ANTIFOULING PERFORMANCE OF THE EMBRYO AND EGGCASE OF THE DOGFISH SCYLIORHINUS-CANICULA

The antifouling performance of the dogfish Scyliorhinus canicula (L.) (Elasmobranchii: Squaliformes) eggcase-embryo combination was studied under experimental conditions, in conjunction with an analysis of foul ing on wild cases. The cases were shown to develop an external heterog eneous microbial biofilm, and an internal heterogeneous microbial biof ilm (when the case opens) composed primarily of cocci and bacilli. Mac rofouling was limited on egg-cases (unless kept under high light inten sities). Macrofouling ranged from <5% (recently laid cases) to 42% (>3 00 days exposure). This is a better performance than many commercial a ntifouling treatments. There was no evidence that the embryo was invol ved in the antifouling process. A priori, three hypotheses are suggest ed that might explain the antifouling mechanism of the dogfish eggcase -embryo combination: (1) the yolk/albumin/embryo emit antifouling chem icals; (2) a bacterial culture develops that prevents further fouling; (3) the case with/without an embryo has antifouling properties. The r esults presented here support the third hypothesis.