Gastrointestinal helminths of Commerson's dolphins Cephalorhynchus commersonii from central Patagonia and Tierra del Fuego

Abstract

The stomachs and intestines of 9 Commerson's dolphins incidentally caught in trawl nets in central Patagonia and 23 stranded on beaches in Tierra del Fuego were surveyed for helminth parasites. A total of 267 individuals belonging to 4 species of parasites (1 nematode, 3 digeneans) were found in the dolphins from the first area: Anisakis sp. (larvae type 1 = A. simplex), Braunina cordiformis, Hadwenius sp. and Pholeter gastrophilus. In the Tierra del Fuego dolphins, 142 specimens belonging to 3 species (2 nematodes, 1 digenean, 1 cestode) were found: A. simplex, Hadwenius sp. and Strobilocephalus triangularis. Only 2 of the helminth species were shared in the 2 study areas, A. simplex and Hadwenius sp., and both were more common in central Patagonia. Among the species, A. simplex was most prevalent and abundant in both study areas. In Tierra del Fuego, adults of A. simplex appeared in only 1 host. Hadwenius sp., P. gastrophilus and S. triangularis are new host records for Commerson's dolphin. Species diversity and species richness were low in both study areas. Helminth communities were more diverse in central Patagonia (t = 1.97, df = 258, p < 0.05) and species richness was higher in central Patagonia (S = 4). No differences in diversity were observed between females and males of central Patagonia (t = 1.97, df = 139, p < 0.05) and between females of central Patagonia and Tierra del Fuego. The results may suggest some differences in habitat use, diet and sex between Commerson's dolphin populations in the 2 study areas.

Helminths of the marine tucuxi, Sotalia fluviatilis (Gervais, 1853) (Cetacea: Delphinidae), in northern Rio de Janeiro State, Brazil

“…The narrow range of preferred prey in its diet could be the factor determining the low diversity of parasite groups. The same pattern was recorded for Commerson's dolphin (Cephalorhynchus commersonii) and franciscana (Pontoporia blainvillei) in Argentinian waters (Aznar et al, 1994;Berón-Vera et al, 2001). The absence of significant differences between sex, maturity and seasons was consistent with recent findings in diet studies.…”

Intestinal helminth fauna of striped dolphins (Stenella coeruleoalba) in the western Mediterranean: No effects of host body length, age and sex

“…Likewise, Strobilocephalus triangularis (Diesing 1850) has also been found in Atlantic and Pacific waters, infecting mainly delphinids, i.e ., Cephalorhynchus commersonii , D. delphis , Hyperoodon ampullatus , L. hosei , L. acutus , M. bidens , S. attenuata , S. longirostris , and S. bredanensis (Baer , Delyamure , Dailey and Otto , Raga , Berón‐Vera et al . ). In western Mediterranean waters it has also been reported infecting S. coeruleoalba (Raga and Carbonell ) and T. truncatus (Quiñones et al .…”

Independent host switching events by digenean parasites of cetaceans inferred from ribosomal DNA

“…Pholeter gastrophilus lives in the stomach wall of odontocetes, surrounded by a fibrous nodule of host origin (Aznar et al, 2006). Sexually mature specimens have been reported in at least 17 cetacean species from coastal, oceanic and even freshwater habitats (Raga and Balbuena, 1993;Berón-Vera et al, 2001;Aznar et al, 2006;Quiñones et al, 2013).…”