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Advancing Observation of Ocean Biogeochemistry, Biology, and Ecosystems With Cost-Effective in situ Sensing Technologies ArchiMer
Wang, Zhaohui Aleck; Moustahfid, Hassan; Mueller, Amy V.; Michel, Anna Pm; Mowlem, Matthew; Glazer, Brian T.; Mooney, T. Aran; Michaels, William; Mcquillan, Jonathan S.; Robidart, Julie C.; Churchill, James; Sourisseau, Marc; Daniel, Anne; Schaap, Allison; Monk, Sam; Friedman, Kim; Brehmer, Patrice.
Advancing our understanding of ocean biogeochemistry, biology, and ecosystems relies on the ability to make observations both in the ocean and at the critical boundaries between the ocean and other earth systems at relevant spatial and temporal scales. After decades of advancement in ocean observing technologies, one of the key remaining challenges is how to cost-effectively make measurements at the increased resolution necessary for illuminating complex system processes and rapidly evolving changes. In recent years, biogeochemical in situ sensors have been emerging that are threefold or more lower in cost than established technologies; the cost reduction for many biological in situ sensors has also been significant, although the absolute costs are still...
Tipo: Text Palavras-chave: In situ; Sensor; OceanObs; Ocean technology; EOVs; Biogeochemistry; Biology; Cost effective.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00514/62567/66921.pdf
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Bonga shad ( Ethmalosa fimbriata ) spawning tactics in an upwelling environment ArchiMer
Baldé, Bocar Sabaly; Döring, Julian; Ekau, Werner; Diouf, Malick; Brehmer, Patrice.
Successful recruitment in small pelagic fish populations inhabiting upwelling zones is subject to variation in fecundity and is driven by spatial and temporal fluctuations in environmental conditions, that is, mainly sea surface temperature, salinity and food availability. These fluctuations in abiotic factors have stimulated small pelagic fish populations to exhibit specifically adapted spawning tactics. To better understand to what extent a short‐lived exploited fish species such as bonga shad Ethmalosa fimbriata has adapted to an upwelling environment, we have investigated the interrelationship between upwelling intensity as a proxy for productivity and population fecundity by means of a virtual population analysis. We found that females of intermediate...
Tipo: Text Palavras-chave: Climate change; Clupeid; Data-poor fisheries; Fecundity; Optimal environmental window; Reproductive adaptation; Small pelagic fish.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00516/62765/67164.pdf
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Competition or cooperation in transboundary fish stocks management: Insight from a dynamical model ArchiMer
Nguyen-trong, Hieu; Brochier, Timothee; Auger, Pierre; Trinh, Viet Duoc; Brehmer, Patrice.
An idealized system of a shared fish stock associated with different exclusive economic zones (EEZ) is modelled. Parameters were estimated for the case of the small pelagic fisheries shared between Southern Morocco, Mauritania and the Senegambia. Two models of fishing effort distribution were explored. The first one considers independent national fisheries in each EEZ, with a cost per unit of fishing effort that depends on local fishery policy. The second one considers the case of a fully cooperative fishery performed by an international fleet freely moving across the borders. Both models are based on a set of six ordinary differential equations describing the time evolution of the fish biomass and the fishing effort. We take advantage of the two time...
Tipo: Text Palavras-chave: Shared fish stock; Aggregation of variables; ODE; Pelagic; Fisheries management; West Africa.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00442/55310/72108.pdf
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Complex small pelagic fish population patterns arising from individual behavioral responses to their environment ArchiMer
Brochier, Timothee; Auger, Pierre-amael; Pecquerie, Laure; Machu, Eric; Capet, Xavier; Thiaw, Modou; Mbaye, Baye Cheikh; Braham, Cheikh-baye; Ettahiri, Omar; Charouki, Najib; Sene, Ousseynou Ndaw; Werner, Francisco; Brehmer, Patrice.
Small pelagic fish (SPF) species are heavily exploited in eastern boundary upwelling systems (EBUS) as their transformation products are increasingly used in the world food chain. Management relies on regular monitoring, but there is a lack of robust theories for the emergence of the populations’ traits and their evolution in highly variable environments. This work aims to address existing knowledge gaps by combining physical and biogeochemical modelling with an individual life-cycle based model applied to round sardinella (Sardinella aurita) off northwest Africa, a key species for regional food security. Our approach focused on the processes responsible for seasonal migrations, spatio-temporal size-structure, and interannual biomass fluctuations....
Tipo: Text Palavras-chave: Small pelagic fish; Sardinella aurita; Fish migration; Eastern boundary upwelling system; Individual based biophysical models; Dynamic energy budget.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00433/54433/56088.pdf
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Contrasted optimal environmental windows for both sardinella species in Senegalese waters ArchiMer
Diankha, Ousmane; Ba, Aliou; Brehmer, Patrice; Brochier, Timothee; Sow, Bamol Ali; Thiaw, Modou; Gaye, Amadou Thierno; Ngom, Fambaye; Demarcq, Herve.
We investigate Sardinella aurita and Sardinella maderensis recruitment success relative to the variability of oceanographic conditions in Senegalese waters using generalized additive models (GAM). Results show that recruitment of both species is marked by a strong intra-annual (seasonal) variation with minimum and maximum in winter and summer, respectively. Their interannual variations are synchronous until 2006 (recruitment decreasing), while from 2007 there is no synchrony. The model developed shows that sardinella recruitment variability is closely related to the tested environmental variables in the study area. However, the key environmental variables influencing the recruitment success are different for both species: the Coastal Upwelling Index and...
Tipo: Text Palavras-chave: Recruitment success; Sardinella aurita; Sardinella maderensis; Upwelling; West Africa.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00611/72299/71189.pdf
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Does coastal lagoon habitat quality affect fish growth rate and their recruitment? Insights from fishing and acoustic surveys ArchiMer
Brehmer, Patrice; Laugier, Thierry; Kantoussan, J.; Galgani, Francois; Mouillot, D..
Ensuring the sustainability of fish resources necessitates understanding their interaction with coastal habitats, which is becoming ever more challenging in the context of ever increasing anthropogenic pressures. The ability of coastal lagoons, exposed to major sources of disturbance, to provide resources and suitable habitats for growth and survival of juvenile fish is especially important. We analysed three lagoons with different ecological statuses and habitat quality on the basis of their eutrophication and ecotoxicity (Trix test) levels. Fish abundances were sampled using fishing and horizontal beaming acoustic surveys with the same protocols in the same year. The relative abundance of Anguilla anguilla, Dicentrarchus labrax or the Mugilidae group was...
Tipo: Text Palavras-chave: Fish; Shallow water; Ecotoxicity; Lagoon; Habitat quality; Amphidromous.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00148/25963/24083.pdf
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Effect of environmental conditions on the seasonal and inter-annual variability of small pelagic fish abundance off North-West Africa: The case of both Senegalese sardinella ArchiMer
Thiaw, Modou; Auger, Pierre-amael; Ngom, Fambaye; Brochier, Timothee; Faye, Saliou; Diankha, Ousmane; Brehmer, Patrice.
The objective of this study was to assess the effect of environmental variations on the abundance of Sardinella aurita and Sardinella maderensis in Senegalese waters in the upwelling system. Monthly data indicating the abundance of sardinella were first estimated from commercial statistics, using Generalized Linear Model from 1966 to 2011. Abundance indices (AIs) were then compared with environmental indices, at the local scale, a Coastal Upwelling Index (CUI) and a coastal Sea Surface Temperature (SST) index, and on a large scale, the North Atlantic Oscillation (NAO), the Atlantic Multidecadal Oscillation (AMO) and the Multivariate El Nino Southern Oscillation Index (MEI), using correlations and times series analyses. The results showed that the abundance...
Tipo: Text Palavras-chave: Climatic change; Oceanography; Sardinella aurita; Sardinella maderensis; Small pelagic; Small-scale fisheries.
Ano: 2017 URL: https://archimer.ifremer.fr/doc/00611/72307/71213.pdf
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Exploitation des données sonar, type omnidirectionnel (type SR240) IRD
Brehmer, Patrice.
Le SR240 est un sonar multifaisceaux de longue portée, son utilisation au niveau du traitement des données passe par divers calculs et méthodes qui lui sont spécifiques. La méthode de dépouillement des données n'est pas répétée (cf. rapport précédent), seuls les principaux calculs et méthodes à connaître sont résumés ici (correction de la taille des bancs, erreurs systématiques de taille, réglages, densité, indice de compaction, les biais...). Des résolutions sont à prendre pour les prochaines campagnes VARGET (IRD, ISRA, FLASA) au niveau des réglages acoustiques. Test de la fonction TVG, en 30 log R, validité du paramètres "along beam dimension" : taille des bancs. Des méthodes sont proposés afin de diminuer voir contrôler les différents biais apportés...
Tipo: Text Palavras-chave: SONAR; TRAITEMENT DE DONNEES; POISSON MARIN; ESPECE PELAGIQUE; METHODE D'ANALYSE; PROSPECTION ACOUSTIQUE; ERREUR; MESURE; SIMULATION.
Ano: 1999 URL: http://www.documentation.ird.fr/hor/fdi:010022926
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Field investigations and multi-indicators for shallow water lagoon management: perspective for societal benefit ArchiMer
Brehmer, Patrice; Thang Do Chi,; Laugier, Thierry; Galgani, Francois; Laloe, Francis; Darnaude, Audrey M.; Fiandrino, Annie; Mouillot, David.
1. Abiotic and biotic variables of coastal lagoons are highly heterogeneous in both space and time, and this heterogeneity complicates the assessment of their ecological status. These variables are essential to the monitoring and preservation of these fragile ecotones and the resources and services they sustain. 2. An integrative approach for evaluating the ecological status of coastal lagoons, based on field investigations of the key parameters driving their functioning and a set of selected ecological indicators matching lagoon management information needs for societal benefits, is investigated. Consistency in lagoon status evaluation from multiple and different variables was estimated, through a case study comparing three adjacent yet contrasting French...
Tipo: Text Palavras-chave: Coastal lagoon; Ecological assessment; Ecotoxicology; Eutrophication; Indicator; Management; Mediterranean Sea; Observatory.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00056/16702/14202.pdf
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Fine-scale vertical structure of sound-scattering layers over an east border upwelling system and its relationship to pelagic habitat characteristics ArchiMer
Diogoul, Ndague; Brehmer, Patrice; Perrot, Yannick; Tiedemann, Maik; Abou Thiam,; El Ayoubi, Salaheddine; Mouget, Anne; Migayrou, Chloe; Sadio, Oumar; Sarre, Abdoulaye.
Understanding the relationship between sound-scattering layers (SSLs) and pelagic habitat characteristics is a substantial step to apprehend ecosystem dynamics SSLs are detected on echo sounders representing aggregated marine pelagic organisms. In this study, SSL characteristics of zooplankton and micronekton were identified during an upwelling event in two contrasting areas of the Senegalese continental shelf. Here a cold upwelling-influenced inshore area was sharply separated by a strong thermal boundary from a deeper, warmer, stratified offshore area. Mean SSL thickness and SSL vertical depth increased with the shelf depth. The thickest and deepest SSLs were observed in the offshore part of the shelf. Hence, zooplankton and micronekton seem to occur...
Tipo: Text
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00606/71777/70261.pdf
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First Evidence of Anoxia and Nitrogen Loss in the Southern Canary Upwelling System ArchiMer
Machu, Eric; Capet, Xavier; Estrade, Philippe; Ndoye, S.; Brajard, J.; Baurand, Francois; Auger, P.-a.; Lazar, A.; Brehmer, Patrice.
The northeastern Atlantic hosts the most ventilated subsurface waters of any eastern boundary upwelling system, while coastal upwelling source waters are slightly above hypoxic levels. Anoxic conditions have previously been found offshore inside mesoscale eddies whose core waters undergo oxygen consumption for many months. Based on circumstantial in situ observations this study demonstrates that the Senegalese coastal ocean is subjected to episodic occurrence of zero dissolved oxygen concentration at depth along with elevated nitrite concentration (11 mmol/m3) and nitrate/nitrite deficit to phosphate, thereby indicating severe anoxia and intense nitrogen loss. The anoxic event was associated with a prolonged upwelling relaxation episode in March 2012 and a...
Tipo: Text Palavras-chave: Oxygen; Canary upwelling system; Anoxia; Denitrification; Shallow continental shelf.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00479/59020/61640.pdf
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Mesures in situ des index de réflectivité à l'aide d'un écho-sondeur type "Dual beam" (129 kHz, BioSonics) et chalutage d'identification spécifique : Venezuela orientale : mission Varget 2/1996-99 (Orstom-Flasa-CroDT) IRD
Brehmer, Patrice; Cotel, Pascal.
Tipo: Text Palavras-chave: POISSON MARIN; PROSPECTION ACOUSTIQUE; CHALUTAGE; ESPECE; IDENTIFICATION; ECHANTILLONNAGE; MESURE IN SITU.
Ano: 2003 URL: http://www.documentation.ird.fr/hor/fdi:010030152
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Multibeam sonar detection of suspended mussel culture grounds in the open sea: Direct observation methods for management purposes ArchiMer
Brehmer, Patrice; Vercelli, Catherine; Gerlotto, Francois; Sanguinede, Fabien; Pichot, Yves; Guennegan, Yvon; Buestel, Dominique.
The exploitation of offshore mussel farms is becoming important throughout the world, but monitoring this activity remains a difficult task. Here, we propose a specific method for this purpose. A total of 140 long-lines were monitored on a mussel culture ground in the French Mediterranean Sea during four experimental surveys deploying multibeam sonar devices mounted on poles (Reson Seabat 6012, 455 kHz) on small boats. This allowed geo-referenced observations to be made of the submerged mussel long-lines, as well as three-dimensional (3D) drawings of the long-line structures and the sea bed shapes, using long-line longitudinal sonar sampling. Three sonar data-analysis methods were applied: (i) direct two-dimensional (2D) visual interpretation of raw sonar...
Tipo: Text Palavras-chave: Management; Sonar; Open sea; Long line; Mussel.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-1672.pdf
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New applications of hydroacoustic methods for monitoring shallow water aquatic ecosystems: the case of mussel culture grounds ArchiMer
Brehmer, Patrice; Gerlotto, François; Guillard, Joelle; Sanguinede, Fabien; Guennegan, Yvon; Buestel, Dominique.
The development of acoustics tools and methods for monitoring anthropized ecosystems represents a new field for the application of acoustics. Monitoring such an environment was not possible with single vertical echo sounders, due to the fact that the artificial structures and the natural targets were not distinguishable. Monitoring data were collected along the French Mediterranean coastline, during five short surveys of mussel culture longline areas. Both the Reson Seabat 6012 multibeam sonar (455 kHz) and the Simrad SR 240 omnidirectional sonar (23.75 kHz) were used for target detection. The former tools allow accurate allocation of the different types of echoes to artefacts, fish schools and scattered fish. The school characteristics collected included...
Tipo: Text Palavras-chave: Ecosystem; Artificial reef; Mussel longline; Fish school; Monitoring; Multibeam sonar.
Ano: 2003 URL: http://archimer.ifremer.fr/doc/2003/publication-574.pdf
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On the Dynamics of the Southern Senegal Upwelling Center: Observed Variability from Synoptic to Superinertial Scales ArchiMer
Capet, Xavier; Estrade, Philippe; Machu, Eric; Ndoye, Siny; Grelet, Jacques; Lazar, Alban; Marie, Louis; Dausse, Denis; Brehmer, Patrice.
Upwelling off southern Senegal and Gambia takes place over a wide shelf with a large area where depths are shallower than 20 m. This results in typical upwelling patterns that are distinct (e.g., more persistent in time and aligned alongshore) from those of other better known systems, including Oregon and Peru where inner shelves are comparatively narrow. Synoptic to superinertial variability of this upwelling center is captured through a 4-week intensive field campaign, representing the most comprehensive measurements of this region to date. The influence of mesoscale activity extends across the shelf break and far over the shelf where it impacts the midshelf upwelling (e.g., strength of the upwelling front and circulation), possibly in concert with wind...
Tipo: Text
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00374/48541/48842.pdf
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Resilience of Key Biological Parameters of the Senegalese Flat Sardinella to Overfishing and Climate Change ArchiMer
Ba, Kamarel; Thiaw, Modou; Lazar, Najih; Sarr, Alassane; Brochier, Timothee; Ndiaye, Ismaila; Faye, Alioune; Sadio, Oumar; Panfili, Jacques; Thiaw, Omar Thiom; Brehmer, Patrice.
The stock of the Senegalese flat sardinella, Sardinella maderensis, is highly exploited in Senegal, West Africa. Its growth and reproduction parameters are key biological indicators for improving fisheries management. This study reviewed these parameters using landing data from small-scale fisheries in Senegal and literature information dated back more than 25 years. Age was estimated using length-frequency data to calculate growth parameters and assess the growth performance index. With global climate change there has been an increase in the average sea surface temperature along the Senegalese coast but the length-weight parameters, sex ratio, size at first sexual maturity, period of reproduction and condition factor of S. maderensis have not changed...
Tipo: Text
Ano: 2016 URL: https://archimer.ifremer.fr/doc/00616/72851/72887.pdf
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Schooling behaviour of small pelagic fish: phenotypic expression of independent stimuli ArchiMer
Brehmer, Patrice; Gerlotto, François; Laurent, Charline; Cotel, Pascal; Achury, Alina; Samb, Birane.
We compared echo sounder measurements of fish schools on Venezuelan and Senegalese coastal shelves. In both areas Sardinella aurita was the predominant aggregative species; the stocks are known to be genetically independent. Persistent school typology is described by analysing 7 acoustic surveys in Venezuela and comparing with pioneer observations in Senegal. The echo types encountered in both countries were comparable, with S. aurita and their associated species having comparable schooling behaviour. School morphology appears to be more related to species than to global characteristics of their ecosystems, as fish school descriptors were similar for both stocks. Nevertheless, S. aurita may adopt different school morphologies. Differentiation between day...
Tipo: Text Palavras-chave: Small pelagic fish; Schooling; Phenotypic expression; In situ observations; Echo type; Diel cycle; Behaviour.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2536.pdf
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Spatial distribution of main clupeid species in relation to acoustic assessment surveys in the continental shelves of Senegal and The Gambia ArchiMer
Sarre, Abdoulaye; Krakstad, Jens-otto; Brehmer, Patrice; Mbye, Ebou Mass.
This work compiles hydroacoustic recordings and catch data over Senegambia (Senegal and The Gambia) from assessment surveys on the major clupeid species to identify sources of bias in abundance estimates caused by their horizontal distribution. The latitudinal distribution of small pelagic fish is often well known, while their "across shelf" distribution on the continental shelf is less understood. The southern part of the Senegambian shelf has a wide shallow water (< 10 m) area that makes up 20% (1500NM(2)) of the total shelf surface, while the northern part accounts for 3% (200NM(2)). These areas are not assessed by conventional fisheries acoustics surveys and therefore increase the uncertainty of the assessment of these species. Our findings show...
Tipo: Text Palavras-chave: Fish distribution; Ethmalosa fimbriata; Ilisha africana; Sardinella spp.; West Africa.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00426/53765/72090.pdf
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Spawning energetics and otolith microchemistry provide insights into the stock structure of bonga shad Ethmalosa fimbriata ArchiMer
Doering, Julian; Wagner, Carola; Tiedemann, Maik; Brehmer, Patrice; Ekau, Werner.
The gross energy content of spawning batches and the microchemistry of sagittal otoliths in individual female bonga shad Ethmalosa fimbriata were compared between contrasting sampling sites at the Senegalese southern coast and inside the hypersaline Sine Saloum Estuary. Results show that females spawning in the estuary's middle reaches invested almost three times more energy into reproduction (115 +/- 65 J g(-1) body mass) than their neritic counterparts (39 +/- 34 J g(-1) body mass). Also, female otolith levels of Ba:Ca, Sr:Ca and Zn:Ca either differed significantly between study sites or could be linked to heterogeneous environmental variables. A quadratic discriminant function analysis provided evidence of segregated spawning populations of E. fimbriata...
Tipo: Text Palavras-chave: Clupeidae; Inverse estuary; Oocyte; Reproductive investment; Senegal; Stock discrimination; Spawning components.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00484/59567/62545.pdf
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Studying the contribution of different fishing gears to the Sardinella small-scale fishery in Senegalese waters ArchiMer
Diankha, Ousmane; Demarcq, Herve; Fall, Massal; Thiao, Djiga; Thiaw, Modou; Sow, Bamol Ali; Gaye, Amadou Thierno; Brehmer, Patrice.
This study investigated variations of landings of two key species, Sardinella aurita and Sardinella maderensis, in Senegalese waters over a ten-year period (2004-2013). Using generalized additive models, it was found that fishing gear played a major role in explaining differences in monthly landings for both species (51-71% deviance explained). Its effect was more significant in the southern part of Senegal. Fishing effort (number of trips) accounted only for 4-18% of variability in landings. Purse seine (PS) fishing was the most important contributor to the landings of both species. In addition, in the southern area, surrounding gillnet fishing was also important for S. maderensis. Modeling results showed that the relationship between monthly effort and...
Tipo: Text Palavras-chave: Effects of fishing; Generalized additive model; Sardinella aurita; Sardinella maderensis; Purse seine; Surrounding gillnet; Senegal.
Ano: 2017 URL: https://archimer.ifremer.fr/doc/00616/72808/72585.pdf
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