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Monitoring n° 30 of the BLAYAIS nuclear power plant takes into account studies conducted between April and November 2007. Physicochemistry, Bathymetry, Hydrobiology, Bacteriology, Zooplankton, Benthic macrofauna, are reported., L'étude de surveillance n° 30 du site électronucléaire du BLAYAIS (département de la Gironde) concerne la période de avril à novembre 2007. Les domaines pélagique et benthique sont étudiés (physico-chimie, bathymétrie, hydrobiologie, bactériologie, zooplancton, macrofaune benthique).

Six cores sampled at two mud fields located on the northern Portuguese continental shelf have been studied in order to evaluate the control processes of fine sedimentation. The southern mud patch, offshore from the Douro River, is limited on the western side by some Cretaceous and Paleocene outcrops that constitute reliefs of 5-30 m in width; on the contrary, the northern mud patch, offshore from the Minho River, extends along a flat region. Granulometric distribution shows that the sediments from the Minho mud patch are coarser than those from the Douro mud patch, where the grain size diminishes towards the west. Carbonate content is also higher in the Minho mud field. The sediment organisation in fining-up sequences in the Minho mud patch and in the eastern part of the Douro mud patch indicates sediment remobilisation by storms. The Douro mud patch has higher sedimentation rates than the Minho mud patch. The highest values are probably related to the existence of reliefs, which may offer hydrodynamic protection or function as a fine sediment barrier. The elemental distribution for chemical elements was determined in different fractions of these cores. Geochemical patterns are generally quite similar for both mud fields, indicating a common continental origin for the sediments. The major differences in the chemical composition are mainly controlled by the grain-size distribution, either reflecting the presence of coarse quartz particles or a local enrichment in biogenic material. En este trabajo se han estudiado seis testigos de la zona norte de la plataforma continental portuguesa con el objetivo de evaluar los procesos que controlan la sedimentación de materiales finos en esta región. Los fangos acumulados más al sur, frente a la desembocadura del río Duero, están limitados al oeste por relieves cretácicos y paleocenos de 5 a 30 m de altura. Los fangos septentrionales, frente a la desembocadura del río Miño, se extienden sobre una región plana. La distribución granulométrica muestra que estos últimos son más gruesos que los depositados frente al Duero, en los que el tamaño de grano disminuye hacia el oeste. El contenido en carbonato es más elevado en la zona del Miño. Las secuencias granodecrecientes encontradas en los fangos del Miño y en los del sector oriental del Duero indican retrabajamiento del sedimento por tormentas. La tasa de sedimentación es mayor en los fangos situados frente al Duero, donde los valores más altos están relacionados probablemente con la existencia de relieves, los cuales ofrecerían una protección hidrodinámica o actuarían como una barrera para los sedimentos. La distribución de la concentración de diversos elementos químicos a lo largo de los testigos fue determinada para diferentes fracciones. El patrón geoquímico es bastante similar en ambas zonas y pone de manifiesto una procedencia continental de los sedimentos. Las principales diferencias en la composición química están fundamentalmente controladas por la distribución granulométrica, bien por la presencia de granos gruesos de cuarzo, bien por un enriquecimiento local en material biogénico. Instituto Español de Oceanografía

The sedimentology and micropalaeontological content of a core located in the Forua marsh of the Nature Reserve of the Urdaibai (Soutern Bay of Biscay) have been analysed in order to characterise the modem Holocene evolution of this marsh. Based upon lithology and benthic Foraminifera assemblages, five units have been identified in this core. The older one represents a subtidal, estuarine palaeoenvironment with marine influences, dated of 4640 years BP, that is, at the end of a transgressive phase initiated at about 5000 y BP, coincident to the Atlantic-Subboreal transition. During the second phase the sea retreated from the Urdaibai and a marsh settled in Forua at around 4500 y BP (end of Neolithic). The filling of this marsh is evidenced by changes of micropalaeontologic assemblages. A third sedimentologic phase is characterised in this area by a brackish marsh that is temporarily flooded with waters from the marine shelf. This event could be related to the transgressive pulsation occurred during the Subboreal-Subatlantic transition (3500-2500 y BP; early-mid Bronze Age). The sedimentary filling of the marsh was completed during the fourth episode, as evidenced by the exclusive occurrence of agglutinated species of Foraminifera typical of upper, vegetated marsh settlements. Calcareous microfauna disappear at the top of this core as a consequence of the total emergence of this area that became a polder used for culturing up to 7 960. The occurrence of few specimens of J. macrescens in the last centimetres of the core evidences the occasional flooding of this area during equinoccial tides

The sedimentology and micropalaeontological content of a core located in the Forua marsh of the Nature Reserve of the Urdaibai (Soutern Bay of Biscay) have been analysed in order to characterise the modem Holocene evolution of this marsh. Based upon lithology and benthic Foraminifera assemblages, five units have been identified in this core. The older one represents a subtidal, estuarine palaeoenvironment with marine influences, dated of 4640 years BP, that is, at the end of a transgressive phase initiated at about 5000 y BP, coincident to the Atlantic-Subboreal transition. During the second phase the sea retreated from the Urdaibai and a marsh settled in Forua at around 4500 y BP (end of Neolithic). The filling of this marsh is evidenced by changes of micropalaeontologic assemblages. A third sedimentologic phase is characterised in this area by a brackish marsh that is temporarily flooded with waters from the marine shelf. This event could be related to the transgressive pulsation occurred during the Subboreal-Subatlantic transition (3500-2500 y BP; early-mid Bronze Age). The sedimentary filling of the marsh was completed during the fourth episode, as evidenced by the exclusive occurrence of agglutinated species of Foraminifera typical of upper, vegetated marsh settlements. Calcareous microfauna disappear at the top of this core as a consequence of the total emergence of this area that became a polder used for culturing up to 7 960. The occurrence of few specimens of J. macrescens in the last centimetres of the core evidences the occasional flooding of this area during equinoccial tides

The microfauna (foraminifers, ostracods) and sedimentology of a core from the supratidal polluted area of the Ria of Gernika (S of Bay of Biscay) have been analysed in this work. Four different episodes have been recognised in the last 6400 years in this area, based upon microfaunaI assemblages and sedimentological facies. The older one represents a subtidal palaeoenvironment with marine influences at the base of this core. A subsequent increase of the energy in a tidal palaeoenvironment is evidenced by the occurrence of rhythmic fades and estuarine characteristic microfaunaI assemblages. This level is correlated to transgressive pulsations previously described in the Bay of Biscay 3500 to 2500 y. BP. Third episode shows a progressive shallowing of the palaeoenvironment, with low-salinity and mixed waters in a supratidal marshy milieu. To the core top, a very fine sediment with abundant plant roots and very scarce microfauna indicate the present filling of this part of the estuary

The sedimentology and micropaleontological content (benthic foraminifera) of a core located in the Anbeko polder of the Urdaibai estuary (Southern Bay of Biscay) have been analysed in order to characterize the holocene evolution of this polder. Based upon sedimentology and micropalaeontological assemblages, four units have been identified in this core. During the first phase this area was under marine conditions, with a a maximum marine influence around 5000 years BP. The pulsation described during the Atlantic-Subboreal transition of the Holocene is then registered in this core. Sedimentological facies of the second unit indicate a decrease of energy in this environment, where outer estuarine foraminifera dominated the assemblages. The third phase indicates the progressive filling of the estuary, with the appearance of a vegetated marsh, as evidenced by the total dominance of agglutinated foraminifera. This marsh, which is progressively isolated from the tidal influence, was anthropologically transformed into a polder during the 1 8th. century

The microfauna (foraminifers, ostracods) and sedimentology of a core from the supratidal polluted area of the Ria of Gernika (S of Bay of Biscay) have been analysed in this work. Four different episodes have been recognised in the last 6400 years in this area, based upon microfaunaI assemblages and sedimentological facies. The older one represents a subtidal palaeoenvironment with marine influences at the base of this core. A subsequent increase of the energy in a tidal palaeoenvironment is evidenced by the occurrence of rhythmic fades and estuarine characteristic microfaunaI assemblages. This level is correlated to transgressive pulsations previously described in the Bay of Biscay 3500 to 2500 y. BP. Third episode shows a progressive shallowing of the palaeoenvironment, with low-salinity and mixed waters in a supratidal marshy milieu. To the core top, a very fine sediment with abundant plant roots and very scarce microfauna indicate the present filling of this part of the estuary

The sedimentology and micropaleontological content (benthic foraminifera) of a core located in the Anbeko polder of the Urdaibai estuary (Southern Bay of Biscay) have been analysed in order to characterize the holocene evolution of this polder. Based upon sedimentology and micropalaeontological assemblages, four units have been identified in this core. During the first phase this area was under marine conditions, with a a maximum marine influence around 5000 years BP. The pulsation described during the Atlantic-Subboreal transition of the Holocene is then registered in this core. Sedimentological facies of the second unit indicate a decrease of energy in this environment, where outer estuarine foraminifera dominated the assemblages. The third phase indicates the progressive filling of the estuary, with the appearance of a vegetated marsh, as evidenced by the total dominance of agglutinated foraminifera. This marsh, which is progressively isolated from the tidal influence, was anthropologically transformed into a polder during the 1 8th. century