Impact of Pulsed Laser Irradiations from Nd:YAG Laser on the Larvae of the Fouling Barnacle Balanus amphitrite

The environmental hazards originating from the persistent use of antifouling agents containing toxic chemicals are alarming. Therefore, methods that do not rely on toxic elements are wanted. The effectiveness of pulsed laser irradiations from an Nd:YAG laser to induce damage to the larvae of a fouling barnacle, Balanus amphitrite, was evaluated in the laboratory. The average fluence tested was 0.1 J cm^{m 2}. Three larval stages, viz. nauplii stage II and stage IV and cyprid larvae were exposed to laser irradiations for 2 s, 10 s, 30 s, 1 min, 5 min and 15 min in the case of nauplii stage II, and 2, 10 and 30 s in case of nauplii stage IV and cyprid larvae. Mortality occurred immediately after, as well as 1 and 3 d after the irradiation, and the settlement rate of cyprid larvae was investigated in the laboratory. Mortality in stage II, stage IV and cyprid larvae immediately after 2 s irradiation was 30.1 ± 0.5%, 9.3 ± 0.2 and 16.7 ± 4.8, respectively. Mortality after 3 d however showed higher values, viz. 84.4 ± 6.7%, 50 ± 4%, and 75 ± 9.4 in stage II, stage IV and cyprid larvae, respectively. Mortality increased with the period of laser irradiation. The stage II nauplii showed 100% mortality after 10 s irradiation. The mortality observed in stage IV and cyprid larvae was less than that found for the stage II nauplii. The IV stage larvae which survived could successfully moult to the next stage, whilst the irradiated cyprid larvae could not settle. The results thus showed that pulsed low power laser irradiations could cause significant damage to the larvae of this common fouling barnacle.

Keywords:

• Pulsed Laser Irradiations
• Barnacle Larvae
• Antifouling Technique
• Larval Mortality
• Larval Settlement
• Balanus Amphitrite