Quantifying Tidal Movements of the Shore Crab Carcinus maenas on to Complex Epibenthic Bivalve Habitats

Andreas M. Waser*, Rob Dekker, Johannes Ij Witte, Niamh McSweeney, Bruno J. Ens, Jaap van der Meer

*Corresponding author for this work

    Research output: Contribution to JournalArticleAcademicpeer-review


    Many subtidal predators undertake regular tidal migrations into intertidal areas in order to access abundant prey. One of the most productive habitats in soft bottom intertidal systems is formed by beds of epibenthic bivalves such as blue mussels (Mytilus edulis) and Pacific oysters (Crassostrea gigas). In the Dutch Wadden Sea, these bivalves might face substantial predation pressure by the shore crab (Carcinus maenas), which increased considerably in numbers during the last 20 years. However, the quantification of this species on bivalve beds is challenging, since most methods common for quantifying animal abundance in marine habitats cannot be used. This study investigated the potential of two methods to quantify the abundance of C. maenas on 14 epibenthic bivalve beds across the Dutch Wadden Sea. The use of the number of crabs migrating from subtidal towards intertidal areas as a proxy of abundance on bivalve beds yielded unreliable results. In contrast, crabs caught with traps on the beds were correlated with the abundance assessed on the surrounding bare flats by beam trawl and therefore provided usable results. The estimates, however, were only reliable for crabs exceeding 35 mm in carapace width (CW). The application of these estimates indicated that crab abundances on bivalve beds were influenced by the biogenic structure. Beds dominated by oysters attracted many large crabs (> 50-mm CW), whereas abundances of medium-sized crabs (35–50-mm CW) showed no relationship to the oyster occurrence. The combination of traps and trawls is capable of quantifying crab abundance on bivalve beds, which offers the possibility to study biotic processes such as predator-prey interactions in these complex structures in more detail.

    Original languageEnglish
    Pages (from-to)507-520
    Number of pages14
    JournalEstuaries and Coasts
    Issue number2
    Early online date11 Aug 2017
    Publication statusPublished - Mar 2018


    This study was carried out as part of the project Mosselwad, which is funded by the Dutch Waddenfonds (WF 203919), the Ministry of Infrastructure and Environment (Rijkswaterstaat), and the provinces of Fryslân and Noord Holland. We thank Bram Fey, Klaas-Jan Daalder, Wim-Jan Boon, and Hein de Vries, crew of the Royal NIOZ research vessel RV Navicula, for their help. We also wish to thank Afra Asjes, Annabelle Dairain, Niel de Jong, Erika Koelemij, Lotte Meeuwissen, Felipe Ribas, Anneke Rippen, Robert Twijnstra, Marin van Regteren, and Kai Wätjen who helped in the sampling and processing of shore crabs. We thank Arnold Bakker, Tristan Biggs, Maarten Brugge, Annabelle Dairain, Erika Koelemij, Lotte Meeuwissen, Anneke Rippen, Sofia Saraiva, Cor Sonneveld, and Arno wa Kangeri for helping in sampling and processing bivalves on the different bivalve beds. Furthermore, we thank Patricia Ramey-Balci and two anonymous reviewers for constructive feedback on an earlier draft of the manuscript.

    FundersFunder number
    Ministerie van Infrastructuur en Milieu


      • Animal abundance
      • Crassostrea gigas
      • Mytilus edulis
      • Tidal migration
      • Wadden Sea


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