An assessment of the efficacy of chemical descalers for managing non-indigenous marine species within vessel internal seawater systems and niche areas

This study assessed the efficacy of commercially available descalers and factors that influence their efficacy as tools for marine biosecurity management. Laboratory experiments found calcium carbonate (CaCO₃) degradation varied up to 29% (from 111 to 143 g/l) amongst seven products tested. Increasing the concentration of hydrochloric, phosphoric and acid-surfactant descalers from 25 to 75% did not increase the rate or total degradation of the mussel, <i>Mytilus planulatus</i>. Warming descaling solutions (from 11 to 26°C) significantly increased the rate of mussel mortality, decay and total degradation in all treatments. Circulating treatments increased mussel mortality and decay rate in hydrochloric and acid-surfactant descalers, but had no detectable effect on total degradation after 24h. Hydrochloric acid based descalers (<i>Rydlyme</i>®, <i>3H</i>® and <i>Dynamic Descaler</i>®) were more effective than phosphoric acid (<i>Barnacle Buster</i>®) and acid-surfactant (<i>Triple 7 Enviroscale Plus</i>®) treatments. Organic material was largely resistant to degradation under all treatments. The implications for descalers as marine biosecurity tools are discussed.