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Auteur DRUON, J.-N.; FROMENTIN, J.-M.; AULANIER, F.; HEIKKONEN, J.
Titre Potential feeding and spawning habitats of Atlantic bluefin tuna in the Mediterranean Sea Type Article scientifique
Année 2011 Publication Marine Ecology-progress Series Revue Abrégée
Volume 439 Numéro Pages 223-240
Mots-Clés Habitat mapping; Bluefin tuna; Thunnus thynnus; Feeding; Spawning; Mediterranean Sea; Remote sensing; Satellite data
Résumé Atlantic bluefin tuna Thunnus thynnus (ABFT) is a fish of high market value which has recently become strongly overexploited, notably in the Mediterranean Sea. This area is an essential habitat for ABFT reproduction and growth. We present here an approach for deriving the daily mapping of potential ABFT feeding and spawning habitats based on satellite-derived sea surface temperature (SST) and chl a concentration. The feeding habitat was mainly derived from the simultaneous occurrence of oceanic fronts of temperature and chl a content while the spawning habitat was mostly inferred from the heating of surface waters. Generally, higher chl a contents were found to be preferred for the feeding habitat and a minimum SST value was found for the spawning habitat. Both habitats were defined by the presence of relevant oceanographic features and are therefore potential and functionally-linked habitats. This approach provides, for the first time, a synoptic view of the potential ABFT habitats in the Mediterranean Sea. The model performs well in areas where both satellite data and ABFT observations are available, as 80% of presence data are in the vicinity of potential habitats. The computed monthly, seasonal and annual maps of potential feeding and spawning habitat of ABFT from 2003 to 2009 are in good agreement with current knowledge on ABFT. Overall, the habitat size of ABFT is about 6% of the Mediterranean Sea surface. The results displayed a strong seasonality in habitat size and locations as well as high year-to-year variations (30 to 60%), particularly for the potential spawning habitat, which is key information for evaluating the utility of ABFT Marine Protected Areas in the Mediterranean Sea.
Adresse IFREMER, Ctr Rech Halieut Mediterraneen & Trop, F-34203 Sete, France.
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Editeur Inter-research Lieu de Publication Éditeur
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Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0171-8630 ISBN Médium
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Auteur Fertouna-Bellakhal, M.; Dhib, A.; Fathalli, A.; Bellakhal, M.; Chomérat, N.; Masseret, E.; Laabir, M.; Turki, S.; Aleya, L.
Titre Alexandrium pacificum Litaker sp. nov (Group IV): Resting cyst distribution and toxin profile of vegetative cells in Bizerte Lagoon (Tunisia, Southern Mediterranean Sea) Type Article scientifique
Année 2015 Publication Revue Abrégée Harmful Algae
Volume 48 Numéro Pages 69-82
Mots-Clés Alexandrium pacificum Litaker sp. nov (Alexandrium catenella-group IV (Whedon & Kofoid), Balech); cysts; Mapping; Ribotype; Toxin profile; Vegetative cells
Résumé Abstract

A high spatial resolution sampling of Alexandrium pacificum cysts, along with sediment characteristics (% H2O, % organic matter (OM), granulometry), vegetative cell abundance and environmental factors were investigated at 123 study stations in Bizerte Lagoon (Tunisia). Morphological examination and ribotyping of cells obtained from a culture called ABZ1 obtained from a cyst isolated in lagoon sediment confirmed that the species was A. pacificum. The toxin profile from the ABZ1 culture harvested during exponential growth phase was simple and composed of the N-sulfocarbamoyl toxins C1 (9.82 pg toxin cell−1), the GTX6 (3.26 pg toxin cell−1) and the carbamoyl toxin Neo-STX (0.38 pg toxin cell−1). The latter represented only 2.8% of the total toxins in this strain. High abundance of A. pacificum cysts correlated with enhanced percentages of water and organic matter in the sediment. In addition, sediment fractions of less than 63 μm were examined as a favorable potential seedbed for initiation of future blooms and outbreaks of A. pacificum in the lagoon. A significant difference in the cyst distribution pattern was recorded among the lagoon's different zones, with the higher cyst abundance occurring in the inner waters. Also, no correlation due to the specific hydrodynamics of the lagoon was observed in the spatial distribution of A. pacificum cysts and vegetative cells.
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ISSN 1568-9883 ISBN Médium
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Auteur Genovesi, B.; Mouillot, D.; Laugier, T.; Fiandrino, A.; Laabir, M.; Vaquer, A.; Grzebyk, D.
Titre Influences of sedimentation and hydrodynamics on the spatial distribution of Alexandrium catenella/tamarense resting cysts in a shellfish farming lagoon impacted by toxic blooms Type Article scientifique
Année 2013 Publication Revue Abrégée Harmful Algae
Volume 25 Numéro Pages 15-25
Mots-Clés Alexandrium; Hydrodynamics; Mapping; Resting cyst; Sediment; Spatial correlation; Thau Lagoon (Mediterranean Sea)
Résumé
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Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 1568-9883 ISBN Médium
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Auteur Marre, G.; Deter, J.; Holon, F.; Boissery, P.; Luque, S.
Titre Fine-scale automatic mapping of living Posidonia oceanica seagrass beds with underwater photogrammetry Type Article scientifique
Année 2020 Publication Revue Abrégée Marine Ecology Progress Series
Volume 643 Numéro Pages 63-74
Mots-Clés Benthic habitat mapping; Monitoring; Posidonia oceanica; Reconstruction uncertainty; Submerged aquatic vegetation; Underwater photogrammetry
Résumé The Mediterranean seagrass Posidonia oceanica, which provides highly valuable ecosystem services, is subject to increasing anthropogenic pressures, causing habitat loss or fragmentation. Whilst airborne images and acoustic data can be used for monitoring seagrass coverage at a macro-scale and over long time periods, monitoring its health in the short term requires precision mapping in order to assess current regression/progression of individual meadows. However, current fine-scale underwater techniques in the field are imprecise and time-demanding. We propose an automatic classification approach based on underwater photogrammetry for an operational, cost- and time-effective fine-scale monitoring method. The method uses a property of the sparse cloud generated during bundle adjustment—the reconstruction uncertainty—to map seagrass patches. The mean precision, recall and F1 score of the method over 21 study sites with different morphologies were 0.79, 0.91 and 0.84, respectively. However, the fragmentation level of the meadows had a significant negative effect on classification performances. The temporal monitoring of 3 sites using this method proved its operability and showed a positive evolution index of the corresponding meadows over a period of 3 yr. This method is generalizable for most encountered configurations and can be integrated in a large monitoring system, as it enables the production of numerous seagrass maps over a short period of time. Moreover, our methodology could be generalized and applied in the study of other submerged aquatic vegetation by adjusting the method’s parameters.
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ISSN 0171-8630, 1616-1599 ISBN Médium
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Auteur Triki, H.Z.; Daly-Yahia, O.K.; Malouche, D.; Komiha, Y.; Deidun, A.; Brahim, M.; Laabir, M.
Titre Distribution of resting cysts of the potentially toxic dinoflagellate Alexandrium pseudogonyaulax in recently-deposited sediment within Bizerte Lagoon (Mediterranean coast, Tunisia) Type Article scientifique
Année 2014 Publication Revue Abrégée Marine Pollution Bulletin
Volume 84 Numéro 1-2 Pages 172-181
Mots-Clés Alexandrium pseudogonyaulax; autocorrelation; bay; Benthic; blooms; cysts; dynamics; eutrophication; gonyaulax-excavata; gulf; Harmful algae; Mapping; Mediterranean Lagoon of Bizerte; resting cysts; Sediment characteristics; spatial-distribution; surface sediments
Résumé This study investigated the spatial distribution of Alexandrium pseudogonyaulax resting cysts in recently-deposited sediment of Bizerte lagoon (South-Western Mediterranean, Tunisia). This lagoon is the subject of many anthropogenic impacts, such as holding important fishing and aquaculture activities. A. pseudogonyaulax has been shown to produce Goniodomin A, which is a biologically-active compound. We showed that this dinoflagellate produces two types of resting cysts, which could be distinguished by the presence or the absence of a paratabulate wall. The average cyst density across the whole lagoon was rather high, reaching 639 cysts g(-1) of dry sediment (DS). Cyst densities varied widely among the sampled stations, with the highest density of 1685 cyst g(-1) DS being recorded at station 51 near a mussel farm. With respect to sediment characteristics, the highest cyst densities were found within silty sediments with high water content values. The distribution of A. pseudongoyaulax cysts in Bizerte lagoon appears to be related to hydrodynamic factors. (C) 2014 Elsevier Ltd. All rights reserved.
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Langue English Langue du Résumé Titre Original
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ISSN 0025-326x ISBN Médium
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Notes <p>ISI Document Delivery No.: AL0GF<br/>Times Cited: 0<br/>Cited Reference Count: 45<br/>Triki, Habiba Zmerli Daly-Yahia, Ons Kefi Malouche, Dhafer Komiha, Yosr Deidun, Alan Brahim, Mouldi Iaabir, Mohamed<br/>JEAI ECO-BIZ (Jeune Equipe Associee, Ecologie de la lagune de Bizerte) program – IRD (Institut Francais pour la Recherche et le Developpement), IRD; TOTAL Foundation<br/>This work benefitted from financial supports from the JEAI ECO-BIZ (Jeune Equipe Associee, Ecologie de la lagune de Bizerte) program funded by IRD (Institut Francais pour la Recherche et le Developpement), IRD also funded 2 months stay of Dr. Mohamed Laabir in Tunis (INAT). Thanks to TOTAL Foundation for funding LAGUNOTOX project which supported financially the stay of Mrs Triki-Zmerli in Montpellier.<br/>Pergamon-elsevier science ltd<br/>Oxford</p> Approuvé pas de
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