Comparative attachment of barnacle cyprids ( Balanus amphitrite Darwin, 1854; B. improvisus Darwin, 1854; & B. ebumeus Gould, 1841) to polystyrene and glass substrata

The cyprid larval stage of the barnacle Balanus amphitrite Darwin is often used in assays of larval attachment to substrata, yet its settlement response may not be representative of other barnacles. We compared attachment of cyprids of three balanomorph species to polystyrene and glass substrata. Larvae released by adults in the laboratory were reared to the cyprid stage, and attachment was monitored at daily intervals to determine whether it varied with larval age, substratum type, salinity, or storage at low temperatures. Attachment of B. amphitrite and B. improvisus Darwin after a one-day period was low in almost all assays, but increased over a few days to a high level of attachment. Balanus amphitrite tended to attach in higher numbers to glass than to polystyrene whereas B. improvisus attached more to polystyrene. Older cyprids did not attach in higher numbers than younger cyprids. Cooling cyprids prior to experimentation sometimes temporarily retarded attachment of B. improvisus and B. amphitrite. Balanus ebumeus Gould cyprids attached in low numbers to both substrata in all assays. All three species attached in salinities from 10 to 30 ppt despite more restricted distributions of adults along salinity gradients in nature.