Temporal dynamic of the relationship between the parasitic isopod Aporobopyrus curtatus (Crustacea: Isopoda: Bopyridae) and the anomuran crab Petrolisthes armatus (Crustacea: Decapoda: Porcellanidae) in southern Brazil

Abstract

ABSTRACT. The prevalence of the parasite Aporobopyrus curtatus in Petrolisthes armatus from southern Brazil was determined, and the effect the parasite had on host reproduction was evaluated. Of all 775 crabs sampled in Araçá region from March 2005 to July 2006, 3.2% presented bopyrid parasites. All the parasitized individuals had one branchial chamber occupied by two mature parasites, with no preference for the right or left chamber. Male and female hosts were infested in equal proportions. Parasitized juveniles, large individuals and ovigerous females were not found in our study. The absence of parasitized ovigerous females seems to be insufficient evidence to support the hypothesis of parasitic castration and would require a histological study to confirm their reproductive death. The percentage of infestation observed in our study (3.1%) is lower than the one found in other studies and it could indicate the existence of factor(s) regulating the density of A. curtatus in the Araçá region. At least in this population, the low but constant presence of the bopyrid A. curtatus population did not appear to have a negative effect on the porcellanid population, and parasitized individuals did not play a significant role in the natural history of P. armatus. Keywords: parasitism, castration, porcelain crab, southern Brazil, Atlantic Ocean. Dinámica temporal en la relación entre el isópodo parásito Aporobopyrus curtatus(Crustacea: Isopoda: Bopyridae) y el cangrejo anomuro Petrolisthes armatus (Crustacea: Decapoda: Porcellanidae) en el sur de Brasil RESUMEN. Se determinó la prevalencia del parásito Aporobopyrus curtatus en Petrolisthes armatus en el sur de Brasil y se evaluó el efecto de su presencia en la reproducción de su huésped. De marzo de 2005 a julio de 2007 se muestreó en la Region de Araçá un total de 775 cangrejos, de los cuales el 3,2% presentó bopíridos parásitos. Todos los individuos parasitados presentaron una cámara branquial ocupada por dos parásitos maduros, sin preferencia por la cámara derecha o izquierda. Machos y hembras hospedadores fueron infectados en la misma proporción. La ausencia de parásitos en hembras ovígeras no es evidencia suficiente para apoyar la hipótesis de castración parasítica, y se necesita un estudio histológico para confirmar la muerte reproductiva. El porcentaje de infectación observado (3,1%) es inferior al encontrado en otros estudios y puede ser indicativo de la existencia de factor(es) que regulan la densidad de A. curtatus en la region de Araçá. En conclusión, estos resultados sugieren que, al menos en esta población, la baja y constante incidencia del bopírido A. curtatus parece no afectar la población del porcelánido, y los individuos parasitados no tienen un papel significativo en la historia natural de P. armatus. Palabras clave: parasitismo, castración, cangrejo de porcelana, sur de Brasil, océano Atlántico.

Crustaceans as hosts of parasites throughout the Phanerozoic

“…7), infestation throughout ontogeny or preferential infection of larger specimens rather than solely in juveniles can explain the larger median size of infested individuals. This hypothesis is consistent with the lack of epicarideans in small host size classes in some studies (Mantelatto and Miranda 2010; Lee et al 2016).…”

“…Consequently, swellings should be visible early on in the life of infested decapod hosts and, all else being equal, the proportion of specimens that is infested would remain about the same or decrease due to the adverse effects of parasitism on the host (see above) as host size increases. Such patterns are indeed shown in papers that also report on parasite prevalence per size class (e.g., Oliveira and Masunari 1998; Roccatagliata and Lovrich 1999; González and Acuña 2004; Mantelatto and Miranda 2010; but see Román-Contreras and Romero-Rodríguez 2013). On the other hand, epicarideans can also infest their host throughout host ontogeny as shown by a relatively weak or lack of correlation between parasite size (including immature specimens) and host size (Brockerhoff 2004; Smith et al 2008; Griffen 2009; Rasch and Bauer 2015).…”

“…Consequently, a lower growth rate leading to smaller average and maximum sizes within parasitized specimens may be expected. Multiple studies have indeed shown that modern parasitized decapods are smaller on average than uninfected specimens of the same taxon (e.g., Roccatagliata and Lovrich 1999, for a lithodid anomuran; González and Acuña 2004, for a galatheoid; Petrić et al 2010, for a galatheoid), but other studies found that infested individuals are of similar size (e.g., Mantelatto and Miranda 2010, for porcellanid anomuran) or even larger (e.g., McDermott 1991, for a brachyuran; Lee et al 2016, for a carid shrimp). For maximum size, many examples exist in which the non-parasitized individuals were larger (O’Brien and Van Wyk 1985, and references; Roccatagliata and Lovrich 1999), but one study showed no difference (O’Brien and Van Wyk 1985).…”

“…Regarding the timing of infestation, infestation of many modern decapods by bopyroids is suggested to occur almost exclusively in juvenile hosts based on (1) a positive and often significant relationship between parasite size and host size (e.g., Allen 1966; Beck 1980; Abu-Hakima 1984; Cash and Bauer 1993; Oliveira and Masunari 1998; Roccatagliata and Lovrich 1999; González and Acuña 2004; Mantelatto and Miranda 2010; Román-Contreras and Romero-Rodríguez 2013; Baeza et al 2018), (2) the observation that immature parasites are found in small hosts only (Van Wyk 1982; Oliveira and Masunari 1998, both for a porcellanids), and (3) small specimens are shown to be more readily infested than large specimens (Anderson 1990, for a carid shrimp). Consequently, swellings should be visible early on in the life of infested decapod hosts and, all else being equal, the proportion of specimens that is infested would remain about the same or decrease due to the adverse effects of parasitism on the host (see above) as host size increases.…”