Desiccation as a mitigation tool to manage biofouling risks: trials on temperate taxa to elucidate factors influencing mortality rates

<p>The desiccation tolerance of biofouling taxa (adults and early life-stages) was determined under both controlled and ‘realistic’ field conditions. Adults of the ascidian <i>Ciona</i> spp. died within 24 h. Mortality in the adult blue mussel <i>Mytilus galloprovincialis</i> occurred within 11 d under controlled conditions, compared with 7 d when held outside. The Pacific oyster <i>Crassostrea gigas</i> was the most desiccation-tolerant taxon tested (up to 34 d under controlled conditions). Biofouling orientated to direct sunlight showed faster mortality rates for all the taxa tested. Mortality in <i>Mytilus</i> juveniles took up to 24 h, compared with 8 h for <i>Ciona</i>, with greater survival at the higher temperature (18.5°C) and humidity (~95% RH) treatment combination. This study demonstrated that desiccation can be an effective mitigation method for a broad range of fouling taxa, especially their early life-stages. Further work is necessary to assess risks from other high-risk species such as algae and cyst forming species.