Una nueva mirada a la caracterización del sustrato de las zonas de marisqueoel caso de los bancos arenosos intermareales de la costa Norte de Galicia (NW de la Península Ibérica)

Abstract

A battery of multivariate analyses including cluster (CA), principal component (PCA) and generalised linear mixed models (GLMMs) were performed to define the spatial organization of sandbanks of five of the Ría Altas (Ortigueira, Barqueiro, Viveiro, Foz and Ribadeo) and to identify the sedimentological parameters driving the obtained clustering. Grain size distri- bution and calcium carbonate content, organic matter, Si and Al oxides and trace metals were the parameters used to cha- racterize the intertidal sediments. Field data to conduct these analyses were collected through the first 50 cm of 57 shellfish harvesting sandbanks located in five previously named embayments. The multivariate analysis revealed that the sandbanks organized around four clusters that do not depend exclusively on the embayment were they were located, but characterized by the imprint of the Cabo Ortegal complex material (with high levels of MgO, Mn, Cr, Ni, V and Fe2O3; Ría de Ortigueira) or by the imprint of the Ollo de Sapo and Manto de Mondoñedo influence (high levels of SiO2, Rb, K2O and Ba; the rest of the embayments). The cluster analysis also separated the sandbanks with higher terrestrial influence in the inner part of the embayments (with high levels of Al2O3, Zn, Ba and TiO2) from those with higher marine influence, which were located in the outer part (with high levels of Sr, CaO and CaCO3).