Assortative epibiosis of leatherback, olive ridley and green sea turtles in the Eastern Tropical Pacific

Abstract

Sea turtles host a diverse array of epibionts, yet it is not well understood what factors influence epibiont community composition. To test whether epibiont communities of sea turtles are influenced by the hosts’ nesting or foraging habitats, we characterized the epibiota of leatherback, olive ridley and green turtles nesting at a single location on the Pacific coast of Costa Rica. We also compared the epibiota of these turtles to conspecific populations nesting elsewhere in the East Pacific. If epibiont communities are influenced by nesting habitats, we predicted that sympatrically nesting turtles would have comparable epibiont taxa. Alternatively, if epibiont communities are influenced by foraging habitats, we predicted the diversity of epibiont taxa should reflect the type and diversity of the hosts’ foraging habitats. We identified 18 epibiont taxa from 18 leatherback, 19 olive ridley and six green turtles. Epibiont diversity was low on leatherbacks (four taxa), but higher for olive ridley and green turtles (12 and nine epibiont taxa respectively). The epibiont communities of olive ridley and green turtles were not statistically different, but both were different from leatherbacks. In addition, conspecific sea turtles from other nesting locations hosted more similar epibiont communities than sympatrically nesting, non-conspecifics. We conclude that epibiont diversity of nesting sea turtles is partially linked to the diversity of their foraging habitats. We also conclude that the surface properties of the skin and carapace of these turtles may contribute to the uniqueness of leatherback turtle epibiont communities and the similarities between olive ridley and green turtle epibiont communities.

Geographical variation in the diatom communities associated with loggerhead sea turtles (Caretta caretta)

“…Species number in a single sample varied between 11 and 111 taxa (including taxa observed outside the counts) ( Fig 4A), and the median from the same area was generally lower in the skin samples (26) than in the carapace samples (51). Among carapace samples, the South African samples were the most taxa-abundant, whereas the lowest number of taxa characterized Florida and some of the Croatian samples ( Fig 4A).…”

“…Other sea turtle species such as olive ridley and green turtle show a different feeding behavior and have a different diet [25], which may influence the epizoic diatom species composition. Robinson et al [51] observed that the macro-epibiont diversity of nesting sea turtles is partially linked to the diversity of their foraging habitats. Thus, sea turtle species with more diverse foraging areas should have more diverse epibiont communities.…”

Spatial distribution of epibionts on olive ridley sea turtles at Playa Ostional, Costa Rica

“…Those organisms that live on the surfaces of other organisms are referred to as epibionts [3], a grouping of diverse taxa with a wide range of life-histories, physiological tolerances, and mechanisms for attaching to their host [4]. It is therefore not surprising to discover that epibiont communities vary among different host species [5,6], populations [7], and even between different body-areas on a single host [8,9]. To understand why this variation occurs requires knowledge of the factors driving spatial variation in the distribution of epibionts, both on the scale of an ocean or a host’s body.…”

Epibiotic Diatoms Are Universally Present on All Sea Turtle Species

“…Sea turtles often harbour complex communities of epibionts [ 1 , 2 , 3 ]. These epibiont communities can provide valuable insights into the hosts’ behaviour [ 4 , 5 ] and health [ 6 , 7 ]; however, most studies on sea turtle epibiosis have focused exclusively on macro-epibiota.…”