Biogeographic patterns of the marine bivalve Cerastoderma edule along the European coasts

• Main Author: Krakau, Manuela
• Other Authors: Reise, Karsten, Hanel, Reinhold
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2008
• Subjects: ddc:570; thesis; cockle; biogeography; haplotype diversity; large scale pattern; Herzmuschel; Biogeographie; Haplotypendiversität; großskalige Muster; Barents Sea; Norway; Northeast Atlantic
• Online Access: https://nbn-resolving.org/urn:nbn:de:gbv:8-diss-29907; https://macau.uni-kiel.de/receive/diss_mods_00002990; https://macau.uni-kiel.de/servlets/MCRFileNodeServlet/dissertation_derivate_00002444/diss_krakau2008.pdf

The cockle Cerastoderma edule is a common bivalve that inhabits the marine soft-bottom intertidal along European shores. This invertebrate plays a key role in coastal food webs of the Northeast Atlantic coasts due of its high abundances. I studied cockles from 19 sites along the distribution range with the aim to describe the variation of geographic population structures on different analytical levels. Cockles from the Barents Sea to the African Atlantic coast were analysed with respect to their geographical differentiation in shell morphology, parasite load and population genetics. Morphological characteristics were analysed for a potential geographic pattern within the European cockle C. edule. Spatial differences of eight shell characteristics within samples from 18 sites were studied. However, biogeographic groups could not be discovered due to strong local variability in shell form parameters. Environmental conditions and/or co-existing species were suspected to shape the plasticity of cockle shells at each site. At sites where the sister species C. glaucum occurred together with C. edule, high variability of shell characters was found in both species. The lack of morphological character displacement in mixed populations confined reliable species identification to the DNA level. Since parasites often strongly influence host morphology and its life history traits, the biogeography of the trematode assemblage was studied for C. edule as first and second intermediate host. At ten European locations ranging from Norway to Portugal, 30 cockle specimens per site were sampled to detect trematode diversity and abundance. Cockles from the Scandinavian sites shared dominant trematode species (Himasthla elongata, Meiogymnophallus minutus and Renicola roscovita) with the south-western European populations. However, two geographical groups could be revealed, based on the occurrence of rare species and changes in the abundances of common trematodes. The geographic distribution of suitable hosts for closing parasite life ...