There is a wealth of published information on the epibiont communities of sea turtles, yet many of these studies have exclusively sampled epibionts found only on the carapace. Considering that epibionts may be found on almost all body-surfaces and that it is highly plausible to expect different regions of the body to host distinct epibiont taxa, there is a need for quantitative information on the spatial variation of epibiont communities on turtles. To achieve this, we measured how total epibiont abundance and biomass on olive ridley turtles Lepidochelys olivacea varies among four body-areas of the hosts (n = 30). We showed that epibiont loads on olive ridleys are higher, both in terms of number and biomass, on the skin than they are on the carapace or plastron. This contrasts with previous findings for other hard-shelled sea turtles, where epibionts are usually more abundant on the carapace or plastron. Moreover, the arguably most ubiquitous epibiont taxon for other hard-shelled sea turtles, the barnacle Chelonibia spp., only occurred in relatively low numbers on olive ridleys and the barnacles Stomatolepas elegans and Platylepas hexastylos are far more abundant. We postulate that these differences between the epibiont communities of different sea turtle taxa could indicate that the carapaces of olive ridley turtles provide a more challenging substratum for epibionts than do the hard shells of other sea turtles. In addition, we conclude that it is important to conduct full body surveys when attempting to produce a holistic qualitative or quantitative characterization of the epibiont communities of sea turtles.

22There is a wealth of published information on the epibiont communities of sea turtles, yet many of 23 these studies have exclusively sampled epibionts found only on the carapace. Considering that 24 epibionts may be found on almost all body-surfaces and that it is highly plausible to expect different 25 regions of the body to host distinct epibiont taxa, there is a need for quantitative comparative 26 studies to investigate spatial variation in the epibiont communities of turtles. To achieve this, we 27 measured how total epibiont abundance and biomass on olive ridley turtles Lepidochelys olivacea 28 varies among four body-areas of the hosts (n = 30). We show that epibiont loads on olive ridleys are 29 higher, both in terms of number and biomass, on the skin than they are on the carapace or plastron. 30 This contrasts with previous findings for other hard-shelled sea turtles, where epibionts are usually 31 more abundant on the carapace. Moreover, the arguably most ubiquitous epibiont taxon for other 32 hard-shelled sea turtles, the barnacle Chelonibia spp., only occurs in relatively low numbers on olive 33 ridleys, while the barnacles Stomatolepas elegans and Platylepas hexastylos are far more abundant. 34 We postulate that these differences between the epibiont communities of different sea turtle taxa 35 could indicate that the carapaces of olive ridley turtles provide a more challenging substratum for 36 epibionts than do the hard shells of other sea turtles. In addition, we conclude that it is important to 37 conduct full body surveys when attempting to produce a holistic qualitative or quantitative 38 characterization of the epibiont communities of sea turtles. 39 40 KEYWORDS 41 Epibiosis, Lepidochelys olivacea, East Tropical Pacific, arribada, barnacles, turtle-scape, settlement 42 substratum, site selection 43 44