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)

Jennifer A Rasch,Raymond T Bauer

doi:10.1590/s0104-64972015002317

Abstract

Caridean shrimps are often infested by ectoparasites from the isopod family Bopyridae. Urobopyrus processae is a widespread species of bopyrid parasitizing the branchial (gill) chambers of members of the caridean family Processidae, including Ambidexter symmetricus. We examined hypotheses on differential infestation based on gender, castration of the host by the parasite, correlation between host and parasite size, and the fecundity of female parasites. Infestation rates varied from 1.3 to 32.1% between 2010 and 2011. Infested shrimps ranged from 1.26 mm to 6.24 mm carapace length (CL) between 2010 and 2011. Female shrimps were infested at a higher rate than males (2010 P = 0.0376; 2011 P = 0.0023). We report for the first time the differential selection between left and right branchial chambers in a caridean shrimp by a bopyrid parasite (P = 0.0209). Female parasite total length (TL) increased with host size (CL) in both years of sampling (2010 R2adj = 0.6863; 2011 R2adj= 0.8206). The size of male parasite TL was explained by both host CL (2010 R2adj = 0.4591; 2011 R2adj = 0.5490) and parasite female TL (2010 R2adj = 0.5606; 2011 R2adj = 0.6195). The number of embryos in a brood of the female parasite (85-3096) was varied positively with female TL (R2adj = 0.625). Our results show that the bopyrid-shrimp host relationship in processids is typical of those studied in other carideans, indicating similar selective pressures act on bopyrids infesting the branchial chambers of shrimps.

Highlights

Decapod crustaceans are often infested by isopod parasites from the family Bopyridae
We collected a total of 1309 Ambidexter symmetricus in 2010 and 1177 in 2011, which was the only processid shrimp species collected infested with Urobopyrus processae
Infestation rates in 2010 varied from 2.1% to 17.8% with a mean infestation rate of 8.6%, while in 2011 infestation rates varied from 1.3% to 32.1% with a mean of 8.2%, not including the July data (n = 2, infestation rate = 50%) because of its small sample size (Fig. 2)

Summary

Introduction

Decapod crustaceans are often infested by isopod parasites from the family Bopyridae. The majority of the members of this family are ectoparasites attaching within the branchial (gill) chamber or on the abdomens of their hosts (O’Brien and Van Wyk, 1985; Markham, 1986). These parasites do not kill their hosts as a requirement for development but instead depend on them for nutrition and as their habitat (Anderson and May, 1978). Most species are usually parasitic castrators (Baudoin, 1975; Beck, 1979; O’Brien and Van Wyk, 1985; Romero-Rodríguez and Román-Contreras, 2013), this is not always the case (Calado et al, 2006). The relationships between populations of hosts and their parasites may follow classical predator-prey interactions (Anderson and May, 1978; Romero-Rodríguez and Román-Contreras, 2013) and cause sex ratio distortion in their hosts (Hatcher et al, 1999)

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Conclusion