Condition factor of Astyanax intermedius Eigenmann, 1908 (OSTEICHTHYES, CHARACIDAE) parasitised by Paracymothoa astyanaxi Lemos de Castro, 1955 (CRUSTACEA, CYMOTHOIDAE) in the Grande River, Serra do Mar State Park - Santa Virgínia Unit, São Paulo, Brazil

Abstract

In this work the length-weight relationship and the condition factor of Astyanax intermedius parasitised and not by Paracymothoa astyanaxi were analysed in the Grande River. The length-weight relationship was estimated for females, males and immatures, and seasonally for the fishes and the parasites through the expression W = aL b . The condition factor of non-parasitised specimens differed seasonally and between sexes, contrasting with the results for parasitised fishes which showed no differences between sexes and season. The condition factor of non-parasitised specimens was higher than that of the parasitised fishes. Specimens of Astyanax intermedius parasitised do not have the same biotic conditions compared to non-parasitised individuals, in which the condition factor was similar over the years. In conclusion, parasitism by P. astyanaxi has deleterious effects on this host population which may cause changes in the reproductive and food dynamics of parasitised specimens due to low body conditions. Keywords: parasitism, condition factor, length-weight relationship. Foram analisados a relação peso-comprimento e o fator de condição de Astyanax intermedius parasitados ou não pelo isópode Paracymothoa astyanaxi. A relação peso-comprimento foi estimada para fêmeas, machos e imaturos, e sazonalmente tanto para os peixes quanto para o parasito, por meio da expressão P = aC b . O fator de condição dos exemplares não parasitados diferiu sazonalmente e entre os sexos, contrastando com os valores do fator de condição dos peixes parasitados, que não apresentaram diferenças sazonais e entre os sexos. O fator de condição dos exemplares não parasitados foi sempre maior do que o dos exemplares parasitados. Os exemplares de Astyanax intermedius parasitados não passaram pelas mesmas condições bióticas dos indivíduos não parasitados, apresentando um fator de condição semelhante ao longo do ano. Conclui-se que o parasitismo por P. astyanaxi atua de forma deletéria na população desse hospedeiro, podendo causar alterações nas dinâmicas reprodutiva e alimentar dos exemplares parasitados em razão da baixa condição corpórea. Fator de condição de Astyanax intermediusPalavras-chave: parasitismo, fator de condição, relação peso-comprimento.

Spatial variation in the parasitic isopod load of the Japanese halfbeak in western Japan

“…The prevalence of M. parvostis on Japanese halfbeak in the present study (41.6−74.4%) was relatively high among known fish−cymothoid systems, where prevalence is typically less than 30%, e.g. approximately 14% in Paracymothoa astyanaxi Lemos de Castro, 1955 parasitizing Astyanax intermedius Eigenmann, 1908(Gomiero et al 2012) and up to 28% in Anilocra nemipteri Bruce, 1987 parasitizing Scolopsis bilineata (Bloch, 1793) (Roche et al 2012). However, some studies have reported a similar high prevalence of cymothoid isopods (e.g.…”

“…Nevertheless, many studies have found that cymothoid infection does not influence the growth and body condition of hosts (Colorni et al 1997, Leonardos & Trilles 2003, Carrassón & Cribb 2014. In contrast, a few studies have found that cymothoid infection significantly deteriorates host condition (Gomiero et al 2012, Sala-Bozano et al 2012. Östlund-Nilsson et al (2005) found no significant differences between the body condition of wild-caught cardinal fish Cheilodipterus quinquelineatus Cuvier, 1828 infected and uninfected with the cymothoid isopod Anilocra apogonae Bruce, 1987.…”

Influence of the flood pulse on the reproduction of Tocantinsia piresi (Miranda Ribeiro) and Auchenipterus nuchalis (Spix & Agassiz) (Auchenipteridae) of the middle Xingu River, Brazil

“…Higher mean K values were recorded in T. piresi and female A. nuchalis during the ebb season, while lower values were found primarily during the dry and filling periods. The condition factor is a quantitative index of the physiological characteristics of fishes (Le Cren, 1951), and reflects the energy balance between weight and growth, and their relationship with the reproductive and nutritional characteristics of fish species (Vazzoler, 1996;Araujo and Vicentini, 2001;Lima-Júnior and Goitein, 2006;Gomiero et al, 2012).…”

Feeding, body condition and reproductive investment of Astyanax intermedius (Characiformes, Characidae) in relation to rainfall and temperature in a Brazilian Atlantic Forest stream

“…Astyanax intermedius is part of a lineage known as the 'scabripinnis complex' (Characidae family) that apparently diversified within isolated hydrographic basins, with species restricted to small headwater drainages of the Para ıba do Sul River basin, adjacent coastal rivers of Rio de Janeiro state, and the Doce River basin, Minas Gerais state (Britski 1972;Moreira-Filho & Bertollo 1991;Kavalco & Moreira-Filho 2003;Lima et al 2003;Bertaco & Lucena 2006;Lezama et al 2011). Size of maturation is about 4 cm standard length (SL), maximum size is 10 cm SL (Gomiero et al 2012) and juveniles and mature adults are found throughout the year, indicating that the species has an extended reproductive period (U. P. Souza, unpublished data). Size of maturation is about 4 cm standard length (SL), maximum size is 10 cm SL (Gomiero et al 2012) and juveniles and mature adults are found throughout the year, indicating that the species has an extended reproductive period (U. P. Souza, unpublished data).…”

“…Similar to other species within the genus, A. intermedius has a life history strategy that would be classified as opportunistic (sensu Winemiller 1989;Winemiller & Rose 1992), represented by small-bodied species with early maturation, continuous reproduction, low fecundity but high reproductive effort, rapid population turnover and capacity for rapid colonisation (Winemiller 1989;Lamouroux et al 2002;). Size of maturation is about 4 cm standard length (SL), maximum size is 10 cm SL (Gomiero et al 2012) and juveniles and mature adults are found throughout the year, indicating that the species has an extended reproductive period (U. P. Souza, unpublished data).…”