Valvulineria Bradyana (Fornasini) in organic matter-enriched environment (Ombrone River Mouth, Central Italy)

Abstract

This paper discusses the significance of the high frequency of Valvulineria bradyana in recent benthic foraminiferal as-semblages, from a circalittoral environment, near to the Ombrone River mouth (Southern Tuscany). In spite of long seasonal periods of low oxygen levels, this species may reach high densities in typical assemblages, where it sometime constitutes more than 50%. Valvulineria bradyana is characterised by good tolerance to scarcely oxygenated environments and by opportunistic behaviour, which allow it to take advantage of the high trophic levels due to the river contributions, more than any other species in the studied assemblages. For this behaviour, marked r-selective features may be attributed to Valvulineria bradyana. Moreover, the structure of the assemblages constitutes a conceptual model that might be useful for paleoecological reconstruction.