Control region sequences indicate that multiple externae represent multiple infections by Sacculina carcini (Cirripedia: Rhizocephala)

Abstract

The rhizocephalan barnacle, Sacculina carcini, is a common parasite of the European shore crab, Carcinus maenas, in which it causes significant detrimental physical and behavioral modifications. In the vast majority of cases, the external portion of the parasite is present in the form of a single sac-like externa; in rare cases, double or even triple externae may occur on the same individual host. Here, we use a highly variable DNA marker, the mitochondrial control region (CR), to investigate whether multiple externae in S. carcini represent infection by multiple parasites or asexual cloning developed by a single parasite individual. Sequences for multiple externae from C. maenas hosts from the Danish inlet, Limfjorden, and from the mud flates at Roscoff, France, were compared. In almost all cases, double or triple externae from an individual host yielded different haplotypes. In the few cases where identical haplotypes were identified from externae on a multiple-infected host, this always represented the most commonly found haplotype in the population. This indicates that in Sacculina carcini, the presence of multiple externae on a single host reflects infection by different individual parasites. A haplotype network of CR sequences also suggests a degree of geographical partitioning, with no shared haplotypes between the Limfjorden and Roscoff. Our data represent the first complete CR sequences for a rhizocephalan, and a unique gene order was also revealed. Although the utility of CR sequences for population-level work must be investigated further, the CR has proved a simple to use and highly variable marker for studies of S. carcini and can easily be applied to a variety of studies in this important parasite.

Two new cryptic and sympatric species of the king crab parasiteBriarosaccus(Cirripedia: Rhizocephala) in the North Pacific

“…In Briarosaccus , however, the rate of multiple infections is lower than expected by chance and usually only occurs in heavily parasitized host populations (Sloan, 1984 ). This indicates infestations of the crab by multiple female Briarosaccus larvae in the case of multiple externae, as it has been shown for the rhizocephalan Sacculina carcini Thompson, 1836 using the mitochondrial control region (Rees & Glenner, 2014 ).…”

“…York, Blacket & Appleton, 2008 ; Pinou et al ., 2013 ), and especially in the morphological poor Rhizocephala (e.g. Murphy & Goggin, 1970 ; Rees & Glenner, 2014 ), which are largely deficient of diagnostic characters.…”

Population dynamics and development of the rhizocephalan Sacculina carcini, parasitic on the shore crab Carcinus maenas

“…After cooling to room temperature, 75 µl of neutralization buffer (40 mM Tris-HCl, pH 5) was added before immediate use in PCR or storage at 4°C. PCR-based screening was performed on the extracted DNA utilizing previously developed S. carcinispecific control region primers (Rees & Glenner 2014). PCR reactions were carried out in 25 µl final volumes, initially containing only the Sacculina-specific primers.…”

Infestation of parasitic rhizocephalan barnaclesSacculina beauforti(Cirripedia, Rhizocephala) in edible mud crab,Scylla olivacea

“…The prevalence of parasitic barnacles is reported around the world, including European countries (Rees & Glenner, 2014), Japan (Lutzen & Takahashi, 1997), Taiwan (Huang & Lutzen, 1998), China (Yang et al, 2014), Malaysia (Boschma, 1949), Australia (Knuckey, Davie & Cannon, 1995), America (Tolley et al, 2006) and India (Raffi et al, 2012). As well as mud crabs, rhizocephalan parasites are known to invade a wide range of other marine and intertidal crab species such as the European green crab, Carcinus maenas (LINNAEUS 1758) (Thresher et al, 2000), intertidal crab, Hemigrapsus sanguineus (DE HAAN 1853) (Lutzen & Takahashi, 1997), sand crab, Portunus pelagicus (LINNAEUS 1758) (Bishop & Cannon, 1979; Weng, 1987) and three-spotted crab, Portunus sanguinolentus (HERBST 1783) (Raffi et al, 2012; Yang et al, 2014).…”

“…Alteration in the morphological primary and secondary sexual characteristics in crabs are possible and does occur in nature ( Høeg, 1984 ; Rees & Glenner, 2014 ). One of the most common causes reported are specific parasitic infection ( Ayaki et al, 2005 ).…”