Con la idea de evaluar la respuesta cuantitativa de los foraminíferos con respecto a la distancia relativa a la boca del estuario (RDEM) en los sistemas estuarinos del sur del Golfo de Vizcaya, se ha desarrollado una función de transferencia basada en un matriz de datos compuesta por 88 muestras y 41
especies obtenidas en seis estuarios del norte de España. La RDEM ha sido considerada como un indicador del gradiente de salinidad. La relación entre los resultados obtenidos e inferidos indica el óptimo funcionamiento de la función de transferencia (r2 jack = 0.76) y permiten llevar a cabo reconstrucciones
precisas de la evolución reciente de la RDEM a partir del análisis del registro sedimentario.

Estuaries are located between the continental and oceanic end members, resulting in strong variations of salinity and all other parametres linked to the penetration of seawater into the estuary. An estuary could be defined most simply based on salinity, being an area where freshwater enters saline water and during at least some period of time, water is neither truly
saline nor truly fresh. However, data over diurnal and longer time series are seldom available. On the other hand, benthic organisms are good ecological indicators, given their
inherent ability to integrate sediment quality and changing environmental conditions, and therefore to provide an insight of the spatial variations derived from the salinity influence.
Recently, advances in high-resolution studies have been made through the development of foraminifera-based transfer functions. This technique is an important palaeoecological tool
that provides objective, quantitative and reproducible estimates of the environmental parametre studied, associated with explicitly stated error terms (Birks, 1995). Consequently,
we hypothesize that transfer functions would provide an adequate method to quantify the assemblage turnover along the salinity gradient in the southern Bay of Biscay, using the relative distance to the estuary mouth (RDEM) as a proxy for salinity. In this paper we present a new transfer function based on the
modern distributions of intertidal foraminifera recorded in six estuaries from the southern Bay of Biscay (Figure 1) and provide an improved quantitative assessment with defined error terms of the potential of regional intertidal foraminifera for salinity studies (in terms of RDEM).

Cearreta, A., Leorri, E., Iriondo, I., González, M.J., Aristondo, O., 2008. Quantitative tools for environmental reconstructions of the
recent estuarine infill using benthic foraminifera. Geogaceta 45, 67-70