Parasites of franciscana (&lt;i&gt;Pontoporia blainvillei&lt;/i&gt;) from São Paulo and Paraná States, Brazil

J Marigo,A L V Andrade,M R Oliveira,R A Dias,F C W Rosas,J L Catão-Dias

doi:10.5597/lajam00015

Abstract

The franciscana, Pontoporia blainvillei, is a threatened small cetacean of the western South Atlantic Ocean and is commonly caught incidentally in fishing nets along its distribution. Detailed studies regarding parasite loads of P. blainvillei have been recommended as a tool to evaluated ecological segregation and stock structure. We analyzed metazoan parasites from stomach, intestines and lungs of 41 franciscanas from three close geographical areas: Group 1, Guarujá and Praia Grande (São Paulo State), n=12 (24° 00'S, 46° 17'W); Group 2, Cananéia (São Paulo State), n=17 (25° 00'S, 47° 56'W); Group 3, Paraná State, n=12 (25° 30'S, 48° 23'W). The sample consists mainly of immature specimens, less than 3 years old. No parasites were found in the lungs analyzed. The acanthocephalan (Polymorphus sp.) found in two stomachs were considered occasional. The trematode Hadwenius pontoporiae (Digenea: Campulidae) was the only parasite found in the intestines with 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. In this study there was a significant difference between the number of parasites among the three groups (Kruskal-Wallis test, p=0.012). Groups 2 and 3 are geographically close, and exhibited non-significant differences in the total number of parasites found (Mann-Whitney test, p=0.063). Groups 1 and 3, that are further apart geographically, differed significantly in the total number of parasites found (Mann-Whitney test, p=0.003). Through the analysis of data from the areas where H. pontoporiae was found [i.e. Areas 1, 2, 3 (this study), Rio Grande do Sul State and Argentina], it could be noticed that the prevalence and mean intensity increase as latitude increases. H. pontoporiae may continue to be useful as a biological tag for identifying franciscana's ecological stocks, together with information from genetic, morphometric and other biological studies. However, it is essential that standardized methodology be used in the collection of the parasite data.

Highlights

The franciscana, Pontoporia blainvillei, is considered one of the most threatened small cetacean in the western South Atlantic Ocean (Secchi et al, in press a) and is the most common cetacean incidentally caught in fishing nets along the coast of São Paulo and Paraná states, Brazil (e.g. Rosas, 2000; Bertozzi and Zerbini, 2002; Santos et al, 2002)
Parasites have been useful as an additional source of information on various aspects of host biology, including stock identity
Previous studies of the parasite fauna of franciscana along the coast of southern Brazil (Rio Grande do Sul State), Uruguay and Argentina suggest the occurrence of two segregated populations (Aznar et al, 1995; Andrade, 1996)

Summary

Introduction

The franciscana, Pontoporia blainvillei, is considered one of the most threatened small cetacean in the western South Atlantic Ocean (Secchi et al, in press a) and is the most common cetacean incidentally caught in fishing nets along the coast of São Paulo and Paraná states, Brazil (e.g. Rosas, 2000; Bertozzi and Zerbini, 2002; Santos et al, 2002). Szidat, 1964; MacKenzie, 1987; Dailey and Vogelbein, 1991; Moser, 1991; Aznar et al, 1995; Balbuena et al, 1995; Aznar et al, 1997a, Walker, 2001). The use of such information as a tool to examine the stock structure of the franciscana has already been recommended (Reeves and Leatherwood, 1994; IBAMA, 1997). Previous studies of the parasite fauna of franciscana along the coast of southern Brazil (Rio Grande do Sul State), Uruguay and Argentina suggest the occurrence of two segregated populations (Aznar et al, 1995; Andrade, 1996)

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