Diversity and composition of macro- and meiofaunal carapace epibionts of the hawksbill sea turtle (Eretmochelys imbricata Linnaeus, 1822) in Atlantic waters

Abstract

The presence of macro-epibionts on turtle carapaces is a well-known phenomenon, whereby carapaces are occupied by dynamic and fully functional epibiont communities. However, meiofaunal organisms have been largely ignored in turtle shell studies despite their omnipresence and higher abundances and diversity than the macrofauna. Epifauna from the hawksbill sea turtle Eretmochelys imbricata was investigated during summer 2010 with the aim to advance our knowledge on meiofaunal epibiont communities on turtle carapaces and gain insights into their interaction with settled macrofauna. Eighteen epibiont higher taxa were found (17 meiofauna, 5 macrofauna), 5 of which are common for macro- and meiofauna. Meiofauna was present on all turtle carapaces, but macrofauna occurred on only 8 out of 19 investigated carapaces, suggesting that carapace colonization by meiofauna precedes macrofauna recruitment. In addition, the macrofauna embedded on the carapaces increased the microhabitat complexity, favoring richer and more abundant meiofauna communities. The significant positive correlations between meiofauna and macrofauna taxa (up to 90 %) suggests the presence of mutual facilitating processes and indicates the positive effects between meio- and macrofaunal epibionts important for their recruitment and establishment. The hawksbill sea turtle carapaces were occupied by fully functional and active epifaunal communities, with adult and reproductive stages for most meiofaunal and macrofaunal taxa. Turtle carapaces can therefore be seen as a biological substrate that can serve as a platform for faunal dispersal, as has been observed for barnacles, enhancing the geographical distribution of several species through sea turtle migration. In addition to the main focus of this paper on meio- and macrofaunal epibiont communities, we provide an updated list of taxa found on carapaces of the hawksbill sea turtle and discuss the geographical scope and dispersion potential of some of these taxa.