PARASITES OF FRANCISCANA DOLPHINS (Pontoporia blainvillei) FROM SÃO
PAULO AND PARANÁ STATES, BRAZIL
Juliana Marigo, DVM,1, Fernando C.W. Rosas,2 Ana L.V. Andrade,3 Márcia R.
Oliveira,4 Carolina P. Bertozzi,5 Valeria Ruoppolo,1 Ricardo A. Dias,6 and José L.
Catão-Dias, DVM, MSc, PhD,1,7 *
1
Departamento de Patologia, Faculdade de Medicina Veterinária e Zootecnia,
Universidade de São Paulo, São Paulo, SP, 05508-000, Brazil; 2Instituto Nacional de
Pesquisa da Amazônia, Manaus, AM, 69011-970, Brazil; 3Instituto de Biologia,
Universidade Federal de Pelotas, Pelotas, RS, 96100-000; 4Departamento de Zoologia,
Universidade Federal do Paraná, Curitiba, PR, Brazil; 5Projeto BioPesca, Praia
Grande, SP, Brazil; 6Departamento de Medicina Veterinária Preventiva e Saúde
Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo,
São Paulo, SP, 05508-000, Brazil; 7Fundação Parque Zoológico de São Paulo, São
Paulo, SP, 04301-905, Brazil
Abstract
The Franciscana dolphin (Pontoporia blainvillei) is considered to be one of the most
threatened small cetaceans in the western South Atlantic Ocean and is the most common
cetacean caught incidentally in fishing nets along its distribution.5 Studies on the stock
structure and abundance of the Franciscana dolphin in its home range are needed to
evaluate the impact of this incidental mortality on the population.2
Parasites have been useful as an additional source of information regarding various
aspects of host biology, including stock identity.1 Therefore, detailed studies regarding
parasite burden of P. blainvillei have been recommended as a tool to evaluate ecological
segregation and stock structure.3
In the present study, we analyzed metazoan parasites from the stomach, intestines, and
lungs of 41 Franciscana dolphins caught incidentally in fishing nets or stranded in
beaches from three geographically close areas: group 1, Guarujá and Praia Grande (São
Paulo State), n = 12 (24o00’S, 46o17’W); group 2, Cananéia (São Paulo State), n = 17
(25o00’S, 47o56’W); and group 3 (Paraná State), n = 12 (25o30’S, 48o23’W). The sample
population consisted primarily of immature animals between 0 and 3 years of age.
No parasites were found in the lungs. Acanthocephalans (Polymorphus sp.) were found in
the stomachs of two animals and were considered an incidental finding. The trematode
Hadwenius pontoporiae (Digenea: Campulidae) was the only parasite found in the
intestines, with a prevalence of 100% for group 1, 82.35% for group 2, and 58.33% for
group 3. The mean intensity of H. pontoporiae for groups 1, 2, and 3 was 39.5, 25.05,
and 13.5 parasites per host, respectively.
Sampling wild animals is often opportunistic, so that samples are rarely suitably agestratified or diverse enough to detect heterogeneity in host-parasite associations4. No
significant correlation between total body length and infection levels was observed
(Pearson’s correlation coefficient = 0.51, p > 0.01). Franciscanas from Rio Grande do Sul
State showed a negative correlation between mean intensity and total body length and age
of the host, suggesting that the immune response increases with age1.
In this study there was a significant difference in number of parasites among the three
groups (Kruskal-Wallis test, p = 0.012). Groups 2 and 3 were geographically close and
exhibited non-significant differences in the total number of parasites found (MannWhitney test, p = 0.063). Groups 1 and 3 were further apart geographically and differed
significantly in total number of parasites (Mann-Whitney test, p = 0.003).
Analysis of data from areas where H. pontoporiae has already been found, including
those of this study (Rio Grande do Sul State1 and Argentina2), demonstrates an increasing
prevalence and mean intensity of parasite infection with increasing latitude. Therefore, H.
pontoporiae may continue to be used as a biological tag for Franciscana dolphin stock
studies with standardized methodology throughout its distribution, along with other
characteristics, always considering the number of factors that may affect the results.
ACKNOWLEDMENT
This work was supported by FAPESP (grant # 00/14669-0).
LITERATURE CITED
1. Andrade, A.L.V. 1996. Comunidade componente de helmintos gastrointestinais da
franciscana (Cetacea, Pontoporiidae) no Rio Grande do Sul, Brasil, e sua utilização
como marcador biológico na identificação de estoques. MSc Thesis. Universidade do
Rio Grande do Sul.
2. Aznar, F.J., J.A. Balbuena, and J.A. Raga. 1994. Helminth communities of
Pontoporia blainvillei (Cetacea: Pontoporiidae) in Argentinean waters. Can. J. Zool.
72: 1-5.
3. Aznar, F.J., J.A. Raga, J. Corcuera, and F. Monzón. 1995. Helminths as biological
tags for franciscana (Pontoporia blainvillei) (Cetacea: Pontoporiidae) in Argentinean
and Uruguayan waters. Mamm. 59: 427-435.
4. Gulland, F.M.D. 1997 The impact of parasites on wild animal populations.
Parasitologia 39: 287-291.
5. Secchi, E.R., P.H. Ott, E.A. Crespo, P.G. Kinas, S.N. Pedraza, and P. Bordino. 2001.
A first estimate of franciscana (Pontoporia blainvillei) abundance of southern Brazil.
J. . Cetacean Res. Manage. 3: 95-100.
Marigo, J.; Rosas, F.C.W.; Andrade, A.L.V.; Oliveira, M.R.; Bertozzi, C.P.; Ruoppolo, V.;
Dias, R.A.; Catão-Dias, J.L. 2002. Parasites of franciscana dolphins (Pontoporia blainvillei) from
São Paulo and Paraná States, Brazil. Annual Meeting of the American Association of Zoo
Veterinarians, 5-10 de outubro de 2002, Milwaukee, Wisconsin, E.U.A.