Institut Francais De Recherche Research Articles

Recent satellite-derived sea ice volume flux through the Fram Strait: 2011–2015

The Fram Strait (FS) is the primary region of sea ice export from the Arctic Ocean and thus plays an important role in regulating the amount of sea ice and fresh water entering the North Atlantic seas. A 5 a (2011–2015) sea ice thickness record retrieved from CryoSat-2 observations is used to derive a sea ice volume flux via the FS. Over this period, a mean winter accumulative volume flux (WAVF) based on sea ice drift data derived from passivemicrowave measurements, which are provided by the National Snow and Ice Data Center (NSIDC) and the Institut Francais de Recherche pour d’Exploitation de la Mer (IFREMER), amounts to 1 029 km3 (NSIDC) and 1 463 km3 (IFREMER), respectively. For this period, a mean monthly volume flux (area flux) difference between the estimates derived from the NSIDC and IFREMER drift data is–62 km3 per month (–18×106 km2 per month). Analysis reveals that this negative bias is mainly attributable to faster IFREMER drift speeds in comparison with slower NSIDC drift data. NSIDC-based sea ice volume flux estimates are compared with the results from the University of Bremen (UB), and the two products agree relatively well with a mean monthly bias of (5.7±45.9) km3 per month for the period from January 2011 to August 2013. IFREMER-based volume flux is also in good agreement with previous results of the 1990s. Compared with P1 (1990/1991–1993/1994) and P2 (2003/2004–2007/2008), the WAVF estimates indicate a decline of more than 600 km3 in P3 (2011/2012–2014/2015). Over the three periods, the variability and the decline in the sea ice volume flux are mainly attributable to sea ice motion changes, and second to sea ice thickness changes, and the least to sea ice concentration variations.

Encyclopedias of Life: From Diderot to the Yeti Crab

Encyclopedias of Life: From Diderot to the Yeti Crab

Discovery of continental stretching and oceanic spreading in the Tasman Sea

A deep seismic survey conducted within the western part of New Caledonia's Exclusive Economic Zone (EEZ) (Figure 1) from 8 September–5 October 2004 revealed for the first time the thinned continental and oceanic natures of the crust beneath the eastern Tasman Sea.The survey which was conducted by an international group of scientists a board the Institut Francais de Recherche pour l'Exploitation de la MER (Ifremer) R/V L'Atalante, aimed at improving the understanding of the geological framework, crustal characteristics, and evolution of the submarine basin and ridge system located west of New Caledonia's mainland. The study area, located east of both Australia and the oceanic Tasman Sea Basin, is composed of continental fragments: the Lord Howe Rise and the Norfolk Ridge, which are separated by the New Caledonia and Fairway basins.

Acoustics in Fisheries and Aquatic Ecology

The ICES Symposium on Acoustics in Fisheries and Aquatic Ecology (SAFAE) was held in Montpellier, France, from 10 to 14 June 2002. There were 303 participants from 37 countries, emphasizing the strongly international character of the meeting. This Symposium was the fifth organized by ICES in a series concerned with acoustics in fisheries and related fields. The first two were held in Bergen (1973 and 1982), the third in Seattle (1987), and the fourth in Aberdeen (1995; ICES Journal of Marine Science, Vol. 53, no. 2). To complete the historical picture, two symposia on the special problems of shallow-water acoustics should be mentioned, one held in London (1997) and one in Seattle (1999; Aquatic Living Resources, Vol. 13, no. 5). By 2002, however, it was seen that shallowwater, marine, and freshwater acoustics required a joint approach to problem-solving and the sharing of experience. It was therefore decided that this ICES Symposium would encompass all these applications within the general theme of acoustical methods for the study of aquatic biota and their exploitation. Organized under ICES auspices, the primary sponsors of the meeting were the Institut de Recherche pour le Developpement (IRD) and the Institut Francais de Recherche pour l’Exploitation de la Mer (IFREMER); cosponsors were the Acoustical Society of America, the UK Institute of Acoustics, the US National Marine Fisheries Service, and the Societe Francaise d’Acoustique. The coconveners were Francois Gerlotto (IRD) and Jacques Masse (IFREMER). They were assisted by a Scientific Steering Committee comprising Pablo Carrera (Spain), David Farmer (Canada), Masahiko Furusawa (Japan), D. Van Holliday (USA), William Karp (USA), Ole Arve Misund (Norway), John Simmonds (UK), and Will Tesler (Russia). The conference secretariat was efficiently organized by Laurence Vicens from the Centre Halieutique of the IRD, which provided much logistical support, as did IFREMER, especially through the editorial work of Brigitte Milcendeau. The main objectives of the Symposium were: to bring together scientists with diverse interests in fisheries and aquatic acoustics, covering a broad range of environments; to present their research in this rapidly evolving field; to review what can be achieved with new technology and theoretical approaches; and to consider future directions of study. There was a big response to the call for papers. The 256 abstracts submitted were allocated among the following ten theme sessions:

Prediction of sea level anomalies using ocean circulation model forced by scatterometer wind and validation using TOPEX/Poseidon data

Uncertainties in the surface wind field have long been recognized as a major limitation in the interpretation of results obtained by oceanic circulation models. It is especially true in the tropical oceans, where the response to wind forcing is very strong on short time scales. The purpose of this paper is to show that these uncertainties can be greatly reduced by using spaceborne wind sensors that provide accurate measurements on a global basis. Surface winds over the global oceans have been measured by scatterometry since the launch of the European Remote Sensing Satellite (ERS-1) in August 1991 by the European Space Agency, Noordwijk, The Netherlands, and is currently provided by ERS-2, launched in April 1995. The ground-track wind vectors are processed to compute mean weekly surface winds onto a 1/spl deg/ square grid at the Institut Francais de Recherche pour l'Exploitation de la Mer (IFREMER), Plouzane, France. These winds are validated by comparison with the buoy array in the tropical Pacific ocean, showing good agreement. In order to further evaluate this wind field, the three-dimensional (3D) ocean model OPA7 developed at Laboratoire d'Oceanographie Dynamique et de Climatologie, Paris, France, is forced over the tropical oceans by the ERS-derived wind stress fields and by fields from the atmospheric model Arpege/Climat. Selected ocean parameters are defined in order to validate the ocean model results with measurements of the tropical ocean and global atmosphere (TOGA) buoys in the Pacific ocean. The ability of the model to describe the short scale (a few weeks to a few years) oceanic variability is greatly enhanced when the satellite-derived surface forcing is used. Further comparison of the ocean model results with the TOPEX-Poseidon altimeter measurements is presented.

Comparing Ku-band NSCAT scatterometer and ERS-2 altimeter winds

Differences between sea surface wind speed estimated from the measurements of two different Ku-band satellite-borne sensors are investigated. The first sensor is the altimeter radar on board the European Remote Sensing Satellite, ERS-2, of the European Space Agency. The second one is the NASA scatterometer, NSCAT, on board the Japanese satellite ADvanced Earth Observing System (ADEOS). Because of the different physical processes involved in the measurements of the two sensors, differences are expected between the two retrieved surface wind speed data. The analyzed data set was extracted from the ERS-2 acid NSCAT collocated data base set up, within ADEOS validation activities, by the French Centre ERS d'Archivage et de Traitement (CERSAT), from the Institut Francais de Recherche pour l'Exploitation de la Mer. The dataset covers almost the whole life of NSCAT, from September, 1996, to June, 1997, and consists in more than 800000 pairs of collocated altimeter and scatterometer measurements. On average, wind speed estimates were found to be in agreement over the medium 4-9 ms/sup -1/ wind speed range. At low speed, NSCAT wind speed is overestimated relative to the altimeter one, and inversely, at high wind speed, over 10-17 ms/sup -1/ range, NSCAT is underestimated. The impact of significant wave height and incidence angle on difference between wind speed retrievals from the two sensors was then investigated. Some systematic behaviors were observed as a function of these two parameters and discussed in view of other available analysis and backscatter modeling development.

Diets of Albacore,Thunnus alalunga, and Dolphins,Delphinus delphisandStenella coerulaeoalba, Caught in the Northeast AtlanticAlbacore Drift-net Fishery:A Progress Report

A comparative dietary study of a community of large oceanic predators has been made possible by the availability of data on gut contents from tunas and other by-catch species sampled during the Institut Francais de Recherche pour l 'Exploitation de la Mer (IFREMER) fishery department study of the ecological impact of the French tuna driftnet fishery in the Northeast Atlantic. The stomach contents of common (Delphinus delphis) and striped dolphins, (Stenella coerulaeoalba), albacore (Thunnus alalunga), swordfish (Xiphias gladius), wreckfish (Polyprion americanum), blue shark (Prionace glauca), Ray's bream (Brama brama), and other minor species were collected in the summer 1993. This pilot study examined a small number of these samples, paying particular attention to comparisons between the diets of dolphins and tunas, associated versus non-associated in the catches. Besides the problem of by-catch, this set of samples represented a unique opportunity to investigate dietary relationships between co-existing oceanic predators and the ecological position of the dolphins in this community.

Diversity in pearl millet germplasm from Central African Republic

Most of the pearl millet (Pennisetum glaucum (L.) R. Br.) growing areas in Central African Republic (CAR) were explored by the GRD, ICRISAT in collaboration with the Ministry of Rural Development, CAR, Bangui and 129 pearl millet samples were collected during December 1988–January 1989. Considerable diversity was observed for several characters when 146 accessions including 17 collected by Institut francais de recherche scientifique pour le développement en coopération (ORSTOM) were evaluated at ICRISAT Asia Center (IAC), Patancheru. Time to flower ranged from 57 to 140 days with a mean of 128±1.1 days in rainy season and from 57 to 132 days with a mean of 73±0.8 days during postrainy season. Plant height ranged from 140 to 410 cm with a mean of 311±6.1 cm in the rainy season and from 75 to 310 cm with a mean of 155±2.6 cm during the postrainy season. The number of tillers varied between 1 to 6 per plant, spikes were mostly cylindrical and medium sized with a mean length of 20 cm during both seasons. They produced mostly gray or cream colored, globular grain, with partly corneous endosperm. Cluster analysis categorized accessions into similarity groups facilitating sampling a limited number of entries to represent the diversity of the pearl millet germplasm from Central African Republic.

Research Agenda on Sustainability of Irrigated Agriculture

The materials presented in this paper are the result of a North Atlantic Treaty Organization (NATO) Advanced Research Workshop on “Sustainability of Irrigated Agriculture (Sustainability of Water Resources Utilization in Agriculture),” which was held in Vimeiro, Portugal between 21 and 26 March 1994. The workshop was cosponsored by the Science and Technology for Development (STD) program of the European Union, Centre International de Hautes Etudes Agronomiques Mediterraneennes (IHEAM), Centre Technique de Cooperation Agricole et Rurale (CTA), Institut Francais de Recherche pour L’ingenierie de L’agriculture et de L’environnement (CEMAGREF) and Junta Nacional de Investigacao cienifica e tecnologica (JNICT). The purpose of that workshop was to provide in-depth discussion on irrigated agriculture among researchers and professionals of different disciplines coming from both developed and developing countries. The workshop objective was to integrate existing science and technology into improved irrigation system performance and agricultural water management, and to provide recommendations for future research directed toward sustainability of water use in agriculture. A total of 43 papers were presented and discussed under the following topics: (1) Sustainability of world irrigation systems; (2) water management and water policies; (3) sustainability of indigenous water and soil conservation systems; (4) irrigation water management and scheduling; (5) on-farm irrigation systems; (6) irrigation scheme management; (7) sustainability and environmental concerns; and (8) technological transfer. The research priorities presented in this paper evolved from group discussions and are based on a common understanding of the challenges that our generation faces to ensure sustainable agricultural development, both in developed and developing countries. The priorities were established by voting of the workshop participants.

Methodology in the study of seabass (Lates calcarifer Bloch): nutritional requirements in Singapore

This paper describes the effort of the Marine Aquaculture Section of the Primary Production Department in Singapore and the Institut Francais de Recherche pour l'Exploitation de la Mer in developing adequate facilities for fish nutritional requirement studies in Singapore, and in introducing appropriate nutritional methodology so that results are reliable and accurate. One of the first achievements was the demonstration of homogeneous fish (tropical seabass, Lates calcarifer Bloch) growth response in a newly established tank system before any nutritional experiments were initiated. The application of statistical procedures that take into consideration the power of a test and number of replications required has allowed for more accurate interpretation of results. This can be seen in the results of the first nutritional requirement experiment on the optimal dietary protein level of the seabass at constant energy.

Sonic imaging reveals new plate boundary structures offshore New Zealand

Recent bathymetry and sonar imagery studies of offshore portions of the plate boundary transecting New Zealand allow the first confident mapping of detailed tectonic and sedimentary patterns of the region. Working in late 1993 aboard the R/V L'Atalante of the Institut Francais de Recherche pour l' Exploitation de la Mer (IFREMER), we recorded soundings of a wide swath of seabed to elucidate major structural transitions along the plate boundary. Results of the study, part of the GEODYNZ‐SUD program developed jointly by institutions in France and New Zealand, will be complemented by New Zealand cruises to the Puysegur and Hikurangi margins. The total data set will be processed and interpreted during the next two years.

Evidence for sinistral strike-slip deformation in The Solomon Island arc

During the SOPACMAPS 2 crusie carried out by IFREMER (Institut Francais de Recherche pour l'Exploitation de la Mer) and ORSTOM (Institut Francais de Recherche Scientifique pour le developement en Cooperation) on theR/V L'Atalante, in the Central Solomon Arc area, multibeam bathymetric and imagery data and single-channel seismic reflection profiles were collected from an area of about 3500 km2, to evaluate regional tectonics. Structural data geophysical profiles interpretation provide evidence for left-lateral transtensional tectonics on the southern edge of the Central Solomon Trough. This transtensional deformation is represented by faulting, block tilting, and rhombohedral deformation. The regional geology and the analysis of the sedimentary cover allow us to demonstrate that this tectonic occurred in two different phases during Oligocene to Miocene and Pliocene to Pleistocene times.

Ostréiculteurs et biologistes : la nature des uns et des autres

Oyster farmers and biologists, the one's nature and the other's. This study analyses the link between scientific knowledges on the one hand, and other knowledges, bred from the practical growing of oysters. The way that the biologists and the oyster farmers built separately their own image of the object around which revolves their activity, the oyster, has been particularly studied. Oyster has flourished along the French coast since the end of the XIXth century in spite of numerous difficulties. During that time, the oyster farmers have always approached pragmatically the conception and the development of this shell breeding. However, since the early seventies repeated epizooties destroyed the stock and caused some damage to regional economics. Then the IFREMER (Institut francais de recherche pour l'exploitation de la mer : French Institute for sea research ) set up research projects in attempt to stop these diseases. The gathering of this body of knowledges brought to the definition of production standards, in the form of local trade rules. Facing these were, and still are, the knowledges of the oyster farmers. Through analysis of their links, two different types of knowledge, the scientific and the pra-tical one. were integrated into the same study. This confrontation allowed to distinguish the characteristics of the one's knowledges in the light of the other's. Therefore, in a first time, practical and scientific knowledges are exposed to the size of practitioner's oyster farm through the study of one particular group making by the Cancales oyster farmers (Bretagne j, and for the second, by each oyster's scientific approach. After describing both approaches. the object of this article is to build relations between the one's oyster and the other's around the two notions of space and time before studying knowledges' transfers. This last analysis could reveal the strategic goals for acquiring some scientific knowledges inside the two groups by comparing the appropriation mechanisms, in the oyster farmer's case at least. to the purchase of any other good. All these processes were then linked to a more global question about the sociological meaning of a knowledge.

MOVIES-B: an acoustic detection description software. Application to shoal species' classification

Resume Software, MOVIES-B, developed by lFREMER (Institut francais de recherche pour l'exploitation de la mer), enables the recognition of echogram features as acoustic detection structures according to spatial-energetic contiguity criteria. These structures (shoals, plankton layers) are described by energetic, morphological, spatial and temporal descriptors. Specifying acoustic detections as individual shoals will allow shoal by shoal echo-integration and may lead to better biomass estimation and shoal species description. The conceptual and operational framework of MOVIES-B is presented in the first part of this paper. The second part presents preliminary work performed in order to assess the feasibility of classification and possible species identification of shoals using MOVIES-B software. This research has studied the data set obtained from four fisheries acoustic surveys, in the Bay of Biscay. The data set is a matrix of 29 descriptors from 13,122 shoals. A limited knowledge of species composition was obtained from trawling. Eight species were captured: Sardina pilchardus, Clupea harengus, Sprattus sprattus, Engraulis encrasicolus, Micrornesistius poutassou, Trachurus sp., Scomber sp. and Capros aper. Cluster analysis and linear discriminant analysis were performed on trawled identified shoals data (808 shoals), after a reduction of the space descriptors by a stepwise technique. A partition into 6 clusters was carried out and clusters are described by species composition and continuous variables values. After grouping the six species shoals in two groups, 84% of shoals from the testing data set could be correctly classified using the linear discriminant function.

Contrôle non destructif par courants de Foucault : expérience et modélisation pour la conception et l'optimisation de capteurs

For inspecting tubular steel subsea structures, the conventional non destructive testing techniques require the removal of the marine fouling and corrosion protection coatings. These costly cleaning operations down to bare metal can be avoided with a new contactless technique which has been developed by the Institut Francais de Recherche et d'Exploitation de la Mer. This technique consists in inducing a strong alternative electric current flow at several frequencies in the material. Corresponding localized perturbations of this current flow caused by defects such as inclusions or cracks are then detected. The current perturbation is sensed with a small non contacting probe to detect the associated magnetic flux signal at the surface of the structure. Exploratory experiments allow us to conclude that this technique is very promising. The improvements in sensitivity and in characterization of the defects need a better quantitative understanding of the way in which slots in conducting materials interact with electric currents. We propose a numerical model, using our software: the Trifou code. This code solves tridimensional electromagnetic problems, by computing the current density in massive conductors under the effect of a knwon and time varying electromagnetic excitation. By taking advantage of our experience in modelling the eddy current testing of the frech nuclear power plants, we have reproduced one of the experiments. Numerical results are presented and make the deflection of current lines at slot edges visible. The electric activity of the modeled slot has been pointed out and we suggest that the flaw may be interpreted as a back electromotive force source which creaes divergence free local currents. Then, we have established a numerical method based on a local approach, to obtain the defect signal with a low computing cost. Numerical results fit the shape of the experimental results. In particular, we can determine the position of the crack. A more accurate comparison, for example on the crack depth, is difficult because of the uncertainty on the physical properties of the materials

TIVA A SELF CONTAINED IMAGE/DATA ACOUSTIC TRANSMISSION SYSTEM FOR UNDERWATER APPLICATION

Underwater exploration and exploitation programs have early expressed the need for pictures and images. Still cameras and TV cameras have been used to take photographs and films of the sea bottom, of the living resources, of undersea man built equipments. Sophisticated instruments have recently been designed with enhanced characteristics (high definition and sensitivity, color. ... ). Unfortunately, because of the needed bandwidth to transmit the signal, the only way to get real-time data was to use cables. This technique is however limited to a few hundred meters of water. Another mean to transmit image data over long distances was needed. Within the framework of its programs related to underwater intervention, IFREMER (Institut Francais de Recherche pour l'Exploitation de la Mer) and ORCA Instrumentation have designed a self-contained system to transmit images from the sea bottom to a surface vessel : TIVA. The use of acoustic waves enables the source to be completely separated from the receiver. This technique is bandwidth limited and the maximum baud rate is far beyond the ones which can be achieved in the labs. The quantity of information within an image is so large that a long time is needed to transmit the whole set of data. Compression algorithms have been studied and applied to actual data in order to decrease this transmission time. The modulation and the associated demodulation equipments were specifically designed for the application. The specific constraints of the equipment (self-contained instrument, memory, space, power limitations. ... ) and the desire to process the data in a very short time before the transmission, led to a trade-off between the power of the compression algorithm and the other characteristics such as current consumption, memory size ... The equipment has been successfully used to send images in real time during the survey of the TITANIC'S wreck. Scientific at-sea campains (penetrometry, shear vane meter deployment ...) have been optimized with the use of TIVA and its capacity to send images and data to the user at the surface. The transmission of data gathered by different underwater instruments on control systems was first done by using electrical and/or electromechanical cables which linked the source to the receiver. However these technics are limited to a few hundred meters of water because of logistic problem and price. Then, acoustic transmission is the only way to break the material link between the source (the camera or other instruments) and the receiver (the display) if long distances have to be reached. IFREMER and ORCA Instrumentation have designed a self contained equipment which achieves the transmission of image data through more than 4000 meters of water over an acoustic data link.

New ecological and ultrastructural data on the dinoflagellate Dinophysis sp. from the French coast

In situ phytoplankton sampling over 24h was carried out in July 1985 during part of a monitoring program established by the Institut Francais de Recherche pour l'Exploitation de la Mer (IFREMER) to survey the blooming of toxic dinoflagellates off the French coast. Analysis of the data suggested a vertical migration of Dinophysis sp. (acuminata?) populations through the sea-water column. These diurnal displacements should be taken into account in the course of monitoring surveys of diarrhetic shellfish poisoning (DSP). Culture assays which were performed in parallel remained unsuccessful. However, Dinophysis sp. survived in an enriched sea-water medium for 4 to 5 wk under low light intensity (8 to 10 W m-2) and constant temperature (16° to 18 °C). Cell ultrastructure, in pariticular the organization of chloroplasts, is described. All the combined results tend to confirm the photosynthetic capacity of this species.

U.S., France plan ocean study

The National Oceanic and Atmospheric Administration (NOAA) and the Institut Francais de Recherche pour l'Exploitation de la Mer (IFREMER) recently announced plans to conduct joint oceanographic investigations on the Mid‐Atlantic Ridge from 1990 to 1992, according to an announcement from NOAA. The multidisciplinary project will focus on the structure, dynamics, and composition of the deep sea floor, the circulation and dispersion of hydrothermal fluids, the related biological communities, and the presence of metalliferous deposits on the Mid‐Atlantic Ridge. Several U.S. and French agencies will participate in the project, which is a continuation of work by the two countries on the East Pacific Rise.

8703616 Method for cultivating microorganisms, particularly of the frankia group and preparation of bacterial inoculums: Gia Diem Hoang, Yvon Ren@ Dommergues, Orstom, B.P. 1386, Dakar, Senegal assigned to Institut Francais De Recherche Scientifique Pour L

8703616 Method for cultivating microorganisms, particularly of the frankia group and preparation of bacterial inoculums: Gia Diem Hoang, Yvon Ren@ Dommergues, Orstom, B.P. 1386, Dakar, Senegal assigned to Institut Francais De Recherche Scientifique Pour L

Lost CTD recovered by French sub

On March 11, 1986, the R/V Noroit, a research vessel belonging to IFREMER (Institut Francais de Recherche, pour l'Exploitation de la Mer, Paris), was on station in the northeast Atlantic Ocean (46°54′N, 11°14′W). The crew were performing a deep conductivity‐temperature‐depth (CTD) cast (water depth 4750 m) as part of a survey of abyssal circulation in that region. The towed CTD instrument unit was 120 m from the bottom when the cable ruptured, resulting in the loss of the instrument and 4788 m of cable. The cause of the cable failure was quickly diagnosed as corrosion on a rarely used part of the cable.