Molluscan fauna in the freshwater tidal area of the River Minho estuary, NW of Iberian Peninsula

¹ CIIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Rua dos Bragas, 4050-123 Porto, Portugal.
² ICBAS, Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Departamento de Estudos de Populações, Laboratório de Ecotoxicologia, Lg. Prof. Abel Salazar 2, 4099-003 Porto, Portugal.

Corresponding author: ronaldo.sousa@cimar.org

Abstract

Ten species of molluscs were identified in the freshwater tidal area of the River Minho estuary. Species richness per site ranged from 1 to 9. Abundance ranged from 230 to 4130 individuals per m², with an average of 1412 individuals per m2. Corbicula fluminea(Müller, 1774) presented the highest density, corresponding to 88.7 % of the total specimens gathered, followed by Pisidium amnicum (Müller, 1774) with 5.8 %. Biomass ranged from 17.0 to 249.6 g AFDW m-2, with an average of 99.8 g AFDW m-2. C. fluminea was the species dominating the total biomass (95.4 %), followed by Bithynia tentaculata (Linnaeus, 1758) with 1.6 %. A multivariate analysis revealed a community with two distinct groups : one group almost or exclusively represented by C. fluminea, and another group with a more diverse assemblage.