Ecological and reproductive aspects of Neoechinorhynchus pimelodi Brasil-Sato & Pavanelli (Eoacanthocephala, Neoechinorhynchidae) of Pimelodus maculatus Lacépède (Siluroidei, Pimelodidae) of the São Francisco River, Brazil

Abstract

ABSTRACT. Ecological and reproductive aspects of Neoechinorhynchus pimelodiBrasi l-Sato & Pavanelli , 1998, in Pimelodus macula/us Lacepede, 1803 collected in the Sao Francisco river during periods of drought (July 1995 and1996) and flood ings (January 1996 and 1997) of this river basin are provided. In tropical regions where the amount of rainfall alters the hydrological regimen of limnol ogical systems water temperature has not had an imp0l1ant role in infectio ns ofN. pimelodi in P. macula/lis. Prevalence was somewhat higher during drought periods. Intensity of infection varied sl ightly between collecting periods. Mature male and female acanthocephalans were present in all periods. Females were predominant. Mature females were present in higher numbers during flooding periods with a corresponding decrease in juvenile acanthocephalans. Recruitment and constant losses of N. pilllelodi seem to be controlled by transm ission mechani sms independently of dens ity. Mec han isms may consist of infected prey availability (potential intermediate hosts) and changes of preferred alimentalY items in the diets of juvenile and mature P. maclllallls. KEY WORDS. Acanthocephala, Neoechinorhynchuspimelodi, Pimelodus macula/us, ecology, reproduction There are no published works in Brazil which refer to the populational dynamics of fish parasites. This is especially true of acanthocephalans. Research work on populational dynamics of neoechinorhynchid acanthocephalans in fresh water fi sh of temperate countri es have shown seasonal aspects in the life cycles of these parasites. This is chiefly due to oscillations in water temperature. In the present paper aspects of ecology and reproduction of acanthocephal ans in fresh water fish are analysed within a tropical geographical di stribution. The lotic system o[the Sao Francisco river basin is basically altered by rainfall variations which characterise flooding and drought periods. MATERIAL AND METHODSPimelodus macula/us Lacepede, 1803, "mand i-amarelo", were collected in the Sao Francisco river, state of Minas Gerais, Brazil, downstream the Tres Marias reservoir. In this lotic environment co ll ections were carried out in July 1995 and

Helminth fauna parasitizing Pimelodus pohli (Actinopterygii: Pimelodidae) from the upper São Francisco River, Brazil

“…Recently, Lopes et al (2011) recorded N. pimelodi in P. maculatus and B. westermanni in the Paraná Basin. In the parasite community of P. pohli, N. pimelodi was the only one with a uniform distribution, but in the congeneric host P. maculatus, its distribution was widely dispersed, both during periods of flooding and drought in the upper São Francisco River region PAVANELLI, 1999).…”

“…In the São Francisco River Basin, the records on the parasite fauna of pimelodids were established for Conorhynchos conirostris (Valenciennes, 1840) by Pinto et al (1974), Pinto and Noronha (1976), Vicente et al (1985), and Brasil-Sato and Santos (2005); for Pseudoplatystoma corruscans (Spix & Agassiz, 1829) by Rego and Gibson (1989), Kohn et al (1997), and Corrêa and Brasil-Sato (2008); for Bergiaria westermanni (Lütken, 1874) by Moreira et al (1991) and Vicente and Pinto (1999); for P. maculatus by BrasilSato and Pavanelli ( , 1999Pavanelli ( , 2000Pavanelli ( , 2004, Brasil-Sato (2003), and Monteiro et al (2010); and for P. pohli by Martins et al (2012). In this last work, the authors have established the first record of a parasite species, Prosthenhystera obesa (Diesing, 1850), in the gall bladder of P. pohli.…”

Parasitism by argulids (Crustacea: Branchiura) in piranhas (Osteichthyes: Serrasalmidae) captured in the Caiçara bays, upper Paraguay River, Pantanal, Mato Grosso state, Brazil

“…According to Le Cren (1951), the condition factor is a quantitative indicator of fish fitness, reflecting recent feeding conditions and is obtained using the weight-length relation of the individual. According to Brasil-Sato & Pavanelli (1999) and Lizama et al (2006), the relative condition factor can be used as a tool for studies of the relationship between the host's health and level of parasitism. In this study Pygocentrus nattereri and Serrasalmus maculatus show significant differences in condition factor between parasitized and non-parasitized fish.…”

Estructura comunitaria de helmintos de perros vagabundos de San Juan de Lurigancho, Lima, Perú

“…(1999) que mostró una prevalencia combinada de 70,3%, UGOSHUKWU & EJlMADU (I 985a) de 86,9% y KAZACOS (1978) de 86,5%. Esto se explicaría, debido a que las comunidades parasitarias de los hospederos sujetos a la influencia de frecuentes a1teraciones ambientales, pueden sufrir variaciones en su riqueza y estructura comunitaria (CrSLO & CAIRA 1993;BRASIL-SATO & PAVANELLI 1999). EI céstodo E. granulosus, no se detectó en el presente estudio, esto armoniza con lo encontrado por P ANDEY et ai.…”