Northwestern France Research Articles

Shelly cheniers on a modern macrotidal flat (Mont-Saint-Michel bay, France) — Internal architecture revealed by ground-penetrating radar

The relationship between short-term morphodynamics and internal structure of shelly chenier ridges is investigated using ground-penetrating radar and core X-ray analysis, complemented with a comparison of aerial photographs. These cheniers are located on the uppermost part of a macrotidal flat in Mont-Saint-Michel bay (North-Western France). They actively migrate landward over the salt-marshes by washover processes when they are submerged during the coincidence of spring tides and enhanced wave activity. The architecture of the cheniers is imaged using high-frequency radar antennas (400MHz to 2.6GHz). Three types of cheniers are recognized, featuring differences in morphology and internal structure. The altitude of the banks on the tidal flat relative to the level of tidal flooding, as well as local sediment supply, seem to be important forcing parameters in chenier development and stages of evolution.On a multi-annual time scale, evolution of this chenier system is influenced by a combination of the 18-year and the 4-year tidal cycles, superimposed on wave activity. During minima of the 18-year cycle, spring tide level is globally lower on the tidal flat, allowing salt marsh progradation and chenier ridge development. During peak periods of the tidal cycle, former barriers are reworked by wave action and experience onshore migration associated with salt marsh erosion. The 4-year tidal cycle coupled with enhanced wave activity is probably responsible for the deposition of large washover units, observed in GPR reflection profiles.

Fungal, bacterial and plant dsDNA contributions to soil total DNA extracted from silty soils under different farming practices: Relationships with chloroform-labile carbon

Twelve differently-managed silty soils from North-Western France were chosen to compare two common methods of quantifying soil microbial biomass: Chloroform fumigation and extraction-labile carbon (CL_C) and microbial double stranded DNA (dsDNA). We also determined the contributions of each of the fungal, bacterial, and plant kingdoms to the total community dsDNA using real-time Polymerase Chain Reaction with kingdom-specific ribosomal primer sets. Regardless of the method, the highest microbial biomasses were associated with long-term untilled plots. Site (locations) specificities could also be detected, especially in conventionally cultivated lands. Regardless of site, a strong linear relationship could be drawn between CL_C and dsDNA in tilled lands (r = 0.91, n = 15, P = 0.01) and in grasslands (r = 0.78, n = 21, P = 0.01). Moreover, we propose a logarithmic model describing all of our silty soils, irrespective of management. In order to explain the non-linearity (log) of this relationship, we tested the hypothesis of a weak plant dsDNA contribution in total dsDNA in comparison with the well-documented root cell contribution to CL_C quantifications. Plant dsDNA never exceeded 2.6% of total dsDNA content for all of the soils studied. Among groups examined, the bacterial dsDNA contribution to the community dsDNA pool was the most site- and/or pedoclimatic-dependent. Fungi constituted a major component of total microbial biomass in grassland or in land with permanent plant cover where their proportion reached almost 50% of total dsDNA. More precisely, fungal dsDNA concentration was highly related to tillage. Our study demonstrated the expediency of the total microbial dsDNA quantification in agricultural silty soils rather than the time-consuming quantification of CL_C. Quantifying the relative contribution of bacterial or fungal biomass in total dsDNA by real-time PCR allows to access to a new level of knowledge of the soil microbial biomass and to reveal the balances between those two kingdoms according to soils or farming practices.

Habitat fragmentation and extinction rates within freshwater fish communities: a faunal relaxation approach

Aim To estimate population extinction rates within freshwater fish communities since the fragmentation of palaeo-rivers due to sea level rise at the end of the Pleistocene; to combine this information with rates estimated by other approaches (population surveys, fossil records); and to build an empirical extinction–area relationship. Location Temperate rivers from the Northern Hemisphere, with a special focus on rivers discharging into the English Channel, in north-western France. Methods (1) French rivers. We used a faunal relaxation approach to estimate extinction rates in coastal rivers after they became isolated by the sea level rise. Tributaries within the Seine were used to build a species–area relationship for a non-fragmented river system to predict species richness in coastal rivers before their fragmentation. (2) Other rivers. Extinction rates obtained for four other Holarctic river systems fragmented at the end of the Pleistocene, the fragmented populations of one salmonid species (Japan) and the fossil records from the Mississippi Basin were included in the study. Results (1) French rivers. Within strictly freshwater fish species, rare and/or habitat specialist species were the most affected by fragmentation. In contrast, euryhaline species were not affected. A negative relationship between extinction rate and river basin size was observed. (2) Other rivers. Our study established a common scaling relationship for freshwater fish population extinction rates that spans seven orders of magnitude in river basin size. Main conclusions This study strongly suggests that extinctions of fish populations occurred within French coastal rivers after they became isolated 8000 years ago. The patterns observed at regional and inter-continental scales are consistent with the expectation that large populations are less prone to extinction than small ones, resulting in a strong extinction–area relationship coherent over a large spatio-temporal scale. Our study is the first multi-scale quantitative assessment of background extinction patterns for freshwater fishes.

Volney and the science of morality in revolutionary France

Abstract Today, Constantin Francois Volney (1757-1820) is an obscure figure. He was once one of the most notorious philosophers in Europe. Celebrated and reviled in equal measure, this philosopher, historian, linguist, travel writer and politician was for two generations the most widely read philosopher of the French Revolution. His work was banned in many countries, but it was distributed by networks of admirers across Europe and its colonial world. Throughout one of the most turbulent eras in European history, Volney sought to develop a philosophical system that would ground private morality and public governance in a scientific understanding of the physiology of the human body and the laws of collective life. His attempts to do so, and the context in which those attempts were made, shed light on the genealogy and early politics of the social sciences in Europe. Introduction The subject of this article would not normally be considered a 'key thinker' in the accepted sense ofthat term. Constantin-Francois Volney (1757-1820) is not often cited as one of the great figures of European intellectual tradition. He has inspired no continuous movement that professes devotion to his philosophy. We do not speak of 'Volneyism' as we speak of 'Marxism' or 'Kantianism'. From the perspective of canonical intellectual history, he is usually regarded as little more than a footnote. Yet I want to suggest in what follows that Volney can be thought of as a key thinker in another sense. Today Volney is a relatively obscure figure in French history. He is known primarily to specialists on the 1789 Revolution or to students of European orientalism - a field in which he exercised considerable influence by virtue of his first book, an account of a three-year voyage to Egypt and Syria published in 1787.1 Volney was, however, once one of the most notorious writers in Europe. As a consequence of a short book published in 1791, entitled Les Ruines, ou Meditation sur les revolutions des empires, he was internationally condemned as a religious infidel and a political incendiary. Even inside revolutionary France his work aroused controversy. Over ensuing decades dozens of books and pamphlets were written to combat his influence. Several of his works were banned. Yet, despite persistent hostility, his writings could be purchased in 14 languages. They were read, debated and strategically disseminated by supporters across Europe and the Americas. Indeed, while Volney developed increasing ambivalence towards the French Revolution, he became one of its major intellectual exports. Viewed from a global perspective, Volney was almost certainly the most widely read philosopher of the French Revolution until at least the 1830s.2 It is this that has led the literary critic Marilyn Butler to label Volney 'the Foucault of his day'.3 It is this, too, which means that, however obscure Volney has now become, this understudied philosopher can provide us with a key for unlocking, or understanding, issues in the intellectual and cultural history of his era. This essay is about one of those issues. It uses Volney as a case study for examining a quest to build a science of morality during the era of the French Revolution. More specifically, it uses Volney as a means of exploring one particular strategy for realising that quest. It is a strategy based on the desire to reconcile the selfish aspirations of individuals with the pursuit of the public good. For Volney, it was an attempt to align social life with natural law. Volney 's efforts in this arena saw him become one of the most influential and controversial writers of his age. I Volney was born Constantin-Francois de Chassebeuf to a family of provincial lawyers in Craon in north-western France. His mother died when he was two and his family life was, by his own account, unhappy. Resisting paternal pressure to study law, he devoted himself to philosophy and ancient history before moving to Paris in his early twenties to study medicine and, unusually, Arabic. …

The effects of urban or rural landscape context and distance from the edge on native woodland plant communities

The increasing rate of urban sprawl continues to fragment European landscapes threatening the persistence of native woodland plant communities. The dynamics of woodland edges depend on the characteristics of woodland patches and also on landscape context. Our aim was to assess the extent of edge influences on the understorey vegetation of small native woodlands in rural and urban landscapes. The study was carried out in two cities of north-western France. Ten comparable woodlands, each of about 1.5 ha, were surveyed; five were situated adjacent to crops and five adjacent to built-up land. Vascular plant species were recorded in 420 3 × 3 m plots placed at seven different distances from the edge (from 0 to about 45 m from the edge). Soil pH, light levels, level of disturbance and tree and shrub cover were also recorded. Plant species were first classified as non-indigenous or indigenous and then three groups of indigenous species were distinguished according to their affinity for forest habitat (forest specialists, forest generalists and non-forest species). We inferred certain ecological characteristics of understorey vegetation by using Ellenberg values. An inter-class correspondence analysis was carried out to detect patterns of variation in plant community composition. Linear mixed models were used to test the effects of adjacent land use, distance from the edge and their interactions on the species richness of the different groups and on the ecological characteristics of vegetation. Total species richness, richness of forest generalists and of non-forest species decreased from edge to interior in both urban and rural woodlands. The number of non-indigenous species depended mainly on urban–rural landscape context. Urban woodland edges were not as rich in forest specialists as rural edges. More surprisingly, the number of forest specialists was higher in rural edges than in rural interiors. Community composition was mainly affected by urban–rural context and to a lesser degree by the edge effect: the community composition of urban edges resembled that of urban interiors whereas in rural woodlands vegetation near edges (up to 10 m) strongly differed from interiors with a pool of species specific to edges. Urban woodland vegetation was more nitrophilous than rural vegetation in both edges and interiors. A major difference between urban and rural vegetation was the distribution of basiphilous species according to distance from the edge. Generally edge vegetation was more basiphilous than interior vegetation however the presence of basiphilous species fell off quickly with distance from the edge in rural woodlands (in the first 10–15 m) and more slowly (from 25 m onwards) in urban woodlands. This pattern was linked to variation in measured soil pH. As regards the conservation of flora in small native woodlands, it appeared that invasion of exotic and non-forest species was currently limited in both urban and rural landscape contexts but might pose problems in the future, especially in urban woodlands. Forest species were not negatively affected by the edge effect and indeed edges seemed to provide important habitats for this group. Hence conservationists should pay particular attention to the protection of edges in urban woodlands.

Devonian (Givetian) Hyolitha from the Kersadiou Formation, Massif Amoricain, France

Among hyoliths from the Givetian Kersadiou Formation in northwestern France one form is assigned to Hyolithes triliratus Hall, 1879, which is used as the basis for Brittanella new genus. The occurrence of this species in France supports affinity for fauna in that region to the Eastern Americas Realm. Other hyoliths from this unit include one species of Hyolithes Eichwald, which is left in open nomenclature, and one conch and one platyclaviculate operculum that cannot be identified to genus. The occurrence of these fossils in concretions in an oxygen-stressed dark gray shale supports the notion that this environment served as a refuge for taxa that were less efficient competitors with other normal marine benthos in the Devonian.

Devonian (Givetian) Hyolitha from the Kersadiou Formation, Massif Amoricain, France

Among hyoliths from the Givetian Kersadiou Formation in northwestern France one form is assigned to Hyolithes triliratus Hall, 1879, which is used as the basis for Brittanella new genus. The occurrence of this species in France supports affinity for fauna in that region to the Eastern Americas Realm. Other hyoliths from this unit include one species of Hyolithes Eichwald, which is left in open nomenclature, and one conch and one platyclaviculate operculum that cannot be identified to genus. The occurrence of these fossils in concretions in an oxygen-stressed dark gray shale supports the notion that this environment served as a refuge for taxa that were less efficient competitors with other normal marine benthos in the Devonian.

Un dépôt d’anneaux en pierre du Néolithique ancien à Falaise, « zone d’activité Expansia II » ?

An archaeological diagnostic at Falaise revealed a pile of 6 stone rings, isolated from any domestic or burial features. The isolation suggests that the find can be interpreted as a ritual hoard. This hypothesis is possibly confirmed by other aspects: the alternating sizes and raw materials, as well as the site location between two dense early Neolithic settlement zones. The finds probably date to the late Villeneuve-Saint-Germain/Blicquy. The flat, wide rings have traces of manufacture and use. Analysis indicates that they were worn as arm ornaments, at the minimum in pairs. The raw materials, very common in assemblages from north-western France, are of regional origin. Comparable finds in France are rare, limiting interpretation of the hoard. This practice is not frequent and usually involves ring roughouts or worn grindstones, although these technical constraints do not rule out a certain ritualisation. At Falaise, the latter is perceptible but the objects are neither rare nor unusual. For this reason, the phenomenon differs from hoards of axe blades in Danubian cultures of the Rhineland, or of prestige axes at the beginning of the middle Neolithic.

Further investigations on the sand-dwelling genus Cabra (Dinophyceae, Peridiniales) in South Brittany (northwestern France), including the description of C. aremorica sp. nov.

Cabra is a genus of marine thecate sand-dwelling dinoflagellates that is poorly known and of which only two species are described, C. matta and C. reticulata. In one fixed sample collected in 2007 in South Brittany, both of these species were recorded, together with a new third one. Cells of the three taxa were isolated and their morphology was characterized using scanning electron microscopy. New features previously unseen in C. matta were observed including the presence of a dense group of pores on the first antapical plate and the existence of pores of two different size classes on thecal plates. Cabra aremorica sp. nov. is 37–40 µm long and 31–38 µm deep and possesses a thecal pattern very similar to the other species described in the genus. However, C. aremorica differs from them by its overall ornamentation consisting in shallow alveolae, its polyhedral shape, and its very atypical apical pore complex. Observations of the third cingular plate c3 on the three Cabra species revealed the presence of a narrow extension that lays vertically and borders the ‘x’ (5″) plate on the ventral side of cells, which appears to be a constant feature in the genus. This fact not previously reported is crucial for the interpretation of the plate pattern and is very peculiar among dinoflagellates.

MORPHOLOGY AND MOLECULAR PHYLOGENY OF PROROCENTRUM CONSUTUM SP. NOV. (DINOPHYCEAE), A NEW BENTHIC DINOFLAGELLATE FROM SOUTH BRITTANY (NORTHWESTERN FRANCE)1

A new marine benthic Prorocentrum species from sandy habitats of South Brittany (northwestern France), P. consutum sp. nov., is described using LM and SEM and molecular phylogenetic analyses. Cells have a subcircular to broadly ovoid shape and are plainly flattened. They are 57-61 lm long and 52-55 lm wide. A central pyrenoid is present, and the kidney-shaped nucleus is positioned in the posterior region. In right valve view, the periflagellar area is deeply excavated, and the left valve forms a prominent apical ridge. The periflagellar area consists of nine platelets, and a small narrow collar is present around the flagellar pore. The ornamentation of this new species is very peculiar and is characterized by a ring of round areolae located at the periphery of the valves, each areola containing three or four pores. Apart from this ring of areolae, the cell surface is smooth and with scattered pores. Pores are not present in the center of the right or left valve. The intercalary band is generally narrow and faintly striated horizontally. The molecular phylogenetic position of P. consutum sp. nov. was inferred using SSU and LSU rDNA. In both analyses, this species branched with high support in the clade comprising species with a symmetric shape and appeared to be a sister group to that formed by P. lima and other tropical benthic species, such as P. arenarium, P. belizeanum, P. hoffmannianum, and P. maculosum.

Preservation of cell structures in a medieval infant brain: A paleohistological, paleogenetic, radiological and physico-chemical study

Cerebral tissues from archaeological human remains are extremely rare findings. Hereby, we report a multidisciplinary study of a unique case of a left cerebral hemisphere from a 13th century AD child, found in north-western France. The cerebral tissue–reduced by ca. 80% of its original weight–had been fixed in formalin since its discovery. However, it fully retained its gross anatomical characteristics such as sulci, and gyri; the frontal, temporal and occipital lobe as well as grey and white matter could be readily recognised. Neuronal remains near the hippocampus area and Nissl bodies from the motor cortex area were observed (Nissl, Klüver–Barrera staining). Also, computed tomography (CT) and magnetic resonance imaging (T1, proton density, ultra short echo time sequences) were feasible. They produced high quality morpho-diagnostic images. Both histological and radiological examinations could not confirm the pathologist's previously suggested diagnosis of cerebral haemorrhage as the cause of death. Reproducible cloned mtDNA sequences were recovered from the skeleton but not from the brain itself. This was most likely due to the combined effect of formaldehyde driven DNA–DNA and/or DNA–protein cross-linking, plus hydrolytic fragmentation of the DNA. The chemical profile of the brain tissue, from gas-chromatography/mass-spectroscopy analysis, suggested adipocerous formation as the main aetiology of the mummification process. The hereby presented child brain is a unique paleo-case of well-preserved neuronal cellular tissue, which is a conditio sine qua non for any subsequent study addressing wider perspectives in neuroscience research, such as the evolution of brain morphology and pathology.

Déterminisme climatique des années de croissance extrême chez le chêne sessile dans la moitié nord de la France

The growth response of sessile oak to extreme climatic years has been investigated from 1914 to 1993 using extreme years growth, i.e. pointer years. 31 mature and pure stands were cored in northern France (720 trees), under varied climates, from oceanic to semi-continental conditions. The analysis has highlighted similarities in growth characteristics throughout the study area : abrupt growth changes depend mainly on summer temperatures and precipitations (from May to July), narrow rings generally correlate with warm and dry climate (1921, 1976, 1989). Narrow rings also occur with strong winter frosts (1956). Pointer years analysis has allowed to define 2 main regions in northern France, with specific responses to extreme climatic events : plots in north-western France (from Brittany to Champagne) under oceanic climate, with a decennial pointer years frequency around 0,2 strongly correlated with summer De Martonne Index, and plots in north-east France (Lorraine, Alsace, Franche-Comté) under semi-continental climate, with higher frequency (around 0,3), depending on both summer and winter conditions.

L’articulation entre enjeux environnementaux et aménités paysagères dans les politiques publiques des vallées du nord-ouest de la France

Au centre des problématiques de gestion de l’eau et affectées de valeurs écologiques, les vallées se trouvent au cœur des enjeux d’aménagement (trame verte/bleue, voies vertes, etc.). Cet article propose de s’interroger sur la place accordée à leur dimension paysagère par les différentes politiques publiques, qu’elles soient globales (développement local) ou sectorielles (environnementales en particulier). La réflexion est menée à partir de l’analyse des modes de gestion à l’œuvre dans une partie de la vallée de l’Orne, la Suisse normande, qui renferme des paysages de gorges boisées emblématiques, supports d’une vocation touristique importante à l’échelle régionale. Celle-ci montre à la fois la prédominance des mesures environnementales par rapport aux politiques dédiées au paysage et témoigne de la confusion et de la difficile articulation entre enjeux d’environnement et développement des aménités paysagères.

Les foraminifères benthiques des Faluns du Miocène moyen du Blésois (Loir-et-Cher) et de Mirebeau (Vienne) dans le Centre-Ouest de la France

Middle Miocene Benthic Foraminifera from the Faluns of Blésois (Loir-et-Cher) and of Mirebeau (Vienne) in the Center-West of France.The “Faluns du Blésois” (Loir-et-Cher) and “Falun de Mirebeau” (Vienne), in Central-Western France, constitute the easternmost deposits of Mid-Miocene age due to the transgression of Atlantic waters. Benthic Foraminifera are diversified and very well preserved. The unilocular hyaline species are particularly abundant and diverse. One hundred eighty six species are listed and among which eight are new: Fissuripolymorphina plana n. sp., Lagenosolenia acarinata n. sp., Palliolatella robusta n. sp., Seguenzaella miocenica n. sp., Buliminella arcuata n. sp., Bisaccioides tonnetoi n. sp., Parrellina notonieri n. sp., Falsobolivina lobata n. sp. Three of those species are assigned to the new genera: Seguenzaella n. gen. and Falsobolivina n. gen. Two stratigraphic units are distinguished in the “Faluns”, each characterized by its sedimentary facies and its taxon association. All listed species occurs in the basal unit (fine sand), but diversify and abundance vary in according to grain-size. The taxonomic richness is impoverished in the coarser interbeded sands. As a consequence, only a few large-sized species occur in the upper unity on account of the coarse granulometry and strong hydrodynamism. Some species are common to Central and Western Tethyan Basin, but affinities with the diversity of the Aquitaine basin is much higher. The microfauna of the Blésois and Mirebeau Faluns announce the species diversity found in the Pliocene of the North Western France, with the survival of many taxa.

Cabra reticulata sp. nov. (Dinophyceae), a new sand-dwelling dinoflagellate from the Atlantic Ocean

A new sand-dwelling dinoflagellate species, Cabra reticulata sp. nov., is described from sandy habitats in the south of Brittany (northwestern France). This new species possesses the characteristics of the ‘unusual’ genus, Cabra Murray et Patterson. The thecal plate formula is Po Pt 3′ 1a 4″ ‘x’ 3c ?s 5′″ 1″″ (or alternatively interpreted as Po Pt 4′ 0a 4″ ‘x’ 3c ?s 5′″ 1″″). Because of the strong lateral compression, cells of C. reticulata are frequently seen laterally and have a polygonal shape, with three prominent antapical pointed flanges and a dorsal spine in the anterior part of the hypotheca. The cingulum is ascending and incomplete. The thecal surface is ornamented with strong reticulations forming polygonal areolae, which differs from C. matta Murray et Patterson, the type species of the genus. In addition to their different size and shape, a detailed study of C. reticulata by scanning electron microscopy also revealed several different plate features. Plates of the cingulum, c1 and c3, have no reticulations and are ornamented with shallow round areolae, while c2 is only faintly reticulated. Plate 1″″ is also characteristic because dorsally it forms a prominent pointed flange and ventrally bears a peculiar small area of densely arranged pores or tiny areolae. A similar finding has previously been described in Roscoffia capitata Balech. In the description of the genus, it was suggested that Cabra is closely related to species of the genus Roscoffia, and our observations strengthen this hypothesis. Prior to this study, C. reticulata was probably observed in the Virgin Islands, Caribbean Sea, but was tentatively identified as Thecadinium sp. and not fully described. Thus, C. reticulata appears to be present on both sides of the Atlantic Ocean and to occupy benthic habitats in temperate and tropical areas.

Solid partitioning and solid-liquid distribution of 210Po and 210Pb in marine anoxic sediments: roads of Cherbourg at the northwestern France

A sequential extraction protocol has been used to determine the solid-phase partition of 210Po and 210Pb in anoxic marine sediment from the roads of Cherbourg (France) in the central English Channel. Measurements were also obtained in pore waters, in which 210Po activities range between 1 and 20 mBq L −1 and 210Pb activities between 2.4 and 3.8 mBq L −1, with highest activities in the topmost layer. These activities are higher than in seawater, suggesting that sediment act as a source of both 210Po and 210Pb for overlying water. The 210Po profile in the pore waters is apparently correlated with those obtained for Fe, Mn and SO 4 2 −, suggesting an influence of early diagenetic processes on the 210Po solid-liquid distribution. In the sediment, 210Po is predominantly bound to organic matter or chromium reducible sulphides, and residuals (clay minerals and refractory oxides). Our results indicate that 210Po is not significantly bound to AVS, i.e. acid volatile sulphides: bioturbation could play a role by the early redistribution of 210Po bound to acid volatile sulphides in the sediment. 210Po, 210Pb and Pb exhibit differences in terms of distribution, probably due to a different mode of penetration in the sediment. This work provides information on solid and liquid distribution of 210Po and 210Pb in marine sediment. These data are very scarce in the litterature.

A decision-oriented model to evaluate the effect of land use and agricultural management on herbicide contamination in stream water

Modelling stream water pollution by herbicides in agricultural areas is a critical issue since numerous and incompletely known processes are involved. A decision-oriented model, SACADEAU-Transf, which represents water and pesticide transfer in medium-sized catchments (10–50 km 2) is presented. This model aims at evaluating the effect of land use, agricultural practice and landscape on the contamination of stream water in rural catchments. The processes are represented in an easily understandable way with a moderate amount of information, producing semi-quantitative and spatialized outputs. Modelling focuses on the first few months after herbicide application when high levels of contamination are generally observed, by considering transfer through the catchment area via surface and subsurface flow. The surface flow, based on a tree plot network representation of the catchment, is controlled by soil-surface properties and saturated conditions. The subsurface flow based on Topmodel concepts is controlled by the topography. Herbicide transfer is coupled to water transfer by taking into account the main characteristics of the chemicals. The model simulates the daily water and herbicide outflow at the outlets of the farmers' fields as well as from the catchment. Preliminary results on maize herbicide transfer are presented for an agricultural catchment with an area of 17 km 2 located in north-western France. The relevance of SACADEAU-Transf model is discussed in view of the qualities required for the decision-oriented models developed for improving agro-environmental management.

Harbour porpoises (Phocoena phocoena) in north-western France: aerial survey, opportunistic sightings and strandings monitoring

The harbour porpoise(Phocoena phocoena)is one of the common small cetaceans of European waters. This discreet and undemonstrative species is strongly represented throughout the cold waters of the northern hemisphere, and is the most abundant cetacean in the North Sea. In the last few years, some observations and studies indicate a shift of harbour porpoise distribution in European waters, from northern regions of the North Sea to the southern North Sea, English Channel and Celtic Sea. This shift may include a comeback around the coasts of France. Harbour porpoises inhabit shelf-waters and are often observed in shallow waters, conditions offered for instance by the coasts of Brittany in north-western France. We used opportunistic sightings, aerial survey and a ten-year strandings database to study the presence of harbour porpoises along the coasts of Brittany. Opportunistic sightings made by non-specialists did not confirm a strong presence of harbour porpoises along the Brittany coasts, most probably because of the undemonstrative behaviour of this cetacean. However, aerial survey and stranding analysis indicate that harbour porpoises have become natural inhabitants of the Brittany coasts once more: 68.6% of cetacean school sightings made during a 1578 km aerial survey of the Brittany coasts concerned harbour porpoises, with an encounter rate of 1.5 individuals per 100 km that peaked to 5.8 per 100 km to the top of the shallow waters of the south-western Western English Channel. The number of harbour porpoise strandings increased each year from 1997 to 2007, making a total of 135 along the coasts of Brittany. Other cetaceans did not show such an increase during the same period. Strandings of harbour porpoises were also characterized by an apparent increase as a proportion in relation to all the cetacean strandings during the months of September to January, by a marked impact of by-catch during winter, and by an almost total absence of stranded calves. The comeback of the harbour porpoise along Brittany coasts is clearly confirmed by our data, and a stable population seems to be established again along the coasts of Brittany. This tends to confirm the shift of the distribution of the species in certain European waters. Long term monitoring, diet and genetic studies are now planned for a better understanding of this shift, and for the effective implementation of a conservation plan.

An oyster-associated hepatitis A outbreak in France in 2007

Following the notification of nine hepatitis A cases clustered in the Cotes d Armor district in northwestern France, epidemiological, environmental and microbiological investigations were set up in order to identify the source and vehicle of contamination and implement control measures. In total, 111 cases were identified in the outbreak, all of whom lived or had stayed as tourists in the Cotes d Armor district. Of the cases, 87% had eaten raw shellfish, and 81% specifically oysters. Traceback investigations carried out on raw shellfish consumed by the cases showed that the raw shellfish originated from a single shellfish farm. The shellfish were probably contaminated either in the submersible tanks or in a depuration land-based tank where they were stored. The source of contamination was not identified but shellfish could have been tainted by sewage overflows or by wastewater releases from a polluted storm sewer close to the shellfish farm or from on-site sanitation facilities. To prevent future hepatitis A outbreaks due to shellfish consumption from this area, hazards specific to each farm should be analysed. Timely information on sewage overflows should also be part of communities efforts regarding sewage collection and treatment.

An intercomparison study of luminescence dating protocols and techniques applied to medieval brick samples from Normandy (France)

A luminescence dating study has been applied to inform the history and archaeology of two early medieval buildings in north western France. Five bricks were sampled from the medieval churches (10th–11th centuries A.D.) of Rugles and Condé-sur-Risle in Normandy. The samples were divided and tested in the luminescence laboratories of the University of Durham (UK) and of Iramat-CRP2A, University of Bordeaux 3 (France). The fine grain and quartz inclusion techniques were applied, and tests included an examination of the anomalous fading of the luminescence signal from fine grain samples and coarse grains of feldspar. With one exception, the dates produced using the fine grain technique, although corrected for fading, were significantly younger than those produced with quartz inclusions. Although most of the corrected fine grain dates were consistent with the medieval construction of the churches, the brick fabric is of Roman type by archaeological assessment, and this is supported by the quartz coarse grain dates. We conclude that the bricks sampled are re-used, likely to be of Roman origin, and that the reliability of measurements with feldspars in brick fabrics requires wider investigation.