PNNL

Abstract

Ocean acidification directly affects the productivity and survival of coastal industries and ecosystems. For marine aquaculture, the increased acidity of seawater results in reduced availability of carbonates for marine organisms to build their shells leading to decreased aquaculture quality and productivity. The industry has been implementing recirculating aquacultures systems (RAS) to reduce CO2 in feedwaters, but recent interest in ocean-based CO2 capture has led to additional strategies that may be relevant. The new methods in addition to CO2 removal offer capture options for enhanced aquaculture sustainability. Here we review and compare early-stage and commercially available technologies for deacidification of seawater and their suitability for aquaculture. Most methods considered rely on voltage-induced pH swing to shift the carbonate/bicarbonate equilibrium toward release of CO2, with subsequent capture of the released CO2 as a gas or as solid mineral carbonates. The modular design and distributed deployment potential of these systems offers promise, but current demonstrations are limited to bench-scale, highlighting the need for sustained research and development before they can be implemented for marine aquaculture.