Comparative Parasitology 67(2) 2000 - Peru State College

Comp. Parasitol.
67(2), 2000 pp. 210-217
Ecological Aspects of Endohelminths Parasitizing Cichla monoculus
Spix, 1831 (Perciformes: Cichlidae) in the Parana River near Porto
Rico, State of Parana, Brazil
PATRICIA MIYUKI MACHADO,1 SILVIA CAROLINA DE ALMEIDA,1
GlLBERTO CEZAR PAVANELLI,2'3 AND RlCARDO MASSATO TAKEMOTO2
1 Postgraduate Course in Ecology of Continental Aquatic Environments and
2 Center for Research in Limnology, Ichthyology and Aquaculture (DBI/NUPELIA), State University of
Maringa, Avenida Colombo 5790, Bloco G-90, 87020-900 Maringa, Parana, Brazil (e-mail:
gcpavanelli@uem.br)
ABSTRACT: We examined 136 specimens of Cichla monoculus Spix, 1831, collected in the Parana River near
Porto Rico, State of Parana, Brazil, from July 1996 through October 1997. Of the total number of fish, 133
(97.8%) were infected with at least 1 species of helminth. A total of 8 helminth species was recorded: 3 Digenea,
Clinostomum sp., Diplostomum (Austrodiplostomuni) compactum (Lutz, 1928), and Diplostomum sp.; 3 Cestoda,
Proteocephalus microscopicus Woodland, 1935, Proteocephalus rnacrophallus (Diesing, 1850), and Sciadocephalus
megalodiscus Diesing, 1850; 1 Nematoda, Contracaecum sp.; and 1 Acanthocephala, Quadrigyrus machadoi
Fabio, 1983. Proteocephalus microscopicus and P. macrophallus showed the highest values of prevalence
and intensity of infection, followed by Contracaecum sp. In the endoparasite community of C. monoculus, the
cestodes are both dominant and codominant species. The typical pattern of overdispersion or aggregation was
observed for P. microscopicus, P. macrophallus, S. megalodiscus, Q. machadoi, and Contracaecum sp. Prevalence
and total host length were positively correlated in fish parasitized by P. microscopicus, P. macrophallus,
and S. megalodiscus. Infection intensity and host length were positively correlated only for P. microscopicus.
There were significant differences in the prevalence of P. macrophallus and Q. machadoi in males and females
of C. monoculus. Clinostomum sp., Diplostomum sp., D. (A.) compactum, and Q. machadoi were found for the
first time in C. monoculus.
KEY WORDS: ecology, endohelminths, Digenea, Cestoda, Nematoda, Acanthocephala, freshwater fish, tucunare,
Cichla monoculus, Cichlidae, Teleostei, Parana River, Brazil.
Of the main factors influencing the composition
of endoparasite communities, the feeding
habits of the hosts are most important, since diverse
animals that serve as intermediate hosts
for the hosts' parasites are found in their diets
(Dogiel, 1970). Changes in the diet and feeding
habits of fishes also influence the composition
of their parasite fauna (Dogiel, 1970) and account
for the differences in the parasite faunas
of young and adults (Burn, 1980; Scott, 1982;
Moser and Hsieh, 1992). It is also well understood
that the fluctuations in water level characteristic
of floodplains may modify the feeding
habits of fish because of changes in the quantity
and quality of available food (Junk, 1980; Lowe-
McConnell, 1987; Brasil-Sato and Pavanelli,
1999). The influence of the sex of the hosts is
another important factor responsible for the variation
in the composition of their parasitofauna
and may be related to behavioral, biological, and
physiological differences between male and fe-
3 Corresponding author.
210
Copyright © 2011, The Helminthological Society of Washington
male fish (Paling, 1965; Muzzall, 1980; Fernandez,
1985; Moser and Hsieh, 1992; Takemoto et
al., 1996; Machado et al., 1994). The number of
studies in Brazil on the ecology of helminth parasites
of fish, especially in floodplain environments,
is still small.
The tucunare, Cichla monoculus Spix, 1831,
the object of this investigation, is an important
commercial and sport fish in the Upper Parana
River. It is a native of the Amazon Basin and
was first recorded in the Parana River in 1986
(Agostinho et al., 1994). It is a predator (Lowe-
McConnell, 1969), considered piscivorous because
of the predominance of fish in its diet
(FUEM/CIAMB/PADCT, 1995) and carnivorous
because it eats shrimp (Fontenele and Peixoto,
1979; Gery, 1984; Bonetto and Castello, 1985)
and benthopelagic fish (Ortega and Vari, 1986).
This study was intended to extend our existing
knowledge of the helminth fauna parasitizing
the fishes of the Parana River floodplain, to
show the structure and diversity of the endoparasitic
infrapopulations of the tucunare, and to