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Benthic changes in the Ria de Foz (northwest Spain) after the construction of a seawall

Abstract:

Long-term changes in the benthos of Spain's coastal waters are still largely unknown. The present paper compares data from January 2002 taken in the ría de Foz (northwest Spain) with the results of a study conducted in 1984-1985, in order to detect possible changes in benthic macrofauna (species composition, abundance, distribution and benthic assemblages) after the construction of a seawall. The same sampling design was used as in the 1980s. This comparison of the 1984-1985 and 2002 samples shows changes in the distribution of the three benthic assemblages detected, and in the abundance and dominance of the main species. These changes are mainly attributed to the construction of a seawall in the mouth of the estuary, which has introduced modifications in its hydrodynamic and sedimentary regimes, making the inner ría more sheltered than before. The new conditions have also promoted the extension of the meadows of the seagrass Zostera noltii Hornemann, 1832 and the community of Cerastoderma edule (L., 1758)-Scrobicularia plana (Da Costa, 1778). © Instituto Español de Oceanografía, 2003.