Variation in juvenile stages and success of male acquisition in Danish and French populations of the parasitic barnacle Sacculina carcini (Cirripedia: Rhizocephala) parasitizing the shore crab Carcinus maenas

ABSTRACT

Population and developmental characteristics of the rhizocephalan parasite Sacculina carcini were studied in the Limfjord, Denmark and at Roscoff, France. The frequency of juvenile externae in the Limfjord was higher during summer (69.8% of all externae) than during winter (43%). At Roscoff, 62.6% of externae were juvenile in May-June, but only 8.4% in September. The percentage of juveniles with settled males in the Limfjord was higher in summer (20.7% of all juveniles) compared to winter (6.7%). Juveniles at Roscoff in summer had less success in male acquisition (18.0%). The mean number of settled male cyprids per juvenile externa was 0.56 in summer and 0.12 during winter in the Limfjord, but only 0.27 in the summer at Roscoff. Laboratory kept virgin externae invaded by male cyprids ceased to attract additional males within 5–6 days after the first male settlement and then grew into adults within 3 weeks. Externae without males, kept in isolation, did not grow or show any other signs of maturation. Our results confirm and extend previous data on the role of males and their effect on externa development in S. carcini, and show that the success of male acquisition is susceptible to both seasonal and regional variation.

SUBJECT EDITOR:

• Manuela Truebano

KEYWORDS:

• Parasitism
• rhizocephalan barnacles
• externa development
• seasonal and regional variation
• population dynamics
• population structure

Acknowledgements

We wish to thank the staff of the Danish Shellfish Center, Nykøbing Mors, Denmark, for collecting the experimental animals and to the Station Biologique de Roscoff for expert assistance. We also thank colleges assisting the study, in particular, U. Springberg, Msc and C. Grubb Msc.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Arn Rytter Jensen http://orcid.org/0000-0002-3056-7273

Jens T. Høeg http://orcid.org/0000-0002-3596-1691

Henrik Glenner http://orcid.org/0000-0002-8961-7319

Additional information

Funding

This work was supported by the Carlsbergfondet [grant 2008_01_0491] for a long term population study and grant 2013_01_0130 to specifically study the role of the males; Danish Agency for Science and Higher Education [International Network Grant 4070-00148B]; and a grant from the European Union ASSEMBLE Program and the Meltzer Research Fund.