Relevance of crustacean carapace wettability for fouling

Carapace wettability and density of fouling organisms (bacteria, diatoms, p rotozoa, fungi, macro-organisms) were investigated for 45 crustacean specie s (Hoplocarida, Decapoda) from 15 families in the Gulf of Thailand. The res ults show that crustaceans can create and maintain characteristic carapace wettabilities. About 21 species (47 %) possess highly wettable carapaces wi th contact angles below 20 degrees. Contact angles between 20 degrees and 4 0 degrees were recorded for four species (2%), angles between 40 degrees an d 60 degrees for eight species (4%) and from 60 degrees to 70 degrees for 1 1 (24%) species. One species, Alpheus euphrosyne (Alpheidae, Decapoda), exh ibited an extremely low surface wettability (contact angle: 91 degrees). De nsities of colonisers and contact angles did not correlate. Very low wettab ility by water (theta > 90 degrees) may only contribute little to fouling r eduction in A. euphrosyne which showed the most hydrophobic carapace surfac e and was colonised by the lowest numbers of bacteria among all species and no other colonisers at all. We conclude that surface wettability is of lit tle relevance for antifouling defence in crustaceans.