Infection of adult migratory river shrimps, Macrobrachium ohione, by the branchial bopyrid isopod Probopyrus pandalicola

Abstract

Abstract. Macrobrachium ohione is a migratory (amphidromous) river shrimp (Decapoda, Caridea) that may be parasitized by the branchial parasite Probopyrus pandalicola (Isopoda, Bopyridae). The parasite disrupts gonadal maturation and spawning in female shrimps, resulting in the total loss of reproduction. Shrimps are usually infected by bopyrid parasites during the late zoeal or early postlarval stages; in this study, we investigated the apparent parasite infection of adult shrimps. We analyzed the relationships between parasite body size (total length) and host shrimp body size (carapace length) to test the hypothesis that parasite infection of adult shrimps occurs during the shrimps' reproductive migrations. The results presented here indicate that infection of adult shrimps is common in M. ohione in the Atchafalaya and Mississippi Rivers, Louisiana, USA. In the two upriver sites sampled, Butte La Rose (BLR) and River Bend (RB), parasite size was not associated with host body size. In these locations, many parasitized adult M. ohione were infected with immature P. pandalicola (40.3% in BLR and 51.2% in RB), indicating that the shrimps were adults at the time of infection. A possible explanation is that when female shrimps enter the estuary to hatch larvae, they molt and spawn another brood. The smaller male shrimps that accompany the females downstream are also assumed to molt and continue growth. The intermediate host of the parasite is an estuarine copepod, and thus the parasite cryptoniscus larva that infects the host shrimp is primarily estuarine as well. Newly molted shrimps have soft cuticles, which may facilitate their infection by parasite cryptonisci. Our conclusion is that most infections of adult shrimps occur during their migration into estuarine waters, the primary habitat of infective parasite larvae, and that host vulnerability is probably increased following host ecdysis.

Temporal variation in population structure of the isopod Urobopyrus processae Richardson, 1904 (Isopoda: Bopyridae) infesting the branchial chamber of the night shrimp Ambidexter symmetricus Manning and Chace, 1971 (Decapoda: Processidae)

“…However, female parasites are asymmetrical in shape (Fig. 1B, D) and were measured along the longest line from the anterior end to the end of the pleotelson (Cash and Bauer, 1993;Conner and Bauer, 2010). Development of embryos within the marsupium was divided into four successive stages: stage I, which is spherical in shape, whitish; stage II, which is oblong in shape and yellowish; stage III, which is oblong in shape and yellowish in color with brown pigments; and epicaridium larva, with external appendages and visible eyespots (Beck, 1980a;Romero-Rodríguez and Román-Contreras, 2013).…”

“…Bopyrid parasites often infest young shrimps and grow with the hosts in marine and brackish ecosystems (Pike, 1960;Kuris, 1974;Owens, 1983;Cash and Bauer, 1993;Roccatagliata and Lovrich, 1999;Romero-Rodríguez and Román-Contreras, 2013). However, in rare cases, parasites may infest older and larger host shrimps, e.g., in amphidromous shrimps which may be infested during reproductive migrations to estuaries (Conner and Bauer, 2010). Another possible side effect of a parasite on a host is gigantism.…”

Infestation of two shrimp species of the genus Palaemon Fabricius, 1798 (Decapoda, Palaemonidae) by an isopod of the genus Probopyrus Giard & Bonnier, 1888 (Bopyridae) from the Brazilian southeast coast

“…(larger than 1 mm TL) were found in larger shrimps (larger or equal to 3.97 mm CL). Cryptoniscid larvae usually infest shrimps during the host's early developmental stages and grow together with the hosts, although this is not always the case; in rare cases, bopyrids may infest older and larger shrimp hosts (Conner and Bauer, 2010). Video observations of P. pandalicola infesting Palaemon pugio (Holthuis, 1949) suggest that most bopyrids must survive through the ecdysis of the host (Cash and Bauer, 1993).…”

“…Male parasites are symmetrical in shape and were measured from the anterior edge of the cephalon to the posterior edge of the pleotelson, while females are asymmetrical in shape and were measured along the longest side from the anterior margin of the body to the end of the pleotelson (Cash and Bauer, 1993). Immature and mature parasites were differentiated according to Conner and Bauer (2010). The use of the term "prevalence" followed Margolis et al (1982), and expressed the percentage of infested shrimps present in the sampled population.…”

Effects of the parasitic isopod Ichthyoxenus japonensis Richardson, 1913 (Isopoda, Cymothoidae) on the growth and gonad development of the goldfish Carassius auratus Linnaeus, 1758

“…Gonads of infected fish, however, were hardly visible. The mechanism of parasitic castration of the host remains poorly known, but hormonal interference (Beck, 1980;Lima et al, 2007) and nutritional drain caused by the parasite (Anderson, 1977;Walker, 1977;Conner & Bauer, 2010) have been proposed as explanations. Another cymothoid isopod, Riggia paranensis Szidat, 1948, which burrows into the flesh of its fish host, Cyphocharax gilbert Quoy & Gaimard, 1824, also causes parasitic castration (Azevedo et al, 2006).…”