Behavioral changes in the grass shrimp, Palaemonetes pugio (Holthuis), induced by the parasitic isopod, Probopyrus pandalicola (Packard)

Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA
Journal of Experimental Marine Biology and Ecology (Impact Factor: 1.87). 08/1999; 241(2):223-233. DOI: 10.1016/S0022-0981(99)00084-2


Preliminary observations indicated that the grass shrimp, Palaemonetes pugio, parasitized by the isopod, Probopyrus pandalicola, captured significantly fewer prey items (Daphnia) and exhibited reduced activity compared to unparasitized conspecifics. Further research focused on elucidating the factors involved in altering the shrimp’s behavior. When viewed from above in an opaque container, activity levels of parasitized shrimp were considerably lower than unparasitized shrimp; however, when viewed from the side in a glass container, differences in activity were also seen, but not under all circumstances. In response to the observer above, the parasitized shrimp reduced their activity disproportionately. When (in the opaque tank) prey capture of Artemia was examined, there was no difference between parasitized and unparasitized shrimp’s capture rate. This is attributable to the greater activity of Artemia, which makes them more likely than Daphnia to encounter a relatively inactive predator. There was not a significant difference in prey capture when Cyprinodon larvae were used as prey and tanks were not observed from above. When predator avoidance was studied using mummichogs (Fundulus heteroclitus), we expected that the more conspicuous parasitized shrimp would be preyed upon more, but this was not the case. Their lowered activity in the presence of a predator apparently reduced their conspicuousness, so that they were not preyed on more than the unparasitized shrimp.

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    • "). This could indirectly influence mortality by changing the host's susceptibility to predation, if, for example, males are more likely to leave their burrows and/or fight to mate with females (Bass and Weis 1999). While Griffen (2009) hypothesizes that this could be an important factor in the O. griffenis–U. "

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    • "This also applies to aquatic, mainly marine, invertebrates. The consumption rate of coastal gastropods such as Ilyanassa obsoleta and Littorina littorea is markedly reduced when infected by various trematode species (Clausen et al., 2008; Curtis and Hurd, 1981; Larsen and Mouritsen, 2009; Wood et al., 2007), mud snails (Hydrobia ulvae) being an exception (Mouritsen and Jensen, 1994), and studied copepods, amphipods, isopods and decapods also show reduced consumption when infected by various helminth worms or parasitic isopods (Bass and Weis, 1999; Brown and Pascoe, 1989; Hernandez and Sukhdeo, 2008; Pascoe et al., 1995; Pasternak et al., 1995; see Crompton, 1970, for an exception). Aside from the present study, no studies have been conducted on any crab–rhizocephalan association. "
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    ABSTRACT: Parasites generally influence the feeding behavior of their host and may therefore indirectly impact ecosystem structure and functioning if the host plays an ecological key role. The ecologically important shore crab (Carcinus maenas) is commonly infected by the rhizocephalan parasite Sacculina carcini that aside from inflicting behavioral change, castration and ceased molting, also feminizes its male host morphologically. The latter results in reduced cheliped size, and, together with the other parasite-induced effects, this may potentially impact host feeding behavior. In two separate laboratory experiments, we offered infected and uninfected adult male crabs respectively ad libitum small, easy-to-handle blue mussels (Mytilus edulis) (10–15 mm in shell-length), and a limited, size-structured prey population (15–45 mm in shell-length; seven size-classes, ten mussels per class) during 10–15 days. Corrected for carapace width, the per capita consumption rate of the infected and uninfected crabs was similar in either experiment, both regarding number of mussels and amount of tissue dry-weight consumed. Also, the median mussel size preyed upon when exposed to the size-structure prey population was unaffected by infection. However, infected crabs preyed less frequently (26%) on intermediate mussel sizes (25–30 mm) than uninfected crabs. For both infected and uninfected crabs the median prey size increased linearly with maximum claw height. Host dry weight was significantly reduced by infection, assumed to be the result of the morphological feminization (reduced appendage size) rather than reflecting poorer general condition of infected individuals. Infected crabs were nonetheless subjected to a higher mortality rate than uninfected crabs during the experimental period. We conclude that Sacculina infection has a very limited effect on its host crabs' feeding biology and that any measurable ecosystem ramifications of the host–parasite association must originate from other processes; for instance reduced mean size (infection inhibits molting) and density (infection increases mortality) of the crab population where parasitism is high.
    Journal of Experimental Marine Biology and Ecology 08/2013; 446:209-215. DOI:10.1016/j.jembe.2013.05.029 · 1.87 Impact Factor
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    • "However, documentation on other bopyrids of the same genus shows devastating effects to their respective hosts, such as a reduction of respiratory rate in Palaemonetes argentinus (Nobili, 1901) due to infection with Probopyrus ringueleti (Verdi & Schuldt, 1987) (cf. Anderson, 1975; Schuldt & Rodrigues-Capítulo, 1987; Neves et al., 2000), re-allocation of the host's energetic reserves (Bass & Weis, 1999; Astete-Espinoza & Caceres, 2000; Neves et al., 2004), and sexual sterility (Pike, 1960). Under histopathological examination, the normal spreading of the gill filaments was found incomplete (fig. "
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