title: To Swim or Not to Swim: Potential Transmission of Balaenophilus manatorum (Copepoda: Harpacticoida) in Marine Turtles.
abstract: Species of Balaenophilus are the only harpacticoid copepods that exhibit a widespread, obligate association with vertebrates, i.e., B. unisetus with whales and B. manatorum with marine turtles and manatees. In the western Mediterranean, juveniles of the loggerhead sea turtle, Caretta caretta are the only available hosts for B. manatorum, which has been found occurring at high prevalence (>80%) on them. A key question is how these epibionts are transmitted from host to host. We investigated this issue based on experiments with live specimens of B. manatorum that were cultured with turtle skin. Specimens were obtained from head-started hatchlings of C. caretta from the western Mediterranean. Hatched nauplii crawled only on rough substrates and lacked the ability to swim. Only copepodites IV and V, and adults, were able to perform directional swimming. Legs 2, 3 and 4 played a major role in swimming and were only well-developed in these stages. Nauplii reared in wells with turtle skin readily fed on this item. Late copepodites and adults also fed on turtle skin but did not consume other potential food items such as fish skin, baleen plates or planktonic algae. Evidences suggest that the transmission of B. manatorum should rely on hosts' bodily contacts and/or swimming of late developmental stages between spatially close hosts. The possibility of long-ranged dispersal is unlikely for two reasons. First, all developmental stages seem to depend on turtle skin as a food resource. Second, the average clutch size of ovigerous females was small (< 70 eggs) for free-living phases to successfully contact turtles that occur at very low densities (< 0.6 turtles·km-2) in the western Mediterranean. The high prevalence of B. manatorum in loggerhead turtles in this area raises the question whether these turtles have contacts, or tend to closely aggregate, more than is currently believed.
authors.affiliation: Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain.
authors.forename: Francesc
authors.identifier: http://orcid.org/0000-0002-7310-4287
authors.initials: F
authors.lastname: Domènech
authors.affiliation: Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Tomás
authors.affiliation: Veterinary Services, Biology Department, Oceanogràfic, Valencia, Spain.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Crespo-Picazo
authors.affiliation: Veterinary Services, Biology Department, Oceanogràfic, Valencia, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: García-Párraga
authors.affiliation: Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain.
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Raga
authors.affiliation: Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain.
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Aznar
mesh_terms: D000818:Animals; D033342:Copepoda / Q000502:physiology*; D006790:Host-Parasite Interactions; D013550:Swimming; D013559:Symbiosis; D014426:Turtles / Q000469:parasitology*