Electrochemically Induced Alkalinity Enhancement Increases Coral Growth Rates in the Local Microenvironment

Coral reef ecosystem health is rapidly declining worldwide. Restoration strategies such as propagation and outplanting aim to recover reef function but can be hindered by slow growth rates that limit scalability, necessitating technologies that accelerate growth to match the scale of reef degradation. Electrochemically induced alkalinity enhancement (eAE) offers a promising approach to locally enhance carbonate chemistry and favor calcification. We developed replicate eAE systems composed of steel cathodes and a platinized anode housed within an evacuation pump to remove oxidative waste products. System performance was evaluated with carbonate chemistry incubations, microelectrode profiling, and two laboratory experiments with Acropora cervicornis and Pseudodiploria clivosa microfragments. The eAE system created a high alkalinity microenvironment under 1 cm s ^-1 flow speeds, elevating pH _T by 0.14 ± 0.02 to 8.16 at the height of the ‘short’ 5 mm P. clivosa microfragments. At 3 cm s ^-1 , pH _T at 5 mm was 8.03, and under both flow speeds, pH _T returned to bulk levels (8.02) at the height of the 15 mm P. clivosa and 50 mm A. cervicornis fragments. After sixty days, short P. clivosa microfragments exposed to eAE calcified 43% faster and had 53% greater planar tissue growth rates than controls. These enhancements occurred exclusively within the elevated pH boundary layer and did not extend to taller fragments (≥15 mm), highlighting eAE’s limited spatial extent. Our findings demonstrate eAE’s potential to accelerate microfragment skirting rates. Integrating eAE into coral propagation pipelines could enhance nursery productivity, reduce generation times, and improve the overall scalability of reef restoration efforts.