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Southern limit of distribution of the soft-shell clam Mya arenaria on the Atlantic East Coast


The invasive soft-shell clam Mya arenaria was recorded for the first time in the Tagus estuary, central Portugal. Propagules of the soft-shell clam were probably unintentionally introduced into the Tagus estuary through ballast water. Mya arenaria was observed in muddy sands in the upper intertidal zone. The assemblage in which the soft-shell clam was observed was composed of typical estuarine species such as the gastropod Hydrobia ulvae, the bivalve Scrobicularia plana and several polychaete species. The population density of Mya arenaria in the finding area was 40 ind m−2 with a fresh biomass of 163.5 g FW m−2.

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Part of this research was funded by the Spanish Government through the Spanish Agency for Foreign Cooperation (AECI, acronym in Spanish). We are grateful to the Lisbon Port Authority for their full cooperation and logistic support.

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Correspondence to Anxo Conde.

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Conde, A., Novais, J. & Domínguez, J. Southern limit of distribution of the soft-shell clam Mya arenaria on the Atlantic East Coast. Biol Invasions 12, 429–432 (2010).

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  • Mya arenaria
  • Tagus estuary
  • Ballast water