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

TY - JOUR

T1 - Population dynamics and development of the rhizocephalan Sacculina carcini, parasitic on the shore crab Carcinus maenas

AU - Mouritsen, Kim N.

AU - Geyti, Sissel N.S.

AU - Lützen, Jørgen

AU - Høeg, Jens T.

AU - Glenner, Henrik

PY - 2018/11/20

Y1 - 2018/11/20

N2 - The ecologically important shore crab Carcinus maenas is commonly infected in its native range by the rhizocephalan Sacculina carcini. However, several aspects of this host-parasite interaction are poorly understood. Here, we analyse data from approximately 60 000 Danish crabs to unravel factors governing infection patterns in time and space, and according to host sex and size. Female crabs were more frequently infected (12.6%) than males (7.9%). Sites with high salinity supported the highest infection prevalence. Infection prevalence peaked in summer (10 to 15%) and winter (20 to 35%) due in part to emergence of virginal externae in summer (main outbreak) and autumn (minor outbreak) preceded by peaks in crabs with lost externa (scars). Younger externae and scars dominated among males, whereas adult externae were most frequent among females. Infection prevalence increased with size in females but decreased in males, and modified (feminized) males showed lower scar frequency than unmodified ones. Modified males occurred frequently among the smaller size classes, whereas unmodified males dominated the larger size classes. Externa size was positively related to host size in both genders (same linear relationship). Molecular analyses suggested that hosts below 16 mm in carapace width do not become infected. Dissections of infected hosts revealed marked reduction of ovaries, whereas testes were unaffected by sacculinization. Our study demonstrates great spatio-temporal variation in infection prevalence mainly related to the parasite's life history. S. carcini appears capable of infecting all host sizes except the smallest. Owing to incomplete feminization of males, infections are rapidly lost from the larger and highly profitable male hosts.

AB - The ecologically important shore crab Carcinus maenas is commonly infected in its native range by the rhizocephalan Sacculina carcini. However, several aspects of this host-parasite interaction are poorly understood. Here, we analyse data from approximately 60 000 Danish crabs to unravel factors governing infection patterns in time and space, and according to host sex and size. Female crabs were more frequently infected (12.6%) than males (7.9%). Sites with high salinity supported the highest infection prevalence. Infection prevalence peaked in summer (10 to 15%) and winter (20 to 35%) due in part to emergence of virginal externae in summer (main outbreak) and autumn (minor outbreak) preceded by peaks in crabs with lost externa (scars). Younger externae and scars dominated among males, whereas adult externae were most frequent among females. Infection prevalence increased with size in females but decreased in males, and modified (feminized) males showed lower scar frequency than unmodified ones. Modified males occurred frequently among the smaller size classes, whereas unmodified males dominated the larger size classes. Externa size was positively related to host size in both genders (same linear relationship). Molecular analyses suggested that hosts below 16 mm in carapace width do not become infected. Dissections of infected hosts revealed marked reduction of ovaries, whereas testes were unaffected by sacculinization. Our study demonstrates great spatio-temporal variation in infection prevalence mainly related to the parasite's life history. S. carcini appears capable of infecting all host sizes except the smallest. Owing to incomplete feminization of males, infections are rapidly lost from the larger and highly profitable male hosts.

KW - Externa development

KW - Feminization

KW - Host-size selection

KW - Infection prevalence

KW - Parasitism

KW - Phenology

KW - Sex-biased infection

KW - Spatial distribution

U2 - 10.3354/dao03290

DO - 10.3354/dao03290

M3 - Journal article

C2 - 30459292

AN - SCOPUS:85056802328

SN - 0177-5103

VL - 131

SP - 199

EP - 211

JO - Diseases of Aquatic Organisms

JF - Diseases of Aquatic Organisms

IS - 3

ER -