The release and uptake of metals from potential biofilm inhibition products during spiny lobster (Sagmariasus verreauxi, H. Milne Edwards 1851) culture

Zinc (Zn) and copper (Cu) are strong inhibitors of bacterial biofilms in aqueous solutions, but are known toxins of crustaceans. A new metal application method; cold-sprayed metal embedment, known to modulate metal release, was tested for its applications in crustacean larval culture systems. Cold-spray technology allows metal particles to bond to plastics, while modulating metal ion release and biocide activity to the substrate boundary. In this study, Eastern spiny lobster (Sagmariasus verreauxi) larvae (phyllosoma) were cultured in the presence of cold-sprayed Zn and Cu metal surfaces. Metal loss was monitored gravimetrically on embedded surfaces, assessment of water ion concentrations and analysis of phyllosoma body content were undertaken. Phyllosoma moulting, deformity and mortality patterns were monitored. Cold-sprayed Zn- and Cu-embedded surfaces were depleted with losses of 0.69% and 31.2% noted respectively. Culture water concentrations of these metals were elevated and accumulation by phyllosoma occurred. Water Zn concentrations of 18.5 mu g L-1 were associated with chronic eyestalk moult deformities; the first report of Zn causing a non-lethal moult deformity in crustacean larvae. The Cu surface lost a third of its metal mass with a water concentration of 40 mu g L-1 causing acute toxicity and localization of composite granules in the midgut gland. Cu associated mortality was noted by Day 2 of culture with a LD 50 experienced by Day 9. Future work on the use of bioactive metals in aquaculture systems will focus on a range of different metal alloys, and improved modulation of ion release mechanisms through increased particle embedment depth and separation.