Pascal MORIN | Centre National de la Recherche Scientifique / French National Centre for Scientific Research (original) (raw)

Papers by Pascal MORIN

The Tara Oceans Expedition (2009-2013) sampled the world oceans on board a 36 m long schooner, co... more The Tara Oceans Expedition (2009-2013) sampled the world oceans on board a 36 m long schooner, collecting environmental data and organisms from viruses to planktonic metazoans for later analyses using modern sequencing and state-of-the-art imaging technologies. Tara Oceans Data are particularly suited to study the genetic, morphological and functional diversity of plankton. The present data set includes properties of seawater, particulate matter and dissolved matter from physical, optical and imaging sensors mounted on a vertical sampling system (Rosette) used during the 2009-2013 tara Oceans Expedition. It comprised 2 pairs of conductivity and temperature sensors (SEABIRD components), and a complete set of WEtLabs optical sensors, including chrorophyll and CDOM fluorometers, a 25 cm transmissiometer, and a one-wavelength backscatter meter. In addition, a SATLANTIC ISUS nitrate sensor and a Hydroptic Underwater Vision Profiler (UVP) were mounted on the rosette. In the Arctic Ocean and Arctic Seas (2013), a second oxygen sensor (SBE43) and a four frequency Aquascat acoustic profiler were added. The system was powered on specific Li-Ion batteries and data were self-recorded at 24HZ. Sensors have all been factory calibrated before, during and after the four year program. Oxygen was validated using climatologies (WOA09). Nitrate and Fluorescence data were adjusted with discrete measurements from Niskin bottles mounted on the Rosette, and optical darks were performed monthly on board. A total of 839 quality checked vertical profiles were made during the tara Oceans expedition 2009-2013.

The Tara Oceans Expedition (2009-2013) was a global survey of ocean ecosystems aboard the Sailing... more The Tara Oceans Expedition (2009-2013) was a global survey of ocean ecosystems aboard the Sailing Vessel Tara. It carried out extensive measurements of evironmental conditions and collected plankton (viruses, bacteria, protists and metazoans) for later analysis using modern sequencing and state-of-the-art imaging technologies. Tara Oceans Data are particularly suited to study the genetic, morphological and functional diversity of plankton. The present data set includes properties of seawater, particulate matter and dissolved matter that were measured from discrete water samples collected with Niskin bottles during the 2009-2013 Tara Oceans expedition. Properties include pigment concentrations from HPLC analysis (10 depths per vertical profile, 25 pigments per depth), the carbonate system (Surface and 400m; pH (total scale), CO2, pCO2, fCO2, HCO3, CO3, Total alkalinity, Total carbon, OmegaAragonite, OmegaCalcite, and dosage Flags), nutrients (10 depths per vertical profile; NO2, PO4, N02/NO3, SI, quality Flags), DOC, CDOM, and dissolved oxygen isotopes. The Service National d'Analyse des Paramètres Océaniques du CO2, at the Université Pierre et Marie Curie, determined CT and AT potentiometrically. More than 200 vertical profiles of these properties were made across the world ocean. DOC, CDOM and dissolved oxygen isotopes are available only for the Arctic Ocean and Arctic Seas (2013).

The Tara Oceans Expedition (2009-2013) sampled the world oceans on board a 36 m long schooner, co... more The Tara Oceans Expedition (2009-2013) sampled the world oceans on board a 36 m long schooner, collecting environmental data and organisms from viruses to planktonic metazoans for later analyses using modern sequencing and state-of-the-art imaging technologies. Tara Oceans Data are particularly suited to study the genetic, morphological and functional diversity of plankton. The present data set provides environmental context to all samples from the Tara Oceans Expedition (2009-2013), about nutrient concentrations in the targeted environmental feature. Concentrations of nitrite, nitrite+nitrate, phosphate and silicate were determined by ... methods. For each parameter we provide six statistics about all observations that are considered adequate to characterise the targeted environmental feature: number of observations, minimum, first quartile (25 percentile), median, third quartile (75 percentile), and maximum values. Observations were considered adequate if they met the following criteria: <100 km from the sampling location, <2 days from the sampling date/time, and within 10 m of the sampling depth. We also provide the computed distance and date/time lags that were assessed against these criteria. No environmental context is provided when one of these criteria was not met.

Oceanologica Acta, Special issue, 1988

Au cours de la campagne Médiprod IV. de nombreuses mesures de sels nutrÎtifs ont été n!al isées s... more Au cours de la campagne Médiprod IV. de nombreuses mesures de sels nutrÎtifs ont été n!al isées sur l'ensemble du bassin occidental de la Méditerranée , et plus particulièrement sur la partie est de la mer d' Alboran ct dans le détroit de Gibra lt ar. Ces mesures ont conduit à une nouvelle estimation d u bilan des échanges de l'azote entre la Méditerranée et l'Océan Atlantique. Les résultats montrent d'abord que l'azote sous forme organique dissoute. non pris en compte jusque-là, représente plus de 50 % de l'azote de l'eau atlantique en trante et, ensuite. que les apports cont inentaux au bassin n•c ntrcnt pas pour plus de JO % dans les apports totaux. Les valeurs supérieures à 20 du rapport NIP en Méditerranée sont expliquées à partir de l'al imentation du bassin par les couches supérieures de l'eau allantique et par des processus de minéralisation inte rnes au bassin. Une couche de 100 à 400 m d'é paisseur d 'cau de fond se distingue de l'eau profonde par ses caractéristiques ch imiques (concentration en sels nutritifs moins é levées, teneur en oxygène dissous plus forte) qui confirment son origine superfici e lle .

PLoS ONE, 2013

Kelp ecosystems form widespread underwater forests playing a major role in structuring the biodiv... more Kelp ecosystems form widespread underwater forests playing a major role in structuring the biodiversity at a regional scale. Some seaweeds such as Laminaria digitata are also economically important, being exploited for their alginate and iodine content. Although some studies have shown that kelp ecosystems are regressing and that multiple causes are likely to be at the origin of the disappearance of certain populations, the extent to which global climate change may play a role remains speculative. Here we show that many populations of L. digitata along European coasts are on the verge of local extinction due to a climate-caused increase in sea temperature. By modeling the spatial distribution of the seaweed, we evaluate the possible implications of global climate change for the geographical patterns of the species using temperature data from the Coupled Model Intercomparison Project phase 5 (CMIP5). Projections of the future range of L. digitata throughout the 21st century show large shifts in the suitable habitat of the kelp and a northward retreat of the southern limit of its current geographic distribution from France to Danish coasts and the southern regions of the United Kingdom. However, these projections depend on the intensity of warming. A medium to high warming is expected to lead to the extirpation of the species as early as the first half of the 21st century and there is high confidence that regional extinction will spread northwards by the end of this century. These changes are likely to cause the decline of species whose life cycle is closely dependent upon L. digitata and lead to the establishment of new ecosystems with lower ecological and economic values.

Science of The Total Environment, 2018

Tritium concentrations in oceans were compiled from the literature, online databases and original... more Tritium concentrations in oceans were compiled from the literature, online databases and original measurements in order to determine the global distribution of tritium concentrations according to latitude and depth in all oceans. The total inventory of tritium decay corrected in 2016 has been estimated using evaluation of the natural and artificial contributions in 23 spatial subdivisions of the total ocean. It is determined equal to 26.8 ± 14 kg including 3.8 kg of cosmogenic tritium. That is in agreement with the total atmospheric input of tritium from nuclear bomb tests and the natural inventory at steady-state estimated from natural production rates in the literature (27.8-29.3 kg in the Earth). We confirm the global increase in tritium according to latitude observed in the Northern hemisphere since 1967 with a maximum in the Arctic Ocean. The minimum tritium concentrations observed in the Southern Ocean were close to steady-state with known natural tritium deposition. 1 We focused on the temporal évolution of surface (0 to 500 m) tritium concentrations in a selected area of the North Atlantic Ocean (30°N-60°N) where we found the 2016 concentration to be 0.60 ± 0.10 TU (1o). Results showed that in that area, between 1988 and 2013, tritium concentrations: i) decreased faster than the sole radioactive decay, due to a mixing with lower and lateral less concentrated waters, and ii) decreased towards an apparent steady state concentration. The halftime mixing rate of surface waters and the steady state concentration were respectively calculated to be 23 ± 5 years (1o) and 0.38 ± 0.07 TU (1o). This apparent steady-state concentration in the North Atlantic Ocean implies a mean tritium deposition of 1870 ± 345 Bq.m-2 (1o), five folds higher than the known inputs (natural, nuclear tests fallout and industrial releases, ~367 Bq.m-2) in this area.

Limnol Oceanogr, 2004

During an intense (up to 33 ϫ 10 6 cells L Ϫ1) Alexandrium minutum bloom in the Penzé estuary (Fr... more During an intense (up to 33 ϫ 10 6 cells L Ϫ1) Alexandrium minutum bloom in the Penzé estuary (France), total NO 3 , NH 4 , and PO 4 requirements of the bloom were, respectively, 184, 25, and 20 mol L Ϫ1 , with peak uptake rates of 43, 6, and 4.8 mol L Ϫ1 d Ϫ1. The measured ambient concentrations of NH 4 and PO 4 were far short of this peak demand, whereas those of NO 3 were far in excess, indicating that NO 3 supply is important for sustaining the bloom. Comparison of the measured NO 3 uptake rates with advective fluxes indicates that a reduction of NO 3 concentrations in river waters to Ͻ200 mol L Ϫ1 would be necessary to contain the bloom in the Penzé estuary. The role of NO 3 was restricted to sustenance of the bloom, whereas warm conditions resulting in a water column stability seem to have triggered the bloom, and a self-shading, probably coupled with a phosphorus limitation, caused its decline.

ABSTRACT The Romanche and Chain Fracture Zones (RFZ and CFZ) are known as pathways for the Lower ... more ABSTRACT The Romanche and Chain Fracture Zones (RFZ and CFZ) are known as pathways for the Lower North Atlantic Deep Water (LNADW) and the Antarctic Bottom Water (AABW) from the western trough to the eastern trough of the equatorial Atlantic Ocean across the Mid-Atlantic Ridge. We report hydrographic observations describing the evolution of the LNADW and AABW properties during their transit through the equatorial fracture zones. To the west of the RFZ and CFZ sills, the LNADW and AABW cores are separated by a deep thermocline (pycnocline) which marks the transition between the two water masses. The deep thermocline is eroded eastward and vanishes in the eastern basin. This zonal asymmetry is the signature of a zonal baroclinic pressure gradient associated in each fracture zone with eastward flows of LNADW and AABW below 3800 m depth. During the eastward transit through the RFZ, the near-bottom AABW becomes less dense (saltier ,,0.07 ø and warmer 00.7øC), richer in oxygen 00.3 mL L -1, but less rich in silicate 030/mol L -1. Simultaneously, the LNADW core becomes fresher and colder at a given density, and the oxygen maximum characterizing the LNADW core weakens by 0 0.2 mL L -. We argue that the property changes within the AABW and LNADW are due to intense vertical mixing. In addition to vertical mixing with the AABW, it seems likely that isopycnal mixing of the LNADW with the Eastern Basin Deep Water contributes to the property evolution of the LNADW exiting the RFZ. In the CFZ, evidence is also given of mixing occuring within the AABW and the LNADW. A sudden change in the AABW properties observed across the CFZ main sill suggests the blocking of the eastward progression of the densest AABW by the CFZ main sill. However, this dense water can reach the eastern basin by flowing northeastward through valleys, the sills of which are deeper than thoses of the CFZ. Finally, a simple hydraulic control model applied to the RFZ and CFZ flows predicts a transport of 1.4 (0.1) 10 e m 3 s - of water colder than 1.9øC across the RFZ (CFZ) main sill.

The Romanche and Chain Fracture Zones (RFZ and CFZ) are known as pathways for the Lower North Atl... more The Romanche and Chain Fracture Zones (RFZ and CFZ) are known as pathways for the Lower North Atlantic Deep Water (LNADW) and the Antarctic Bottom Water (AABW) from the western trough to the eastern trough of the equatorial Atlantic Ocean across the Mid-Atlantic Ridge. We report hydrographic observations describing the evolution of the LNADW and AABW properties during their transit through the equatorial fracture zones. To the west of the RFZ and CFZ sills, the LNADW and AABW cores are separated by a deep thermocline (pycnocline) which marks the transition between the two water masses. The deep thermocline is eroded eastward and vanishes in the eastern basin. This zonal asymmetry is the signature of a zonal baroclinic pressure gradient associated in each fracture zone with eastward flows of LNADW and AABW below 3800 m depth. During the eastward transit through the RFZ, the near-bottom AABW becomes less dense (saltier ,,0.07 ø and warmer 00.7øC), richer in oxygen 00.3 mL L -1, but...

The Atlantic meridional overturning circulation (AMOC) simulated by 10 models from phase 5 of the... more The Atlantic meridional overturning circulation (AMOC) simulated by 10 models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) for the historical (1850-2005) and future climate is examined. The historical simulations of the AMOC mean state are more closely matched to observations than those of phase 3 of the Coupled Model Intercomparison Project (CMIP3). Similarly to CMIP3, all models predict a weakening of the AMOC in the twenty-first century, though the degree of weakening varies considerably among the models. Under the representative concentration pathway 4.5 (RCP4.5) scenario, the weakening by year 2100 is 5%-40% of the individual model's historical mean state; under RCP8.5, the weakening increases to 15%-60% over the same period. RCP4.5 leads to the stabilization of the AMOC in the second half of the twenty-first century and a slower (then weakening rate) but steady recovery thereafter, while RCP8.5 gives rise to a continuous weakening of the AMOC throughout the twenty-first century. In the CMIP5 historical simulations, all but one model exhibit a weak downward trend [ranging from 20.1 to 21.8 Sverdrup (Sv) century 21 ; 1 Sv [ 10 6 m 3 s 21 ] over the twentieth century. Additionally, the multimodel ensemblemean AMOC exhibits multidecadal variability with a ;60-yr periodicity and a peak-to-peak amplitude of ;1 Sv; all individual models project consistently onto this multidecadal mode. This multidecadal variability is significantly correlated with similar variations in the net surface shortwave radiative flux in the North Atlantic and with surface freshwater flux variations in the subpolar latitudes. Potential drivers for the twentieth-century multimodel AMOC variability, including external climate forcing and the North Atlantic Oscillation (NAO), and the implication of these results on the North Atlantic SST variability are discussed.

Continental Shelf Research, 1991

The Tara Oceans Expedition (2009-2013) sampled the world oceans on board a 36 m long schooner, co... more The Tara Oceans Expedition (2009-2013) sampled the world oceans on board a 36 m long schooner, collecting environmental data and organisms from viruses to planktonic metazoans for later analyses using modern sequencing and state-of-the-art imaging technologies. Tara Oceans Data are particularly suited to study the genetic, morphological and functional diversity of plankton. The present data set provides environmental context to all samples from the Tara Oceans Expedition (2009-2013), about nutrient concentrations in the targeted environmental feature. Concentrations of nitrite, nitrite+nitrate, phosphate and silicate were determined by ... methods. For each parameter we provide six statistics about all observations that are considered adequate to characterise the targeted environmental feature: number of observations, minimum, first quartile (25 percentile), median, third quartile (75 percentile), and maximum values. Observations were considered adequate if they met the following criteria: <100 km from the sampling location, <2 days from the sampling date/time, and within 10 m of the sampling depth. We also provide the computed distance and date/time lags that were assessed against these criteria. No environmental context is provided when one of these criteria was not met.

Oceanologica Acta, Special issue, 1988

PLoS ONE, 2013

Science of The Total Environment, 2018

Limnol Oceanogr, 2004

Continental Shelf Research, 1991