Infestation pattern and parasitic castration of the crustacean Riggia paranensis (Crustacea: Cymothoidea) on the fresh water fish Cyphocharax gilbert (Teleostei: Curimatidae)

Abstract

Cyphocharax gilbert infested by Riggia paranensis shows parasitic castration. The prevalence of parasitism in C. gilbert varied among different environments, being higher in the middle rio Itabapoana. Fish were collected monthly using two cast nets (thrown 30 times during the day) and gillnets kept in the river during 12 hour, from sunset to sunrise, between September 1997 and August 2000. Infestation pattern was investigated on 1358 specimens. Most of them were infested (57.9%), with one or two parasites; the majority (62.9%) was collected during the rainy season (spring-summer). The parasite did not show preference for sex or size of hosts. A total of 91.5% of the 511 examined parasites had a body size that represented 10.1% to 20% of host standard length. The reproductive condition of 311 specimens of R. paranensis was analyzed checking the presence of oocytes in the ovarian and eggs or embryos in the marsupium. Nearly 73% of them were at reproductive phase, and had a body size that represented 5.1% to 20% of host standard length. The size of the immature parasites varied from 0.1% to 5% of the host size. The results suggest that R. paranensis may adopt a fast growth rate strategy and increase the investment in reproduction when they occupy most of the host's pericardial space.<br>Cyphocharax gilbert infestado por Riggia paranensis apresenta castração parasitária. A prevalência do parasito varia entre diferentes ambientes, sendo maior no trecho médio do rio Itabapoana. Os peixes foram coletados mensalmente neste rio usando duas tarrafas (lançadas por 30 vezes durante o dia) e redes de espera por 12 horas, do crepúsculo ao amanhecer, entre setembro de 1997 e agosto de 2000. O padrão de infestação foi investigado em 1358 peixes. Peixes infestados apresentaram um ou dois parasitos, representando 57,9% da população e a maioria deles (62,9%) foi coletada no período de maior precipitação (primavera-verão). O parasito não apresentou preferência por sexo ou tamanho do hospedeiro. No total, 91,5% de 511 parasitos examinados apresentaram um tamanho corpóreo que representou de 10,1% a 20% do comprimento padrão do hospedeiro. A condição reprodutiva em 311 espécimes R. paranensis foi analisada através da presença de oócitos no ovário e ovos ou embriões no marsúpio, sendo que cerca de 73% estavam em fase de reprodução, apresentando um tamanho corporal que variou entre 5,1% a 20% do comprimento padrão do hospedeiro. O tamanho dos parasitos imaturos variou de 0,1% a 5% do tamanho do hospedeiro. Os resultados sugerem que R. paranensis pode adotar uma estratégia de rápido crescimento e deve aumentar o investimento em reprodução quando ocupa grande parte do espaço disponível na cavidade pericardial do hospedeiro

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

“…There was no difference in length distribution of male and female of A. intermedius parasitised as in Luque et al (1996), Tavernari et al (2005), Azevedo et al (2006) and Lizama et al (2008) in studies with other species of marine and freshwater fishes. These authors verified that there was no difference in parasitism between males and females or according to the size of the host.…”

Parasites of fish larvae: do they follow metabolic energetic laws?

“…Information about parasitic castrators related to crustaceans (n = 14) and fish (n = 6) was obtained from the literature (Christensen and Kanneworff 1965;Mahon 1976;Wenner and Windsor 1979;McDermontt 1991;Lützen and Jespersen 1992;Shields and Earley 1993;Adlard and Lester 1994;Muñoz 1997;Muñoz and George-Nascimento 1999;Calado et al 2005Calado et al , 2008George-Nascimento and Bustos 2006;Azevedo et al 2006;Shukalyuk et al 2005;Cañete et al 2008;Fogelman et al 2009;Heins and Baker 2010;Petrić et al 2010). Only the castrator-host systems with antecedents confirming the castration on the host, total or partial, and with one parasite species were considered in this study.…”

Mercury concentration in the freshwater bonefish Cyphocharax gilbert (Curimatidae) and its parasite the crustacean Riggia paranensis (Cymothoidae)

“…The populations of this species have a spawning period of two annual reproductive cycles, beginning in February and August Lima et al, 2007). However, C. gilbert shows parasitic castration when infested by the crustacean R. paranensis, being unable to reproduce (Azevedo et al, , 2006Gomes da Silva et al, 2005;Lima et al, 2007). Infested fish lack gonadal development and two sex-specific proteins in the plasma (Gomes da , and they have low levels of sex steroids (Lima et al, 2007).…”

“…Infested fish lack gonadal development and two sex-specific proteins in the plasma (Gomes da , and they have low levels of sex steroids (Lima et al, 2007). The prevalence of parasitism in the fish C. gilbert varies from place to place, but it is around 60% in the middle Itabapoana River (Azevedo et al, , 2006, an area that became a target for gold mining in the middle 1980's (Malm et al, 1989b;Torres et al, 1991). In the upper and middle part of the river, it can be observed that domestic and industrial effluents reduce water quality.…”