Boat anchoring impacts coastal populations of the pen shell, The largest bivalve in the Mediterranean

Iris E. Hendriks*, Simone Tenan, Giacomo Tavecchia, Núria Marbà, Gabriel Jordà, Salud Deudero, Elvira Álvarez, Carlos M. Duarte

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


The decline of important coastal habitats, like seagrass meadows, is likely to influence populations of associated species, like the noble pen shell, Pinna nobilis. Here we used a Bayesian formulation of individual covariate models to derive a reliable estimate of populations of P. nobilis in shallow, and thus usually most impacted, areas around the island of Majorca, Balearic Islands, Spain. At six evaluated sites we find quite distinct densities ranging from 1.4 to 10.0 individuals/100m2. These differences in density could not be explained by habitat factors like shoot density and meadow cover, nor did dislodgement by storms (evaluated by maximum wind speeds at the sites) seem to play an important role. However, noble pen shell density was related to anchoring as at sites where anchoring was not permitted the average density was 7.9 individuals/100m2 while in sites where ships anchored the density was on average 1.7 individuals/100m2. As for the conservation of Posidonia oceanica meadows, for the associated population of P. nobilis it would be of utmost importance to reduce anchoring pressure as a conservation measure for these endangered and protected bivalves.

Original languageEnglish (US)
Pages (from-to)105-113
Number of pages9
JournalBiological conservation
StatePublished - Apr 2013
Externally publishedYes

Bibliographical note

Funding Information:
This is a contribution to the MEDEICG project, funded by the Spanish Ministry of Economy and Compatitivy (Contract No. CTM2009-07013), and the Praderas project, funded by the Fundación BBVA. The authors thank the many divers helping out with the field surveys; R. Martinez, L. Basso, M. Cabanellas-Reboredo, M. Noguera, E. Diaz, L. Royo, S. Sardu, A. Canepa. I.E.H. was supported by a grant from the Juan de la Cierva program, Spanish government (JCI-2007-123-844). G.J. acknowledges a JAE-DOC contract funded by the Spanish Research Council (CSIC). Funds were partially provided by the Regional Government of Balearic Islands and FEDER funding. ST was funded by a PhD grant from the Science Museum (Trento) in collaboration with the University of Pavia.


  • Bayesian analysis
  • Capture-recapture
  • Data augmentation
  • Habitat
  • Hierarchical models
  • Individual covariate
  • Pinna nobilis
  • Population size
  • Population structure

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Nature and Landscape Conservation


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