Asociaciones de Foraminíferos bentónicos en los sedimentos recientes del estuario de Tina Mayor (Asturias-Cantabria)

Abstract

A total of 35 species of benthic foraminifers have been taxonomically determined in recent sediments of the Tina Mayor estuary (Asturias-Cantabria provinces, N. Spain). Alive individuals belonging to 22 species, reach up to 30.2% of the total obtained specimens. Most abundant species in both biocenotic and thanatocenotic individuals are: Ammonia tepida, Cribroelphidium williamsoni, Lobatula lobatula, Miliammina fusca and Trochammina inflata. Multivariate analyses (Cluster-Q) of samples, considering all benthic foraminifer species, indicate that this microfauna is distributed into four main groups, corresponding to different sub-environments in this estuary: 1) marine, 2) high vegetated marsh, 3) low marsh-upper intertidal of channels, and 4) subtidal lower zone of those channels. Furthermore it is possible to differentiate sub-groups taking into account the sediment type. The sediment is an important factor that produces variations in the percentage of main species, as well as richness and diversity of the assemblages. The geomorphological pattern dividing the estuary into three areas (head, mid estuary and mouth) do not correspond with the results provided by benthic foraminifers, which assemblages only distinguishes the mouth of marine character and the euryhaline mid estuary environments, while the head is not separated from the mid estuary