Yves-Marie Paulet - Academia.edu (original) (raw)

Papers by Yves-Marie Paulet

Invertebrate Reproduction & Development, Feb 1, 1991

Summary The reproduction of a population of the scallop Pecten maximus in Brittany (France) has b... more Summary The reproduction of a population of the scallop Pecten maximus in Brittany (France) has been studied for two years using two different methods:(i) determination of the gonad index;(ii) measurement of oocyte diameters by image analysis of histological ...

Journal of Experimental Marine Biology and Ecology, Jul 1, 1988

... 145156 145 Eisevier JEM 01089 Reproduction and larval development in two Pecten maximus (L.) ... more ... 145156 145 Eisevier JEM 01089 Reproduction and larval development in two Pecten maximus (L.) populations from Brittany YM Paulet1, A. Lucas&#x27; and A. Gerard2 laboratoire de Zoologie, Faculte des Sciences ... In the bay of Brest, mature individuals are present all year round. ...

Estuarine Coastal and Shelf Science, Sep 1, 2016

Although stable isotope ratios are increasingly used to investigate the trophic ecology of marine... more Although stable isotope ratios are increasingly used to investigate the trophic ecology of marine organisms, their spatial variations are still poorly understood in the coastal environment. In this study, we measured the stable isotope composition (δ13C, δ15N) of suspended particulate organic matter (SPOM) (primary producer), a suspension feeder, the great scallop Pecten maximus (primary consumer), megabenthic decapods and benthic fishes (secondary consumers) along a depth gradient (from 5m to 155m depth) across the continental shelf of the Bay of Biscay. Although the three trophic levels exhibited similar δ13C patterns along the gradient, the δ15N patterns varied between SPOM, scallops and carnivores. The δ15N difference between SPOM and scallops decreased with increasing depth, suggesting that non trophic factors may affect the stable isotope composition of scallops at deepest sampling stations. An opposed trend was found between scallops and carnivores, suggesting that the trophic level of these carnivores increased at higher depth, possibly as an adaptation to lower prey abundances. Although our results suggest that primary consumers are suitable to establish isotopic baselines in coastal environments, we stress the need for further studies aiming at characterizing the variability of stable isotopes in coastal biota, and the respective effects of baseline, trophic and metabolic factors in their isotopic composition.

Geochimica et Cosmochimica Acta, 2022

Oxygen-isotope measurements of fossil carbonates remain the most common method for paleoclimatic ... more Oxygen-isotope measurements of fossil carbonates remain the most common method for paleoclimatic temperature reconstructions. A well-known limitation of this approach is the influence of the oxygen isotope composition of water in which mineralization occurs, which may vary significantly through space and time, and is often difficult to constrain precisely. Carbonate clumped-isotope thermometry is an alternative approach applicable to many carbonates. It is based on measurements of D 47 (a tracer of small statistical anomalies in the abundance of rare, doubly-substituted carbonate isotopologues), and requires no independent information on the oxygen-isotope composition of parent waters. Here, we report new calibration observations of clumped isotopes in four species of calcitic marine bivalves (A. colbecki, N. cochlear, S. cucullata, M. gigas) from various ecosystems including coastal and deep-sea environments, with calcification temperatures ranging from À2°C to 27°C and very different amplitudes of seasonal temperature variability. At two localities with large seasonal temperature variability, calcification time intervals were constrained using a sclerochronological approach to test whether seasonal gradients of temperature can be accurately quantified based on D 47 measurements. Our results indicate that the mature bivalves we analyzed have clumped-isotope compositions entirely consistent with earlier calibration studies processed in the I-CDES reference frame and based on biogenic/abiotic/synthetic materials. By contrast, juvenile M. gigas oysters yield substantially lower D 47 values than expected based on their calcification environments, suggesting that their early growth phase is associated with yet poorly understood isotopic biases affecting both d 18 Ο and D 47 values. The link between seawater temperatures and bivalve D 47 values is thus potentially applicable to seasonal reconstructions, but only if shell sections formed in cold seasons are precisely identified and precisely sampled, and taking into account that winter calcification is likely to be biased due to reduced growth rate. Moreover, the excellent agreement between our observations and the existing I-CDES calibrations further demonstrates the efficacy of the I-CDES standardization approach,

Scientific Reports, May 29, 2019

Gadolinium-based contrast agents (GBCAs), routinely used in magnetic resonance imaging (MRI), end... more Gadolinium-based contrast agents (GBCAs), routinely used in magnetic resonance imaging (MRI), end up directly in coastal seawaters where gadolinium concentrations are now increasing. Because many aquatic species could be sensitive to this new pollution, we have evaluated the possibility of using shellfish to assess its importance. Gadolinium excesses recorded by scallop shells collected in Bay of Brest (Brittany, France) for more than 30 years do not reflect the overall consumption in GBCAs, but are largely controlled by one of them, the gadopentetate dimeglumine. Although its use has been greatly reduced in Europe over the last ten years, gadolinium excesses are still measured in shells. Thus, some gadolinium derived from other GBCAs is bioavailable and could have an impact on marine wildlife.

Marine Ecology Progress Series, 2004

Marine Biology, May 1, 1996

A male genital defect was reported in a Nucella lapillus (L.) population at Dumpton Gap (England)... more A male genital defect was reported in a Nucella lapillus (L.) population at Dumpton Gap (England). This defect was termed "Dumpton syndrome" (DS) and appears to be a genetic feature. Its main characteristic is the absence of penis (aphally) in males and in females. In 1992, such a phenomenon was discovered in populations in the vicinity of Brest (Brittany, France). DS-affected females exhibit fewer tributyltin-induced imposex characteristics than expected in normal individuals. The percentage of female sterilization is thus lower, favouring population survival. In consequence, the DS is considered to be a "pollution-resistance" feature. Comparison with the Dumpton population revealed similarities and differences in the DS characteristics. It is thus hypothesized that the DS observed at the two locations is due to two different biological mechanisms. Indeed, aphallic males with a split prostate were observed but no underdevelopment of their vas deferens and testis was noted in the present study. In this gonochoristic gastropod species, the most DS-affected males in Brest possess an ovotestis and it is thus hypothesized that feminity is remnant in N. lapillus. Incidence of abnormality is ten times higher in females than in males. This suggested that a sex-difference operates in the Brest phenomenon.

Invertebrate Reproduction & Development, Aug 1, 1993

The distribution of serotonin-like immunoreactivity was studied in the central nervous system and... more The distribution of serotonin-like immunoreactivity was studied in the central nervous system and the gonad of Pecten maximus. Cerebral and pedal ganglia contain a well developed serotonin-immunoreactive neuronal subpopulation, whereas positive neurons are scarce in the visceral ganglion. The distribution pattern of immunoreactive elements in the gonad indicate that serotonin is involved in peripheral neurotransmission of this organ. Seasonal variations of monoamines (serotonin, dopamine and noradrenaline) have been investigated in the nervous system using HPLC. Lower concentrations of serotonin are observed during winter in the central nervous system; dopamine levels of the visceral ganglion are correlated to gonadal growth.

HAL (Le Centre pour la Communication Scientifique Directe), 2003

$Research paper thumbnail of Mg-isotopic fractionation in the manila clam (Ruditapes philippinarum): New insights into Mg incorporation pathway and calcification process of bivalves$

Geochimica et Cosmochimica Acta, Nov 1, 2013

We estimate the magnesium stable isotopic composition (d 26 Mg) of the major compartments involve... more We estimate the magnesium stable isotopic composition (d 26 Mg) of the major compartments involved in the biomineralisation process of euryhaline bivalve, the manila clam Ruditapes philippinarum. Our aim is to identify the fractionation processes associated with Mg uptake and its cycling/transport in the bivalve organism, in order to better assess the controlling factors of the Mg isotopic records in bivalve shells. d 26 Mg were determined in seawater, in hemolymph, extrapallial fluid (EPF), soft tissues and aragonitic shell of adult clams collected along the Auray River estuary (Gulf of Morbihan, France) at two sites showing contrasted salinity regimes. The large overall d 26 Mg variations (4.16&) demonstrate that significant mass-dependent Mg isotopic fractionations occur during Mg transfer from seawater to the aragonitic shell. Soft tissues span a range of fractionation factors relative to seawater (D 26 Mg soft tissue-seawater) of 0.42 ± 0.12& to 0.76 ± 0.12&, and show evidence for biological isotopic fractionation of Mg. Hemolymph and EPF are on average isotopically close to seawater (D 26 Mg hemolymph-seawater = À0.20 ± 0.27&; 2 sd; n = 5 and D 26 Mg EPF-seawater = À0.23 ± 0.25&; 2 sd; n = 5) indicating (1) a predominant seawater origin for Mg in the intercellular medium and (2) a relatively passive transfer route through the bivalve organism into the calcifying fluid. The lightest isotopic composition is found in shell, with d 26 Mg ranging from À1.89 ± 0.07& to À4.22 ± 0.06&. This range is the largest in the dataset and is proposed to result from a combination of abiotic and biologically-driven fractionation processes. Abiotic control includes fractionation during precipitation of aragonite and accounts for D 26 Mg aragonite-seawater % 1000 ln a aragonite-seawater = À1.13 ± 0.28& at 20°C based on literature data. Deviations from inorganic precipitate (expressed as D 26 Mg Physiol) appear particularly variable in the clam shell, ranging from 0.03& to À2.20&, which indicates that bivalve shell formation can proceed either under fractionation similar to inorganically-precipitated aragonite or under variable physiological influences. These physiological isotopic effects may be consistent with a regulation of dissolved Mg content in hemolymph and/or EPF due to Mg incorporation into soft tissue and/or Mg fixation by organic macromolecules. Using closed-and open-system models we estimate that D 26 Mg Physiol can be satisfactorily resolved with a remaining Mg fraction in hemolymph and/or EPF of 74% down to 2%. However, this feature is not reflected in our hemolymph and EPF data and may indicate that regulation processes and isotopic fractionation may take place in self-contained spaces located close to calcification sites. The potential role of the shell organic matrix, which may host non-lattice-bound Mg in the shell, is also discussed but remains difficult to assess with our data.

HAL (Le Centre pour la Communication Scientifique Directe), 2009

HAL (Le Centre pour la Communication Scientifique Directe), Jun 16, 2019

Specimens of carpet shell Ruditapes decussatus from the Mesolithic shell midden (6th millennium B... more Specimens of carpet shell Ruditapes decussatus from the Mesolithic shell midden (6th millennium BC) of Beg-an-Dorchenn (Brittany, France) were studied in order to access their period of collect as well as some insight on Paleo-temperature reconstructions. Cross sectioned shells display very clear growth structures free from diageneses allowing to assess a growth rhythm of 2 increments per lunar day. From this temporal framework, daily growth increments, fortnightly ridges, winter annual growth break and spawning events were characterized. The R. decussatus studied shells collected in late autumn and/or early spring period. Chemical analyses of shell carbonates were also conducted to access a preliminary range of potential sea temperature data from oxygen isotopes values (δ18Oshell). δ18Oshell shows seasonal variations but do not displays the whole range of temperature as R. decussatus have a growth break during winter. However, the range of reconstructed SST did not show nonsensical values and suggest sea temperatures slightly higher than the current ones. Thus, R. decussatus is particularly suited to address paleo-environmental issue at high temporal resolution such as the seasonal periodicity. To conclude additional sclerochronological and chemical researches on other mollusk species from Beg-an-Dorchenn or other Mesolithic shell middens along the European Atlantic facade will contribute to the problematics of seasonal occupation as well as climate variability at the Mesolithic-Neolithic transition.

Biogeosciences, Nov 13, 2009

Here we present a novel approach for the interpretation of stable isotope signatures recorded in ... more Here we present a novel approach for the interpretation of stable isotope signatures recorded in benthic foraminifera from subtidal estuarine environments. The stable isotopic composition (δ 18 O and δ 13 C) of living Ammonia tepida and Haynesina germanica is examined at four stations in the Auray River estuary (Gulf of Morbihan, France) sampled in two contrasting seasons, spring 2006 and winter 2007. Comparing benthic foraminiferal δ 18 O measurements with theoretical oxygen isotopic equilibrium values, calculated on the basis of water temperature and salinity measurements in the upper and lower estuary, i.e., T-S-δ 18 O eq. diagrams, strongly suggests that foraminiferal faunas sampled at the four stations calcified during different periods of the year. This interpretation can be refined by using the benthic foraminiferal δ 13 C, which is mainly determined by the mixing of sea and river water. In the upper estuary foraminifera mainly calcified in early spring and winter, whereas in the lower estuary calcification mainly took place in spring, summer and autumn. This new method provides insight into the complexity of estuarine benthic foraminiferal stable isotope records. In addition, it can also be used to obtain new information on preferred calcification periods of benthic foraminiferal taxa in different parts of the estuary.

Journal of the Marine Biological Association of the United Kingdom, Aug 1, 2000

Previous studies carried out with Pecten maximus (Bivalvia: Pectinidae) juveniles in the Bay of B... more Previous studies carried out with Pecten maximus (Bivalvia: Pectinidae) juveniles in the Bay of Brest have demonstrated that diatom and, more obviously, toxic dinoflagellate blooms could have a negative effect on the daily growth rate. The aim of this study was to characterize the daily shell growth from early 1998 to late spring 1999 with a careful qualitative and quantitative description of the pelagic primary production. Our results, in accordance with previous studies, demonstrate that there are episodic declines in the growth rate. Concurrent events of low growth rate and large bottom-concentrations of algae following diatom blooms (Cerataulina pelagica or Rhizosolenia delicatula), suggests that this high concentration of phytoplankton on the bottom layer, may affect food intake or respiratory activity of the scallops by gill clogging or oxygen depletion. In this study, silicic acid or phosphorus are inferred to be limiting factors responsible for the collapse of the spring bloom. Further, we suggest that, in an N-enriched ecosystem, Si or P-limitation and the changing sinking velocities of phytoplankton, could affect the biology of benthic suspension-feeders.

Aquaculture, Mar 1, 1999

The influence of environmental factors on reproduction and energy partitioning was investi-Ž. gat... more The influence of environmental factors on reproduction and energy partitioning was investi-Ž. gated in scallops Pecten maximus maintained in a hatchery under 'winter' and 'spring' conditions of changing temperature and day-length. Biometric measurements revealed that 'spring' conditions favoured gonad growth whereas 'winter' conditions were associated with somatic Ž. growth adductor muscle and digestive gland. Biochemical analysis showed that in parallel with gonad growth, total proteins, carbohydrates and lipids accumulated in the female part of the gonad under 'spring' conditions. The lipid level of the digestive gland, which was more than 40% of the dry weight under both experimental conditions, emphasised the role of this organ in the storage of reserves. Quantitative histological analysis of oogenesis established that experimental conditions did not influence the total number of oocytes in the gonad but affected the partitioning between previtellogenic and vitellogenic oocytes. The contribution of vitellogenic oocytes was higher under 'spring' conditions. Energy partitioning was strongly influenced by experimental conditions: 89% of the production was channelled into the gonad under 'spring' conditions compared with 40% under 'winter' conditions.

Chemical Geology, Mar 1, 2015

The influence of salinity and water chemistry on Mg/Ca, Sr/Ca and Ba/Ca ratios in the aragonitic ... more The influence of salinity and water chemistry on Mg/Ca, Sr/Ca and Ba/Ca ratios in the aragonitic shells of the Manila clam were investigated. Clams were reared at constant temperature (20 °C) under different controlled conditions of salinity, commonly encountered in their natural habitat. Clams were held in three tanks with a constant salinity of 35 for the first 35 days and then two tanks were changed to lower salinities (20 and 28) for the next 29 days. Individual shell Mg/Ca, Sr/Ca and Ba/Ca ratios were studied through time. Despite stable conditions (temperature, salinity, and Mg/Cawater) for clams reared at salinity 35 during the experiment, Mg/Ca shell ratios increased through the time. Moreover the salinity decrease at t35 slowed the increase of Mg/Ca shell ratios at salinity 28 and resulted in a Mg/Cashell decrease at salinity 20, despite similar Mg/Cawater ratios in the different salinity treatments. Microprobe analyses illustrate that Mg varies along contemporaneous growth lines. The variable shell Mg/Ca ratios suggests that incorporation of magnesium into shell carbonate is strongly regulated by the organism and not by environmental conditions. Interestingly, microprobe analyses illustrated that Mg was not associated with shell sulfur as other studies have suggested. Sr/Ca shell ratios of clams reared at salinity 35 and under constant conditions were also not as constant as expected if Sr/Ca ratios were an environmental proxy. There was an inverse correlation between shell Sr/Ca and salinity despite a slight positive correlation between salinity and Sr/Ca ratios of the water, indicating that Sr/Ca ratios do not reflect environmental conditions. A strong inverse correlation between salinity and Ba/Ca shell ratios (and a positive correlation between Ba/Ca shell and Ba/Ca water) was observed. Therefore, Ba/Ca shell ratios seem to be a promising proxy of high-resolution (1 day) salinity variations in estuarine waters (via the relationship between Ba/Ca water and salinity). This study clearly illustrates that both Mg/Ca and Sr/Ca ratios in aragonite shells are not under environmental control and that Ba/Ca ratios are, with the later tracking high-resolution water Ba/Ca ratios and hence estuarine salinity variations. Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

Geology, 2005

Although Sr/Ca ratios in abiogenic calcite are strongly controlled by precipitation rates, such a... more Although Sr/Ca ratios in abiogenic calcite are strongly controlled by precipitation rates, such a kinetic effect has never been demonstrated in calcitic bivalve shells. Therefore, we report Sr/Ca ratios together with daily growth rates in the calcitic shells of four individuals of the bivalve Pecten maximus (age class I). Ratios of Sr/Ca were found to be variable among individuals that grew at the same location, illustrating that vital effects dominate over environmental controls. Although daily growth rate was correlated with shell Sr/Ca ratios, it explained only half of the Sr/Ca variations. However, daily shell surface area increment, an estimation of the total quantity of carbonate precipitated for a given time, explained 74% of the Sr/Ca variability in the shells of P. maximus. This proves, for the first time in a calcitic bivalve, that shell Sr/Ca partitioning is mainly controlled by kinetic effects. The Sr/Ca ratio should therefore be tested as a potential proxy of calcification rate in modern or fossil calcitic biocarbonates.

Finds and Results from the Swedish Cyprus Expedition: A Gender Perspective at the Medelhavsmuseet, 2007

Analytica Chimica Acta, Sep 1, 2003

The aim of this study was to determine a simple routine procedure to preserve, decarbonate and an... more The aim of this study was to determine a simple routine procedure to preserve, decarbonate and analyse low-carbonated filters of suspended particulate organic matter (POM) for particulate organic carbon and nitrogen content, δ 13 C and δ 15 N. Our goal was to analyse these four parameters from a single and entire filter of POM without altering the organic material. First, freezing (-20°C) versus oven-drying (60°C) were compared as the initial preservation step. Afterwards, non-acidified samples were compared to acid-treated samples using 0.12N HCl (diluted HCl rinsing at the end of the filtration) or 12N HCl (filters exposed to HCl fumes for four hours in a dessicator). Regarding the preservation methods, our results indicate that freezing increases the uncertainty of δ 15 N measurements and, in combination with concentrated HCl treatment, leads to a loss of particulate nitrogen and an alteration of the δ 15 N signature. Consequently, we recommend drying to preserve filter samples. Regarding acid treatments, we found that (i) diluted HCl would not be sufficient to fully remove the carbonate from our samples, (ii) in contrast, a four-hour exposure of the filters to the HCl fumes was enough to remove all the inorganic carbon, and (iii) the concentrated HCl treatment did not alter the nitrogen measurements (only when drying without freezing is used to preserve the filters). Consequently, we propose that low-carbonated POM filters are preserved by drying and carbonates are removed by exposing the filters to HCl fumes (four hours) for the analysis of particulate organic C and N content and isotope ratios.

HAL (Le Centre pour la Communication Scientifique Directe), Feb 1, 2022