Are barnacle larvae able to escape from the threat of UV?

Earlier laboratory experiments suggested that environmental levels of UV-B radiation can damage the eyes of barnacle naupliar larvae and impair their phototactic behaviors. However, since barnacle larvae may avoid UV by migrating to deeper waters, it is not known whether such impairment would actually occur under field conditions. For the first time, this study provides both field and laboratory evidences to show that prevailing UV-B in the natural habitat of barnacle larvae could be an important environmental factor affecting natural barnacle populations. We here showed that although barnacle nauplii may avoid UV-B irradiation by downward migration, the amount of UV energy (9.8 × 10⁻⁶ J) received by a naupliar eye during downward migration in the natural water column is within the same order of magnitude as the total energy (7.5 × 10⁻⁶ J) sufficient to cause damages to naupliar eye and impair their phototactic responses. It is possible that solar UV-B prevailing at shallow waters would pose a similar threat to other zooplankton species over large geographic scale.