Prey species of franciscana Pontoporia blainvillei as paratenic hosts of helminths.

Abstract

The distribution of franciscana Pontoporia blainvillei Gervais & d'Orbigny, 1884, is restricted to the estuarine and coastal waters of the southwestern Atlantic. The diet of this dolphin is composed of fishes, squids, and shrimps, many of which harbor helminths that may infect franciscana. Larval forms of the trematode Synthesium pontoporiae and the acanthocephalan Bolbosoma turbinella have been recorded in franciscana; however, they have not yet been identified in any of the prey species of this cetacean. We evaluated 3 components of the diet of franciscana as possible transmission sources of parasitiasis. Specimens of São Paulo squid Doryteuthis sanpaulensis (n = 50), banded croaker Paralonchurus brasiliensis (n = 43), and rough scad Trachurus lathami (n = 50) were necropsied. Organs were washed and examined under a stereomicroscope. Helminths were collected and mounted on slides. None of the species analyzed showed infection by metacercariae of S. pontoporiae. Helminths found in São Paulo squid have not been recorded in franciscana. Cistacanths of Corynosoma australe were found in the coelomic cavity and mesentery of croaker (prevalence [P] = 53.49%; mean infection intensity [MII] = 6.74) and scad (P = 4%; MII = 1.50). Cistacanths of B. turbinella were also found in the same sites in scad (P = 14%; MII = 2.14). Banded croaker and rough scad are recorded in this study as new paratenic hosts for C. australe, while scad is a new paratenic host for B. turbinella.