocean acidification, that has decreased seawater pH and carbonate ion concentration markedly since the Industrial Revolution. Many marine organisms, like mollusks and corals, build hard shells and skeletons using carbonate ions, and they exhibit negative overall responses to ocean acidification. This adds to other chronic and acute environmental pressures and promotes shifts away from calcifier-rich communities.

In this study, we examine the possible implications of ocean acidification on mollusk harvests worldwide by examining present production, consumption, and export and by relating those data to present and future surface ocean chemistry forecast by a coupled-climate ocean model (Community Climate System 3.1; CCSM3). We identify the “threshold date” when future ocean chemistry will distinctly differ from that of today (2010), and when mollusk harvest levels similar to those of the present cannot be guaranteed. We assess nations’ susceptibility to ocean acidification-driven decreases in mollusk harvests by comparing nutritional and economic dependences on mollusk harvests, overall societal adaptability, and the amount of time until the threshold date. Projected threshold dates for individual countries will occur 14-46 years after 2010. Countries with low adaptability, high nutritional or economic dependence on mollusks, rapidly approaching threshold dates, or rapidly growing populations will therefore be most vulnerable to ocean acidification-driven mollusk harvest decreases. These threshold dates suggest how soon nations should implement strategies, such as increased aquaculture of resilient species, to help maintain current per capita mollusk harvests.