Temporal dynamics of the benthic assemblage in the muddy sediments of the harbour of Baiona (Galicia, nw Iberian Peninsula)

• Autores: Juan Moreira, Antía Lourido Soto, Jesús Souza Troncoso
• Localización: Thalassas: An international journal of marine sciences, ISSN 0212-5919, Vol. 26, Nº. 2, 2010, págs. 9-22
• Idioma: inglés
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• Resumen

  • Construction of artificial structures on the shoreline such as seawalls, breakwaters and jetties translates, in many cases, in changes in local current dynamics, alteration of sedimentation rates, siltation and organic enrichment. The temporal variation of the benthic fauna inhabiting the muddy sediments at the harbour of Baiona (Galicia, Spain) sheltered by an extensive breakwater was studied from May 1996 to May 1997 by means of quantitative sampling.

    Sediment was characterized by high content of silt and total organic matter; these results contrast to previous studies done in the same area, which reported a dominance of sandy fractions in the sediment. A total of 17987 individuals representing 187 different taxa belonging to 11 phyla were found. The polychaete, Cossura pygodactylata, and the bivalve, Thyasira flexuosa, were the numerically dominant species at the studied site. Number of species, total abundance and densities of dominant species showed great monthly fluctuations and no clear seasonal patterns of temporal evolution could be detected. Values of diversity and evenness were, in general, high and stable through time. The composition of the assemblage was richer than that of assemblages from similar muddy sediments in other harbour areas from Europe but was poorer than those inhabiting surrounding sandy sediments at the Ensenada de Baiona. The values of the AMBI index and the numerical dominance of opportunistic species such as some deposit-feeding polychaetes indicated some degree of disturbance possibly linked to pulses in organic input derived from human activities in the area and, in first instance, to the construction of the harbour breakwater several decades ago.