Balaenophilus manatorum in Debilitated and Bycatch-Derived Loggerhead Sea Turtles Caretta caretta from Northwestern Adriatic Sea

Abstract

Balenophilus manatorum (Copepoda: Harpaticoida) is one of the few components of the epibiontic fauna of Caretta caretta that show a “true” parasitic association with their host. From rrosive to ulcerative cutaneous lesions may seldom appear as a consequence of the copepod feeding on keratin on turtles’ skin. Debilitating Turtle Syndrome (DTS) is the final outcome of a chronic insufficient assumption of nutrients, generally occurring with the impairment of immune functions and high epibiota burdens. In this survey, the presence of B. manatorum in C. caretta from the Northwestern Adriatic Sea was investigated and the relation between infection indices and the co-occurrence of DTS was studied. Clinical examination was performed at the time of rescue, including routine hematological assessment; external parasites were isolated mechanically from turtles’ skin and morphologically identified through observation with an optic microscope and SEM. Ten turtles were classified as affected by DTS, all of them being small juveniles with typical clinical and clinicopathological presentation. A higher prevalence, abundance, and density of infection were found in turtles affected by the syndrome. The presence of massive skin coverage by the burrowing barnacle Pletylepas hexastylos prevented a proper evaluation of the pathology associated with B. manatorum in turtles affected by DTS. In any event, eventual skin damages caused by the parasite may represent a port of entry for secondary infections in such immunocompromised animals. Therefore, infection by B. manatorum should not go overlooked in debilitated turtles and should be opportunely treated.