Meiofauna life on loggerhead and hawksbill sea turtles

Giovanni dos Santos1, Yirina Vazquez2, Letícia Pontes1, Ian Silver-Gorges3, Alexandra Silva4, Quintin Bergman5, Mariana Fuentes3, Sofia Zarate6 and Jeroen Ingels7, (1)UFPE Federal University of Pernambuco, Zoology, Recife, Brazil, (2)Federal University of Paraiba, Biology, Areia, Brazil, (3)Florida State University, Tallahassee, United States, (4)UFPE Federal University of Pernambuco, Recife, Brazil, (5)Purdue University, Fort Wayne, United States, (6)Columbia University, New York, United States, (7)Florida State University, FSU Coastal and Marine Laboratory, St Teresa, United States
Sea turtles can host a wide range of marine organisms as epibionts. These epibionts range in size from microscopic diatoms and meiofauna (<1mm) to fish that can grow to over half a meter. Here, we present an ecological turtle meiofauna (and macrofauna) study based on 19 Eretmochelys imbricata (Hawksbill, from Brazil) and 23 Caretta caretta (Loggerhead, from northern Gulf of Mexico) individuals. We found that turtle carapaces can host 10s to 100,000s of epibionts. These epibionts comprise dynamic and fully functional communities. As the turtle breeds, feeds and migrates, it provides a host ecosystem continuously exposed to potential colonizers, enhancing meio- and macrofaunal dispersal, and the geographic distribution of epibiont species. We observed significant positive correlations between meio- and macrofauna diversity, suggesting mutual facilitating and genera enrichment processes occur across size classes and phyla, which may be important for epifaunal recruitment and establishment. Results also suggest that the macrofauna play a bioconstructing role, creating microenvironments that can enhance diversity of nematode assemblages. Perhaps more importantly is the fact that nematode diversity on turtles exceeded diversity on other hard substrates (while comprising similar function). Turtles can therefore be seen as travelling hotspots of nematode biodiversity compared to other epibiotic substrates. Two major implications of this work are that 1) the extremely high numbers of meiofauna and nematodes warrant re-examination of the meiofauna paradox since the potential of meiofaunal migration is extraordinary considering the high numbers and the capacity of turtles to migrate large distances; and that 2) meiofauna community analysis can be used to distinguish between groups of turtle individuals, suggesting that our methods may prove useful in discriminating turtle migration and foraging patterns. The latter implies that epibiont studies, even if only based on higher-taxa community analysis, may aid sea turtle conservation studies.

Keyword: Nematodes, turtles epibionts, ecological interactions, Caretta caretta, Eretmochelys imbricata