Fouling barnacles: Larval development, settlement behavior and control technology

Abstract

Macrofouling on ship hulls, cooling conduits and heat exchangers cause serious revenue loss. Though more than 4,000 species have been identified as causative organisms, only a few groups are dominant in a given fouling community. Among them, barnacles are the most troublesome species. They are sedentary, hard-shelled crustaceans, with a worldwide distribution and, therefore, are one of the main targets in the effort to develop antifouling technology. After attaining reproductive maturity, the broods release young larvae known as nauplu, which undergo six stages of metamorphic changes and ultimately develop into what is known as cypris. Cypris is a nonfeeding larva and is remarkably equipped for selection of a suitable site for attachment and subsequent development into an adult barnacle. Biofilms universally associated with substrata exposed to the marine environment, largely decide the  suitability of the substratum for the cypris larva, through molecular cues. Knowledge about barnacle development, settlement cues and mechanism of larval attachment onto the surface is essential not only to understand biofouling process but also to adapt suitable control technology. This paper is an attempt to review information on barnacle larval development, settlement behavior and control technology, especially to the indian context.